Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[andy pugh]

On Sun, 11 Dec 2022 at 17:41, John Dammeyer  wrote:

Thanks for the photos.  Novel concept.


Not entirely, I think that RotarySMPs Schaublin has magnets buried in the
bed to be detected by hall sensors. (though magnets do have obvious
problems with swarf)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912

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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[John Dammeyer]

> From: andy pugh [mailto:bodge...@gmail.com]
> 
> On Thu, 8 Dec 2022 at 20:36, John Dammeyer  wrote:
> 
> The X axis is interesting in how it's set up.  The switches appear to be in
> > series with the NO switch on the X all the way out point and the NC switch
> > at the X all the way in point.  The rod moves and opens the circuit at
> > either end.  Very clever.
> >
> 
> That setup is quite clever, and seems to be predicated on being able to
> adjust the stops.
> It is, however, not very well protected and not very aesthetic.

 
Yes. They are covered.  The photos are with the covers removed.


> For protection from swarf I have taken to embedding my sensors in the
> machine. Here is the limit switch for the X axis of my lathe:
> https://photos.app.goo.gl/heHHn4rEm42nge259
> For the purpose of the photo the ball nut carrier linking screw has been
> removed and the  carriage has been pushed forwards.
> The targets are two shallow holes machined into the underside of the
> cross-slide.
> This is the Z-axis target, another shallow hole, in this case plugged with
> delrin to stop it filling with chips.
> https://photos.app.goo.gl/CcjZELb8uRwehPX36
> (I know it looks like aluminium in the photo, because at that point it was,
> but aluminium didn't work, as despite being non-inductive, it is conductive
> enough to couple into the machine frame)
> 
> --

Thanks for the photos.  Novel concept.
John



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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[andy pugh]

On Thu, 8 Dec 2022 at 20:36, John Dammeyer  wrote:

The X axis is interesting in how it's set up.  The switches appear to be in
> series with the NO switch on the X all the way out point and the NC switch
> at the X all the way in point.  The rod moves and opens the circuit at
> either end.  Very clever.
>

That setup is quite clever, and seems to be predicated on being able to
adjust the stops.
It is, however, not very well protected and not very aesthetic.

For protection from swarf I have taken to embedding my sensors in the
machine. Here is the limit switch for the X axis of my lathe:
https://photos.app.goo.gl/heHHn4rEm42nge259
For the purpose of the photo the ball nut carrier linking screw has been
removed and the  carriage has been pushed forwards.
The targets are two shallow holes machined into the underside of the
cross-slide.
This is the Z-axis target, another shallow hole, in this case plugged with
delrin to stop it filling with chips.
https://photos.app.goo.gl/CcjZELb8uRwehPX36
(I know it looks like aluminium in the photo, because at that point it was,
but aluminium didn't work, as despite being non-inductive, it is conductive
enough to couple into the machine frame)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912

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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[John Dammeyer]

Hi Leonardo,

> 
> Just to clarify because sometimes it confuses me too. And please someone
> correct me if I'm wrong:
> 
> Positive and negative soft limits are always with respect to the 0 home
> position. No matter where the home switch is located or if that 0 position
> is aligned with the switch. In fact, your 0 position could be
> (theoretically) anywhere in your joint's travel as long as you're inside
> your hard limits of course (I didn't experiment with sharing both home and
> limit switches so I don't know the behaviour with that setup) the only
> thing changing will be the min and max limit that will allow you to
> establish the safe distance before hitting the hard limits.
> 

That's the way I understand it too.  The Home switch position (if not required 
in the INI/HAL files) becomes whatever the position is.  Theoretically I guess 
on start-up the G53 locations are initialized to 0.  However if the carriage is 
way over to the left rather than the center a soft limit of -10" would run into 
the chuck if there's only 1" of movement left.

I know on the mill when the G-Code is loaded I'm often told that the movements 
will exceed my machine dimensions.  But that's because I've set a physical home 
switch and my work envelope is configured in the [JOINT] sections of the INI 
file.
MIN_LIMIT = -0.04
MAX_LIMIT = 13.5
Now if I've set G54.x == 0 at machine world coordinate 2.0" I'm within MIN and 
MAX LIMITs.  But if the G-Code I load wants to do a X-3.5 it won't let me.  The 
fault is move will exceed limit.
So then if I move the X axis over by 2" so in G53 it's now at 4.0" and reset 
the G54.x = 0 with the Touch Off button, now the G-Code will work.  And in AXIS 
the trace  of the tool motion is now inside that red line 3D envelope.

Attached is a low res photo of limit switches set up on a Harrison lathe.  The 
Z axis are U shaped pieces holding the switch with a thumb screw to tighten 
into place.  Needless to say the smart thing to do is to set the switch 
locations so the carriage can't run into either the chuck on the left or the 
tailstock on the right.

The X axis is interesting in how it's set up.  The switches appear to be in 
series with the NO switch on the X all the way out point and the NC switch at 
the X all the way in point.  The rod moves and opens the circuit at either end. 
 Very clever.

John

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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[Leonardo Marsaglia]

>
> The G54 causes the DRO actual machine positions to be offset from the G53
> machine world coordinates.  So do the soft limits use the part coordinate
> system(G54)  or the world coordinate system (G53)?  I think G53.
>

Exactly, soft limits are based upon your origin of coordinates on the G53
coordinate system. So, no matter what you do in G54 or G5n the TP will
guarantee that soft limits aren't exceeded.

@Leonardo.  What you've done isn't really much different other than perhaps
> I'm sharing a limit switch with the home switch.  In your case if your
> limit switch is mid bed somewhere (for Z) then that becomes G53.z ==
> 0..  And you're right.  It doesn't matter because I'm pretty sure the
> soft limits are referenced from that G53.z == position and the G54 is
> referenced from wherever you do the Touch Off sequence using the G53 values
> to make the DRO POS.xyz == 0..
>

Just to clarify because sometimes it confuses me too. And please someone
correct me if I'm wrong:

Positive and negative soft limits are always with respect to the 0 home
position. No matter where the home switch is located or if that 0 position
is aligned with the switch. In fact, your 0 position could be
(theoretically) anywhere in your joint's travel as long as you're inside
your hard limits of course (I didn't experiment with sharing both home and
limit switches so I don't know the behaviour with that setup) the only
thing changing will be the min and max limit that will allow you to
establish the safe distance before hitting the hard limits.

El jue, 8 dic 2022 a las 15:09, John Dammeyer ()
escribió:

> Thanks for the feedback.
>
> Here are the other two screen shots.  One showing how the G54 is now
> applied to the tool position after the touch off so that now the POSition
> accurately reflects the work coordinate system.  The other shows that I
> want to move in from 0.500" to 0.475" to do a 0.025" pass.  This would
> change the diameter to 0.950".
>
> Haven't looked into how G7 diameter mode is handled yet.
>
> My only experience with LinuxCNC at the moment is on the mill and since I
> didn't want to run into mechanical end stops at full tilt I enabled limit
> and home switches.  So even though it's not easy to see the world
> coordinates of the machine a G0 G53 X0 does take my mill to the point 0.1"
> from the limit/home switch.
>
> And it's true that once I've done the homing (my LCNC won't do programmed
> moves without it) I never look at the G54..Gnn values anymore.  Don't even
> use G92.  I suspect most of those are targeted more at production
> environments.
>
> However to understand the G54 part workspace coordinates I believe one has
> to get a feel of what's happening under the covers.  For example, show the
> second DRO screen in AXIS, and it's clear the G54 values never change when
> the machine is moving around.
>
> The G54 causes the DRO actual machine positions to be offset from the G53
> machine world coordinates.  So do the soft limits use the part coordinate
> system(G54)  or the world coordinate system (G53)?  I think G53.
>
> @Leonardo.  What you've done isn't really much different other than
> perhaps I'm sharing a limit switch with the home switch.  In your case if
> your limit switch is mid bed somewhere (for Z) then that becomes G53.z ==
> 0..  And you're right.  It doesn't matter because I'm pretty sure the
> soft limits are referenced from that G53.z == position and the G54 is
> referenced from wherever you do the Touch Off sequence using the G53 values
> to make the DRO POS.xyz == 0..
>
> @Andy -- Yes.  Your approach for Z as the end of the work for every job is
> how I designed my ELS too.There the keypad has a BEGIN/END button and
> generally Z is set to 0.000 after the end of the part is faced off.  The
> BEGIN is slightly to the right of that for ramping up to speed and the END
> is either travelled to and set or keyed in from the keypad.  So turning
> 2.000" might have BEGIN = 0.200" and END will have -2.000".
>
> Therefore, Touch Off at the face and then using G0 Z0.2, and G1 Z-2.0 is
> essentially the same.  (Non synchronized to spindle in this case of course).
>
> It's the tool table that ultimately has me interested.  You can't change
> to a different tool and then face off again to find that elusive G54.x ==
> 0.  Although I guess one could use a feeler gauge or thin paper to sneak up
> to the work to touch it and then enter the new, now measured, offset into
> Tool Touch Off or even just into Touch Off.
>
> Sometime today or tomorrow I'll add tool table support to the program and
> post some more pictures.
>
> John
>
>
> > -Original Message-
> > From: John Dammeyer [mailto:jo...@au

Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[John Dammeyer]

Thanks for the feedback.

