Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

On Thursday 18 April 2019 15:29:35 Roland Jollivet wrote:

>  > > Ditto if using an R8 directly, the R8 gets tightened with a 20
>  > > volt
> > >
> > > electric impact wrench driving an 8 point 10mm socket a lot
> > > tighter than I can draw it by hand with the supplied toy 10mm
> > > endwrench.  If not, the TTS in the R8 may slip and walk out. The
> > > life of that socket before it splits might be 50 times, its hell
> > > on good quality sockets.
>
> Hi Gene
>
> I found this video that may be food for thought.
>
I saw it even before I bought this thing.  And like you, either they 
can't write code that will do all that in one swell foop, or there was 
something wrong from the gitgo that I still haven't spotted.  That was 
also one honking big machine. I have not figured out what the piece 
bouncing around in the plate attached to the bottom of the motot to 
supply an anchor for the shaft lock.  It should be in or out, not 
bouncing around like a loose horseshoe.

I discounted the idea originally because of the cost of all those gears, 
and the ER32 nuts too.  Very well built, way too well built IMO. If I 
build it with a swing arm so it can stay off the table, I might consider 
such a set of relay gears to rotate the socket.  But that also would use 
up 1.5" of vertical move room this 6040 doesn't have to spare.  No way 
could I swap 2 drill bits half that long with the travel I have.

But with good driver code, it could work well on a machine you've already 
spent 10G's on.

> It's very slow because they were just testing out, and there's no
> follow up video either..  (still looking)
>
> https://www.youtube.com/watch?v=V0v_aP8hXR8
>
> From what I see;
> - this is a six station ATC
> - a motor drives a belt that drives two small gears
> - each small gear drives three large gears
> - each large gear carries a socket.
>
> While their sockets all rotate the same way, you could just cascade
> all the large gears in a straight line, and use opposite motion
> sequence for alternate pockets. With some mechanical loss as you go
> down the line.

I've not fine tuned it yet, but I finally did find the low speed torque 
boost controls in this VFD  So I may have that problem whupped. Maybe. 
Turns out the factory defaults place the frequency breakpoints for a 3 
point curve so low they have no effect at usable revs.  Nice way to keep 
a lid operator from burning up his motor, or the VFD, in the first 30 
minutes. 

Usefull settings TBD, but its progress.

Thanks & take care Rolland.

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)
Genes Web page 



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[Emc-users] Something to think about re the hack-a-day tool changer

[Roland Jollivet]

 > > Ditto if using an R8 directly, the R8 gets tightened with a 20 volt
> > electric impact wrench driving an 8 point 10mm socket a lot tighter
> > than I can draw it by hand with the supplied toy 10mm endwrench.  If
> > not, the TTS in the R8 may slip and walk out. The life of that
> > socket before it splits might be 50 times, its hell on good quality
> > sockets.
> >

Hi Gene

I found this video that may be food for thought.

It's very slow because they were just testing out, and there's no follow up
video either..  (still looking)

https://www.youtube.com/watch?v=V0v_aP8hXR8

>From what I see;
- this is a six station ATC
- a motor drives a belt that drives two small gears
- each small gear drives three large gears
- each large gear carries a socket.

While their sockets all rotate the same way, you could just cascade all the
large gears in a straight line, and use opposite motion sequence for
alternate pockets. With some mechanical loss as you go down the line.

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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[TJoseph Powderly]

 Forwarded Message 
Subject: 	Re: [Emc-users] Something to think about re the hack-a-day 
tool changer

Date:   Thu, 18 Apr 2019 23:22:19 +0700
From:   TJoseph Powderly 
To: Gene Heskett 



Hi Gene

On 04/18/2019 10:57 PM, Gene Heskett wrote:

On Thursday 18 April 2019 11:50:00 Ken Strauss wrote:
Google is your friend! ft-lb =Nm * 0.73756 So 75Nm = 55.3 ft lbs 
55 ft/lbs? Here the tool will walk out and break, very quickly at that 
tension. Doubtfull I have used less than 75 ft-pounds on the TTS 
adapters I use fairly universally on the G0704. 

on the web you can find suggested max torque for er collets
https://www.techniksusa.com/metal/torque_chart.htm
that url has torque wrench adapters as well ( $$$ )

( i have eoc8a collets tho, and have found no numeric values, only
descriptions of hand tightening )

you can find mfctrs saying use 75-80% of the max torque value.
you can find the caveats that the tool shank has to fully contact the
collet, not larger or smaller allowed.
you can find that the release is going to have stiction and release
requires more initial force.
other caveats about cleaning and air blasts are used in industry
( even collets covering the air blast holes and checking back pressure
in attempts to check good seating )

Andy's pragmatic checking of needed torque with a proper torque wrench
is very good ( what works is a good place to start)

also note the xatc ver 0.3 is already old and the google group on xatc
is cold since 2016.
you're kinda the lead developer now


-Original Message- From: Gene Heskett 
[mailto:ghesk...@shentel.net] Sent: Thursday, April 18, 2019 11:45 
AM To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] 
Something to think about re the hack-a-day tool changer On Thursday 
18 April 2019 07:47:51 andy pugh wrote:
On Thu, 18 Apr 2019 at 10:22, Roland Jollivet 

 wrote:
To recap; small steppers 'drive' the carousel around to tighten 
the motor. 
No, the motor drives round the carousel to tighten the collet. It 
is really rather clever. Assuming that it can't work based purely 
on guess-work seems silly. 
No, not silly, experience Andy, experience reaching into the bank 
account to replace tooling that broke by walking out of the holder 
when I thought it was tight enough.
I suggested a very simple test using the same torque wrench as Gene 
presumably uses now to tighten his collets to the correct torque to 
test the hypothesis. 
All 4 of my 5 torque wrenches are in foot/pounds. The smallest is in 
inch pounds. How much is 75Nm, in inch pounds.
But, assuming a 5mm pitch screw and 5:1 motor reduction: (0.5 Nm 
stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a 75mm arm 
that is 235Nm. Correct torque for an ER20 is 75Nm. 
That is no where near tight enough to keep it from walking out of 
the collet and breaking the tool because its digging 3/8" on a cut 
that should be 20 thou if it hadn't walked out. Here I use an end 
wrench about 15" long, ground thin enough to fit the flats on the 
TTS holder, and a 10 or 12" crescent wrench and a pull on the 
wrenches that is likely in excess of 100 lb-ft. I don't have a 
newtom-meters to pound-foot conversion handy but that certainly is 
tighter than 75Nm. Ditto if using an R8 directly, the R8 gets 
tightened with a 20 volt electric impact wrench driving an 8 point 
10mm socket a lot tighter than I can draw it by hand with the 
supplied toy 10mm endwrench. If not, the TTS in the R8 may slip and 
walk out. The life of that socket before it splits might be 50 
times, its hell on good quality sockets.
(Though I am not convinced that an ER17 can really lift a 300kg 
mass, so suspect I messed something up. ) 
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) Genes Web page 
 
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Cheers, Gene Heskett

tomp


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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

On Thursday 18 April 2019 11:50:00 Ken Strauss wrote:

> Google is your friend!
> ft-lb =Nm * 0.73756
> So 75Nm = 55.3 ft lbs
>
55 ft/lbs?  Here the tool will walk out and break, very quickly at that 
tension. Doubtfull I have used less than 75 ft-pounds on the TTS 
adapters I use fairly universally on the G0704.

> > -Original Message-
> > From: Gene Heskett [mailto:ghesk...@shentel.net]
> > Sent: Thursday, April 18, 2019 11:45 AM
> > To: emc-users@lists.sourceforge.net
> > Subject: Re: [Emc-users] Something to think about re the hack-a-day
> > tool changer
> >
> > On Thursday 18 April 2019 07:47:51 andy pugh wrote:
> > > On Thu, 18 Apr 2019 at 10:22, Roland Jollivet
> >
> >  wrote:
> > > > To recap; small steppers 'drive' the carousel around to tighten
> > > > the motor.
> > >
> > > No, the motor drives round the carousel to tighten the collet.
> > >
> > > It is really rather clever. Assuming that it can't work based
> > > purely on guess-work seems silly.
> >
> > No, not silly, experience Andy, experience reaching into the bank
> > account to replace tooling that broke by walking out of the holder
> > when I thought it was tight enough.
> >
> > > I suggested a very simple test using the same torque wrench as
> > > Gene presumably uses now to tighten his collets to the correct
> > > torque to test the hypothesis.
> >
> > All 4 of my 5 torque wrenches are in foot/pounds. The smallest is in
> > inch pounds.  How much is 75Nm, in inch pounds.
> >
> > > But, assuming a 5mm pitch screw and 5:1 motor reduction:
> > > (0.5 Nm stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a
> > > 75mm arm that is 235Nm.
> > > Correct torque for an ER20 is 75Nm.
> >
> > That is no where near tight enough to keep it from walking out of
> > the collet and breaking the tool because its digging 3/8" on a cut
> > that should be 20 thou if it hadn't walked out.  Here I use an end
> > wrench about 15" long, ground thin enough to fit the flats on the
> > TTS holder, and a 10 or 12" crescent wrench and a pull on the
> > wrenches that is likely in excess of 100 lb-ft. I don't have a
> > newtom-meters to pound-foot conversion handy but that certainly is
> > tighter than 75Nm.
> >
> > Ditto if using an R8 directly, the R8 gets tightened with a 20 volt
> > electric impact wrench driving an 8 point 10mm socket a lot tighter
> > than I can draw it by hand with the supplied toy 10mm endwrench.  If
> > not, the TTS in the R8 may slip and walk out. The life of that
> > socket before it splits might be 50 times, its hell on good quality
> > sockets.
> >
> > > (Though I am not convinced that an ER17 can really lift a 300kg
> > > mass, so suspect I messed something up. )
> >
> > 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)
> > Genes Web page 
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
> ___
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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)
Genes Web page 



