Re: [Emc-users] Resetting rotary movement count

2016-01-10 Thread Marcus Bowman 

On 10 Jan 2016, at 00:22, andy pugh wrote:

> On 5 January 2016 at 11:34, Dave Caroline  wrote:
>> Here is an example of with and without limits in a trunnion design
>> http://www.ebay.co.uk/itm/CNC-Rotary-Table-Dividing-Head-Rotational-Axis-4th-5th-Axis-A-B-Axis-100MM-Chuck-/161679996211
> 
That's an interesting configuration. There are a lot of small attractive 
looking Chinese 4th axes at reasonable prices, but I do have reservations. If I 
coudl be convinced they were accurate, I would happily order one; but other 
Chinese accessories are not of the standard to which I aspire, so I'm hesitant.

> Here is another, the B axis on this:
> https://www.youtube.com/watch?v=mEsuTX6Empc
> 
Ah yes; Centroid. Gorgeous stuff. I've seen photos of their kit before, but 
that system with the clip-on t-slotted table looks very useful indeed, and it 
has given me some ideas.

Marcus

> I mention it as it is also a very simple and rigid one that would be
> an easy retrofit to many tilting-head mills.
> 
> -- 
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Re: [Emc-users] Resetting rotary movement count

2016-01-10 Thread Erik Christiansen 
On 10.01.16 09:45, Marcus Bowman wrote:
> On 10 Jan 2016, at 00:22, andy pugh wrote:
> 
> > On 5 January 2016 at 11:34, Dave Caroline  
> > wrote:
> >> Here is an example of with and without limits in a trunnion design
> >> http://www.ebay.co.uk/itm/CNC-Rotary-Table-Dividing-Head-Rotational-Axis-4th-5th-Axis-A-B-Axis-100MM-Chuck-/161679996211
> > 
> That's an interesting configuration. There are a lot of small
> attractive looking Chinese 4th axes at reasonable prices, but I do
> have reservations. If I coudl be convinced they were accurate, I would
> happily order one; but other Chinese accessories are not of the
> standard to which I aspire, so I'm hesitant.

ISTM that the table can only tilt +/- 45° or so. Since the need for a
symmetrical swing is obviated by rotation of the chuck, I'd rather have
one which could swing 90° one way, from horizontal to vertical.

The coarser axis has a resolution of 0.3°, assuming 1.8° steppers, and
holding accuracy will be a function of cutting forces, I figure. If
anything finer than full steps are attempted, holding torque quickly
goes downhill. A clamping brake on the table would be a handy
addition. (A cone brake might might minimise misalignment as the brake
is applied?)

Erik

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Re: [Emc-users] Resetting rotary movement count

2016-01-10 Thread Gene Heskett 
On Sunday 10 January 2016 06:56:35 Erik Christiansen wrote:

> On 10.01.16 09:45, Marcus Bowman wrote:
> > On 10 Jan 2016, at 00:22, andy pugh wrote:
> > > On 5 January 2016 at 11:34, Dave Caroline 
 wrote:
> > >> Here is an example of with and without limits in a trunnion
> > >> design
> > >> http://www.ebay.co.uk/itm/CNC-Rotary-Table-Dividing-Head-Rotation
> > >>al-Axis-4th-5th-Axis-A-B-Axis-100MM-Chuck-/161679996211
> >
> > That's an interesting configuration. There are a lot of small
> > attractive looking Chinese 4th axes at reasonable prices, but I do
> > have reservations. If I coudl be convinced they were accurate, I
> > would happily order one; but other Chinese accessories are not of
> > the standard to which I aspire, so I'm hesitant.
>
> ISTM that the table can only tilt +/- 45° or so. Since the need for a
> symmetrical swing is obviated by rotation of the chuck, I'd rather
> have one which could swing 90° one way, from horizontal to vertical.
>
> The coarser axis has a resolution of 0.3°, assuming 1.8° steppers, and
> holding accuracy will be a function of cutting forces, I figure. If
> anything finer than full steps are attempted, holding torque quickly
> goes downhill. A clamping brake on the table would be a handy
> addition. (A cone brake might might minimise misalignment as the brake
> is applied?)
>
> Erik