Here are the other two screen shots.  One showing how the G54 is now applied to 
the tool position after the touch off so that now the POSition accurately 
reflects the work coordinate system.  The other shows that I want to move in 
from 0.500" to 0.475" to do a 0.025" pass.  This would change the diameter to 
0.950".

Haven't looked into how G7 diameter mode is handled yet.

My only experience with LinuxCNC at the moment is on the mill and since I 
didn't want to run into mechanical end stops at full tilt I enabled limit and 
home switches.  So even though it's not easy to see the world coordinates of 
the machine a G0 G53 X0 does take my mill to the point 0.1" from the limit/home 
switch.

And it's true that once I've done the homing (my LCNC won't do programmed moves 
without it) I never look at the G54..Gnn values anymore.  Don't even use G92.  
I suspect most of those are targeted more at production environments.

However to understand the G54 part workspace coordinates I believe one has to 
get a feel of what's happening under the covers.  For example, show the second 
DRO screen in AXIS, and it's clear the G54 values never change when the machine 
is moving around. 

The G54 causes the DRO actual machine positions to be offset from the G53 
machine world coordinates.  So do the soft limits use the part coordinate 
system(G54)  or the world coordinate system (G53)?  I think G53.

@Leonardo.  What you've done isn't really much different other than perhaps I'm 
sharing a limit switch with the home switch.  In your case if your limit switch 
is mid bed somewhere (for Z) then that becomes G53.z == 0..  And you're 
right.  It doesn't matter because I'm pretty sure the soft limits are 
referenced from that G53.z == position and the G54 is referenced from wherever 
you do the Touch Off sequence using the G53 values to make the DRO POS.xyz == 
0..

@Andy -- Yes.  Your approach for Z as the end of the work for every job is how 
I designed my ELS too.There the keypad has a BEGIN/END button and generally 
Z is set to 0.000 after the end of the part is faced off.  The BEGIN is 
slightly to the right of that for ramping up to speed and the END is either 
travelled to and set or keyed in from the keypad.  So turning 2.000" might have 
BEGIN = 0.200" and END will have -2.000".

Therefore, Touch Off at the face and then using G0 Z0.2, and G1 Z-2.0 is 
essentially the same.  (Non synchronized to spindle in this case of course).

It's the tool table that ultimately has me interested.  You can't change to a 
different tool and then face off again to find that elusive G54.x == 0.  
Although I guess one could use a feeler gauge or thin paper to sneak up to the 
work to touch it and then enter the new, now measured, offset into Tool Touch 
Off or even just into Touch Off.

Sometime today or tomorrow I'll add tool table support to the program and post 
some more pictures.  

John


> -Original Message-
> From: John Dammeyer [mailto:jo...@autoartisans.com]
> Sent: December-07-22 11:32 PM
> To: 'Enhanced Machine Controller (EMC)'
> Subject: Re: [Emc-users] Home switches for LinuxCNC on a Lathe
> 
> I've done a bit more work on this.  I've made an assumption that the  home 
> switch is about 5" from the
> theoretical lathe centerline with a specific tool inserted in a fixed holder.
> 
> I home the cross slide setting 0.000 into the world coordinates G53 location. 
>  Then move it -4.0" inwards
> which puts it conveniently at exactly 0.5" from the real lathe center line.
> 
> Now we want the DRO to read 0.5" at this point, not -4.000.  So this is where 
> the G54 comes in and the AXIS
> Touch Off Tool dialog.  In that dialog we'd enter 0.5" which then ends up 
> putting a value into the G54 offsets
> locations which then is combined with the G53 to fill in the DRO position 
> fields to show the position relative to
> this new 'home' position.
> 
> Since I had trouble getting my head around this I wrote a small program to 
> simulate some of the AXIS
> interface.  I haven't done the tool table stuff yet.  I want to get this 
> clarified first.
> 
> What I'm not sure about is whether I'm doing the math (and the sign of the 
> value or even the value) correctly
> in the G54 locations.
> 
> I've attached some screen shots.   These shots show the initial move, the 
> touch and then the change to G54.
> It appears to work.
> 
> John
> 
> 

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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[andy pugh]

On Thu, 8 Dec 2022 at 07:37, John Dammeyer  wrote:

> I've done a bit more work on this.  I've made an assumption that the  home
> switch is about 5" from the theoretical lathe centerline with a specific
> tool inserted in a fixed holder.
>

 I don't think that you need to worry about the machine coordinate location
of the home switches.

On my lathe I have designated T1 (WNMG turning / facing tool) as the
"Master" tool. This tool always has X=0 Y=0 in the tool table.
I then touch-off the work with this tool (generally making a test cut and
measuring the result for diameter). This touch-off goes into G54 (or
whatever, though I very rarely use the others)
The, all the other tool offsets in the tool table are relative to that
tool. (and may be tweaked based on test-cuts)

The G54 X should hardly ever change,  but the G54 Z is re-set for every job
to be the right-hand end of the work.

If you had a toolpost-mounted probe then that could be the master tool.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912

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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[Leonardo Marsaglia]

It looks ok to me. But my recommendation is to forget about the distance
between the home switch and the centerline.

For example when I retrofitted the Mazak, I wired all the limits and home
switches and when I was sure the hard limits worked I started playing
around with the homing setup.

Basically I relied on trial and error with the soft limits on the INI until
the machine didn't hit the hard limits while jogging. So I set home
position at the switch to be 0 (although that's not necessary, you can make
that value whatever fits your needs) and from that position I carefully jog
until I detect both positive and negative hard limits. Then I input that on
the INI with some room to avoid overshooting and hitting the hard limits.

The only difference is that your lathe is parallel so your turret feeds in
the opposite way than mine towards the center, but that's not a problem
since you already have that set with your motor's scale sign. So when you
are in G54 and set your diameter or radius (I always work in diameter so I
have G7 as one of my startup codes) you should see how your diameter
decreases as you feed towards the spindle. By the way I'm reassuring this
because reading your post got me thinking about how LCNC knows what's my
turret's orientation.

Hope what I wrote makes sense John.

Take care.





El jue., 8 de diciembre de 2022 04:37, John Dammeyer 
escribió:

> I've done a bit more work on this.  I've made an assumption that the  home
> switch is about 5" from the theoretical lathe centerline with a specific
> tool inserted in a fixed holder.
>
> I home the cross slide setting 0.000 into the world coordinates G53
> location.  Then move it -4.0" inwards which puts it conveniently at exactly
> 0.5" from the real lathe center line.
>
> Now we want the DRO to read 0.5" at this point, not -4.000.  So this is
> where the G54 comes in and the AXIS Touch Off Tool dialog.  In that dialog
> we'd enter 0.5" which then ends up putting a value into the G54 offsets
> locations which then is combined with the G53 to fill in the DRO position
> fields to show the position relative to this new 'home' position.
>
> Since I had trouble getting my head around this I wrote a small program to
> simulate some of the AXIS interface.  I haven't done the tool table stuff
> yet.  I want to get this clarified first.
>
> What I'm not sure about is whether I'm doing the math (and the sign of the
> value or even the value) correctly in the G54 locations.
>
> I've attached some screen shots.   These shots show the initial move, the
> touch and then the change to G54.  It appears to work.
>
> John
>
>
>
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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[John Dammeyer]

I've done a bit more work on this.  I've made an assumption that the  home 
switch is about 5" from the theoretical lathe centerline with a specific tool 
inserted in a fixed holder.

I home the cross slide setting 0.000 into the world coordinates G53 location.  
Then move it -4.0" inwards which puts it conveniently at exactly 0.5" from the 
real lathe center line.

Now we want the DRO to read 0.5" at this point, not -4.000.  So this is where 
the G54 comes in and the AXIS Touch Off Tool dialog.  In that dialog we'd enter 
0.5" which then ends up putting a value into the G54 offsets locations which 
then is combined with the G53 to fill in the DRO position fields to show the 
position relative to this new 'home' position.

Since I had trouble getting my head around this I wrote a small program to 
simulate some of the AXIS interface.  I haven't done the tool table stuff yet.  
I want to get this clarified first.

What I'm not sure about is whether I'm doing the math (and the sign of the 
value or even the value) correctly in the G54 locations.

I've attached some screen shots.   These shots show the initial move, the touch 
and then the change to G54.  It appears to work.

John



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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[dave engvall]

I did something similar on a BP sized mill. Manually move x and y to 
roughly center the beam of a laser diode in a 3 mm hole in a tab at one 
end of the mill. Kick off homing for x and y and it will pick up the 
first index on each axis. You can then move from there to where your 
preferred zero is. I think one can do something similar with glass 
scales but they tend to have several (3) guard lines each side of the R.


Dave

On 12/4/22 5:25 AM, Stuart Stevenson wrote:

You might try the FADAL mill method.

They use two arrows (markers). One on the moving member and one on the
unmoving member. You physically align the arrows and run the home routine.
The next found index mark on the encoder is the home position.

regards
Stuart


On Sun, Dec 4, 2022 at 1:25 AM gene heskett  wrote:


On 12/3/22 22:56, John Dammeyer wrote:

  From what I understand you're talking about a normal parallel lathe so

here

are my thoughts:

Yes.  And thank you.

The Z axis is more interesting.  Before homing I imagine the tail stock
has to be loosened and moved all the way to the right as far away from

the

headstock to ensure finding a home switch.  Or a home switch could be
somewhere in the middle but then which direction to search?