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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Stuart Stevenson]

Gene,
  One N/m is .737 ft/lb
  One hp is approx .745 watts
just think of the hp to watts conversion to mentally calculate the n/m to
ft/lb conversion - you will be close enough for almost any situation

in fact - using .75 for both conversions would work just fine

Stuart


On Thu, Apr 18, 2019 at 10:51 AM Ken Strauss  wrote:

> Google is your friend!
> ft-lb =Nm * 0.73756
> So 75Nm = 55.3 ft lbs
>
> > -Original Message-
> > From: Gene Heskett [mailto:ghesk...@shentel.net]
> > Sent: Thursday, April 18, 2019 11:45 AM
> > To: emc-users@lists.sourceforge.net
> > Subject: Re: [Emc-users] Something to think about re the hack-a-day tool
> > changer
> >
> > On Thursday 18 April 2019 07:47:51 andy pugh wrote:
> >
> > > On Thu, 18 Apr 2019 at 10:22, Roland Jollivet
> >  wrote:
> > > > To recap; small steppers 'drive' the carousel around to tighten the
> > > > motor.
> > >
> > > No, the motor drives round the carousel to tighten the collet.
> > >
> > > It is really rather clever. Assuming that it can't work based purely
> > > on guess-work seems silly.
> >
> > No, not silly, experience Andy, experience reaching into the bank account
> > to replace tooling that broke by walking out of the holder when I
> > thought it was tight enough.
> >
> > > I suggested a very simple test using the same torque wrench as Gene
> > > presumably uses now to tighten his collets to the correct torque to
> > > test the hypothesis.
> >
> > All 4 of my 5 torque wrenches are in foot/pounds. The smallest is in inch
> > pounds.  How much is 75Nm, in inch pounds.
> > >
> > >
> > > But, assuming a 5mm pitch screw and 5:1 motor reduction:
> > > (0.5 Nm stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a 75mm
> > > arm that is 235Nm.
> > > Correct torque for an ER20 is 75Nm.
> >
> > That is no where near tight enough to keep it from walking out of the
> > collet and breaking the tool because its digging 3/8" on a cut that
> > should be 20 thou if it hadn't walked out.  Here I use an end wrench
> > about 15" long, ground thin enough to fit the flats on the TTS holder,
> > and a 10 or 12" crescent wrench and a pull on the wrenches that is
> > likely in excess of 100 lb-ft. I don't have a newtom-meters to
> > pound-foot conversion handy but that certainly is tighter than 75Nm.
> >
> > Ditto if using an R8 directly, the R8 gets tightened with a 20 volt
> > electric impact wrench driving an 8 point 10mm socket a lot tighter than
> > I can draw it by hand with the supplied toy 10mm endwrench.  If not, the
> > TTS in the R8 may slip and walk out. The life of that socket before it
> > splits might be 50 times, its hell on good quality sockets.
> > >
> > > (Though I am not convinced that an ER17 can really lift a 300kg mass,
> > > so suspect I messed something up. )
> >
> >
> > 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)
> > Genes Web page 
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
>
>
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>


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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Ken Strauss]

Google is your friend!
ft-lb =Nm * 0.73756
So 75Nm = 55.3 ft lbs

> -Original Message-
> From: Gene Heskett [mailto:ghesk...@shentel.net]
> Sent: Thursday, April 18, 2019 11:45 AM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Something to think about re the hack-a-day tool
> changer
>
> On Thursday 18 April 2019 07:47:51 andy pugh wrote:
>
> > On Thu, 18 Apr 2019 at 10:22, Roland Jollivet
>  wrote:
> > > To recap; small steppers 'drive' the carousel around to tighten the
> > > motor.
> >
> > No, the motor drives round the carousel to tighten the collet.
> >
> > It is really rather clever. Assuming that it can't work based purely
> > on guess-work seems silly.
>
> No, not silly, experience Andy, experience reaching into the bank account
> to replace tooling that broke by walking out of the holder when I
> thought it was tight enough.
>
> > I suggested a very simple test using the same torque wrench as Gene
> > presumably uses now to tighten his collets to the correct torque to
> > test the hypothesis.
>
> All 4 of my 5 torque wrenches are in foot/pounds. The smallest is in inch
> pounds.  How much is 75Nm, in inch pounds.
> >
> >
> > But, assuming a 5mm pitch screw and 5:1 motor reduction:
> > (0.5 Nm stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a 75mm
> > arm that is 235Nm.
> > Correct torque for an ER20 is 75Nm.
>
> That is no where near tight enough to keep it from walking out of the
> collet and breaking the tool because its digging 3/8" on a cut that
> should be 20 thou if it hadn't walked out.  Here I use an end wrench
> about 15" long, ground thin enough to fit the flats on the TTS holder,
> and a 10 or 12" crescent wrench and a pull on the wrenches that is
> likely in excess of 100 lb-ft. I don't have a newtom-meters to
> pound-foot conversion handy but that certainly is tighter than 75Nm.
>
> Ditto if using an R8 directly, the R8 gets tightened with a 20 volt
> electric impact wrench driving an 8 point 10mm socket a lot tighter than
> I can draw it by hand with the supplied toy 10mm endwrench.  If not, the
> TTS in the R8 may slip and walk out. The life of that socket before it
> splits might be 50 times, its hell on good quality sockets.
> >
> > (Though I am not convinced that an ER17 can really lift a 300kg mass,
> > so suspect I messed something up. )
>
>
> 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)
> Genes Web page 
>
>
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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

On Thursday 18 April 2019 07:47:51 andy pugh wrote:

> On Thu, 18 Apr 2019 at 10:22, Roland Jollivet 
 wrote:
> > To recap; small steppers 'drive' the carousel around to tighten the
> > motor.
>
> No, the motor drives round the carousel to tighten the collet.
>
> It is really rather clever. Assuming that it can't work based purely
> on guess-work seems silly.

No, not silly, experience Andy, experience reaching into the bank account 
to replace tooling that broke by walking out of the holder when I 
thought it was tight enough.  

> I suggested a very simple test using the same torque wrench as Gene
> presumably uses now to tighten his collets to the correct torque to
> test the hypothesis.

All 4 of my 5 torque wrenches are in foot/pounds. The smallest is in inch 
pounds.  How much is 75Nm, in inch pounds.  
 
>
>
> But, assuming a 5mm pitch screw and 5:1 motor reduction:
> (0.5 Nm stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a 75mm
> arm that is 235Nm.
> Correct torque for an ER20 is 75Nm.

That is no where near tight enough to keep it from walking out of the 
collet and breaking the tool because its digging 3/8" on a cut that 
should be 20 thou if it hadn't walked out.  Here I use an end wrench 
about 15" long, ground thin enough to fit the flats on the TTS holder, 
and a 10 or 12" crescent wrench and a pull on the wrenches that is 
likely in excess of 100 lb-ft. I don't have a newtom-meters to 
pound-foot conversion handy but that certainly is tighter than 75Nm.

Ditto if using an R8 directly, the R8 gets tightened with a 20 volt 
electric impact wrench driving an 8 point 10mm socket a lot tighter than 
I can draw it by hand with the supplied toy 10mm endwrench.  If not, the 
TTS in the R8 may slip and walk out. The life of that socket before it 
splits might be 50 times, its hell on good quality sockets. 

 
>
> (Though I am not convinced that an ER17 can really lift a 300kg mass,
> so suspect I messed something up. )


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)
Genes Web page 


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[Emc-users] Something to think about re the hack-a-day tool changer

[Roland Jollivet]

Disabling the X- Y drives sounds fine to me. Let the gantry get taken for
the ride.   (assuming it's easily moved by hand with drives disabled)
Once the nut is tight, reverse the carousel motor for a moment to undo the
load.
Then enable drives and do a Z up, then home the machine.

