[hoss2006]

I figured (guess) .125 for load on the washers and enough left to release.
May only need .010 or so to release
We'll see, let the experimenting begin.
Hoss

[RedDog22]

Awesome. I cant wait to hear your results. One last thing. Normally when you loosen the drawbar you have to give it a wrap to get the collet to let go of the tool holder. Any ideas on how to get around that? Or do you think it wont even show itself?

[hoss2006]

When you loosen the drawbar by hand, it's free to move up away from the collet
because there's nothing to stop it. So then you have to tap it to release the collet.
With the cam and lever being depressed by the air cylinder against the top of the drawbar, the only way it can move is down against the spring washers.
It pushes the drawbar and collet together, releasing the tool. Voila
Hoss

[RedDog22]

After reading your answer I cant believe I even asked it. lol Thanks for answering. I'm not sure why I was thinking only the spring stack was being pushed on...

[RedDog22]

Hey Hoss. Just wondering. Are you doing this up in any cad program?

[M100]

When you loosen the drawbar by hand, it's free to move up away from the collet
because there's nothing to stop it. So then you have to tap it to release the collet.
With the cam and lever being depressed by the air cylinder against the top of the drawbar, the only way it can move is down against the spring washers.
It pushes the drawbar and collet together, releasing the tool. Voila
Hoss

I can't visualize what you're saying. Due to it being a regular operation I can see how the drawbar extends upwards when loosened by hand and the tapping of it to release the collet from the taper but the rest of it puzzles me.

Any chance of a pointer to somewhere online with a cutaway drawing or a sequence of operations showing how the springs are compressed (when they appear to be completely internal to the spindle bore) and how the drawbar is tightened?

[digits]

I can't visualize what you're saying. Due to it being a regular operation I can see how the drawbar extends upwards when loosened by hand and the tapping of it to release the collet from the taper but the rest of it puzzles me.

Any chance of a pointer to somewhere online with a cutaway drawing or a sequence of operations showing how the springs are compressed (when they appear to be completely internal to the spindle bore) and how the drawbar is tightened?

If I understand it correctly, the springs are between what would be the 'nut' on a manual drawbar and (the top of) the spindle. When the drawbar is screwed into the collet, this preloads the springs, which in turn pull the drawbar upwards, securing the collet against the inside of the taper.

The drawbar is then released by pushing down on the nut, not unscrewing it.

[hoss2006]

You got it Digits,
If you look at the Z-bot pdf from Little machine Shop, you can see how it works.

[hoss2006]

Parts to make the power drawbar are ordered.
The project is off and running.
$50 for the air cylinder,spring washers,solenoid valve and relay.
$18 for shipping from 2 sources though.
I'll make the rest of the parts.
I'll give a complete breakdown when it's all together and i know what works.
crap, forgot to get a couple of hardened flat washers for the springs to rub against.
I'll make them too now I guess.
Hoss

[hoss2006]

Got the spring washers already from MSC Direct, less than 24 hours. :cheers:
I'll figure out how many are needed and what stacking arrangement works this weekend.
Ordered the Speed control board from Cnc4pc. It will let Mach 3 turn the spindle on/off via g-code (from what i've read).
Now I can get all the electronics done at the same time;
limit switches, spindle control and drawbar control.
Only up to $88 so far.
Don't figure this will cost anymore than $150 for everything including stock.
We will see.
Hoss

[tpworks]

Removed

[Bob Adams]

Hey Hoss, good going. Where did you buy the air valve? Is it Electric?

[hoss2006]

Hey Bob,
I just got the air valve a little while ago from UPS.
It's 110 VAC that I'll control with a solid state relay.
That's the plan anyway.
Got the Bimba air cylinder too.
they claim it puts out 440 lbs of force but if you do the math,
a 1.5 in dia. bore at 110 PSI = 194 lbs
This will work if i use a 6:1 ratio on the cam lever= 1164 lbs.
Should be plenty enough to release the drawbar.
Have a set of small tool holders done.
they hold up to .500 shafts (endmills)
Will make another larger diameter set to hold up to .750 endmills and drill chucks.
Completely modifying the electronics this weekend or so to house everything
in my old pc case. will get the limit switches, drawbar control, spindle control
and X2 electronics all together and wired up to test.
Onward.
http://www.hossmachine.com

[ataxy]

whats the runout on your holder

[hoss2006]

.0000
My test indicator can't measure anything smaller.
showed no deflection.
before i drilled and tapped for the set screws,
the endmill acted like a shock absorber from the air that couldn't escape
and wouldn't go all the way in.
good enough for who it's for

[ataxy]

wow 0.0000 is in fact pretty good

[digits]

.0000
My test indicator can't measure anything smaller.
showed no deflection.
before i drilled and tapped for the set screws,
the endmill acted like a shock absorber from the air that couldn't escape
and wouldn't go all the way in.
good enough for who it's for

Nice looking tool holders Hoss - did you cut them on your lathe on your mill, or do you have a 'real' lathe as well?

Also, do you need to add some sort of groove in the flanges for an ATC, or will it just locate the tool holders via the flange?

[hoss2006]

Used my real lathe to make the holders.
The mill is in pieces right now.
Phase 1 will be a simple 7 tool rack, probably for (3) large and (4) small holders.
Figure that will be the easiest for the DIYer, Should still fit the stock X2 table.
Those with more than 4 inches Y travel could add on from there.
Be more programming for the Macro for Mach 3 than one similar to the LMS ATC
that moves to the same position each tool change.
Still have to get into figuring that out.
Phase 2 will be an articulating tool rack, probably an 8-10 tool.
Phase 3 will be a Scarlett Johanson robot to change my tool(s).
Hoss

[ataxy]

Phase 3 will be a Scarlett Johanson robot to change my tool(s).
Hoss

see thats the part i am interested in

[Willyb]

Hi Hoss

Sounds like a good looking project. Always wanted to build a ATC and someday I will. Interested in watching your progress. Keep up the good work.

Willy