I think the safest setup  in this case (given your Z axis can crash with
the tailstock if you forget to move it all the way to the right) will be
having the home switch towards the chuck side (with a proper
independent limit switch right at the left of the home switch to avoid
crashes when homing). This way you can set up your homing sequence to

first

home the X axis to move it to a safe place and then home the Z axis

towards

the chuck.

I'm guessing you are suggesting something like what Gene was that the

home switch isn't at the end of travel but somewhere else and once
activated never goes inactive in that same direction.   So if you start a
home sequence and the switch is ON you know you have to go to the right
until it goes OFF.  It can't over travel past the OFF position and go ON
again.  That approach lets the Home Switch be pretty well anywhere.

Unless the limit switch is movable it's useless.  My carriage can go

much further to the left to turn near the part held in the 5C collet than
it can with the part held in the 3-Jaw.  So a crash into the spinning 3-Jaw
can happen without ever touching the limit.  And if the limit does prevent
that one can't turn a part close to the collet.

How does one determine, with that tool tip, where the lathe centerline

is

and set that so G54 X is 0.000?


I think you're asking about tool setting. If you have tool fixtures that
ensure that whenever you change your tool you get the exact same tool
position then it's just like a CNC turret. You just take a skim cut on

the

diameter (or maybe use some fine paper to gauge the tool against the
workpiece) and then measure and input the diameter (or radius depending

if

you're in G7 or G8) in the touch off popup.


Thanks.  I'm going to have to study that a bit further.
I understand that the machine coordinate for x at the home switch is

0.000.

And measuring the tool tip relative to how it mounts into the AXA holder

can be done creating an offset from the home switch.v  Now each time the
tool holder +tool  is put into the AXA the distance from the tool table is
offset from that home position and LCNC knows where the tip and can turn a
diameter.  Theoretically.

However as  soon as the holder is pivoted even slightly the distance of

the tool tip relative to the home switch changes.   And it changes
differently depending on how far the tool protrudes out of the AXA holder
right?

So the tool measurements are only useful with the AXA in one position

and that can change really easily in the home shop.  We're not talking a
commercial production operation where the setup is the same over a long
period of time.

I suppose if you can touch of or measure the new position of the tool

tip you can then use simple trig to determine the angle that the AXA holder
has pivoted.  Unless it also slid in the T-Slot which now moves it in more
than one dimension.

Doe my explanation make sense?  A small shop lathe where the operator

can shift the tool bit around relative to the X home switch and even on the
carriage relative to the Z home switch suggest a tool table for a LCNC
lathe is virtually impossible.

So I can manually turn that shaft.  Leave the X axis where it is and

measure the diameter; say exactly 1.000".   Then click on the "Touch Off"
on the display and enter half the diameter (0.5") for the offset.

Now a request to move the X to 0.480" to do a 0.020" deep pass should

work right?

But the tool table and for that matter the home switch and machine

coordinate system is pretty well useless.  Or have I missed something?

John



Don't adjust your antenna, you got it, John, the reception is perfect.
The main reason for a home sw is the let the machine know where its at
in the absolute sense, I've 

Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[Leonardo Marsaglia]

>
> +100, I have plumbing running across the bed on the right edge of the
> carriage, feeding all the stuff on the apron, and I've crushed it
> against the tailstock base several times. One of the additional bits of
> gingerbread I need to get done.


Done that to oil cans :)

El dom, 4 dic 2022 a las 18:30, gene heskett ()
escribió:

> On 12/4/22 15:43, John Dammeyer wrote:
> >> From: andy pugh [mailto:bodge...@gmail.com]
> >> On Sun, 4 Dec 2022 at 00:32, John Dammeyer 
> wrote:
> >>
> >>>
> >>> The Z axis is more interesting.  Before homing I imagine the tail stock
> >>> has to be loosened and moved all the way to the right as far away from
> the
> >>> headstock to ensure finding a home switch.
> >>>
> >>
> >> My lathe uses a position.txt file hack and single-turn absolute
> resolvers
> >> to avoid needing to home (generally)
> >> But when it needs to home the home sensor is with the saddle all the
> way to
> >> the right.
> >> If I was doing it again I would have put a "tailstock sensor" in the
> saddle
> >> as an extra limit switch.
> >>
> >> --
> >> atp
> >
> > That's a really good idea.  One that isn't over ridden with search for
> home.   Just that extra bit of safety.
>
>
> +100, I have plumbing running across the bed on the right edge of the
> carriage, feeding all the stuff on the apron, and I've crushed it
> against the tailstock base several times. One of the additional bits of
> gingerbread I need to get done.
>
> Cheers, Gene Heskett.
> --
> "There are four boxes to be used in defense of liberty:
>   soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author, 1940)
> If we desire respect for the law, we must first make the law respectable.
>   - Louis D. Brandeis
> Genes Web page 
>
>
>
> ___
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> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>

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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[gene heskett]

On 12/4/22 15:43, John Dammeyer wrote:

From: andy pugh [mailto:bodge...@gmail.com]
On Sun, 4 Dec 2022 at 00:32, John Dammeyer  wrote:



The Z axis is more interesting.  Before homing I imagine the tail stock
has to be loosened and moved all the way to the right as far away from the
headstock to ensure finding a home switch.



My lathe uses a position.txt file hack and single-turn absolute resolvers
to avoid needing to home (generally)
But when it needs to home the home sensor is with the saddle all the way to
the right.
If I was doing it again I would have put a "tailstock sensor" in the saddle
as an extra limit switch.

--
atp


That's a really good idea.  One that isn't over ridden with search for home.   
Just that extra bit of safety.



+100, I have plumbing running across the bed on the right edge of the 
carriage, feeding all the stuff on the apron, and I've crushed it 
against the tailstock base several times. One of the additional bits of 
gingerbread I need to get done.


Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 



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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[John Dammeyer]

> From: andy pugh [mailto:bodge...@gmail.com]
> On Sun, 4 Dec 2022 at 00:32, John Dammeyer  wrote:
> 
> >
> > The Z axis is more interesting.  Before homing I imagine the tail stock
> > has to be loosened and moved all the way to the right as far away from the
> > headstock to ensure finding a home switch.
> >
> 
> My lathe uses a position.txt file hack and single-turn absolute resolvers
> to avoid needing to home (generally)
> But when it needs to home the home sensor is with the saddle all the way to
> the right.
> If I was doing it again I would have put a "tailstock sensor" in the saddle
> as an extra limit switch.
> 
> --
> atp

That's a really good idea.  One that isn't over ridden with search for home.   
Just that extra bit of safety.



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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[andy pugh]

On Sun, 4 Dec 2022 at 00:32, John Dammeyer  wrote:

>
> The Z axis is more interesting.  Before homing I imagine the tail stock
> has to be loosened and moved all the way to the right as far away from the
> headstock to ensure finding a home switch.
>

My lathe uses a position.txt file hack and single-turn absolute resolvers
to avoid needing to home (generally)
But when it needs to home the home sensor is with the saddle all the way to
the right.
If I was doing it again I would have put a "tailstock sensor" in the saddle
as an extra limit switch.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912

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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[John Dammeyer]

Thanks everyone.  Last night I spent a while watching youtube videos.  There 
were a few Tormach ones that clarified things even if they did leave out the 
occasional detail.  I can see that for a CNC converted manual lathe removing 
the compound slide is pretty well a must do.  Both for stability and 
repeatability.

I then spent at least another hour watching more videos on tool setters and 
probes for the mill.   Really need to wire up the tool setter so I can try the 
tool setter with the M6 checkbox checked in the Vers.by probe screen.

