Re: [Emc-users] Question re the 3 jaw on this Sheldon

[Gene Heskett]

On Monday 29 January 2018 00:33:03 Greg Bernard wrote:

> Good description, Gene. Have you ever considered makin' one of them
> new-fangled u-tube videos of your adventures?
>
Yes, but then I think better of it. My place doesn't have the real- 
estate  Kieth Rucker or Joe Pi has, its more like a midden heap than a 
shop and I'm not the cleanest worker. Right now the floor has had about 
a kilobucks worth of mahogany I've been walking on for nearly 2 years, 
seasoning so the when I do start cutting the lids for some blanket 
chests I've promised the boys, and when I get this working, I'll throw a 
tarp over it to keep the sawdust at bay, while I finish 3 more of those. 
I have the rest of the parts cut, doing much of that wood machining on 
the G0704 milling machine and have one 80% assembled, but the mahogany I 
had was so warped and was kiln dried. So the lignin was set and could 
not be pulled straight again. I raised a bit of hell where I bought it 
by taking the first lid into their showroom and let it rock on two 
corners while the 4th one had 4" of air under it. Yeah, warped that bad.

They finally found me some that while it was kiln dried, was at least 
flat, then the son of the owner wanted to charge me for it again. 
Needless to say that got fixed too. Come warmer weather where I can load 
up my trash trailer, I'll lighten the garage floor about 1500 lbs to 
make room for the furniture and get that done. Then, the missus might 
die (COPD), but I hope not, leaving me free to head west of the Missouri 
and deliver them. But I can't do that as long as I have to care for her. 
She fell and broke a hip just 2 weeks shy of a year ago, and of course 
that was fixed, but she hasn't the wind to do the rehab stuff needed to 
get going again.  So I'm doing the cooking etc in between all this.

That, and my camera isn't up to you tubes hidef sharpness, so thats 
reason 2.

But thanks for the flowers, Greg, they are appreciated.

> On Sun, Jan 28, 2018 at 10:49 PM, Gene Heskett  
wrote:
> > On Sunday 28 January 2018 12:39:48 Jon Elson wrote:
> > > On 01/28/2018 01:36 AM, Marcus Bowman wrote:
> > > > I have a TOS 4 jaw self-centring chuck for my mill (lives on a
> > > > plate, and faces upwards, for use holding cylindrical stock
> > > > facing upwards. That's Polish,
> > >
> > > Actually, TOS is Czech, but supposed to be VERY good stuff.
> > > Their high-end chucks go for several thousand $.
> > >
> > > Jon
> >
> > I have come to the conclusion, after taking this chuck apart, that
> > its possible it is a Bison, but well aged, made before they started
> > inlaying a brass logo disk in the face.  Its a 6.25" chuck.
> >
> > The grease in it was much like cold crayons for consistency unless
> > there was a big gob of it that apparently settled to the bottom over
> > several decades without motion. Had a heck of a time getting the
> > scroll disk out as it fit so tight it bound in the hole if tilted 10
> > thou. Had to put a bar of poly in thru the jaw slots, and drive it
> > out 10 thou at a time with a small hammer.
> >
> > Turning the striped body over, I noted the serial number, 4670, was
> > splashed up 3 or 4 thou around the numbers, I knocked them down with
> > a smiths diamond plate, then cleaned the mill table and put it face
> > down on the mill. Lowered my CBN cup wheel down to pinch a sheet of
> > 20 lb under it, wrote a quick loop to drive it in a circle, dropping
> > .0001" for each pass around the circle. Then realized that the head
> > likely wasn't perfectly trammed, so I dropped a plug in the bore
> > hole so it could only move a quarter inch, then restarted the wheel
> > and turned it by hand, dropping it .0001" about every full turn. And
> > I was right, tram was off so it did all the kissing at about the
> > left third of the wheel. Kept that up for about a half hour, until
> > the back face was clean all the way around. Some of the bolt holes
> > were pulled up around a thou for a 1/4" around them. Washed it out
> > clean with paint thinner, using a good bit of a box of Scott towels,
> > smeared some lithium based chassis grease into the scroll's resting
> > place, and had just as much fun re-seating it. That fit could only
> > be achieved useing chalk for the final abrasive, I've done it on
> > $8000 camera lenses. Cleaned up the pinions, greased the scrolls
> > teeth and the pinions and reinstalled those. Feels like well greased
> > fine machinery now. Put the scroll catcher rear center piece back
> > in, (I should mention I found one of those 3 bolts about a turn
> > loose when I took it apart), and it still turned sweet and smooth.
> >
> > Cleaned up the jaws and reinserted them. Jaws can move maybe 5 thou
> > before running into the scroll, so there's no drag there. Put some
> > of that chassis grease in the face of the scroll while I could, then
> > ran half a teaspoon of stp into the ball oiler. Smooth and silky.
> >
> > Looking at the backing plate, wishing I 