Depending on what you want to do. I see those as engraving only helpers 
as neither of the 3 choices on that page have motors big enough to have 
any REAL holding torque to resist even 0.125" carbide mills cutting 
forces.  A version like the British 230 priced one, where the limit of 
rotation for the second axis would be nominally +-360 degrees due to 
life considerations of its motor cable being externally twisted as it 
passes thru the hole in the carriage, makes far more sense, but needs 
scaled up about 4x to make room for additional gear down, and equipped 
with triple-stack, 500oz/in nema 23 motors.  With that scale up, one 
could have room for a pair of 8/1 reductions, which if the belts are 
tight enough, ought to be 0.0375 degree accurate.  I'd assume shop made, 
buying one like the 229 pound sterling one, scaled up big enough to just 
fit on my G0704's table would need the proverbial little red wagon 
loaded with $50 rolls of our dollar coins.  And making it might be fun!

Cheers, Gene Heskett
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Re: [Emc-users] Resetting rotary movement count

2016-01-09 Thread andy pugh 
On 5 January 2016 at 11:34, Dave Caroline  wrote:
> Here is an example of with and without limits in a trunnion design
> http://www.ebay.co.uk/itm/CNC-Rotary-Table-Dividing-Head-Rotational-Axis-4th-5th-Axis-A-B-Axis-100MM-Chuck-/161679996211

Here is another, the B axis on this:
https://www.youtube.com/watch?v=mEsuTX6Empc

I mention it as it is also a very simple and rigid one that would be
an easy retrofit to many tilting-head mills.

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Re: [Emc-users] Resetting rotary movement count [Solved]

2016-01-06 Thread Marcus Bowman 

On 5 Jan 2016, at 23:10, Marcus Bowman wrote:

> 
> 
> On 5 Jan 2016, at 22:48, John Thornton wrote:
> 
>> Just leave the limits out of the ini for the rotary.
>> 
>> http://linuxcnc.org/docs/2.7/html/config/ini-config.html#_axis__lt_num_gt_section
>> 
>> JT
> 
> Thanks, John. I see the emails from Dewey and Jon as well. I met the same 
> problem again this afternoon, when doing extensive manual jogging (trying to 
> get an awkward job concentric). I will try the suggested solution tomorrow.
> 
> Marcus
>> 

Tried that this morning and it works just fine. No problem in going to large 
total number of degrees rotation.
Problem solved.
Many thanks.

Marcus



>> On 1/5/2016 4:43 PM, Marcus Bowman wrote:
>>> 
>>> Anyway; for now I will try much larger limits on the odd occasion when I 
>>> need to do this kind of rotary motion. Or do the job another way. In this 
>>> case, the (diameter of the job + 2 x diameter of cutter) exceeded the Y 
>>> travel on my mill, so I thought that using the rotary table was a 
>>> reasonable solution. I could have done it in the manual lathe, but really 
>>> object to the time that would take, so I stuck it on the mill while I got 
>>> on with other jobs. One of the bonuses of CNC after all.
>>> 
>>> Regards,
>>> 
>>> Marcus
>>> 
>>> 
>> 
>> 
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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Gregg Eshelman 
On 1/5/2016 12:32 AM, Dave Caroline wrote:
> I had problems in this area, I think it is not a feature but a bug
> that an rotary axis cannot be set to 0 or be infinite in its
> rotations, the wrapped rotary docs as an option just seemed wrong for
> this when I last read them a few years ago.
> Winding back is a very slow operation and should not be needed.
>
> There are rotaries with mechanical limits and rotaries without limits,
> an arbitrary large number used as a limit is a kludge waiting to bite
> the unsuspecting.

Why not simply allow a stop-less rotary axis to roll over, with an index 
pulse that indicates where the "ends" are so the control can know 
exactly where the axis' rotation is? Or use an absolute position 
stop-less encoder.


