[TT350]

I’ve been working on an auto drawbar for my mill.
I’m not trying to start an argument but shed some light
on your draw bar.

When I do a tool change I put about 65-75 degrees
of rotation on the wrench after the draw bar has the slack is taken out of it.

If you equal that much force with disk springs a 4”
cylinder @ 90psi of air falls way short of having enough
force to deflect the springs, it won’t even move them.

If you put a spring light enough that a the cylinder
will deflect the spring .020-.030 even then it has a hard time un-sticking the collet.

So I run some jobs with my auto draw bar @ 125psi
to overcome the sticking and fund that the spring load
was not enough to keep the tool holder from “walking”
out of the collet.

I removed my auto draw bar and started adding disk springs until I could hold the tool holder firm enough
that it wouldn’t move under the heaviest of cuts and
the tension is well north of 3000 psi and close to 4000
to deflect then enough to allow a tool change and who knows how much it’s going to take to un-stick the collet?

I'm still working on mine.

[pzzamakr1980]

Hey TT, if you havent had a chance, take a look at Hoss's tool changer thread in benchtop mills forum. His original ATC thread. He discusses the issue of sticking and what he did to fix it. For myself, my tools readily drop out when the drawbar is loosened a little more than slightly. Other peoples don't and no matter how loose the tool has to be pulled out. He also discusses the drawbar pressures and deflection.

Also, I couldnt agree more with the comment about hobbyists purchasing what they want and can afford and businesses trying to get the most for their dollar. I think it sums up the argument perfectly.

[TT350]

I have seen Hoss setup.

When you loosen the draw bar you have to tap it
to “un-stick it” and then the holder will fall out.

I put 25-30 hours of spindle run time on my machine ever
week and I know what it takes to apply enough tension
required to match that of putting 65-75 degrees of
rotation on the draw bar after it’s seated and a 3-4 cylinder with 90 psi shop air ant gona cut it.

[PoppaBear10]

3 and 4 inch cylinders are for babies!!! hehehehehe

Mine is a 5" and some really nasty bellvieles.

All I care is it works and Mr. Tool stays in, when it counts, the ATC has NO problem pulling it out at change time.

scott

[TT350]

I’ve run this job 5 or 6 times before and it will yield
over 125 lbs of waste when it’s done.

I’ve had the opportunity to test draw bar spring tension
and I know what it takes to keep the holder from being
pulled out of the collet under heavy milling for extended
periods of time.

For your 5” cylinder to produce enough force to deflect the springs required to do the job you will need to multiply it’s force.

Your saying “the tool stays in when it counts”
It won’t take much to keep it from falling out while
your shooting the demo video.

Your testing needs to go beyond cycling the ATC.
You need to put it to work for about 3-4 mouths
before you can be sure it’s ready.

I hope you plan on a cover to keep the chips off the tools.

[PoppaBear10]

Here is a ATC cycle Test Video of the changer swapping Tools!!

Here is the link:

http://video.google.com/videoplay?do...71753563&hl=en

Next stage is varifying the 12 Tool Auto Tool Setter Cycle.

Scott

[PoppaBear10]

I just put it up tonight, mabey it hasnt processed yet?
here is the link I have that works..........

http://video.google.com/videoplay?do...71753563&hl=en

scott

[Freddy Bastard]

Wow! I would like to see it taking a large cut after a tool change...
It look's like a robust project.

[Thunderpaw]

Looks good. How about an ATC for the BT-30 tooling?

[TT350]

Can you use it with Duality Lathe?

[PoppaBear10]

Freddy B*sterd:

I will be doing some testing cuts, soon, and get some vids up after.

Please define what YOU mean by "Heavy" cuts? What Material, cutter size/type,
depth of cut, spindle speed, Feed Rate, that your cuttin with your Tormach now.

Thunderpay:

All I would have to do for that is Change the Tool holding Claw design, but,
I dont have a Tormach with that Spindle or that Holder type to test with, perhaps
after I get this one running..............