Re: [Emc-users] ATS-667 again

[David Berndt]

Just a quick note to say the ATS601 seems to work quite well on inital  
testing. It can detect a small drilled hole in a shaft (think a full width  
peck from a 1/8" drill) without much trouble. If you're sensing  
something(s) that isn't a gear tooth and doesn't have to reject objects  
that aren't gear-tooth-like this may be the way to go.




On Sat, 27 Jan 2018 21:37:38 -0500, Gene Heskett   
wrote:



On Saturday 27 January 2018 19:09:07 David Berndt wrote:

A new name, I'll say welcome in case no one else does.


I'll jump in here and be slightly off topic. I've recently been
setting up some ATS688s for spindle encoding on a big straight bevel
gear. Works great. Wish the duty cycle was a bit higher so I wouldn't
have to skew the A/B phases off 90 degrees. But the gear teeth aren't
square like the reference 60-0 target from the data sheet, so this was
pretty much as expected.

I also tried to use a ats668 to detect a drill hole on the gear shaft.
Forget it. Unless you're target really looks like a gear tooth an
ats668 is not what you want. Ordered some ats601s and 675s to try
instead for the index pulse.


I used ats-667's on the 60 tooth bull gear in my Sheldon lathe, used a
piece of 8-32 screw gooped to the side of the gear in line with a tooth
for an index generator. I gooped them into slots carved in the inside
face of a 1/2" thick alu plate carved to match the OD of the gear. So
they essentially can't move. They have worked well but no feedback to
the spindle, its a vfd drive.


Also keep the ats668 (and most others in the line I assume) mounted
fairly rigidly with short leads. I found when my mill head reversed
directions that some sort of magnetic coupling happens with the gear
teeth causing the sensor to vibrate and moved enough to hit the gear
briefly. I spent a couple hours trying to figure out if the torque
from reversal was moving that gear around, bad bearing, etc, until I
figured out it was the sensor moving. It's not super obvious when
you're staring deep into a mill-head head with a flashlight what's
going on.


Been there, done that, my sympathies.


On Sat, 27 Jan 2018 15:35:54 -0500, John Alexander Stewart

 wrote:
> Hi all;
>
> I am restarting an older CNC lathe conversion - an Emco Compact-8,
> fwiw.
>
> I have the 5i25 and 7i76, and 6 ats-667 sensors for spindle. (6,
> because if
> I only ordered 3, I'd end up breaking one, and shipping is
> expensive...)
>
> Any wiring issues I should be aware of?  Field voltage is about 8v;
> well within the range of the ATS-667. I have some small relays for
> driving the VFD for the spindle, also driven off of field power.
>
> The Emco spindle has a 40 tooth gear, and the aluminium pulley has a
> set screw, so I should be ok with that - 40 teeth should be more
> than enough, right?
>

Depends on how much stability and stiffness you want at the lower speeds,
and the "bandwidth" of the control circuit. I had an opto-interrupter
based rig under the cover where I wasn't able to machine more that 64
slots in the wheel, with a long one for index. The noise and such from
such a low slot count made it impossible to run much Pgain, around 3.5
IIRC. Because the pwm-servo is FAST, it and the motor responded to all
that noise, hammering the gear teeth in the 2 speed head something
awfull.