John
> -Original Message-
> From: Leonardo Marsaglia [mailto:ldmarsag...@gmail.com]
> Sent: December-04-22 8:32 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Home switches for LinuxCNC on a Lathe
> 
> >
> > I'm guessing you are suggesting something like what Gene was that the home
> > switch isn't at the end of travel but somewhere else and once activated
> > never goes inactive in that same direction.   So if you start a home
> > sequence and the switch is ON you know you have to go to the right until it
> > goes OFF.  It can't over travel past the OFF position and go ON again.
> > That approach lets the Home Switch be pretty well anywhere.
> >
> 
> Not exactly Gene's setup, although that is a good idea too if you want to
> have your home switch somewhere in the middle of your carriage travel. What
> I thought is something like what I've seen on the CNC lathes we have in the
> shop. You have the home switch right next to your limit switch. Also you
> have to set your soft limits so your travel ends right before hitting the
> hard limits. That way, you're always sure when you turn off your machine
> you'll always be at the right side of the home switch. Of course this eats
> some travel out of your Z axis but that's the price to pay for safety. The
> obvious difference here is that on slanted bed CNC lathes you don't have to
> worry about your carriage hitting the tailstock because they rest in
> different ways (although tools can hit the tailstock that's why X axis is
> always homed and cleared before Z).
> 
> Unless the limit switch is movable it's useless.  My carriage can go much
> > further to the left to turn near the part held in the 5C collet than it can
> > with the part held in the 3-Jaw.  So a crash into the spinning 3-Jaw can
> > happen without ever touching the limit.  And if the limit does prevent that
> > one can't turn a part close to the collet.
> >
> 
> That's why having a proper home sequence is the key to avoid hitting the
> chuck with the tool. You'll have to set the homing for the X axis first and
> send it to a safe location so the Z homing can happen without crashing. Of
> course this is assuming you can guarantee enough clearance for any tool
> installed on your toolpost when doing the X axis homing. If your chuck is
> too large, or you have a tool sticking too far out of your tool post that
> even retracting the X axis to the fullest you can hit your 3 jaw chuck then
> please forget about homing to the chuck side and consider Gene's method.
> 
> 
> > I understand that the machine coordinate for x at the home switch is
> > 0.000.
> >
> 
> Not necessarily. You can set that with the HOME_OFFSET variable. If
> HOME_OFFSET is 0 then your origin is at the home switch or index pulse
> detection. But you can set HOME_OFFSET with whatever value you need. Then
> when the switch trips on the final latch move LCNC instantly sets that
> value for the G53 coordinate system. Beware that if your HOME OFFSET value
> differs from your HOME value, once the switch is tripped for the last time
> and G53 is set, the axis will move to the HOME position at HOME_FINAL_VEL
> or maximum velocity if HOME_FINAL_VEL is 0.
> 
> And measuring the tool tip relative to how it mounts into the AXA holder
> > can be done creating an offset from the home switch.v  Now each time the
> > tool holder +tool  is put into the AXA the distance from the tool table is
> > offset from that home position and LCNC knows where the tip and can turn a
> > diameter.  Theoretically.
> 
> 
> I might be wrong but LCNC doesn't care about the distance between the tool
> tip and the home position or G53 origin. You set your X coordinate for your
> tool against a known position (in this case the easiest is to skim cut and
> input diameter/radius) and LCNC knows that the diameter/radius value you
> entered corresponds to a given absolute machine position.
> 
> 
> > However as  soon as the holder is pivoted even slightly the distance of
> > the tool tip relative to the home switch changes.   And it changes
> > differently depending on how far the tool protrudes out of the AXA hol

Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[John Dammeyer]

Interesting.  Don't need switches for that but do need an index on the 
leadscrew.

> -Original Message-
> From: Stuart Stevenson [mailto:stus...@gmail.com]
> Sent: December-04-22 5:26 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Home switches for LinuxCNC on a Lathe
> 
> You might try the FADAL mill method.
> 
> They use two arrows (markers). One on the moving member and one on the
> unmoving member. You physically align the arrows and run the home routine.
> The next found index mark on the encoder is the home position.
> 
> regards
> Stuart
> 
> 
> On Sun, Dec 4, 2022 at 1:25 AM gene heskett  wrote:
> 
> > On 12/3/22 22:56, John Dammeyer wrote:
> > >>
> > >>  From what I understand you're talking about a normal parallel lathe so
> > here
> > >> are my thoughts:
> > > Yes.  And thank you.
> > >>
> > >>> The Z axis is more interesting.  Before homing I imagine the tail stock
> > >>> has to be loosened and moved all the way to the right as far away from
> > the
> > >>> headstock to ensure finding a home switch.  Or a home switch could be
> > >>> somewhere in the middle but then which direction to search?
> > >>>
> > >>
> > >> I think the safest setup  in this case (given your Z axis can crash with
> > >> the tailstock if you forget to move it all the way to the right) will be
> > >> having the home switch towards the chuck side (with a proper
> > >> independent limit switch right at the left of the home switch to avoid
> > >> crashes when homing). This way you can set up your homing sequence to
> > first
> > >> home the X axis to move it to a safe place and then home the Z axis
> > towards
> > >> the chuck.
> > >
> > > I'm guessing you are suggesting something like what Gene was that the
> > home switch isn't at the end of travel but somewhere else and once
> > activated never goes inactive in that same direction.   So if you start a
> > home sequence and the switch is ON you know you have to go to the right
> > until it goes OFF.  It can't over travel past the OFF position and go ON
> > again.  That approach lets the Home Switch be pretty well anywhere.
> > >
> > > Unless the limit switch is movable it's useless.  My carriage can go
> > much further to the left to turn near the part held in the 5C collet than
> > it can with the part held in the 3-Jaw.  So a crash into the spinning 3-Jaw
> > can happen without ever touching the limit.  And if the limit does prevent
> > that one can't turn a part close to the collet.
> > >
> > >>
> > >> How does one determine, with that tool tip, where the lathe centerline
> > is
> > >>> and set that so G54 X is 0.000?
> > >>>
> > >>
> > >> I think you're asking about tool setting. If you have tool fixtures that
> > >> ensure that whenever you change your tool you get the exact same tool
> > >> position then it's just like a CNC turret. You just take a skim cut on
> > the
> > >> diameter (or maybe use some fine paper to gauge the tool against the
> > >> workpiece) and then measure and input the diameter (or radius depending
> > if
> > >> you're in G7 or G8) in the touch off popup.
> > >>
> > > Thanks.  I'm going to have to study that a bit further.
> > > I understand that the machine coordinate for x at the home switch is
> > 0.000.
> > >
> > > And measuring the tool tip relative to how it mounts into the AXA holder
> > can be done creating an offset from the home switch.v  Now each time the
> > tool holder +tool  is put into the AXA the distance from the tool table is
> > offset from that home position and LCNC knows where the tip and can turn a
> > diameter.  Theoretically.
> > >
> > > However as  soon as the holder is pivoted even slightly the distance of
> > the tool tip relative to the home switch changes.   And it changes
> > differently depending on how far the tool protrudes out of the AXA holder
> > right?
> > >
> > > So the tool measurements are only useful with the AXA in one position
> > and that can change really easily in the home shop.  We're not talking a
> > commercial production operation where the setup is the same over a long
> > period of time.
> > >
> > > I suppose if you can touch of or measure the new position of the tool
> > tip you can then use simple trig to determine the angle that 

Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[Leonardo Marsaglia]

>
> I'm guessing you are suggesting something like what Gene was that the home
> switch isn't at the end of travel but somewhere else and once activated
> never goes inactive in that same direction.   So if you start a home
> sequence and the switch is ON you know you have to go to the right until it
> goes OFF.  It can't over travel past the OFF position and go ON again.
> That approach lets the Home Switch be pretty well anywhere.
>

Not exactly Gene's setup, although that is a good idea too if you want to
have your home switch somewhere in the middle of your carriage travel. What
I thought is something like what I've seen on the CNC lathes we have in the
shop. You have the home switch right next to your limit switch. Also you
have to set your soft limits so your travel ends right before hitting the
hard limits. That way, you're always sure when you turn off your machine
you'll always be at the right side of the home switch. Of course this eats
some travel out of your Z axis but that's the price to pay for safety. The
obvious difference here is that on slanted bed CNC lathes you don't have to
worry about your carriage hitting the tailstock because they rest in
different ways (although tools can hit the tailstock that's why X axis is
always homed and cleared before Z).

Unless the limit switch is movable it's useless.  My carriage can go much
> further to the left to turn near the part held in the 5C collet than it can
> with the part held in the 3-Jaw.  So a crash into the spinning 3-Jaw can
> happen without ever touching the limit.  And if the limit does prevent that
> one can't turn a part close to the collet.
>

That's why having a proper home sequence is the key to avoid hitting the
chuck with the tool. You'll have to set the homing for the X axis first and
send it to a safe location so the Z homing can happen without crashing. Of
course this is assuming you can guarantee enough clearance for any tool
installed on your toolpost when doing the X axis homing. If your chuck is
too large, or you have a tool sticking too far out of your tool post that
even retracting the X axis to the fullest you can hit your 3 jaw chuck then
please forget about homing to the chuck side and consider Gene's method.


> I understand that the machine coordinate for x at the home switch is
> 0.000.
>

Not necessarily. You can set that with the HOME_OFFSET variable. If
HOME_OFFSET is 0 then your origin is at the home switch or index pulse
detection. But you can set HOME_OFFSET with whatever value you need. Then
when the switch trips on the final latch move LCNC instantly sets that
value for the G53 coordinate system. Beware that if your HOME OFFSET value
differs from your HOME value, once the switch is tripped for the last time
and G53 is set, the axis will move to the HOME position at HOME_FINAL_VEL
or maximum velocity if HOME_FINAL_VEL is 0.

And measuring the tool tip relative to how it mounts into the AXA holder
> can be done creating an offset from the home switch.v  Now each time the
> tool holder +tool  is put into the AXA the distance from the tool table is
> offset from that home position and LCNC knows where the tip and can turn a
> diameter.  Theoretically.


I might be wrong but LCNC doesn't care about the distance between the tool
tip and the home position or G53 origin. You set your X coordinate for your
tool against a known position (in this case the easiest is to skim cut and
input diameter/radius) and LCNC knows that the diameter/radius value you
entered corresponds to a given absolute machine position.


> However as  soon as the holder is pivoted even slightly the distance of
> the tool tip relative to the home switch changes.   And it changes
> differently depending on how far the tool protrudes out of the AXA holder
> right?
>
> So the tool measurements are only useful with the AXA in one position and
> that can change really easily in the home shop.  We're not talking a
> commercial production operation where the setup is the same over a long
> period of time.
>
> I suppose if you can touch of or measure the new position of the tool tip
> you can then use simple trig to determine the angle that the AXA holder has
> pivoted.  Unless it also slid in the T-Slot which now moves it in more than
> one dimension.
>
> Doe my explanation make sense?  A small shop lathe where the operator can
> shift the tool bit around relative to the X home switch and even on the
> carriage relative to the Z home switch suggest a tool table for a LCNC
> lathe is virtually impossible.
>
> So I can manually turn that shaft.  Leave the X axis where it is and
> measure the diameter; say exactly 1.000".   Then click on the "Touch Off"
> on the display and enter half the diameter (0.5") for the offset.
> Now a request to move the X to 0.480" to do a 0.020" deep pass should work
> right?
>
> But the tool table and for that matter the home switch and machine
> coordinate system is pretty well useless.  Or have I missed something?
>

Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[Stuart Stevenson]

You might try the FADAL mill method.