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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Gene Heskett 
On Tuesday 05 January 2016 02:32:51 Dave Caroline wrote:

> I had problems in this area, I think it is not a feature but a bug
> that an rotary axis cannot be set to 0 or be infinite in its
> rotations, the wrapped rotary docs as an option just seemed wrong for
> this when I last read them a few years ago.
> Winding back is a very slow operation and should not be needed.
>
> There are rotaries with mechanical limits and rotaries without limits,
> an arbitrary large number used as a limit is a kludge waiting to bite
> the unsuspecting.
>
> Dave Caroline

I've not seen a rotary that could not turn forever. Can you supply a URL 
to such a device?

I can see both sides of the problem, but it would appear to be a complex 
fix to treat rotary's differently in the touch off, and would be subject 
to throwing away the residual error the planner now tracks.  That would 
be a source of a residual error condition unless it was actually rehomed 
to a sensor.

But how many of us even have a home switch on the A axis?  We tend to lay 
a machinists level on the workpiece, run it till the bubble is centered, 
or if really finicky, matches the table error, and call it zero.  I dare 
say we could count raised hands on our fingers & not need to remove our 
shoes. :)

Or am I the odd man out here?  It has happened before. :(

Cheers, Gene Heskett
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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Gene Heskett 
On Tuesday 05 January 2016 06:34:12 Dave Caroline wrote:

> Here is an example of with and without limits in a trunnion design
> http://www.ebay.co.uk/itm/CNC-Rotary-Table-Dividing-Head-Rotational-Ax
>is-4th-5th-Axis-A-B-Axis-100MM-Chuck-/161679996211
>
> Dave

Ya got me Dave. :)
W/O moving the motor on the left to the trunnion, with slip rings, the 
motor on the right must be restricted.  But I was thinking single axis 
stuff. :)
>
> On 05/01/2016, andy pugh  wrote:
> > On 5 January 2016 at 04:37, Cecil Thomas  
wrote:
> >> By the way if there have been any changes in LCNC that let you
> >> "home" or set the rotary axis back to zero without exiting the
> >> program or actually running the axis back to zero I'd like to know
> >> about it since I haven't looked into it for over 10 years.
> >
> > Re-homing the rotary would reset the absolute position.
> > There are HAL pins to home each axis. (halui.joint.N.home bit in)
> > You can drive a bit pin from G-code.
> > So I think it could be done, but it seems like a kludge.
> >
> > --
> > atp
> > If you can't fix it, you don't own it.
> > http://www.ifixit.com/Manifesto
> >
> > 
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Cheers, Gene Heskett
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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Chris Radek 
On Tue, Jan 05, 2016 at 10:12:15AM +, andy pugh wrote:
> 
> Re-homing the rotary would reset the absolute position.
> There are HAL pins to home each axis. (halui.joint.N.home bit in)
> You can drive a bit pin from G-code.
> So I think it could be done, but it seems like a kludge.

You can't home while gcode is running; you have to stop and switch
to manual mode.

I think dewey has found a fine answer: remove the lines from the ini
and don't worry.  If someone cares about the difference between
MAXDOUBLE and 1e99, we could sure change it.


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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Jon Elson 
On 01/05/2016 03:33 AM, Gene Heskett wrote:
>
> I've not seen a rotary that could not turn forever. Can you supply a URL
> to such a device?
>
>
Yes, stacked rotary axes.  We use one at work.  they have a 
little Yuasa rotary table bolted to a HUGE Yuasa rotary 
table.  The small table has a control cable and an air 
line.  Also, in some setups, the small table will hit the 
machine table if the big table is turned past a certain 
angle.  They use this to cut the insane geometries my boss 
invents.