With a setup like this, homing after a toolchange would be prudent in any
case. And it would only add a few seconds per tool.

"Driving the carousel is an even worse idea.  Then the diameter of the
carousel becomes mechanical disadvantage"
I don't agree. Driving the carousel is more akin to tightening with a hand
wrench. Driving the gantry to do the same is probably beyond the ability of
most small systems.



On Thu, 18 Apr 2019 at 15:22, Todd Zuercher  wrote:

> Driving the carousel is an even worse idea.  Then the diameter of the
> carousel becomes mechanical disadvantage and the subsequent moving of the
> undriven x and y axis is guaranteed loss of position.
>
> Using the XY axis is probably the best option, for this kind of idea. But
> I can think of several reasons the concept on a whole is a bad one.
>
> 1st My experience with collets is they, the tapers they fit in, and the
> nut all need to be properly cleaned and inspected before reassembly and a
> simple blast of air usually isn't good enough, especially if you are
> milling wood products.
>
> 2nd Spindle bearing loading.  This kind of tightening load is going to
> directly load the spindle's bearings and will greatly reduce their service
> life (at least on high speed router spindles like we are talking about
> here).
>
> 3rd I think the potential of cross-threading or otherwise not starting the
> nut right are too high to rely on this for auto tool changes.
>
> Todd Zuercher
> P. Graham Dunn Inc.
> 630 Henry Street
> Dalton, Ohio 44618
> Phone:  (330)828-2105ext. 2031
>
> -Original Message-
> From: Roland Jollivet 
> Sent: Thursday, April 18, 2019 8:04 AM
> To: Enhanced Machine Controller (EMC) 
> Subject: [Emc-users] Something to think about re the hack-a-day tool
> changer
>
> Sorry, guys, I really do understand how it works. I thought I was quite
> clear..
>
> That's why I said the l steppers 'drive' the carousel around. Notice the '
> '. Yes, to spell it out the motion of the X-Y steppers in a circular
> motion results in the carousel rotating. The carousel rotates as a result
> of the XY stepper motion...
>
> The net result is that the carousel rotates while the nut is being
> loosened.
> The motive force for this to occur is the stepper motors. The carousel
> itself is passive.
>
> This is a bad idea because;
> - stiction can result in a much higher force to loosen the nut than
> tighten it
> - any lost steps in the stepper motors will result in a poor subsequent
> trajectory, it will be fighting all the way
> - there is no simple way to monitor the torque necessary, or applied.
>
> So... instead of using the steppers to effect the required action of
> loosening the nut, rather move... the motive force to the carousel.
> Visually the result is the same, but since the carousel is now DRIVEN
> instead of just coasting around, the benifits are;
> - geared DC motors of the required torque are readily available, or use a
> windscreen wiper motor with a further reduction
> - the motor current is easy to monitor
> - disable the stepper drives so the gantry becomes passive and is pulled
> around instead
> - indexing of the carousel only needs a single switch to home it.
>
> Regards
> Roland
>
>
>
> On Thu, 18 Apr 2019 at 13:50, andy pugh  wrote:
>
> > On Thu, 18 Apr 2019 at 10:22, Roland Jollivet
> > 
> > wrote:
> >
> > > To recap; small steppers 'drive' the carousel around to tighten the
> > motor.
> >
> > No, the motor drives round the carousel to tighten the collet.
> >
> > It is really rather clever. Assuming that it can't work based purely
> > on guess-work seems silly.
> >
> > I suggested a very simple test using the same torque wrench as Gene
> > presumably uses now to tighten his collets to the correct torque to
> > test the hypothesis.
> >
> >
> > But, assuming a 5mm pitch screw and 5:1 motor reduction:
> > (0.5 Nm stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a 75mm
> > arm that is 235Nm.
> > Correct torque for an ER20 is 75Nm.
> >
> > (Though I am not convinced that an ER17 can really lift a 300kg mass,
> > so suspect I messed something up. )
> >
> > --
> > 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, 1916
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
>
> ___
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>
> 

[Emc-users] Emc-users] Something to think about re the hack-a-day tool changer

[Roland Jollivet]

Disabling the X- Y drives sounds fine to me. Let the gantry get taken for
the ride.   (assuming it's easily moved by hand with drives disabled)
Once the nut is tight, reverse the carousel motor for a moment to undo the
load.
Then enable drives and do a Z up, then home the machine.

With a setup like this, homing after a toolchange would be prudent in any
case. And it would only add a few seconds per tool.

"Driving the carousel is an even worse idea.  Then the diameter of the
carousel becomes mechanical disadvantage"
I don't agree. Driving the carousel is more akin to tightening with a hand
wrench. Driving the gantry to do the same is probably beyond the ability of
most small systems.


On Thu, 18 Apr 2019 at 15:22, Todd Zuercher  wrote:

> Driving the carousel is an even worse idea.  Then the diameter of the
> carousel becomes mechanical disadvantage and the subsequent moving of the
> undriven x and y axis is guaranteed loss of position.
>
> Using the XY axis is probably the best option, for this kind of idea. But
> I can think of several reasons the concept on a whole is a bad one.
>
> 1st My experience with collets is they, the tapers they fit in, and the
> nut all need to be properly cleaned and inspected before reassembly and a
> simple blast of air usually isn't good enough, especially if you are
> milling wood products.
>
> 2nd Spindle bearing loading.  This kind of tightening load is going to
> directly load the spindle's bearings and will greatly reduce their service
> life (at least on high speed router spindles like we are talking about
> here).
>
> 3rd I think the potential of cross-threading or otherwise not starting the
> nut right are too high to rely on this for auto tool changes.
>
> Todd Zuercher
> P. Graham Dunn Inc.
> 630 Henry Street
> Dalton, Ohio 44618
> Phone:  (330)828-2105ext. 2031
>
> -Original Message-
> From: Roland Jollivet 
> Sent: Thursday, April 18, 2019 8:04 AM
> To: Enhanced Machine Controller (EMC) 
> Subject: [Emc-users] Something to think about re the hack-a-day tool
> changer
>
> Sorry, guys, I really do understand how it works. I thought I was quite
> clear..
>
> That's why I said the l steppers 'drive' the carousel around. Notice the '
> '. Yes, to spell it out the motion of the X-Y steppers in a circular
> motion results in the carousel rotating. The carousel rotates as a result
> of the XY stepper motion...
>
> The net result is that the carousel rotates while the nut is being
> loosened.
> The motive force for this to occur is the stepper motors. The carousel
> itself is passive.
>
> This is a bad idea because;
> - stiction can result in a much higher force to loosen the nut than
> tighten it
> - any lost steps in the stepper motors will result in a poor subsequent
> trajectory, it will be fighting all the way
> - there is no simple way to monitor the torque necessary, or applied.
>
> So... instead of using the steppers to effect the required action of
> loosening the nut, rather move... the motive force to the carousel.
> Visually the result is the same, but since the carousel is now DRIVEN
> instead of just coasting around, the benifits are;
> - geared DC motors of the required torque are readily available, or use a
> windscreen wiper motor with a further reduction
> - the motor current is easy to monitor
> - disable the stepper drives so the gantry becomes passive and is pulled
> around instead
> - indexing of the carousel only needs a single switch to home it.
>
> Regards
> Roland
>
>
>
> On Thu, 18 Apr 2019 at 13:50, andy pugh  wrote:
>
> > On Thu, 18 Apr 2019 at 10:22, Roland Jollivet
> > 
> > wrote:
> >
> > > To recap; small steppers 'drive' the carousel around to tighten the
> > motor.
> >
> > No, the motor drives round the carousel to tighten the collet.
> >
> > It is really rather clever. Assuming that it can't work based purely
> > on guess-work seems silly.
> >
> > I suggested a very simple test using the same torque wrench as Gene
> > presumably uses now to tighten his collets to the correct torque to
> > test the hypothesis.
> >
> >
> > But, assuming a 5mm pitch screw and 5:1 motor reduction:
> > (0.5 Nm stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a 75mm
> > arm that is 235Nm.
> > Correct torque for an ER20 is 75Nm.
> >
> > (Though I am not convinced that an ER17 can really lift a 300kg mass,
> > so suspect I messed something up. )
> >
> > --
> > 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, 1916
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
>
> ___
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> https://lists.sourceforge.net/lists/listinfo/emc-users
>
> 

Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Todd Zuercher]

Driving the carousel is an even worse idea.  Then the diameter of the carousel 
becomes mechanical disadvantage and the subsequent moving of the undriven x and 
y axis is guaranteed loss of position.

Using the XY axis is probably the best option, for this kind of idea. But I can 
think of several reasons the concept on a whole is a bad one.

1st My experience with collets is they, the tapers they fit in, and the nut all 
need to be properly cleaned and inspected before reassembly and a simple blast 
of air usually isn't good enough, especially if you are milling wood products.  