They use two arrows (markers). One on the moving member and one on the
unmoving member. You physically align the arrows and run the home routine.
The next found index mark on the encoder is the home position.

regards
Stuart


On Sun, Dec 4, 2022 at 1:25 AM gene heskett  wrote:

> On 12/3/22 22:56, John Dammeyer wrote:
> >>
> >>  From what I understand you're talking about a normal parallel lathe so
> here
> >> are my thoughts:
> > Yes.  And thank you.
> >>
> >>> The Z axis is more interesting.  Before homing I imagine the tail stock
> >>> has to be loosened and moved all the way to the right as far away from
> the
> >>> headstock to ensure finding a home switch.  Or a home switch could be
> >>> somewhere in the middle but then which direction to search?
> >>>
> >>
> >> I think the safest setup  in this case (given your Z axis can crash with
> >> the tailstock if you forget to move it all the way to the right) will be
> >> having the home switch towards the chuck side (with a proper
> >> independent limit switch right at the left of the home switch to avoid
> >> crashes when homing). This way you can set up your homing sequence to
> first
> >> home the X axis to move it to a safe place and then home the Z axis
> towards
> >> the chuck.
> >
> > I'm guessing you are suggesting something like what Gene was that the
> home switch isn't at the end of travel but somewhere else and once
> activated never goes inactive in that same direction.   So if you start a
> home sequence and the switch is ON you know you have to go to the right
> until it goes OFF.  It can't over travel past the OFF position and go ON
> again.  That approach lets the Home Switch be pretty well anywhere.
> >
> > Unless the limit switch is movable it's useless.  My carriage can go
> much further to the left to turn near the part held in the 5C collet than
> it can with the part held in the 3-Jaw.  So a crash into the spinning 3-Jaw
> can happen without ever touching the limit.  And if the limit does prevent
> that one can't turn a part close to the collet.
> >
> >>
> >> How does one determine, with that tool tip, where the lathe centerline
> is
> >>> and set that so G54 X is 0.000?
> >>>
> >>
> >> I think you're asking about tool setting. If you have tool fixtures that
> >> ensure that whenever you change your tool you get the exact same tool
> >> position then it's just like a CNC turret. You just take a skim cut on
> the
> >> diameter (or maybe use some fine paper to gauge the tool against the
> >> workpiece) and then measure and input the diameter (or radius depending
> if
> >> you're in G7 or G8) in the touch off popup.
> >>
> > Thanks.  I'm going to have to study that a bit further.
> > I understand that the machine coordinate for x at the home switch is
> 0.000.
> >
> > And measuring the tool tip relative to how it mounts into the AXA holder
> can be done creating an offset from the home switch.v  Now each time the
> tool holder +tool  is put into the AXA the distance from the tool table is
> offset from that home position and LCNC knows where the tip and can turn a
> diameter.  Theoretically.
> >
> > However as  soon as the holder is pivoted even slightly the distance of
> the tool tip relative to the home switch changes.   And it changes
> differently depending on how far the tool protrudes out of the AXA holder
> right?
> >
> > So the tool measurements are only useful with the AXA in one position
> and that can change really easily in the home shop.  We're not talking a
> commercial production operation where the setup is the same over a long
> period of time.
> >
> > I suppose if you can touch of or measure the new position of the tool
> tip you can then use simple trig to determine the angle that the AXA holder
> has pivoted.  Unless it also slid in the T-Slot which now moves it in more
> than one dimension.
> >
> > Doe my explanation make sense?  A small shop lathe where the operator
> can shift the tool bit around relative to the X home switch and even on the
> carriage relative to the Z home switch suggest a tool table for a LCNC
> lathe is virtually impossible.
> >
> > So I can manually turn that shaft.  Leave the X axis where it is and
> measure the diameter; say exactly 1.000".   Then click on the "Touch Off"
> on the display and enter half the diameter (0.5") for the offset.
> > Now a request to move the X to 0.480" to do a 0.020" deep pass should
> work right?
> >
> > But the tool table and for that matter the home switch and machine
> coordinate system is pretty well useless.  Or have I missed something?
> >
> > John
> >
> >
> Don't adjust your antenna, you got it, John, the reception is perfect.
> The main reason for a home sw is the let the machine know where its at
> in the absolute sense, I've surveyed my bed for wear, and corrected it
> with a lincurve/offset module combo. Rather satisfying to see the X
> motor turn a bit as the Z is scanned. But, its effect is determined by
> 

Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[gene heskett]

On 12/3/22 22:56, John Dammeyer wrote:


 From what I understand you're talking about a normal parallel lathe so here
are my thoughts:

Yes.  And thank you.



The Z axis is more interesting.  Before homing I imagine the tail stock
has to be loosened and moved all the way to the right as far away from the
headstock to ensure finding a home switch.  Or a home switch could be
somewhere in the middle but then which direction to search?



I think the safest setup  in this case (given your Z axis can crash with
the tailstock if you forget to move it all the way to the right) will be
having the home switch towards the chuck side (with a proper
independent limit switch right at the left of the home switch to avoid
crashes when homing). This way you can set up your homing sequence to first
home the X axis to move it to a safe place and then home the Z axis towards
the chuck.


I'm guessing you are suggesting something like what Gene was that the home 
switch isn't at the end of travel but somewhere else and once activated never 
goes inactive in that same direction.   So if you start a home sequence and the 
switch is ON you know you have to go to the right until it goes OFF.  It can't 
over travel past the OFF position and go ON again.  That approach lets the Home 
Switch be pretty well anywhere.

Unless the limit switch is movable it's useless.  My carriage can go much 
further to the left to turn near the part held in the 5C collet than it can 
with the part held in the 3-Jaw.  So a crash into the spinning 3-Jaw can happen 
without ever touching the limit.  And if the limit does prevent that one can't 
turn a part close to the collet.



How does one determine, with that tool tip, where the lathe centerline is

and set that so G54 X is 0.000?



I think you're asking about tool setting. If you have tool fixtures that
ensure that whenever you change your tool you get the exact same tool
position then it's just like a CNC turret. You just take a skim cut on the
diameter (or maybe use some fine paper to gauge the tool against the
workpiece) and then measure and input the diameter (or radius depending if
you're in G7 or G8) in the touch off popup.


Thanks.  I'm going to have to study that a bit further.
I understand that the machine coordinate for x at the home switch is 0.000.

And measuring the tool tip relative to how it mounts into the AXA holder can be 
done creating an offset from the home switch.v  Now each time the tool holder 
+tool  is put into the AXA the distance from the tool table is offset from that 
home position and LCNC knows where the tip and can turn a diameter.  
Theoretically.

However as  soon as the holder is pivoted even slightly the distance of the 
tool tip relative to the home switch changes.   And it changes differently 
depending on how far the tool protrudes out of the AXA holder right?

So the tool measurements are only useful with the AXA in one position and that 
can change really easily in the home shop.  We're not talking a commercial 
production operation where the setup is the same over a long period of time.

I suppose if you can touch of or measure the new position of the tool tip you 
can then use simple trig to determine the angle that the AXA holder has 
pivoted.  Unless it also slid in the T-Slot which now moves it in more than one 
dimension.

Doe my explanation make sense?  A small shop lathe where the operator can shift 
the tool bit around relative to the X home switch and even on the carriage 
relative to the Z home switch suggest a tool table for a LCNC lathe is 
virtually impossible.

So I can manually turn that shaft.  Leave the X axis where it is and measure the diameter; say 
exactly 1.000".   Then click on the "Touch Off" on the display and enter half the 
diameter (0.5") for the offset.
Now a request to move the X to 0.480" to do a 0.020" deep pass should work 
right?

But the tool table and for that matter the home switch and machine coordinate 
system is pretty well useless.  Or have I missed something?

John



Don't adjust your antenna, you got it, John, the reception is perfect.
The main reason for a home sw is the let the machine know where its at 
in the absolute sense, I've surveyed my bed for wear, and corrected it 
with a lincurve/offset module combo. Rather satisfying to see the X 
motor turn a bit as the Z is scanned. But, its effect is determined by 
the absolute z position established by the home switch. It does not 
respond to z touch off, only to the real position.


Threading to any std, or to one you've invented is nothing but arguments 
to the G76 routine. I've even abused G76 to make compression fittings


The main advantage to cnc'ing a lathe is that its far faster at 
executing the move codes than you can squint at a dial and do it by hand 
in between cuts, it turns the crank in milliseconds and gets on with the 
job.