Jon

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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Marcus Bowman 

On 5 Jan 2016, at 13:30, andy pugh wrote:

> On 5 January 2016 at 13:11, Sarah Armstrong
>  wrote:
>> or
>> 999,999,999,999,999,967,336,168,804,116,691,273,849,533,185,806,555,472,917,961,779,471,295,845,921,727,862,608,739,868,455,469,056.00
> 
> You wouldn't want to get anywhere near this limit, though.
> 
> The real practical limit is the number of significant figures in the
> floating-point format (about 16). The difference between 1e99 and the
> next smallest representable number is about 10^83 complete
> revolutions.
> 
> For a 90:1 rotary and a 4096 count encoder you have an angular
> resolution of 3.5 arc seconds. or .0.001 degrees. After only
> 999 degrees the double precision format can no longer
> discriminate between numbers one encoder count apart. A fairly fast
> rotary could get there in less than 100 years.
> 

Oh well; I suppose there is some hope then ...

Thanks for all your contributions, I had feared I was missing something obvious.
It does seem to me that there is a fundamental difference between linear and 
rotary axes. You would not want to exceed a defined limit on a linear axis 
simply because the slide would come to the end of its travel (or off the end), 
so exceeding the limit does not make mechanical sense.
With a rotary axis, it is entirely different. That suggests that limits should 
not be thought of, or applied, in the same way. I can't see any disadvantages 
in automatically treating rotary axes in a different way. The problem, I guess, 
is that while some axes on a mill or a lathe would naturally be treated as 
rotary, other unspecified machines with unspecified axis movement types would 
then need exceptions. It's a penalty of flexibility.
Anyway; for now I will try much larger limits on the odd occasion when I need 
to do this kind of rotary motion. Or do the job another way. In this case, the 
(diameter of the job + 2 x diameter of cutter) exceeded the Y travel on my 
mill, so I thought that using the rotary table was a reasonable solution. I 
could have done it in the manual lathe, but really object to the time that 
would take, so I stuck it on the mill while I got on with other jobs. One of 
the bonuses of CNC after all.

Regards,

Marcus

> -- 
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> If you can't fix it, you don't own it.
> http://www.ifixit.com/Manifesto
> 
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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread John Thornton 
Just leave the limits out of the ini for the rotary.

http://linuxcnc.org/docs/2.7/html/config/ini-config.html#_axis__lt_num_gt_section

JT

On 1/5/2016 4:43 PM, Marcus Bowman wrote:
>
> Anyway; for now I will try much larger limits on the odd occasion when I need 
> to do this kind of rotary motion. Or do the job another way. In this case, 
> the (diameter of the job + 2 x diameter of cutter) exceeded the Y travel on 
> my mill, so I thought that using the rotary table was a reasonable solution. 
> I could have done it in the manual lathe, but really object to the time that 
> would take, so I stuck it on the mill while I got on with other jobs. One of 
> the bonuses of CNC after all.
>
> Regards,
>
> Marcus
>
>


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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Dave Caroline 
Here is an example of with and without limits in a trunnion design
http://www.ebay.co.uk/itm/CNC-Rotary-Table-Dividing-Head-Rotational-Axis-4th-5th-Axis-A-B-Axis-100MM-Chuck-/161679996211

Dave

On 05/01/2016, andy pugh  wrote:
> On 5 January 2016 at 04:37, Cecil Thomas  wrote:
>> By the way if there have been any changes in LCNC that let you "home"
>> or set the rotary axis back to zero without exiting the program or
>> actually running the axis back to zero I'd like to know about it
>> since I haven't looked into it for over 10 years.
>
> Re-homing the rotary would reset the absolute position.
> There are HAL pins to home each axis. (halui.joint.N.home bit in)
> You can drive a bit pin from G-code.
> So I think it could be done, but it seems like a kludge.
>
> --
> atp
> If you can't fix it, you don't own it.
> http://www.ifixit.com/Manifesto
>
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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Dewey Garrett 
>I had problems in this area, I think it is not a feature but a bug
>that an rotary axis cannot be set to 0 or be infinite in its