So here about 3 months ago, I ordered a 1000 line omron encoder from
fleabay for a $21 bill, and drilled into the rear shaft of the motor to
mount an an extension to drive this encoder, but found I had a
differential encoder whose signal levels weren't TTL. That was solved by
a couple of the dollar ea. rs485 transceivers, which had zero problems
at the motors wide open speed making TTL outputs to feed a 5i25. I had
to write a hal paragraph to determine the gears ratios in the 2 speed
spindle in order to scale it. Then because it has two speeds, cut a dent
in the rim of the gear shift knob and put 2 microswitches on it to tell
lcnc which gear it was in, and took advantage of those switches to add a
small offset to the otherwise zero between gears speed, so that between
gears the motor is turning about 20 rpm. With one of Jon's Pico systems
pwm-servo amps, which is a full 4 quadrant controller, I can be turning
1000 rpms, reach up and grab the knob and turn it, and by the time its
moved 5 degrees, the motor is down to 20 revs, the knob continues to
turn until the gears are touching again, and the knob might resist 50
milliseconds while the gears mesh and slide into position, and the motor
speed is restored to the same spindle rpms in a few milliseconds once
the knob is fully homed in the other gear. So I no longer have to stop
the spindle, manually grab and turn the spindle for gear mesh. Doesn't
yet work if the spindle isn't running.  I need to fix that...

I still use the opto kit on the spindle for its index pulse, but all the
two speed logic is in the hal file.  Snippets available, just ask. And
all the quantization noise 

Re: [Emc-users] Question re the 3 jaw on this Sheldon

[Greg Bernard]

Good description, Gene. Have you ever considered makin' one of them
new-fangled u-tube videos of your adventures?

On Sun, Jan 28, 2018 at 10:49 PM, Gene Heskett  wrote:

> On Sunday 28 January 2018 12:39:48 Jon Elson wrote:
>
> > On 01/28/2018 01:36 AM, Marcus Bowman wrote:
> > > I have a TOS 4 jaw self-centring chuck for my mill (lives on a
> > > plate, and faces upwards, for use holding cylindrical stock facing
> > > upwards. That's Polish,
> >
> > Actually, TOS is Czech, but supposed to be VERY good stuff.
> > Their high-end chucks go for several thousand $.
> >
> > Jon
> >
> I have come to the conclusion, after taking this chuck apart, that its
> possible it is a Bison, but well aged, made before they started inlaying
> a brass logo disk in the face.  Its a 6.25" chuck.
>
> The grease in it was much like cold crayons for consistency unless there
> was a big gob of it that apparently settled to the bottom over several
> decades without motion. Had a heck of a time getting the scroll disk out
> as it fit so tight it bound in the hole if tilted 10 thou. Had to put a
> bar of poly in thru the jaw slots, and drive it out 10 thou at a time
> with a small hammer.
>
> Turning the striped body over, I noted the serial number, 4670, was
> splashed up 3 or 4 thou around the numbers, I knocked them down with a
> smiths diamond plate, then cleaned the mill table and put it face down
> on the mill. Lowered my CBN cup wheel down to pinch a sheet of 20 lb
> under it, wrote a quick loop to drive it in a circle, dropping .0001"
> for each pass around the circle. Then realized that the head likely
> wasn't perfectly trammed, so I dropped a plug in the bore hole so it
> could only move a quarter inch, then restarted the wheel and turned it
> by hand, dropping it .0001" about every full turn. And I was right, tram
> was off so it did all the kissing at about the left third of the wheel.
> Kept that up for about a half hour, until the back face was clean all
> the way around. Some of the bolt holes were pulled up around a thou for
> a 1/4" around them. Washed it out clean with paint thinner, using a good
> bit of a box of Scott towels, smeared some lithium based chassis grease
> into the scroll's resting place, and had just as much fun re-seating it.
> That fit could only be achieved useing chalk for the final abrasive,
> I've done it on $8000 camera lenses. Cleaned up the pinions, greased the
> scrolls teeth and the pinions and reinstalled those. Feels like well
> greased fine machinery now. Put the scroll catcher rear center piece
> back in, (I should mention I found one of those 3 bolts about a turn
> loose when I took it apart), and it still turned sweet and smooth.
>
> Cleaned up the jaws and reinserted them. Jaws can move maybe 5 thou
> before running into the scroll, so there's no drag there. Put some of
> that chassis grease in the face of the scroll while I could, then ran
> half a teaspoon of stp into the ball oiler. Smooth and silky.
>
> Looking at the backing plate, wishing I had a thicker one, I'll go see
> TSC about 3 more bolts tomorrow so it will have a bolt in every hole.
> They are spaced evenly, or at 60 degrees, but I'll have to use the mill
> and holefinder routine to find the exact diameter of the circle, cutting
> all the holes 15 thou bigger as I go. This will have to be done while
> its clamped face down so I can use the holefinder.ngc to find the
> x,y=0.0 center of the bolthole circle by referencing the inside edge
> of the smooth rear spindle hole. And find a flat, sacrificial to lay it
> on letting the holddown clamps do the grounding. If I do the math right,
> it ought to Just Work(TM). ;-)
>
> We'll see how my luck holds out, as it will probably be Tuesday before I
> can mount and try to adjust it. At the pace I work, I'll be doing good
> to get all the holes milled to the new size and the bolts test fitted
> tomorrow.
>
> Thanks for reading this far, comment if you like. :)
> --
> 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 
>
> 
> --
> Check out the vibrant tech community on one of the world's most
> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
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> https://lists.sourceforge.net/lists/listinfo/emc-users
>