With no compound, mine was broken beyond redemption by a fall over no 
one mentioned before I bought it, so LinuxCNC 

Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[John Dammeyer]

> 
> From what I understand you're talking about a normal parallel lathe so here
> are my thoughts:
Yes.  And thank you.
> 
> > The Z axis is more interesting.  Before homing I imagine the tail stock
> > has to be loosened and moved all the way to the right as far away from the
> > headstock to ensure finding a home switch.  Or a home switch could be
> > somewhere in the middle but then which direction to search?
> >
> 
> I think the safest setup  in this case (given your Z axis can crash with
> the tailstock if you forget to move it all the way to the right) will be
> having the home switch towards the chuck side (with a proper
> independent limit switch right at the left of the home switch to avoid
> crashes when homing). This way you can set up your homing sequence to first
> home the X axis to move it to a safe place and then home the Z axis towards
> the chuck.

I'm guessing you are suggesting something like what Gene was that the home 
switch isn't at the end of travel but somewhere else and once activated never 
goes inactive in that same direction.   So if you start a home sequence and the 
switch is ON you know you have to go to the right until it goes OFF.  It can't 
over travel past the OFF position and go ON again.  That approach lets the Home 
Switch be pretty well anywhere.

Unless the limit switch is movable it's useless.  My carriage can go much 
further to the left to turn near the part held in the 5C collet than it can 
with the part held in the 3-Jaw.  So a crash into the spinning 3-Jaw can happen 
without ever touching the limit.  And if the limit does prevent that one can't 
turn a part close to the collet. 

> 
> How does one determine, with that tool tip, where the lathe centerline is
> > and set that so G54 X is 0.000?
> >
> 
> I think you're asking about tool setting. If you have tool fixtures that
> ensure that whenever you change your tool you get the exact same tool
> position then it's just like a CNC turret. You just take a skim cut on the
> diameter (or maybe use some fine paper to gauge the tool against the
> workpiece) and then measure and input the diameter (or radius depending if
> you're in G7 or G8) in the touch off popup.
> 
Thanks.  I'm going to have to study that a bit further.  
I understand that the machine coordinate for x at the home switch is 0.000.  

And measuring the tool tip relative to how it mounts into the AXA holder can be 
done creating an offset from the home switch.v  Now each time the tool holder 
+tool  is put into the AXA the distance from the tool table is offset from that 
home position and LCNC knows where the tip and can turn a diameter.  
Theoretically.

However as  soon as the holder is pivoted even slightly the distance of the 
tool tip relative to the home switch changes.   And it changes differently 
depending on how far the tool protrudes out of the AXA holder right?

So the tool measurements are only useful with the AXA in one position and that 
can change really easily in the home shop.  We're not talking a commercial 
production operation where the setup is the same over a long period of time.

I suppose if you can touch of or measure the new position of the tool tip you 
can then use simple trig to determine the angle that the AXA holder has 
pivoted.  Unless it also slid in the T-Slot which now moves it in more than one 
dimension.

Doe my explanation make sense?  A small shop lathe where the operator can shift 
the tool bit around relative to the X home switch and even on the carriage 
relative to the Z home switch suggest a tool table for a LCNC lathe is 
virtually impossible.

So I can manually turn that shaft.  Leave the X axis where it is and measure 
the diameter; say exactly 1.000".   Then click on the "Touch Off" on the 
display and enter half the diameter (0.5") for the offset.
Now a request to move the X to 0.480" to do a 0.020" deep pass should work 
right?

But the tool table and for that matter the home switch and machine coordinate 
system is pretty well useless.  Or have I missed something?

John




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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[gene heskett]

On 12/3/22 19:27, John Dammeyer wrote:

What with playing around with my new tool setter and trying to decide where to 
put it I've come up with another set of questions which I've not really asked 
but now has been bugging me for a while.
  
Home switches for a LinuxCNC controlled lathe.  For the X axis I can see this as pretty simple as usually nothing impedes movement outward.  Place it at the end of travel and it can serve as both a home and limit switch.
  
The Z axis is more interesting.  Before homing I imagine the tail stock has to be loosened and moved all the way to the right as far away from the headstock to ensure finding a home switch.  Or a home switch could be somewhere in the middle but then which direction to search?
  
If you arrange the switch to be closed on one side, and open on the 
other, linuxcnc knows which way to move to find the switch.


Mine on the Sheldon is around 16" from the chuck, and it can't move far 
enough toward the tailstock to reopen the switch. It is mounted on the 
baxk of the bed, rigged so the gib strip on the rear of the carriage 
actuates it.


Home offset is arbitrary and places it about 2" from the chuck jaws. 
Anyplace will do, but I pull the tool to prevent collisions if there is 
work chucked. You'll touch off both axis's in normal use anyway.



Alright.  So we've established a pair of X=0, Z=0 for home and this is set into 
the G53 X and Z locations.  As I see it the next problem is with tools.  Put a 
carbide insert cutter into the tool holder and it extends out to the centerline 
and to the left of the carriage.
  
How does one determine, with that tool tip, where the lathe centerline is and set that so G54 X is 0.000?


You don't worry about that, you measure the work and touch off at the 
works radius. Its a good idea to take a light cut first to assure roundness.
  
The chuck can be 3 jaw or 4 jaw, 5C collet or even a faceplate or the arbor for turning between centers.   In other words 5 different Z locations relative to that G53 Z=0 position found when homing.
  
And if the work is chucked in and sticks out 3" then do we try and make that end G54 Z=0?


That is what touch off is for.
  
In the past for non-CNC, say I have a DRO on the lathe, I'll face off the end and then set Z to 0.000.  If I want to turn 2" I'll move the carriage until the DRO reads -2.000.  At this point I could reset Z to 0.000 or just make all cuts go from 0.000 to -2.000.
  
Next if scratch the surface with the tool and set G54 Z=0.000  and then cut a pass at 0.010" I've now made the surface round with respect to the rotation.  If I measure it at 1.020" in diameter then I now know the real X 0.000 centerline is 0.510".  Set the G54 X value to 0.510" and from then on I can specify a final diameter and X positions for each cut which may already exist in the G Code.
  
It's all about finding the reference positions on the lathe.  Change tool and it needs to be done again.How is it generally done with LinuxCNC.  Is there a tutorial for that somewhere?


That habit doesn't change. With tp rotation for various cuts, your tool 
table is always out of sync, measure and touch off.
  
Thanks

John
  
  


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Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[Leonardo Marsaglia]

I forgot to clarify.

Usually you don't touch off for X coordinate in G54 because your centerline
is always the center of rotation of the chuck. So basically you only use Z
axis touch off for different part lengths.

And the only time you need to find the centerline is whenever you mount a
drill on your turret. I rarely do that, but a dial indicator on the chuck
could be used to dial by hand around the drill fixture and adjust the X
position until it's centered.

El sáb, 3 dic 2022 a las 21:54, Leonardo Marsaglia ()
escribió:

> Hi John,
>
> From what I understand you're talking about a normal parallel lathe so
> here are my thoughts:
>
>
>> The Z axis is more interesting.  Before homing I imagine the tail stock
>> has to be loosened and moved all the way to the right as far away from the
>> headstock to ensure finding a home switch.  Or a home switch could be
>> somewhere in the middle but then which direction to search?
>>
>
> I think the safest setup  in this case (given your Z axis can crash with
> the tailstock if you forget to move it all the way to the right) will be
> having the home switch towards the chuck side (with a proper
> independent limit switch right at the left of the home switch to avoid
> crashes when homing). This way you can set up your homing sequence to first
> home the X axis to move it to a safe place and then home the Z axis towards
> the chuck.
>
> How does one determine, with that tool tip, where the lathe centerline is
>> and set that so G54 X is 0.000?
>>
>
> I think you're asking about tool setting. If you have tool fixtures that
> ensure that whenever you change your tool you get the exact same tool
> position then it's just like a CNC turret. You just take a skim cut on the
> diameter (or maybe use some fine paper to gauge the tool against the
> workpiece) and then measure and input the diameter (or radius depending if
> you're in G7 or G8) in the touch off popup.
>
>
>
>> The chuck can be 3 jaw or 4 jaw, 5C colletor even a faceplate or the
>> arbor for turning between centers.   In other words 5 different Z locations
>> relative to that G53 Z=0 position found when homing.
>>
>> And if the work is chucked in and sticks out 3" then do we try and make
>> that end G54 Z=0?
>>
>
> Exactly, you're going to have to touch and set every tool Z coordinate and
> also your G54 Z coordinate with respect to your works end face.
>
>
>
> El sáb, 3 dic 2022 a las 21:32, John Dammeyer ()
> escribió:
>
>> What with playing around with my new tool setter and trying to decide
>> where to put it I've come up with another set of questions which I've not
>> really asked but now has been bugging me for a while.
>>
>> Home switches for a LinuxCNC controlled lathe.  For the X axis I can see
>> this as pretty simple as usually nothing impedes movement outward.  Place
>> it at the end of travel and it can serve as both a home and limit switch.
>>
>> The Z axis is more interesting.  Before homing I imagine the tail stock
>> has to be loosened and moved all the way to the right as far away from the
>> headstock to ensure finding a home switch.  Or a home switch could be
>> somewhere in the middle but then which direction to search?
>>
>> Alright.  So we've established a pair of X=0, Z=0 for home and this is
>> set into the G53 X and Z locations.  As I see it the next problem is with
>> tools.  Put a carbide insert cutter into the tool holder and it extends out
>> to the centerline and to the left of the carriage.
>>
>> How does one determine, with that tool tip, where the lathe centerline is
>> and set that so G54 X is 0.000?
>>
>> The chuck can be 3 jaw or 4 jaw, 5C colletor even a faceplate or the
>> arbor for turning between centers.   In other words 5 different Z locations
>> relative to that G53 Z=0 position found when homing.
>>
>> And if the work is chucked in and sticks out 3" then do we try and make
>> that end G54 Z=0?
>>
>> In the past for non-CNC, say I have a DRO on the lathe, I'll face off the
>> end and then set Z to 0.000.  If I want to turn 2" I'll move the carriage
>> until the DRO reads -2.000.  At this point I could reset Z to 0.000 or just
>> make all cuts go from 0.000 to -2.000.
>>
>> Next if scratch the surface with the tool and set G54 Z=0.000  and then
>> cut a pass at 0.010" I've now made the surface round with respect to the
>> rotation.  If I measure it at 1.020" in diameter then I now know the real X
>> 0.000 centerline is 0.510".  Set the G54 X value to 0.510" and from then on
>> I can specify a final diameter and X positions for each cut which may
>> already exist in the G Code.
>>
>> It's all about finding the reference positions on the lathe.  Change tool
>> and it needs to be done again.How is it generally done with LinuxCNC.
>> Is there a tutorial for that somewhere?
>>
>> Thanks
>> John
>>
>>
>>
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>> 