If [AXIS_n]MAX_LIMIT is missing, the value used is 1e99

http://git.linuxcnc.org/gitweb?p=linuxcnc.git;a=blob;f=src/emc/ini/iniaxis.cc;h=ee0a6d6a2ed4cb0440418b063287475484d6f5ab;hb=refs/heads/2.7

src/emc/ini/iniaxis.cc
 163 // set max position limit
 164 limit = 1e99;   // default
 165 axisIniFile->Find(, "MAX_LIMIT", axisString);
 166 
 167 if (0 != emcAxisSetMaxPositionLimit(axis, limit)) {
 168 if (emc_debug & EMC_DEBUG_CONFIG) {
 169 rcs_print_error("bad return from 
emcAxisSetMaxPositionLimit\n");
 170 }
 171 return -1;
 172 }
-- 
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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Stuart Stevenson 
Gentlemen,
On my bridge mill

5 axis
Fanuc 15mb
XYZ linear axes
BC head with the B axis riding on the C axis - picture of same but newer
machine http://mightyusa.com/b-5000%205bc.html

Absolute encoders on all axes
C axis has slip rings - there is no need to unwind while cutting - the axis
can rotate 'infinitely'

notice the quotes around infinitely as the control allows 9,999.999 degrees
of encoder count

XYZB cannot exceed the encoder count because of physical limits

C has unlimited physical motion capability - the control has limited motion
capability
I would think the newer control has larger registers but I do not know this
as fact.

I had to size a large hole through a large punch press connecting rod. The
head barely fit into the hole and the part was tall enough I had to rotate
the B axis up to allow clearance to position the head over the hole. With a
ball nose end mill in the spindle I set the diameter by rotating the B axis
and bored the hole by rotating the C axis.

First pass roughing I rotated the C axis 1 revolution, moved Z down and
rotated C again.
Repeating for every pass with a loop I was surprised the machine stopped
after just a few passes. C axis machine position was 9,999.999 degrees.

I changed the program to reset the C to zero for every pass. Surely this
would allow the program to finish. Not so, the machine stopped in exactly
the same spot.

I was able to cut the part by changing the program to rotate one direction,
move down, rotate the opposite direction, move down, then loop the program.

This worked just fine but it shows fanuc controls handle the axis motion in
the same manner as LinuxCNC. I would guess all controls would handle the
axis motion in the same manner.

I have no experience with a lathe that the spindle is also a C axis.

thanks
Stuart

On Tue, Jan 5, 2016 at 5:34 AM, Dave Caroline 
wrote:

> Here is an example of with and without limits in a trunnion design
>
> http://www.ebay.co.uk/itm/CNC-Rotary-Table-Dividing-Head-Rotational-Axis-4th-5th-Axis-A-B-Axis-100MM-Chuck-/161679996211
>
> Dave
>
> On 05/01/2016, andy pugh  wrote:
> > On 5 January 2016 at 04:37, Cecil Thomas  wrote:
> >> By the way if there have been any changes in LCNC that let you "home"
> >> or set the rotary axis back to zero without exiting the program or
> >> actually running the axis back to zero I'd like to know about it
> >> since I haven't looked into it for over 10 years.
> >
> > Re-homing the rotary would reset the absolute position.
> > There are HAL pins to home each axis. (halui.joint.N.home bit in)
> > You can drive a bit pin from G-code.
> > So I think it could be done, but it seems like a kludge.
> >
> > --
> > atp
> > If you can't fix it, you don't own it.
> > http://www.ifixit.com/Manifesto
> >
> >
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>
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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Sarah Armstrong 
or
999,999,999,999,999,967,336,168,804,116,691,273,849,533,185,806,555,472,917,961,779,471,295,845,921,727,862,608,739,868,455,469,056.00

On 5 January 2016 at 13:03, Dewey Garrett  wrote:

> >I had problems in this area, I think it is not a feature but a bug
> >that an rotary axis cannot be set to 0 or be infinite in its
>
> If [AXIS_n]MAX_LIMIT is missing, the value used is 1e99
>
>
> http://git.linuxcnc.org/gitweb?p=linuxcnc.git;a=blob;f=src/emc/ini/iniaxis.cc;h=ee0a6d6a2ed4cb0440418b063287475484d6f5ab;hb=refs/heads/2.7
>
> src/emc/ini/iniaxis.cc
>  163 // set max position limit
>  164 limit = 1e99;   // default
>  165 axisIniFile->Find(, "MAX_LIMIT", axisString);
>  166
>  167 if (0 != emcAxisSetMaxPositionLimit(axis, limit)) {
>  168 if (emc_debug & EMC_DEBUG_CONFIG) {
>  169 rcs_print_error("bad return from
> emcAxisSetMaxPositionLimit\n");
>  170 }
>  171 return -1;
>  172 }
> --
> Dewey Garrett
>
>
>
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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Dave Caroline 
Dewey I had no idea that size limit existed, same default for negative?

Maybe time for an update to the docs? even removal of the standard
 from stepconf (or at least ask the user)

Dave

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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread andy pugh 
On 5 January 2016 at 13:11, Sarah Armstrong
 wrote:
> or
> 999,999,999,999,999,967,336,168,804,116,691,273,849,533,185,806,555,472,917,961,779,471,295,845,921,727,862,608,739,868,455,469,056.00

You wouldn't want to get anywhere near this limit, though.

The real practical limit is the number of significant figures in the
floating-point format (about 16). The difference between 1e99 and the
next smallest representable number is about 10^83 complete
revolutions.

For a 90:1 rotary and a 4096 count encoder you have an angular
resolution of 3.5 arc seconds. or .0.001 degrees. After only
999 degrees the double precision format can no longer
discriminate between numbers one encoder count apart. A fairly fast
rotary could get there in less than 100 years.

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Re: [Emc-users] Resetting rotary movement count

2016-01-05 Thread Marcus Bowman 


On 5 Jan 2016, at 22:48, John Thornton wrote:

> Just leave the limits out of the ini for the rotary.
> 
> http://linuxcnc.org/docs/2.7/html/config/ini-config.html#_axis__lt_num_gt_section
> 
> JT

Thanks, John. I see the emails from Dewey and Jon as well. I met the same 
problem again this afternoon, when doing extensive manual jogging (trying to 
get an awkward job concentric). I will try the suggested solution tomorrow.

Marcus
> 
> On 1/5/2016 4:43 PM, Marcus Bowman wrote:
>> 
>> Anyway; for now I will try much larger limits on the odd occasion when I 
>> need to do this kind of rotary motion. Or do the job another way. In this 
>> case, the (diameter of the job + 2 x diameter of cutter) exceeded the Y 
>> travel on my mill, so I thought that using the rotary table was a reasonable 
>> solution. I could have done it in the manual lathe, but really object to the 
>> time that would take, so I stuck it on the mill while I got on with other 
>> jobs. One of the bonuses of CNC after all.
>> 
>> Regards,
>> 
>> Marcus
>> 
>> 
> 
> 
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Re: [Emc-users] Resetting rotary movement count

2016-01-04 Thread Chris Radek 
On Mon, Jan 04, 2016 at 11:18:20PM +, Marcus Bowman wrote:
> 
> so the fault message indicates the G10 L20 resets the co-ordinates
> of the selected co-ordinate system, but not the absolute machine
> co-ordinates. This means I do not have a command to prevent
> rotation being cumulative and counting against the Max-Limit for
> that axis. That can't be right??

That's right.  You're setting an offset that makes A=0.

> Is there a way to reset the Max_Limit count (in other words, to do
> the equivalent of G10 L20 for the absolute machine co-ordinates.

Nope, unfortunately.

> Or have I missed something?

Just add some more nines to your MIN and MAX limits.

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Re: [Emc-users] Resetting rotary movement count

2016-01-04 Thread Gene Heskett 
On Monday 04 January 2016 18:34:20 andy pugh wrote:

> On 4 January 2016 at 23:18, Marcus Bowman
>
>  wrote:
> > Taking another view, absolute machine co-ordinates should be just
> > that - absolute. In that case, Max_Limit should refer to a count of
> > the co-ordinates within the currently selected co-ordinate system
> > G54 etc so that I can reset that count by resetting the
> > co-ordinates.
>
> No, the max-limit and min-limit are the hard physical limits of the
> axis, and are absolute.
>
> However, there ought to be a way to disable the limits on a rotary
> axis. You could just use much bigger numbers.  degrees is only 27
> full revolutions. I don't know if there is any limit to how big the
> limits can be, it's probably float-max (10^308)

Is my memory acting its 81 year of age Andy?  ISTR reading someplace, 
quite years ago, that setting those limits to 0.0 disabled them.  Or is 
this true of only the linear axis's?