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Re: [Emc-users] Question re the 3 jaw on this Sheldon

[Gene Heskett]

On Sunday 28 January 2018 12:39:48 Jon Elson wrote:

> On 01/28/2018 01:36 AM, Marcus Bowman wrote:
> > I have a TOS 4 jaw self-centring chuck for my mill (lives on a
> > plate, and faces upwards, for use holding cylindrical stock facing
> > upwards. That's Polish,
>
> Actually, TOS is Czech, but supposed to be VERY good stuff.
> Their high-end chucks go for several thousand $.
>
> Jon
>
I have come to the conclusion, after taking this chuck apart, that its 
possible it is a Bison, but well aged, made before they started inlaying 
a brass logo disk in the face.  Its a 6.25" chuck.

The grease in it was much like cold crayons for consistency unless there 
was a big gob of it that apparently settled to the bottom over several 
decades without motion. Had a heck of a time getting the scroll disk out 
as it fit so tight it bound in the hole if tilted 10 thou. Had to put a 
bar of poly in thru the jaw slots, and drive it out 10 thou at a time 
with a small hammer.

Turning the striped body over, I noted the serial number, 4670, was 
splashed up 3 or 4 thou around the numbers, I knocked them down with a 
smiths diamond plate, then cleaned the mill table and put it face down 
on the mill. Lowered my CBN cup wheel down to pinch a sheet of 20 lb 
under it, wrote a quick loop to drive it in a circle, dropping .0001" 
for each pass around the circle. Then realized that the head likely 
wasn't perfectly trammed, so I dropped a plug in the bore hole so it 
could only move a quarter inch, then restarted the wheel and turned it 
by hand, dropping it .0001" about every full turn. And I was right, tram 
was off so it did all the kissing at about the left third of the wheel. 
Kept that up for about a half hour, until the back face was clean all 
the way around. Some of the bolt holes were pulled up around a thou for 
a 1/4" around them. Washed it out clean with paint thinner, using a good 
bit of a box of Scott towels, smeared some lithium based chassis grease 
into the scroll's resting place, and had just as much fun re-seating it. 
That fit could only be achieved useing chalk for the final abrasive, 
I've done it on $8000 camera lenses. Cleaned up the pinions, greased the 
scrolls teeth and the pinions and reinstalled those. Feels like well 
greased fine machinery now. Put the scroll catcher rear center piece 
back in, (I should mention I found one of those 3 bolts about a turn 
loose when I took it apart), and it still turned sweet and smooth.

Cleaned up the jaws and reinserted them. Jaws can move maybe 5 thou 
before running into the scroll, so there's no drag there. Put some of 
that chassis grease in the face of the scroll while I could, then ran 
half a teaspoon of stp into the ball oiler. Smooth and silky.