Re: [Emc-users] Home switches for LinuxCNC on a Lathe

[Leonardo Marsaglia]

Hi John,

From what I understand you're talking about a normal parallel lathe so here
are my thoughts:


> The Z axis is more interesting.  Before homing I imagine the tail stock
> has to be loosened and moved all the way to the right as far away from the
> headstock to ensure finding a home switch.  Or a home switch could be
> somewhere in the middle but then which direction to search?
>

I think the safest setup  in this case (given your Z axis can crash with
the tailstock if you forget to move it all the way to the right) will be
having the home switch towards the chuck side (with a proper
independent limit switch right at the left of the home switch to avoid
crashes when homing). This way you can set up your homing sequence to first
home the X axis to move it to a safe place and then home the Z axis towards
the chuck.

How does one determine, with that tool tip, where the lathe centerline is
> and set that so G54 X is 0.000?
>

I think you're asking about tool setting. If you have tool fixtures that
ensure that whenever you change your tool you get the exact same tool
position then it's just like a CNC turret. You just take a skim cut on the
diameter (or maybe use some fine paper to gauge the tool against the
workpiece) and then measure and input the diameter (or radius depending if
you're in G7 or G8) in the touch off popup.



> The chuck can be 3 jaw or 4 jaw, 5C colletor even a faceplate or the arbor
> for turning between centers.   In other words 5 different Z locations
> relative to that G53 Z=0 position found when homing.
>
> And if the work is chucked in and sticks out 3" then do we try and make
> that end G54 Z=0?
>

Exactly, you're going to have to touch and set every tool Z coordinate and
also your G54 Z coordinate with respect to your works end face.



El sáb, 3 dic 2022 a las 21:32, John Dammeyer ()
escribió:

> What with playing around with my new tool setter and trying to decide
> where to put it I've come up with another set of questions which I've not
> really asked but now has been bugging me for a while.
>
> Home switches for a LinuxCNC controlled lathe.  For the X axis I can see
> this as pretty simple as usually nothing impedes movement outward.  Place
> it at the end of travel and it can serve as both a home and limit switch.
>
> The Z axis is more interesting.  Before homing I imagine the tail stock
> has to be loosened and moved all the way to the right as far away from the
> headstock to ensure finding a home switch.  Or a home switch could be
> somewhere in the middle but then which direction to search?
>
> Alright.  So we've established a pair of X=0, Z=0 for home and this is set
> into the G53 X and Z locations.  As I see it the next problem is with
> tools.  Put a carbide insert cutter into the tool holder and it extends out
> to the centerline and to the left of the carriage.
>
> How does one determine, with that tool tip, where the lathe centerline is
> and set that so G54 X is 0.000?
>
> The chuck can be 3 jaw or 4 jaw, 5C colletor even a faceplate or the arbor
> for turning between centers.   In other words 5 different Z locations
> relative to that G53 Z=0 position found when homing.
>
> And if the work is chucked in and sticks out 3" then do we try and make
> that end G54 Z=0?
>
> In the past for non-CNC, say I have a DRO on the lathe, I'll face off the
> end and then set Z to 0.000.  If I want to turn 2" I'll move the carriage
> until the DRO reads -2.000.  At this point I could reset Z to 0.000 or just
> make all cuts go from 0.000 to -2.000.
>
> Next if scratch the surface with the tool and set G54 Z=0.000  and then
> cut a pass at 0.010" I've now made the surface round with respect to the
> rotation.  If I measure it at 1.020" in diameter then I now know the real X
> 0.000 centerline is 0.510".  Set the G54 X value to 0.510" and from then on
> I can specify a final diameter and X positions for each cut which may
> already exist in the G Code.
>
> It's all about finding the reference positions on the lathe.  Change tool
> and it needs to be done again.How is it generally done with LinuxCNC.
> Is there a tutorial for that somewhere?
>
> Thanks
> John
>
>
>
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[Emc-users] Home switches for LinuxCNC on a Lathe

[John Dammeyer]

What with playing around with my new tool setter and trying to decide where to 
put it I've come up with another set of questions which I've not really asked 
but now has been bugging me for a while.
 
Home switches for a LinuxCNC controlled lathe.  For the X axis I can see this 
as pretty simple as usually nothing impedes movement outward.  Place it at the 
end of travel and it can serve as both a home and limit switch. 
 
The Z axis is more interesting.  Before homing I imagine the tail stock has to 
be loosened and moved all the way to the right as far away from the headstock 
to ensure finding a home switch.  Or a home switch could be somewhere in the 
middle but then which direction to search?
 
Alright.  So we've established a pair of X=0, Z=0 for home and this is set into 
the G53 X and Z locations.  As I see it the next problem is with tools.  Put a 
carbide insert cutter into the tool holder and it extends out to the centerline 
and to the left of the carriage.
 
How does one determine, with that tool tip, where the lathe centerline is and 
set that so G54 X is 0.000?
 
The chuck can be 3 jaw or 4 jaw, 5C colletor even a faceplate or the arbor for 
turning between centers.   In other words 5 different Z locations relative to 
that G53 Z=0 position found when homing.
 
And if the work is chucked in and sticks out 3" then do we try and make that 
end G54 Z=0?
 
In the past for non-CNC, say I have a DRO on the lathe, I'll face off the end 
and then set Z to 0.000.  If I want to turn 2" I'll move the carriage until the 
DRO reads -2.000.  At this point I could reset Z to 0.000 or just make all cuts 
go from 0.000 to -2.000.
 
Next if scratch the surface with the tool and set G54 Z=0.000  and then cut a 
pass at 0.010" I've now made the surface round with respect to the rotation.  
If I measure it at 1.020" in diameter then I now know the real X 0.000 
centerline is 0.510".  Set the G54 X value to 0.510" and from then on I can 
specify a final diameter and X positions for each cut which may already exist 
in the G Code.
 
It's all about finding the reference positions on the lathe.  Change tool and 
it needs to be done again.How is it generally done with LinuxCNC.  Is there 
a tutorial for that somewhere?
 
Thanks
John
 
 

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Re: [Emc-users] Home switches.

[Jon Elson]

On 05/24/2018 10:04 PM, John Dammeyer wrote:

Quick mini survey.  If you have a knee mill, where have you mounted your
home switches?
I understand it doesn't matter because the machine coordinate system is only
used to establish a fixed reference.  For the rest of the time we use
various world coordinate systems with the G54...


The Z home is nearly all the way up.  X home is near the 
middle of travel.  Y home is with the saddle moving toward 
the front (near maximum +Y travel.)




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Re: [Emc-users] Home switches.

[TERRY Christophersen]

Table toward you and to the left is machine home.
4th axis on the right hand side of the table.
This is how most machines are.

Sent from my iPhone

> On May 25, 2018, at 1:26 AM, Marcus Bowman 
>  wrote:
> 
> 
>> 
>> And that brings up the third question about a 4th axis.  If you have one, do
>> you tend to put it on the left just like a lathe spindle or on the right?
>> Any reason for the preference?  Often there are tool changers on the left so
>> it makes more sense to have the 4th on the right.
> 
> My mill is a benchtop-style arrangement, rather than a Bridgeport-style knee 
> mill.
> My 4th Axis is based on a large diameter rotary table, mounted on its side.
> I always put my 4th axis on the left, because if I put it on the right, it 
> would foul the quill handle, if I used it. Separate quill feed is manual, and 
> although I can't recall the last time I used that handle in conjunction with 
> the 4th axis, it's always a possibility. 
> That position means feeds along the work at -ve X, which is not intuitively 
> convenient, but I live with it.
> 
> Marcus
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Re: [Emc-users] Home switches.

[Marcus Bowman]

> 
> And that brings up the third question about a 4th axis.  If you have one, do
> you tend to put it on the left just like a lathe spindle or on the right?
> Any reason for the preference?  Often there are tool changers on the left so
> it makes more sense to have the 4th on the right.