2nd Spindle bearing loading.  This kind of tightening load is going to directly 
load the spindle's bearings and will greatly reduce their service life (at 
least on high speed router spindles like we are talking about here).

3rd I think the potential of cross-threading or otherwise not starting the nut 
right are too high to rely on this for auto tool changes.

Todd Zuercher
P. Graham Dunn Inc.
630 Henry Street 
Dalton, Ohio 44618
Phone:  (330)828-2105ext. 2031

-Original Message-
From: Roland Jollivet  
Sent: Thursday, April 18, 2019 8:04 AM
To: Enhanced Machine Controller (EMC) 
Subject: [Emc-users] Something to think about re the hack-a-day tool changer

Sorry, guys, I really do understand how it works. I thought I was quite clear..

That's why I said the l steppers 'drive' the carousel around. Notice the '
'. Yes, to spell it out the motion of the X-Y steppers in a circular motion 
results in the carousel rotating. The carousel rotates as a result of the XY 
stepper motion...

The net result is that the carousel rotates while the nut is being loosened.
The motive force for this to occur is the stepper motors. The carousel itself 
is passive.

This is a bad idea because;
- stiction can result in a much higher force to loosen the nut than tighten it
- any lost steps in the stepper motors will result in a poor subsequent 
trajectory, it will be fighting all the way
- there is no simple way to monitor the torque necessary, or applied.

So... instead of using the steppers to effect the required action of loosening 
the nut, rather move... the motive force to the carousel.
Visually the result is the same, but since the carousel is now DRIVEN instead 
of just coasting around, the benifits are;
- geared DC motors of the required torque are readily available, or use a 
windscreen wiper motor with a further reduction
- the motor current is easy to monitor
- disable the stepper drives so the gantry becomes passive and is pulled around 
instead
- indexing of the carousel only needs a single switch to home it.

Regards
Roland



On Thu, 18 Apr 2019 at 13:50, andy pugh  wrote:

> On Thu, 18 Apr 2019 at 10:22, Roland Jollivet 
> 
> wrote:
>
> > To recap; small steppers 'drive' the carousel around to tighten the
> motor.
>
> No, the motor drives round the carousel to tighten the collet.
>
> It is really rather clever. Assuming that it can't work based purely 
> on guess-work seems silly.
>
> I suggested a very simple test using the same torque wrench as Gene 
> presumably uses now to tighten his collets to the correct torque to 
> test the hypothesis.
>
>
> But, assuming a 5mm pitch screw and 5:1 motor reduction:
> (0.5 Nm stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a 75mm 
> arm that is 235Nm.
> Correct torque for an ER20 is 75Nm.
>
> (Though I am not convinced that an ER17 can really lift a 300kg mass, 
> so suspect I messed something up. )
>
> --
> 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, 1916
>
>
> ___
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> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>

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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Andy Pugh]

> On 18 Apr 2019, at 14:04, Roland Jollivet  wrote:
> 
> - disable the stepper drives so the gantry becomes passive and is pulled
> around instead

That’s even worse than the risk of losing steps by driving the carousel with 
the axes. 

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[Emc-users] Something to think about re the hack-a-day tool changer

[Roland Jollivet]

Sorry, guys, I really do understand how it works. I thought I was quite
clear..

That's why I said the l steppers 'drive' the carousel around. Notice the '
'. Yes, to spell it out the motion of the X-Y steppers in a circular
motion results in the carousel rotating. The carousel rotates as a result
of the XY stepper motion...

The net result is that the carousel rotates while the nut is being loosened.
The motive force for this to occur is the stepper motors. The carousel
itself is passive.

This is a bad idea because;
- stiction can result in a much higher force to loosen the nut than tighten
it
- any lost steps in the stepper motors will result in a poor subsequent
trajectory, it will be fighting all the way
- there is no simple way to monitor the torque necessary, or applied.

So... instead of using the steppers to effect the required action of
loosening the nut, rather move... the motive force to the carousel.
Visually the result is the same, but since the carousel is now DRIVEN
instead of just coasting around, the benifits are;
- geared DC motors of the required torque are readily available, or use a
windscreen wiper motor with a further reduction
- the motor current is easy to monitor
- disable the stepper drives so the gantry becomes passive and is pulled
around instead
- indexing of the carousel only needs a single switch to home it.

Regards
Roland



On Thu, 18 Apr 2019 at 13:50, andy pugh  wrote:

> On Thu, 18 Apr 2019 at 10:22, Roland Jollivet 
> wrote:
>
> > To recap; small steppers 'drive' the carousel around to tighten the
> motor.
>
> No, the motor drives round the carousel to tighten the collet.
>
> It is really rather clever. Assuming that it can't work based purely
> on guess-work seems silly.
>
> I suggested a very simple test using the same torque wrench as Gene
> presumably uses now to tighten his collets to the correct torque to
> test the hypothesis.
>
>
> But, assuming a 5mm pitch screw and 5:1 motor reduction:
> (0.5 Nm stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a 75mm
> arm that is 235Nm.
> Correct torque for an ER20 is 75Nm.
>
> (Though I am not convinced that an ER17 can really lift a 300kg mass,
> so suspect I messed something up. )
>
> --
> 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, 1916
>
>
> ___
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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

On Thursday 18 April 2019 04:20:37 Roland Jollivet wrote:

> On Thu, 18 Apr 2019 at 01:22, Gene Heskett  
wrote:
> > On Wednesday 17 April 2019 15:06:02 Chris Albertson wrote:
> >
> > [...]
> >
> > > But if maybe you lock the spindle and turn the nut.
> >
> > This is the case, except you are turnbing the nut by using the xy
> > steppers to drive the carousel which is turning the nut.
> >
> > > Then your spindle
> > > lock needs to have a torque gauge fitted.  The gauge is either a
> > > spring and switch or a load cell.   The switch is much easier to
> > > interface with.
> > > 
>
> Hi Gene
>
> To recap; small steppers 'drive' the carousel around to tighten the
> motor. Bad idea.
I tend to agree, given the power limits available from the steppers.
>
> Here's a different way of looking at it;
> Keep the current stepper arrangement, but drive the carousel instead,
> with a windscreen wiper motor.
> You now have as much torque as you like in the carousel. Add a
> reduction drive if you like. If you mount this under the bed you can
> go to town on it.
>
> The process would be to move into tool position, Z down, then either
> track the motion of the carousel,

Difficult to synch, but probably doable.
> or disable the stepper drives and 
> let them coast as the carousel takes the spindle with it as it
> loosens/tightens. Once you've reached your target Amperage on the
> motor, stop, and Z up. The X,Y is now a 'don't care', so home the
> machine.

That would likely mean moving the tool changer at least to the middle of 
the Y range, or a long move to get y homed again. And the carousel 
becomes half a wheel that has to be in its own home position to allow 
the gantry risers to get past it.
The windshield wiper motor with a big geardown, say 6/1, could then use 
the wipers parking switch to position the carousel at one of 6 tool 
positions, with one more home switch. 

What I had in mind was to borrow the right rear 200mmx200mm so a gunstock 
blank could fit beside it. Then the gantry risers could clear it 
regardless.

And of coarse there's the y offset of the z mount, making the rear 80mm 
in-accessible. Currently the coolant tank occupies the space but theres 
nothing saying I can't make a riser for it to make 18" of working room 
for a swing in carousel under it. The limited Z range will be a problem 
for long tools in any event.

I'd like to steer clear of useing a transfer arm to reach into the 
working area, but powering a rotating socket on the end of it to do the 
tightening and loosening of the collet nut has a certain  cachette to 
it. That way the xy remains at the tool change location so a rehome 
won't be needed. And the transfer arm stays outside the path of the 
gantry when parked at the next tool.  And so do the arm driving motor(s, 
one to drive the arm and one to drive the socket). Driving the socket 
with a rack, with a bearing to back up the rack at the point of contact 
sounds good, and beats a whole chain of spur gears I saw in one design.  
So it sticks out but if the stickout is only when in position there 
shouldn't be anything but air for it to hit.  Design length enough in 
the rack to allow a full turn of the nut, and run it to one end or the 
the other depending on whether you are removing or inserting the tool 
before engaging the nut. Get the gear ratio needed by a bigger spur gear 
on the sockets base and a smaller gear on the wiper motor could do that. 
Thats 3 wiper motors to run.  Thinking... 

> You then further rotate the carousel to home with a single switch so
> it's always ready.

Or put the tool back in the pocket it came out of so the tool table can 
track it w/o that codeing hassle, then rotate to the new pocket before 
the arm picks up the next tool. And with all that, the tool changer is 
going to use up quite a bit of i/o. And a sheet of 1/4" ply cut up just 
to make try patterns. :)  All that bs makes buying an atc equipt spindle 
seem like the cheap option.

Frankly, neither R8 nor the various sizes of ER's were made with tool 
changers in mind. Either style demands a TLO calibration once the new 
tool is in place.  But I keep letting my imagination out to play. Code 
is a lot cheaper than hardware.