Looking at the backing plate, wishing I had a thicker one, I'll go see 
TSC about 3 more bolts tomorrow so it will have a bolt in every hole. 
They are spaced evenly, or at 60 degrees, but I'll have to use the mill 
and holefinder routine to find the exact diameter of the circle, cutting 
all the holes 15 thou bigger as I go. This will have to be done while 
its clamped face down so I can use the holefinder.ngc to find the 
x,y=0.0 center of the bolthole circle by referencing the inside edge 
of the smooth rear spindle hole. And find a flat, sacrificial to lay it 
on letting the holddown clamps do the grounding. If I do the math right, 
it ought to Just Work(TM). ;-)

We'll see how my luck holds out, as it will probably be Tuesday before I 
can mount and try to adjust it. At the pace I work, I'll be doing good 
to get all the holes milled to the new size and the bolts test fitted 
tomorrow.
 
Thanks for reading this far, comment if you like. :)
-- 
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] webrtc as remote control

[Gene Heskett]

On Sunday 28 January 2018 10:28:38 Nicklas Karlsson wrote:

> On Thu, 25 Jan 2018 20:07:23 -0800
>
> Chris Albertson  wrote:
> > webrtc is spec's for about 1 second round trip time.   This would be
> > hugely annoying to use.   Unacceptable lag. ...
>
> Yes without doubt, it would be acceptable reading a manual but not
> writing text and pressing buttons.
>
> > I've read and it is backed u with experience that you need latency
> > LESS THAN 50 ms if you want it to be mostly undetectable by humans.
> > ...
>
> Would guess this to.
>
50ms implies 20 frames a second video. Thats detectable but can be gotten 
used to. Unfortunately on the pi, its about 7 frames a second, and thats 
very noticeable. But it runs the machine ok.

> --
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> most engaging tech sites, Slashdot.org! http://sdm.link/slashdot
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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] ATS-667 again

[Gene Heskett]

On Sunday 28 January 2018 08:25:49 John Alexander Stewart wrote:

> Thanks David and Gene;
>
> Thanks for the responses.
>
> 1) The stiffness of mounting is one that I had not really thought much
> about but makes sense.

> 2) a higher tooth count gear is something I'll look at this AM. Have
> lots of old gears kicking about - and, the idea of adding a bit of
> steel gooped to the side is a good idea!
>
> 3) This lathe is belt driven, so no rigid tapping,

Why not? Unless the carriage screw itself is belt driven that is. Belt 
drive to the spindle is ok as long as and the bull gear the encoder is 
sensing is keyed to the spindle, then the rigid tapping drive to the 
screw motor follows the spindle even if the cutting load slows it.  So 
thats a shrug.

I guess thats just one of the reasons the long carriage bolt gets 
replaced by a ball screw, driven by a motor. Servo or stepper is 
irrelevant, but steppers are easier if lots noisier. Some of that noise 
is because I used a 1600 oz/in off the mill for the z drive, and its  
noisy as all get out at some speeds. Between around 5" and 20" you can 
hear it all over the garage. And while it can run 3x faster on the lathe 
than it could on the mill due to the lack of weight to lift, I really 
should replace it with another copy of whats on the mill, a 940 oz/in 
that can lift the mills 60+ lb head at 90 ipm.

This 1600 oz/in is timing belt coupled to the screw, 32 on the motor, 42 
on the screw, driving a 1450mm long 1" 5 tpi Chinese screw I paid less 
than 200$ for. To keep the screw clean, I made 4 end couplings that 
clamp a couple rubberized cloth bellows nominally 1.5" in diameter, to 
the end mounts and the faces of the nut, so the screw is totally encased 
in the bellows. I even made an air passage thru the nut so the bellows 
wouldn't be under vacuum or air pressure enough to notice as it moves at 
up to 90 ipm. Thats been working nicely for about a year now. Nut has 
been greased twice. If I was to replace both that motor with a 940 
oz/in, and the AC powered driver same as the mill has now, about a 
$290-$300 project, I expect it could do 200 ipm rapids. With maybe 20% 
of the stepper noise. Those 1600 sized nema 34's are 4 wire only and 
have a 22mh coil inductance, and that, unless you can muster up a 300+ 
volt stepper driver, (I've not seen that announcement yet) is going to 
severely impact its high speed torque. The 940 is available as 8 wire, 
which can be paralleled for quite low inductance, so the G0704 mill's z 
went from 27 ipm to 90 ipm by useing the smaller motor.