My mill is a benchtop-style arrangement, rather than a Bridgeport-style knee 
mill.
My 4th Axis is based on a large diameter rotary table, mounted on its side.
I always put my 4th axis on the left, because if I put it on the right, it 
would foul the quill handle, if I used it. Separate quill feed is manual, and 
although I can't recall the last time I used that handle in conjunction with 
the 4th axis, it's always a possibility. 
That position means feeds along the work at -ve X, which is not intuitively 
convenient, but I live with it.

Marcus
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Re: [Emc-users] Home switches.

[Gene Heskett]

On Thursday 24 May 2018 23:04:06 John Dammeyer wrote:

> Quick mini survey.  If you have a knee mill, where have you mounted
> your home switches?
> I understand it doesn't matter because the machine coordinate system
> is only used to establish a fixed reference.  For the rest of the time
> we use various world coordinate systems with the G54...
>
> So the switches:
> For the Y axis so the bed moves towards you or away?

I have mine set to trip about 50 thou from the front hard stop.

Actual home after it hits at high speed, then it backs away slow till the 
opens.
> For the X axis so the bed moves to the left or to the right?

I have that set to trip the switch when the table is about 50 thou from a 
hard stop. So the table is all the way left. If I've put a squirt of 
iso-68 Vactra on the ways, the long out and back moves while homing 
helps to distribute the oil.

> The Z axis obvious because we always want it to move away from the
> tool tip to avoid a crash.
>
And that is about 50 thou from the top of the post. I use home offsets to 
essentially center up the xy when the tables stop moving. No switch on 
the A, I simply run it to the zero index mark and touch it off. My 
biggest problem is the pointed tool 0 image, its out of time with the 
table by about 175 degrees.

> For example, if you periodically put your 4th Axis on the left hand
> side of the bed it's probably better to have the system home so the
> table moves to the left. In effect this makes the tool move to the
> right Just in case you ask it to home but forgot that you had the 4th
> axis bolted down.
>
> And that brings up the third question about a 4th axis.  If you have
> one, do you tend to put it on the left just like a lathe spindle or on
> the right? Any reason for the preference?  Often there are tool
> changers on the left so it makes more sense to have the 4th on the
> right.

Thats entirely up to you, John. With my drive motor sticking out at a 45 
degree angle it has to be on the left end of the table so the motor 
clears the head if its moved that far to the right. Its a long motor 
mount.  When its on the little mill, I drilled and tapped the table for 
the mount.

> Thanks
> John

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Re: [Emc-users] Home switches.

[jeremy youngs]

Home switches should go to the positive side , z up, y towards you and x on
the right.
Most 4 axis I have used were mounted on the negative end ( left ) ( mazak)
but the carousel was not in the path of the 4th axis, the fadals ( which
homed to the center of the table , as well as the daewoo) were mounted to
the right because the carousel would have been an interfering factor, mine
will mount to the right because it will be a threaded lathe spindle ( in
stock ) and I don't want it throwing chips at me or unscrewing, but I have
other hurdles to jump before adding more joints to this machine 

On Thu, May 24, 2018, 22:05 John Dammeyer  wrote:

> Quick mini survey.  If you have a knee mill, where have you mounted your
> home switches?
> I understand it doesn't matter because the machine coordinate system is
> only
> used to establish a fixed reference.  For the rest of the time we use
> various world coordinate systems with the G54...
>
> So the switches:
> For the Y axis so the bed moves towards you or away?
> For the X axis so the bed moves to the left or to the right?
> The Z axis obvious because we always want it to move away from the tool tip
> to avoid a crash.
>
> For example, if you periodically put your 4th Axis on the left hand side of
> the bed it's probably better to have the system home so the table moves to
> the left. In effect this makes the tool move to the right Just in case you
> ask it to home but forgot that you had the 4th axis bolted down.
>
> And that brings up the third question about a 4th axis.  If you have one,
> do
> you tend to put it on the left just like a lathe spindle or on the right?
> Any reason for the preference?  Often there are tool changers on the left
> so
> it makes more sense to have the 4th on the right.
>
> Thanks
> John
>
>
>
>
>
>
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[Emc-users] Home switches.

[John Dammeyer]

Quick mini survey.  If you have a knee mill, where have you mounted your
home switches?
I understand it doesn't matter because the machine coordinate system is only
used to establish a fixed reference.  For the rest of the time we use
various world coordinate systems with the G54...

So the switches:
For the Y axis so the bed moves towards you or away?
For the X axis so the bed moves to the left or to the right?
The Z axis obvious because we always want it to move away from the tool tip
to avoid a crash.

For example, if you periodically put your 4th Axis on the left hand side of
the bed it's probably better to have the system home so the table moves to
the left. In effect this makes the tool move to the right Just in case you
ask it to home but forgot that you had the 4th axis bolted down.

And that brings up the third question about a 4th axis.  If you have one, do
you tend to put it on the left just like a lathe spindle or on the right?
Any reason for the preference?  Often there are tool changers on the left so
it makes more sense to have the 4th on the right.

Thanks
John





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[Emc-users] Home Switches

[Len Shelton]

I am trying to setup a new machine with EMC2 and Axis using home switches.
Everything seems to be working fine, except that z sets itself to 8.5202
after homing.

Even though I have:

HOME = 0.0
HOME_OFFSET = 0.00

Where is it pulling this 8.5202? I can find no reference to any number like
that anywhere in the config files.

Len





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Re: [Emc-users] Home Switches

[stustev]

Do a 'g92 z0' after you home the machine. This will reset the position. Restart 
to confirm.
Sent via BlackBerry from T-Mobile

-Original Message-
From: Len Shelton [EMAIL PROTECTED]

Date: Fri, 7 Nov 2008 11:17:19 
To: 'Enhanced Machine Controller \(EMC\)'emc-users@lists.sourceforge.net
Subject: [Emc-users] Home Switches


I am trying to setup a new machine with EMC2 and Axis using home switches.
Everything seems to be working fine, except that z sets itself to 8.5202
after homing.

Even though I have:

HOME = 0.0
HOME_OFFSET = 0.00

Where is it pulling this 8.5202? I can find no reference to any number like
that anywhere in the config files.

Len





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Re: [Emc-users] Home Switches

[Ray Henry]

On Fri, 2008-11-07 at 11:17 -0600, Len Shelton wrote:
 I am trying to setup a new machine with EMC2 and Axis using home switches.
 Everything seems to be working fine, except that z sets itself to 8.5202
 after homing.
 
 Even though I have:
 
 HOME = 0.0
 HOME_OFFSET = 0.00
 
 Where is it pulling this 8.5202? I can find no reference to any number like
 that anywhere in the config files.

I'd guess that it's in the var file that is being read at startup.
Could be a g92 or one of the coordinate offset systems.  The var file
contents are described in the user handbook in the coordinate systems
chapter.

I don't remember much about it but the AXIS interface system can also be
setup to remember last position between runs for those who don't have
home switches.  I wouldn't think this would be the case but others would
have to figure that out.

Rayh




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Re: [Emc-users] Home Switches

[Len Shelton]

Thanks. That worked. Any idea how it got set? This is a brand new install
and I am not at all new to EMC2.

Len



-Original Message-
From: Chris Radek [mailto:[EMAIL PROTECTED] 
Sent: Friday, November 07, 2008 11:51 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Home Switches

On Fri, Nov 07, 2008 at 11:17:19AM -0600, Len Shelton wrote:
 I am trying to setup a new machine with EMC2 and Axis using home switches.
 Everything seems to be working fine, except that z sets itself to 8.5202
 after homing.
 
 Even though I have:
 
 HOME = 0.0
 HOME_OFFSET = 0.00
 
 Where is it pulling this 8.5202? I can find no reference to any number
like
 that anywhere in the config files.

You have a work offset or a G92 offset.

To clear the work offset, Machine / Zero coordinate system / G54 (or
home and then Touch Off zero) and then be sure to read about Touch
Off in the user manual since you will have to understand how to use
work offsets now that you have homing.  Looks like sections 2.2.1 and
2.3.4.1 are relevant although a little lean.

To clear a G92 offset, program G92.1 in MDI.  (In the upcoming EMC2.3
you will be able to clear G92 offsets in the Machine/Zero... menu
also.)


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Re: [Emc-users] Home Switches

[Chris Radek]

On Fri, Nov 07, 2008 at 12:10:33PM -0600, Len Shelton wrote:
 Thanks. That worked. Any idea how it got set? This is a brand new install
 and I am not at all new to EMC2.

Depends - you don't say which kind of offset it turns out it was.  If
it was G54, you set it with touch off or G10 L2 P1 Z...  If it was
G92, you set it with G92.


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Re: [Emc-users] Home Switches

[Jeff Epler]

Here's the page I always refer to when emc's DRO shows something
different than what I expect:

http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?CoordinateSystems#So_if_you_re_lost_what_should_you_do

Jeff

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Re: [Emc-users] Home Switches

[Jon Elson]

Len Shelton wrote:
 I am trying to setup a new machine with EMC2 and Axis using home switches.
 Everything seems to be working fine, except that z sets itself to 8.5202
 after homing.

 Even though I have:

 HOME = 0.0
 HOME_OFFSET = 0.00

 Where is it pulling this 8.5202? I can find no reference to any number like
 that anywhere in the config files.
   
I think this is based on the last offset between home and a work 
coordinate.  It would be in your x.var file.
Since your home offset is zero, then it should appear as 8.5202 in that 
file, unless your machine is defined in a different unit (mm vs inches) 
hat the default display units.

Jon

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