Thanks and take care, Roland.


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)
Genes Web page 



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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[andy pugh]

On Thu, 18 Apr 2019 at 10:22, Roland Jollivet  wrote:

> To recap; small steppers 'drive' the carousel around to tighten the motor.

No, the motor drives round the carousel to tighten the collet.

It is really rather clever. Assuming that it can't work based purely
on guess-work seems silly.

I suggested a very simple test using the same torque wrench as Gene
presumably uses now to tighten his collets to the correct torque to
test the hypothesis.


But, assuming a 5mm pitch screw and 5:1 motor reduction:
(0.5 Nm stepper * (2 * pi) / 5mm ) * 5:1 = 3kN. On the end of a 75mm
arm that is 235Nm.
Correct torque for an ER20 is 75Nm.

(Though I am not convinced that an ER17 can really lift a 300kg mass,
so suspect I messed something up. )

-- 
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, 1916


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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[TJoseph Powderly]

Hi Roland

On Thu, Apr 18, 2019, 3:23 PM Roland Jollivet 
wrote:

> On Thu, 18 Apr 2019 at 01:22, Gene Heskett  wrote:
>
> > On Wednesday 17 April 2019 15:06:02 Chris Albertson wrote:
> >
> > [...]
> > >
> > > But if maybe you lock the spindle and turn the nut.
> >
> > This is the case, except you are turnbing the nut by using the xy
> > steppers to drive the carousel which is turning the nut.
> >
> > > Then your spindle
> > > lock needs to have a torque gauge fitted.  The gauge is either a
> > > spring and switch or a load cell.   The switch is much easier to
> > > interface with. <
> https://lists.sourceforge.net/lists/listinfo/emc-users>
> >
>
> Hi Gene
>
> To recap; small steppers 'drive' the carousel around to tighten the motor.
> Bad idea.
>
> Here's a different way of looking at it;
> Keep the current stepper arrangement, but drive the carousel instead, with
> a windscreen wiper motor.
> You now have as much torque as you like in the carousel. Add a reduction
> drive if you like. If you mount this under the bed you can go to town on
> it.
>
> Gene might include a visual
>


Gene could give a visual clue with each of these posts.

So search ' xatc ' in Google

Sorry I can't get this phone to copy the hackaday url ( stupid Newton!)

You will see he needs to move the spindle about the carousel center.
Not turn the carousel about it's center.
( The design as it is now)
That needs an xy move of the carousel center Or an arc motion of the center
or
some lever motion or ( insert favorite idea here).

The process would be to move into tool position, Z down, then either track
> the motion of the carousel, or disable the stepper drives and let them
> coast as the carousel takes the spindle with it as it loosens/tightens.
> Once you've reached your target Amperage on the motor, stop, and Z up. The
> X,Y is now a 'don't care', so home the machine.
> You then further rotate the carousel to home with a single switch so it's
> always ready.
>
> Regards
> Roland
>

Hth tomp

>
>
>
>

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[Emc-users] Something to think about re the hack-a-day tool changer

[Roland Jollivet]

On Thu, 18 Apr 2019 at 01:22, Gene Heskett  wrote:

> On Wednesday 17 April 2019 15:06:02 Chris Albertson wrote:
>
> [...]
> >
> > But if maybe you lock the spindle and turn the nut.
>
> This is the case, except you are turnbing the nut by using the xy
> steppers to drive the carousel which is turning the nut.
>
> > Then your spindle
> > lock needs to have a torque gauge fitted.  The gauge is either a
> > spring and switch or a load cell.   The switch is much easier to
> > interface with. 
>

Hi Gene

To recap; small steppers 'drive' the carousel around to tighten the motor.
Bad idea.

Here's a different way of looking at it;
Keep the current stepper arrangement, but drive the carousel instead, with
a windscreen wiper motor.
You now have as much torque as you like in the carousel. Add a reduction
drive if you like. If you mount this under the bed you can go to town on it.

The process would be to move into tool position, Z down, then either track
the motion of the carousel, or disable the stepper drives and let them
coast as the carousel takes the spindle with it as it loosens/tightens.
Once you've reached your target Amperage on the motor, stop, and Z up. The
X,Y is now a 'don't care', so home the machine.
You then further rotate the carousel to home with a single switch so it's
always ready.

Regards
Roland

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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

On Wednesday 17 April 2019 15:06:02 Chris Albertson wrote:

[...]
>
> But if maybe you lock the spindle and turn the nut.

This is the case, except you are turnbing the nut by using the xy 
steppers to drive the carousel which is turning the nut.

> Then your spindle 
> lock needs to have a torque gauge fitted.  The gauge is either a
> spring and switch or a load cell.   The switch is much easier to
> interface with.

This is true, but before I start, how much power to I have in the 
steppers before they start slipping steps? In order to get enough torque 
on the nut, I need to know how much push is available w/o having to 
rehome the thing after I've tightened the nut.  That tells me how long a 
wrench "handle" I need to achieve the required torque.  That handle 
length is the radius of where the nut is from the center bearing of the 
carousel.

> On Wed, Apr 17, 2019 at 12:17 AM Gene Heskett  
wrote:
> > On Wednesday 17 April 2019 01:48:06 Chris Albertson wrote:
> > > I think you could eliminate the load cell and simply measure motor
> > > current.  Given that the motor is locked at zero RPM, the torque
> > > would be a function of current.  Once you calibrate current to
> > > torque it will not change.   You still need to get this data into
> > > a computer but at least you don't need to build a mechanical
> > > widget, just a hall effect sensor on more lead wire.

Take care Chris.


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)
Genes Web page 



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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

On Wednesday 17 April 2019 15:32:09 Ken Strauss wrote:

> The cheap load cells often use a HX711 for the amplifier and A/D.
> See
> https://www.instructables.com/id/How-to-Interface-HX711-Balance-Module
>-With- Load-Ce/ if you're using an Arduino. If you want to roll your
> own interface code see
> https://www.mouser.com/ds/2/813/hx711_english-1022875.pdf
>
Thanks Ken, that is exactly what I needed.  Now all I  need to do is 
round up the bits and pieces.

> > -Original Message-
> > From: Gene Heskett [mailto:ghesk...@shentel.net]
> > Sent: Wednesday, April 17, 2019 10:01 AM
> > To: emc-users@lists.sourceforge.net
> > Subject: Re: [Emc-users] Something to think about re the hack-a-day
> > tool changer
> >
> > On Wednesday 17 April 2019 07:12:53 andy pugh wrote:
> > > On Wed, 17 Apr 2019 at 06:57, Gene Heskett 
> >
> > wrote:
> > > > Some more along the lines of finding out how much force I can
> > > > figure on as being available to tighten or loosen the collet
> > > > nut. I can get, for under a tenner, 4 ea 50Kg load cells and a
> > > > processor board that converts the very low level diffs of a
> > > > wheatstone bridge
> > >
> > > Why not set your torque wrench to the correct torque for your nuts
> > > and then see how far down the handle you have to be to trip the
> > > wrench?
> > >
> > > That tells you what radius of action you need to get the right
> > > torque.
> > >
> > > There is no question that your machine can produce the torque,
> > > given the classical "sufficiently long lever"
> >
> > And that is the final question as to whether or not the idea is
> > actually practical. It assuredly is not if the xy motors are so weak
> > it needs a carousel more then 18" in radius to the circle of sockets
> > just to tighten a tool well enough to dig off .010" of an alu chip
> > without slippage of tool in the collet.  Even that isn't going to be
> > practical but it does serve to outline exactly why the 3" radii
> > carousels we are seeing in the videos will turn out to be an obvious
> > disproof of concept. The videos of it going thru the motions on
> > hackaday would certainly have to suffer from the loose tools
> > syndrome if actually put to work on a usable thickness of alu stock,
> > say .03125" thick. Putting bigger motors on it would be one option,
> > but even 470 oz nema 23's, might not be enough, and most certainly
> > could/would bend the frame or bearing rods. I have the motors from
> > the broken HF I can move, and probably will as that would at least
> > double the power, but just haven't found the round tuit yet. Among
> > other things they have dampers on them. But I'll have to change the
> > A motor again, putting a 435oz on it. I already changed the 90 for a
> > 230, so a 435 can't fail to be even better at holding work. That
> > would leave the pair of 235's for XY, and would leave the longer Y
> > to be moved to Z duties.
> >
> > The 1600oz nema 34 supplied as Z motor in the kit for a G0704, which
> > was a too slow disaster on the G0704, often stalling at 29 ipm, but
> > was strong enough to stretch the bolts anchoring the nut carrier to
> > the z sled, causing those to need replacement quite early, but now
> > moves at 90 ipm with a 940oz motor that has not further damaged
> > those replacement bolts, would be a prime example of overkill.
> > However I reused that motor as Z drive on the Sheldon, where it has
> > no weight to lift, works well at 75 ipm on the Sheldon with the same
> > driver I took out of the G0704. I put in the $180 AC powered drive
> > to spin that 940oz on the GO704. Dead smooth and 20 db quieter. The
> > DM860H drive is a noisy drive, so noisy I had to install miniature
> > quarter round on the keyboard shelf edges to keep stuff on it,
> > including the keyboard and mouse. The 860 has very very poor step vs
> > amps in coils calibration, so there is no nice quiet all steps in
> > the microstep mapping regardless of the current setting. The thing
> > you notice most is that a /8 setting actually does 7 steps because
> > one of them is way too small.
> >
> > But thats not solving this measurement problem. Since this $7 kit,
> > needs an external clock, it seems like that could be done by siggen,
> > for a 500 baud baud rate, and a software uart could do the rest. But
> > the packet length is unk until I have such a kit in my hot little
> > hands. The fleabay adv's don't say.
> >
> > Thanks Andy.
> >
> > 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)
> > Genes Web page 
> >
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
> ___
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> 

Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Ken Strauss]

The cheap load cells often use a HX711 for the amplifier and A/D.
See
https://www.instructables.com/id/How-to-Interface-HX711-Balance-Module-With-
Load-Ce/ if you're using an Arduino. If you want to roll your own interface
code see https://www.mouser.com/ds/2/813/hx711_english-1022875.pdf


> -Original Message-
> From: Gene Heskett [mailto:ghesk...@shentel.net]
> Sent: Wednesday, April 17, 2019 10:01 AM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Something to think about re the hack-a-day tool
> changer
>
> On Wednesday 17 April 2019 07:12:53 andy pugh wrote:
>
> > On Wed, 17 Apr 2019 at 06:57, Gene Heskett 
> wrote:
> > > Some more along the lines of finding out how much force I can figure
> > > on as being available to tighten or loosen the collet nut. I can
> > > get, for under a tenner, 4 ea 50Kg load cells and a processor board
> > > that converts the very low level diffs of a wheatstone bridge
> >
> > Why not set your torque wrench to the correct torque for your nuts and
> > then see how far down the handle you have to be to trip the wrench?
> >
> > That tells you what radius of action you need to get the right torque.
> >
> > There is no question that your machine can produce the torque, given
> > the classical "sufficiently long lever"
>
> And that is the final question as to whether or not the idea is actually
> practical. It assuredly is not if the xy motors are so weak it needs a
> carousel more then 18" in radius to the circle of sockets just to
> tighten a tool well enough to dig off .010" of an alu chip without
> slippage of tool in the collet.  Even that isn't going to be practical
> but it does serve to outline exactly why the 3" radii carousels we are
> seeing in the videos will turn out to be an obvious disproof of concept.
> The videos of it going thru the motions on hackaday would certainly have
> to suffer from the loose tools syndrome if actually put to work on a
> usable thickness of alu stock, say .03125" thick. Putting bigger motors
> on it would be one option, but even 470 oz nema 23's, might not be
> enough, and most certainly could/would bend the frame or bearing rods. I
> have the motors from the broken HF I can move, and probably will as that
> would at least double the power, but just haven't found the round tuit
> yet. Among other things they have dampers on them. But I'll have to
> change the A motor again, putting a 435oz on it. I already changed the
> 90 for a 230, so a 435 can't fail to be even better at holding work.
> That would leave the pair of 235's for XY, and would leave the longer Y
> to be moved to Z duties.
>
> The 1600oz nema 34 supplied as Z motor in the kit for a G0704, which was
> a too slow disaster on the G0704, often stalling at 29 ipm, but was
> strong enough to stretch the bolts anchoring the nut carrier to the z
> sled, causing those to need replacement quite early, but now moves at 90
> ipm with a 940oz motor that has not further damaged those replacement
> bolts, would be a prime example of overkill. However I reused that motor
> as Z drive on the Sheldon, where it has no weight to lift, works well at
> 75 ipm on the Sheldon with the same driver I took out of the G0704. I
> put in the $180 AC powered drive to spin that 940oz on the GO704. Dead
> smooth and 20 db quieter. The DM860H drive is a noisy drive, so noisy I
> had to install miniature quarter round on the keyboard shelf edges to
> keep stuff on it, including the keyboard and mouse. The 860 has very
> very poor step vs amps in coils calibration, so there is no nice quiet
> all steps in the microstep mapping regardless of the current setting.
> The thing you notice most is that a /8 setting actually does 7 steps
> because one of them is way too small.
>
> But thats not solving this measurement problem. Since this $7 kit, needs
> an external clock, it seems like that could be done by siggen, for a 500
> baud baud rate, and a software uart could do the rest. But the packet
> length is unk until I have such a kit in my hot little hands. The
> fleabay adv's don't say.
>
> Thanks Andy.
>
> 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)
> Genes Web page 
>
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users




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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Chris Albertson]

I thought the nut that needed to be torqued down was on the spindle.   You
would not be using a stepper for the spindle motor.
So the "wrench" holds the nut and then you power up the spindle to tighten
the nut.   If that is the case then spindle motor current
tells you the torque on the nut.

But if maybe you lock the spindle and turn the nut.  Then your spindle lock
needs to have a torque gauge fitted.  The gauge is either a spring and
switch or a load cell.   The switch is much easier to interface with.


On Wed, Apr 17, 2019 at 12:17 AM Gene Heskett  wrote:

> On Wednesday 17 April 2019 01:48:06 Chris Albertson wrote:
>
> > I think you could eliminate the load cell and simply measure motor
> > current.  Given that the motor is locked at zero RPM, the torque would
> > be a function of current.  Once you calibrate current to torque it
> > will not change.   You still need to get this data into a computer but
> > at least you don't need to build a mechanical widget, just a hall
> > effect sensor on more lead wire.
> >
> > One thing is to be VERY careful when powering a stalled motor s you
> > can burn it up very easy.   Even if you do add the load cell be sure
> > to measure and limit the current and keep it will under the limit.
> > Then you need to cut the power quickly
>
> Ahh, Chris, this is not a servo, I am talking about the XY motors, which
> are steppers and not particularly strong ones.  They are effectively
> always stalled and the current used is set by the dipswitches on the
> driver.  So generally speaking, measureing the current is meaningless to
> a stepper that has remained locked to the steps issued.
> >
> > Coincides or not but just a second before reading your post I had
> > typed the line below to define where I'm connecting a current sensor
> > to an SMT32F411 chip pin PA4.  So I thought this could apply to your
> > project too.
> >
> > #define MM_CS1  PA4   // A2 Current Sense MUST LIMIT VOLTS TO 3V3
> >
> > One more idea that is even more simple.  I assume you are measuring
> > torque so you know the nut is on hard enough that it will not come
> > loose. Rather then a load cell why not just a simple coil spring and a
> > microswitch.  It will always require the same amount of force to
> > compress the spring and then the switch is tripped and yu can back off
> >   This is basically a load cell with one-bit resolution.
>
> That, with some monkey business incorporating the switch into the sliding
> wrench channel that is pushed out to engage the double flats on the
> chuck shank, might be doable, but the spring to absorb the torque would
> have to be 50x stronger, and if not restrained properly would prevent
> the wrench from being moved out to grab the flats, or retracting it to
> free the spindle. This wrench must be free to move in and out quickly as
> its used only the break the nut loose, then retracted and the motor spun
> yo finish the loosen and drop the tool or tighten to about finger tight,
> prior to using the xy motors, driven in an arc to match the radius the
> sockets are mounted on the carousel disk. This power from the xy motors
> is what breaks the nut loose or cinches it up to hold the tool while
> cutting. Spindle power is not applied during that circular move as the
> retractable wrench has it immobilized anyway, so the the nut is driven
> tight, or backed off depending on which direction the nut and carousel
> is being rotated by the xy motors.  I'd be forced to use an air cylinder
> to get the needed force to move the wrench. Could be done, but not in
> the physical space available since it would take at least a 1"bore x
> 3/4"stroke double action cylinder. I expect there will need to be a
> pause, and the spindle motor pulsed to turn until the wrench engages the
> flats, then pulsed the other way to make sure its fully engaged. How to
> do that while the nut is still tight, is another problem yet to be
> solved if the gator style socket isn't used. I don't know why, but I've
> an aversion to that as I have a set of those and they work but are a
> pain in the ass to place over the hex properly. The set I have do not
> have retractable pins like the gators either.  Different designs maybe?
> Probably.
>
> If you've not watched the videos on hackaday, that would explain it at
> least as well as I can.
>
> > On Tue, Apr 16, 2019 at 9:57 PM Gene Heskett 
> wrote:
> > > On Tuesday 16 April 2019 14:34:15 Gene Heskett wrote:
> > > > Greetings all;
> > > >
> > > > While adding a couple timedelays and a couple or2's to my hal
> > > > file, basically to prove that I can pulse the spindle for the
> > > > nominally 200 msecs used to spin the nut on/off to release the
> > > > collet and supposedly drop the tool, or just drop it all, I came
> > > > up against a designed in problem.  This vfd has a pid in it that
> > > > will no doubt wind up if the speed command is present for any
> > > > great amount of time, so its possible I might have to cobble up a
> > > > set of PID 

Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

On Wednesday 17 April 2019 07:12:53 andy pugh wrote:

> On Wed, 17 Apr 2019 at 06:57, Gene Heskett  
wrote:
> > Some more along the lines of finding out how much force I can figure
> > on as being available to tighten or loosen the collet nut. I can
> > get, for under a tenner, 4 ea 50Kg load cells and a processor board
> > that converts the very low level diffs of a wheatstone bridge
>
> Why not set your torque wrench to the correct torque for your nuts and
> then see how far down the handle you have to be to trip the wrench?
>
> That tells you what radius of action you need to get the right torque.
>
> There is no question that your machine can produce the torque, given
> the classical "sufficiently long lever"

And that is the final question as to whether or not the idea is actually 
practical. It assuredly is not if the xy motors are so weak it needs a 
carousel more then 18" in radius to the circle of sockets just to 
tighten a tool well enough to dig off .010" of an alu chip without 
slippage of tool in the collet.  Even that isn't going to be practical 
but it does serve to outline exactly why the 3" radii carousels we are 
seeing in the videos will turn out to be an obvious disproof of concept.  
The videos of it going thru the motions on hackaday would certainly have 
to suffer from the loose tools syndrome if actually put to work on a 
usable thickness of alu stock, say .03125" thick. Putting bigger motors 
on it would be one option, but even 470 oz nema 23's, might not be 
enough, and most certainly could/would bend the frame or bearing rods. I 
have the motors from the broken HF I can move, and probably will as that 
would at least double the power, but just haven't found the round tuit 
yet. Among other things they have dampers on them. But I'll have to 
change the A motor again, putting a 435oz on it. I already changed the 
90 for a 230, so a 435 can't fail to be even better at holding work. 
That would leave the pair of 235's for XY, and would leave the longer Y 
to be moved to Z duties. 

The 1600oz nema 34 supplied as Z motor in the kit for a G0704, which was 
a too slow disaster on the G0704, often stalling at 29 ipm, but was 
strong enough to stretch the bolts anchoring the nut carrier to the z 
sled, causing those to need replacement quite early, but now moves at 90 
ipm with a 940oz motor that has not further damaged those replacement 
bolts, would be a prime example of overkill. However I reused that motor 
as Z drive on the Sheldon, where it has no weight to lift, works well at 
75 ipm on the Sheldon with the same driver I took out of the G0704. I 
put in the $180 AC powered drive to spin that 940oz on the GO704. Dead 
smooth and 20 db quieter. The DM860H drive is a noisy drive, so noisy I 
had to install miniature quarter round on the keyboard shelf edges to 
keep stuff on it, including the keyboard and mouse. The 860 has very 
very poor step vs amps in coils calibration, so there is no nice quiet 
all steps in the microstep mapping regardless of the current setting. 
The thing you notice most is that a /8 setting actually does 7 steps 
because one of them is way too small.

But thats not solving this measurement problem. Since this $7 kit, needs 
an external clock, it seems like that could be done by siggen, for a 500 
baud baud rate, and a software uart could do the rest. But the packet 
length is unk until I have such a kit in my hot little hands. The 
fleabay adv's don't say.

Thanks Andy.

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)
Genes Web page 



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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[andy pugh]

On Wed, 17 Apr 2019 at 06:57, Gene Heskett  wrote:

> Some more along the lines of finding out how much force I can figure on
> as being available to tighten or loosen the collet nut. I can get, for
> under a tenner, 4 ea 50Kg load cells and a processor board that converts
> the very low level diffs of a wheatstone bridge

Why not set your torque wrench to the correct torque for your nuts and
then see how far down the handle you have to be to trip the wrench?

That tells you what radius of action you need to get the right torque.

There is no question that your machine can produce the torque, given
the classical "sufficiently long lever"

-- 
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, 1916


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Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

On Wednesday 17 April 2019 01:48:06 Chris Albertson wrote:

> I think you could eliminate the load cell and simply measure motor
> current.  Given that the motor is locked at zero RPM, the torque would
> be a function of current.  Once you calibrate current to torque it
> will not change.   You still need to get this data into a computer but
> at least you don't need to build a mechanical widget, just a hall
> effect sensor on more lead wire.
>
> One thing is to be VERY careful when powering a stalled motor s you
> can burn it up very easy.   Even if you do add the load cell be sure
> to measure and limit the current and keep it will under the limit. 
> Then you need to cut the power quickly

Ahh, Chris, this is not a servo, I am talking about the XY motors, which 
are steppers and not particularly strong ones.  They are effectively 
always stalled and the current used is set by the dipswitches on the 
driver.  So generally speaking, measureing the current is meaningless to 
a stepper that has remained locked to the steps issued.
>
> Coincides or not but just a second before reading your post I had
> typed the line below to define where I'm connecting a current sensor
> to an SMT32F411 chip pin PA4.  So I thought this could apply to your
> project too.
>
> #define MM_CS1  PA4   // A2 Current Sense MUST LIMIT VOLTS TO 3V3
>
> One more idea that is even more simple.  I assume you are measuring
> torque so you know the nut is on hard enough that it will not come
> loose. Rather then a load cell why not just a simple coil spring and a
> microswitch.  It will always require the same amount of force to
> compress the spring and then the switch is tripped and yu can back off
>   This is basically a load cell with one-bit resolution.

That, with some monkey business incorporating the switch into the sliding 
wrench channel that is pushed out to engage the double flats on the 
chuck shank, might be doable, but the spring to absorb the torque would 
have to be 50x stronger, and if not restrained properly would prevent 
the wrench from being moved out to grab the flats, or retracting it to 
free the spindle. This wrench must be free to move in and out quickly as 
its used only the break the nut loose, then retracted and the motor spun 
yo finish the loosen and drop the tool or tighten to about finger tight, 
prior to using the xy motors, driven in an arc to match the radius the 
sockets are mounted on the carousel disk. This power from the xy motors 
is what breaks the nut loose or cinches it up to hold the tool while 
cutting. Spindle power is not applied during that circular move as the 
retractable wrench has it immobilized anyway, so the the nut is driven 
tight, or backed off depending on which direction the nut and carousel 
is being rotated by the xy motors.  I'd be forced to use an air cylinder 
to get the needed force to move the wrench. Could be done, but not in 
the physical space available since it would take at least a 1"bore x 
3/4"stroke double action cylinder. I expect there will need to be a 
pause, and the spindle motor pulsed to turn until the wrench engages the 
flats, then pulsed the other way to make sure its fully engaged. How to 
do that while the nut is still tight, is another problem yet to be 
solved if the gator style socket isn't used. I don't know why, but I've 
an aversion to that as I have a set of those and they work but are a 
pain in the ass to place over the hex properly. The set I have do not 
have retractable pins like the gators either.  Different designs maybe? 
Probably.

If you've not watched the videos on hackaday, that would explain it at 
least as well as I can.

> On Tue, Apr 16, 2019 at 9:57 PM Gene Heskett  
wrote:
> > On Tuesday 16 April 2019 14:34:15 Gene Heskett wrote:
> > > Greetings all;
> > >
> > > While adding a couple timedelays and a couple or2's to my hal
> > > file, basically to prove that I can pulse the spindle for the
> > > nominally 200 msecs used to spin the nut on/off to release the
> > > collet and supposedly drop the tool, or just drop it all, I came
> > > up against a designed in problem.  This vfd has a pid in it that
> > > will no doubt wind up if the speed command is present for any
> > > great amount of time, so its possible I might have to cobble up a
> > > set of PID params to essentially disable that. Because I think I
> > > am going to need to have the speed present at the VI1 input before
> > > I enable the fwd or reverse commands for the timed 200 millisecs
> > > to drop or pick up the tool during the change. The wind up in that
> > > case might be advantageous in that it might jerk the nut loose, or
> > > tighten it tighter before the carousel puts the real tighten on
> > > it. But likely difficult to control too.
> > >
> > > But I find its not possible to send this speed request before the
> > > run/dir signals. I can mux2 the spindle speed inputs to the 7i76,
> > > and have the as yet unwritten tool changer code issue the speed
> > > 

Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Chris Albertson]

I think you could eliminate the load cell and simply measure motor
current.  Given that the motor is locked at zero RPM, the torque would be a
function of current.  Once you calibrate current to torque it will not
change.   You still need to get this data into a computer but at least you
don't need to build a mechanical widget, just a hall effect sensor on more
lead wire.