But rigid tapping, or g76, either one, using lcnc for the precise 
coupling, should Just Work if the encoder is sensing the spindle 
correctly and you are driving the z screw with linuxcnc. Steppers just 
stay in time (within their speed limits), while servo's will need an 
encoder to tell lcnc where the screw is.

> and I had adopted 
> Andy Pughs' HAL feedback loop for a two-speed mill which works very
> well. IIRC, Andy had it working for his 6-speed horizontal mill, so
> crossing fingers, I can get it going for this 6-speed lathe.

Andy's insight also showed me how to scale the encoders a/b while still 
giving me an index from the spindle, and thats working well. Andy's 
ability to understand, and recommend, is well appreciated at this old 
farts site.

Considering the pi's less than stellar performance I had a whole lot of 
stuff I wanted to do on this Sheldon, but I built it to run in a 100hz 
thread, where it seems to work just fine. The apron panel now sports two 
of the $20 100ppi encoders, with variable speed per click programming 
that goes down to .00010" per click, so I can still drive it by hand if 
needed. Best of both worlds. Speed of jog is adjusted by holding a 
pushbutton and rotating the dial but the machine doesn't move, release 
the button and the machine moves with the dial until the dial hasn't 
moved for 5 seconds, then disables. That I need to extend as its too 
fast a timeout, but when I fix that, I'll probably move that variable to 
the ini file. Right now its hard coded in the hal file.  And its all 
displayed in the pyvcp panel.

> Funny how a project will sit for a year or two, then get exciting
> again!

Yes, amazing sometimes. Keeps us out of the bars too. ;-)

> John.

-- 
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] webrtc as remote control

[Nicklas Karlsson]

On Thu, 25 Jan 2018 20:07:23 -0800
Chris Albertson  wrote:

> webrtc is spec's for about 1 second round trip time.   This would be hugely
> annoying to use.   Unacceptable lag. ...

Yes without doubt, it would be acceptable reading a manual but not writing text 
and pressing buttons.

> I've read and it is backed u with experience that you need latency LESS
> THAN 50 ms if you want it to be mostly undetectable by humans. ...

Would guess this to.

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Re: [Emc-users] Question re the 3 jaw on this Sheldon

[Gene Heskett]

On Sunday 28 January 2018 02:36:52 Marcus Bowman wrote:

> On 28 Jan 2018, at 07:00, Gene Heskett wrote:
> > On Saturday 27 January 2018 22:03:33 Eric Keller wrote:
> >> Bison maybe?  Currently considered to be pretty good, and priced
> >> accordingly.
> >
> > So I've noted already.
> >
> > All the Bisons I see today have a brass logo button inlaid in the
> > face. That does not exist and no place it was exists on this one.
>
> I have a TOS 4 jaw self-centring chuck for my mill (lives on a plate,
> and faces upwards, for use holding cylindrical stock facing upwards.
> That's Polish, but, like the Bison, has a round recessed glued-in
> badge. The quality is ok. Interestingly. my impression is that there
> arefewer Polish chucks for sale at the moment, because the centre of
> low cost production seems now to be India. Don't let me get started on
> 'quality'. I have a Burnerd Griptru chuck on my lathe. I bought it new
> in 1975, and I would defend the quality and accuracy against all
> comers. It's an adjustable device which uses 3 conical adjustment
> screws in the body to bear on a loose fitting backplate, and although
> it holds its accuracy on everyday tasks, it can be adjusted to within
> 0.001mm for any given diameter (let's say half a tenth, in old money).
> This supplier has a useful conversion kit for standard chucks up to 5
> inches http://www.hemingwaykits.com/acatalog/Adjustable_Backplate.html
> so I suppose you could make a device like that. It's one step up from
> adjustment with a machinist's hammer.