Cheers, Gene Heskett
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[Emc-users] Resetting rotary movement count

2016-01-04 Thread Marcus Bowman 
I created a program to cut a circle from thick steel plate, moving the X axis 
to the radius of the plate, and using the rotary table to rotate the blank. It 
slowly cut its way through until it came to the Max_Limit for the rotary axis 
() then it stopped with an error message saying the next move would exceed 
the limit for that axis.

Here's the puzzling thing, though.

My program repeats the sequence:
do one rotation using G0 A360 Zsomething
then reset the A value using G10 L20 P1 A0

so the fault message indicates the G10 L20 resets the co-ordinates of the 
selected co-ordinate system, but not the absolute machine co-ordinates. This 
means I do not have a command to prevent rotation being cumulative and counting 
against the Max-Limit for that axis. That can't be right??
Is there a way to reset the Max_Limit count (in other words, to do the 
equivalent of G10 L20 for the absolute machine co-ordinates.
Taking one view, I should be able to do this, to prevent this problem.
Taking another view, absolute machine co-ordinates should be just that - 
absolute. In that case, Max_Limit should refer to a count of the co-ordinates 
within the currently selected co-ordinate system G54 etc so that I can reset 
that count by resetting the co-ordinates.

Or have I missed something?

Marcus
   
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Re: [Emc-users] Resetting rotary movement count

2016-01-04 Thread andy pugh 
On 4 January 2016 at 23:18, Marcus Bowman
 wrote:
> Taking another view, absolute machine co-ordinates should be just that - 
> absolute. In that case, Max_Limit should refer to a count of the co-ordinates 
> within the currently selected co-ordinate system G54 etc so that I can reset 
> that count by resetting the co-ordinates.

No, the max-limit and min-limit are the hard physical limits of the
axis, and are absolute.

However, there ought to be a way to disable the limits on a rotary
axis. You could just use much bigger numbers.  degrees is only 27
full revolutions. I don't know if there is any limit to how big the
limits can be, it's probably float-max (10^308)


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Re: [Emc-users] Resetting rotary movement count

2016-01-04 Thread Cecil Thomas 
I have a small lathe that I set up to use a servo drive on the 
spindle, essentially making the spindle a rotary axis.  The servo was 
large enough to provide the torque needed to make the cuts and it 
made coordinated spindle moves wonderfully. (think thread cutting, 
cam grinding, milling cutter relief grinding etc.)
The only problem was that there was no simple way to set the spindle 
back to zero degrees WITHIN a program without actually "unwinding 
it".  I searched long and hard for a solution and was finally 
convinced by those who know a lot more about the workings of the 
trajectory planner than I (which would be anything at all) that it 
can't be done for the reasons just explained.

By the way if there have been any changes in LCNC that let you "home" 
or set the rotary axis back to zero without exiting the program or 
actually running the axis back to zero I'd like to know about it 
since I haven't looked into it for over 10 years.

Cecil


At 06:18 PM 1/4/2016, you wrote:

>Or have I missed something?
>
>Marcus
>
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Re: [Emc-users] Resetting rotary movement count

2016-01-04 Thread Dave Caroline 
I had problems in this area, I think it is not a feature but a bug
that an rotary axis cannot be set to 0 or be infinite in its
rotations, the wrapped rotary docs as an option just seemed wrong for
this when I last read them a few years ago.
Winding back is a very slow operation and should not be needed.

There are rotaries with mechanical limits and rotaries without limits,
an arbitrary large number used as a limit is a kludge waiting to bite
the unsuspecting.

Dave Caroline

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