One thing is to be VERY careful when powering a stalled motor s you can
burn it up very easy.   Even if you do add the load cell be sure to
 measure and limit the current and keep it will under the limit.  Then you
need to cut the power quickly

Coincides or not but just a second before reading your post I had typed the
line below to define where I'm connecting a current sensor to an SMT32F411
chip pin PA4.  So I thought this could apply to your project too.

#define MM_CS1  PA4   // A2 Current Sense MUST LIMIT VOLTS TO 3V3

One more idea that is even more simple.  I assume you are measuring torque
so you know the nut is on hard enough that it will not come loose.
 Rather then a load cell why not just a simple coil spring and a
microswitch.  It will always require the same amount of force to compress
the spring and then the switch is tripped and yu can back off   This is
basically a load cell with one-bit resolution.

On Tue, Apr 16, 2019 at 9:57 PM Gene Heskett  wrote:

> On Tuesday 16 April 2019 14:34:15 Gene Heskett wrote:
>
> > Greetings all;
> >
> > While adding a couple timedelays and a couple or2's to my hal file,
> > basically to prove that I can pulse the spindle for the nominally 200
> > msecs used to spin the nut on/off to release the collet and supposedly
> > drop the tool, or just drop it all, I came up against a designed in
> > problem.  This vfd has a pid in it that will no doubt wind up if the
> > speed command is present for any great amount of time, so its possible
> > I might have to cobble up a set of PID params to essentially disable
> > that. Because I think I am going to need to have the speed present at
> > the VI1 input before I enable the fwd or reverse commands for the
> > timed 200 millisecs to drop or pick up the tool during the change. The
> > wind up in that case might be advantageous in that it might jerk the
> > nut loose, or tighten it tighter before the carousel puts the real
> > tighten on it. But likely difficult to control too.
> >
> > But I find its not possible to send this speed request before the
> > run/dir signals. I can mux2 the spindle speed inputs to the 7i76, and
> > have the as yet unwritten tool changer code issue the speed and
> > timings.
> >
> > Is that the choice?
> >
> > A secondary problem if I do the 3d printed tool holders inside the
> > collet sockets, like the orange pieces in one of the videos on
> > hack-a-day, depending on the tool to drop free when the nut backs out
> > the collet, is that the tool does not always come free, and this looks
> > like a showstopper problem that puts me back to buying a handfull of
> > nuts and collets so I can drop it all and then reposition the carousel
> > to pick up the next tool/nut/collet as an assembly. Either way, it
> > seems like I'll unavoidably need an automatic TLO setting to complete
> > the change.
>
> Some more along the lines of finding out how much force I can figure on
> as being available to tighten or loosen the collet nut. I can get, for
> under a tenner, 4 ea 50Kg load cells and a processor board that converts
> the very low level diffs of a wheatstone bridge made out the these,
> things, and which give a serial output to 12 or more bits.  So all I
> have to do is place the cell kit between a frame and the carriage and
> give it a squeeze to get a measurement.  These are the same as used in
> digital bathroom scales.
>
> Has someone made up a serial protocol for a Mesa board that could collect
> this data, and show me in pounds or kg, how much force I can get out of
> this machine before a motor slips s "cog", which in turn determines how
> big around the carousel has to be to adequately tighten, and of course
> loosen it too.  The module needs a clock, one output on a 7i76D, and one
> data input, so all we need to do is toggle the output line with the
> servo-thread, and read the bit with an input line. A bit bang receiver
> IOW.  Do we already have such a blob of code?
>
>
> Thanks for any comments on my hair brained ideas.
>
> > I figure on a bigger
> > carousel than shown in the videos. That thought is driven by the
> > difficulties I've had with the hand tightened (with a pair of 12 to
> > 16" wrenches) on the ER32's on the G0704.
> >
> > I've wrecked parts and broken tools because they'll walk out of the
> > collet, dig too deep and finally break off.  That bit of history has
> > cost me several hundred in tools so far. :(
> >
> Thanks for any wisdom shared. URL's etc.
>
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."

Re: [Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

On Tuesday 16 April 2019 14:34:15 Gene Heskett wrote:

> Greetings all;
>
> While adding a couple timedelays and a couple or2's to my hal file,
> basically to prove that I can pulse the spindle for the nominally 200
> msecs used to spin the nut on/off to release the collet and supposedly
> drop the tool, or just drop it all, I came up against a designed in
> problem.  This vfd has a pid in it that will no doubt wind up if the
> speed command is present for any great amount of time, so its possible
> I might have to cobble up a set of PID params to essentially disable
> that. Because I think I am going to need to have the speed present at
> the VI1 input before I enable the fwd or reverse commands for the
> timed 200 millisecs to drop or pick up the tool during the change. The
> wind up in that case might be advantageous in that it might jerk the
> nut loose, or tighten it tighter before the carousel puts the real
> tighten on it. But likely difficult to control too.
>
> But I find its not possible to send this speed request before the
> run/dir signals. I can mux2 the spindle speed inputs to the 7i76, and
> have the as yet unwritten tool changer code issue the speed and
> timings.
>
> Is that the choice?
>
> A secondary problem if I do the 3d printed tool holders inside the
> collet sockets, like the orange pieces in one of the videos on
> hack-a-day, depending on the tool to drop free when the nut backs out
> the collet, is that the tool does not always come free, and this looks
> like a showstopper problem that puts me back to buying a handfull of
> nuts and collets so I can drop it all and then reposition the carousel
> to pick up the next tool/nut/collet as an assembly. Either way, it
> seems like I'll unavoidably need an automatic TLO setting to complete
> the change.

Some more along the lines of finding out how much force I can figure on 
as being available to tighten or loosen the collet nut. I can get, for 
under a tenner, 4 ea 50Kg load cells and a processor board that converts 
the very low level diffs of a wheatstone bridge made out the these, 
things, and which give a serial output to 12 or more bits.  So all I 
have to do is place the cell kit between a frame and the carriage and 
give it a squeeze to get a measurement.  These are the same as used in 
digital bathroom scales.

Has someone made up a serial protocol for a Mesa board that could collect 
this data, and show me in pounds or kg, how much force I can get out of 
this machine before a motor slips s "cog", which in turn determines how 
big around the carousel has to be to adequately tighten, and of course 
loosen it too.  The module needs a clock, one output on a 7i76D, and one 
data input, so all we need to do is toggle the output line with the 
servo-thread, and read the bit with an input line. A bit bang receiver 
IOW.  Do we already have such a blob of code?


Thanks for any comments on my hair brained ideas.

> I figure on a bigger
> carousel than shown in the videos. That thought is driven by the
> difficulties I've had with the hand tightened (with a pair of 12 to
> 16" wrenches) on the ER32's on the G0704.
>
> I've wrecked parts and broken tools because they'll walk out of the
> collet, dig too deep and finally break off.  That bit of history has
> cost me several hundred in tools so far. :(
>
Thanks for any wisdom shared. URL's etc.


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)
Genes Web page 



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[Emc-users] Something to think about re the hack-a-day tool changer

[Gene Heskett]

Greetings all;

While adding a couple timedelays and a couple or2's to my hal file, 
basically to prove that I can pulse the spindle for the nominally 200 
msecs used to spin the nut on/off to release the collet and supposedly 
drop the tool, or just drop it all, I came up against a designed in 
problem.  This vfd has a pid in it that will no doubt wind up if the 
speed command is present for any great amount of time, so its possible I 
might have to cobble up a set of PID params to essentially disable that.  
Because I think I am going to need to have the speed present at the VI1 
input before I enable the fwd or reverse commands for the timed 200 
millisecs to drop or pick up the tool during the change. The wind up in 
that case might be advantageous in that it might jerk the nut loose, or 
tighten it tighter before the carousel puts the real tighten on it. But 
likely difficult to control too.

But I find its not possible to send this speed request before the run/dir 
signals. I can mux2 the spindle speed inputs to the 7i76, and have the 
as yet unwritten tool changer code issue the speed and timings.

Is that the choice?

A secondary problem if I do the 3d printed tool holders inside the collet 
sockets, like the orange pieces in one of the videos on hack-a-day, 
depending on the tool to drop free when the nut backs out the collet, is 
that the tool does not always come free, and this looks like a 
showstopper problem that puts me back to buying a handfull of nuts and 
collets so I can drop it all and then reposition the carousel to pick up 
the next tool/nut/collet as an assembly. Either way, it seems like I'll 
unavoidably need an automatic TLO setting to complete the change.

Thanks for any comments on my hair brained ideas. I figure on a bigger 
carousel than shown in the videos. That thought is driven by the 
difficulties I've had with the hand tightened (with a pair of 12 to 16" 
wrenches) on the ER32's on the G0704.

I've wrecked parts and broken tools because they'll walk out of the 
collet, dig too deep and finally break off.  That bit of history has 
cost me several hundred in tools so far. :(

Thanks for any wisdom shared.

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)
Genes Web page 



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