That, scaled up to fit a 7" and change looks like a good idea. But this 
chucks mount bolts are in its outer edge, so the idea might have to be 
inverted somehow. I'll try the enlarged holes in the plate idea first, 
and rather than trying to dial the body, chuck up a second alu rod 1.75" 
in diameter, (I bought 2 of them to make the jig for the ER-40 pieces 
while they were being ground to correct so I've one 8"er left) and dial 
that in at the chuck with the deadblow, then paper shim it for run-out 
6" out. But that I think is going to require the plate be bored for all 
6 bolts just so I've enough choices for places to shim. The thought also 
comes to mind of straddling the bolt holes with about 4mm or 5mm 
setscrews whose tips are polished flat, loosening the bolt and pushing 
with the screws, then re-tighten that bolt. Wash, rinse and repeat for 
every bolt that needs shimmed.

Biggest problem with the lower cost 3 jaw chucks is the small through 
bore usually under 1.5". Which because this one can pass a 1.5"+ 
workpiece, makes it desirable to rescue it.

Or just give up and dial in the 4 jaw, like I've been doing for the 5" on 
TLM for years. The Little Monster, is a cnc'd 7x12 with just about every 
improvement ever done to one of those P.O.S. With such a small saddle 
foot print, the last fix, tapered gibs, makes a decent small lathe out 
of it. With a 1 horse motor, it can break drive parts in a heartbeat, so 
the willow tree branch of a compound had to go. Now it has a block of 
cast iron that can be rotated for tool tip offsets to keep the cutting 
forces within the saddles footprint on the bed, that and the tapered 
gibs has made a whole new lathe out of it. I made a similar but bigger 
block for the Sheldon on it, same idea, rotate it on the crossfeed and 
adjust the qc post to keep down force within the almost too narrow 
crossfeed ways. All bets on tippage go out the window when the die 
grinder with its heavy inline motor hanging 15" out to the rear is 
mounted, but its at least repeatable, so its a shrug. The die grinder is 
about 17" long, but the mount seems plenty rigid enough. It winds up 
mounting in a std 250 series qc holder. Its a little bigger and heavier 
than a black & decker #8, but considering its 15% of the cost of the b 
was in the 1950's, has already outlasted 2 or 3 of the #8's. I'm amazed, 
I must have more than 150 running hours on it, still running like new. I 
dial the voltage down with a powerstat when I have bigger stones or a 4" 
diamond disk mounted. A 1" alox stone does a fine job at 75 volts.

I ramble on a quiet Sunday morning, as always. Gotta have somebody to 
talk to, the missus doesn't have the wind to carry on a real 
conversation any more. And I think best sitting here "talking" about it.

But I'd better go see what I'm fixing for breakfast, and get some fresh 
coffee under construction as it 9:14 locally.

Thanks Marcus.

> Marcus
>
> > What I am fighting with has all the earmarks of its being pulled out
> > of shape. Bolted to the backing plate, the body is not only
> > eccentric, but apparently out of round. Move the dial to the face,
> > after refacing the plate, and the thickness, plate to face, is
> > around 8 thou out. I can paper shim between it and the plate and
> > help it, but is such a wild variation just in turning it 45 degrees,
> > 5 thou or so just between jaw channels, that seems to repeat, per
> > face section with some wobble 

Re: [Emc-users] ATS-667 again

[John Alexander Stewart]

Thanks David and Gene;

Thanks for the responses.

1) The stiffness of mounting is one that I had not really thought much
about but makes sense.

2) a higher tooth count gear is something I'll look at this AM. Have lots
of old gears kicking about - and, the idea of adding a bit of steel gooped
to the side is a good idea!

3) This lathe is belt driven, so no rigid tapping, and I had adopted Andy
Pughs' HAL feedback loop for a two-speed mill which works very well. IIRC,
Andy had it working for his 6-speed horizontal mill, so crossing fingers, I
can get it going for this 6-speed lathe.

Funny how a project will sit for a year or two, then get exciting again!

John.
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