TT350:

I agree with all your Tool Holder, holding concerns, I also believe that the AL
recycling guy, LOVEs to see you drive up....... Man, what a HUGE pile-O-Chips!!
Would it not be Cheaper for you to "Cast" blanks close to size and then do your
final machining???

Duality Lathe: I really dont see why not, I haven't really changed the spindle nose
and the ATC Arm swings far enough away to clear Tormachs 4th axis on that side.
Basically, as far as the Mill head is concerned, I just added a Power Draw Bar.

Note:

This is a "Proto type" ATC, and as such, the final "Commercial" version will have
slight changes to it to make it as painless a "Turn Key" ATC kit as I can make.

Thanks for the replies,

Scott

[TT350]

It is an extrusion that’s being supplied by the customer.

I thought I seen a wire plugged into the accessory port.
Isn’t that where the Duality lathe plugs in?

[PoppaBear10]

TT350:

Ahhh, No that is the plug for Tormachs accessory "Tool Hiegth" setter.

I plug in the Setter only for setting the Tool hiegths, then unplug it.

[Freddy Bastard]

By heavy cut, I mean something similar to this: http://www.tormach.com/MfgDatabase/MFG_20107_LR.wmv
I don't really push my Tormach too far. Most of my work is with small cutters. What kind of warranty do yo uplan to have for the ATC?

[Willyb]

:Please define what YOU mean by "Heavy" cuts? What Material, cutter size/type,
depth of cut, spindle speed, Feed Rate, that your cuttin with your Tormach now.

Hi Scott

A good test for a heavier cut would be to duplicate the 20102 Tormach Video.

http://www.tormach.com/mfg_database.htm

This Video shows a stock Tormach cutting off a 1" X 4" 6061 Aluminum Bar at 5 IPM. This would be a very good test of the amount of pull (Spring Washers) you have on your Draw Bar. The side cutting load tends to try and pull the Tool Holder out of the Collet. I had this happen to me once when I noticed that my Z Axis had changed. I started tightening my Draw Bar a little more after that.


(Machining Information)
Material: 6061 T6 Aluminum
Cutter: 4 flute HHS rougher
0.5” diameter
Speed: 2500 RPM
Feed: 5 IPM
Coolant: Flood
Machine: Tormach PCNC 1100



Willy

[Willyb]

Hi Scott

Does the installation of your ATC require any changes to the stock Tormach Mill other than drilling a few holes, etc? Does the Z Axis travel stay the same?

I am also interested in what modifications a person is required to do to their Tool Holders? Can all of the present Tormach Tooling be used with your ATC? How are the Tool Holders held into the Tool Platter?

Willy

[Thunderpaw]

With BT-30 tooling would there also be a power draw bar add on that would grab retention knobs?

[PoppaBear10]

Freddy:
Willyb:
Thunderpaw:
highspeedmazak:

First let me say, thank you all for your
questions, and ideas as well!

Ok, I will do a replication of those
cuts.

Install:

Yes you have to drill holes.
There is No loss of Z travel,
OTHER, than at where you decide to set
your Tool Change ht.
Currently, I have the tool change ht.
0.5 inches away from Z home,
The "Z" axis Change ht. is a "Permenant" choice,
you have to choose that before you install, since
where you mount the Changer will coinside with
this point. What I mean by this is, you have to
clear the Holder shaft, it is 1.5 inches tall, I clear
that ht. by 0.10, which is in this case 0.5" from
Referenced z home.
I could have moved it all up to right under
the home, but I wanted to "play" space.
I move the X/Y to 1" away from thier homes.
On the settings page, you can pick your own.
I put it here to clear any work.

I am using Tormachs Tool holders, that
I put a Groove in.

BT-30:
When I get to this, It will work. But, it
will be a little while.

It has sequence logic/safties, so it does each move
and then move on to next step. The PLC does the lions
share of the "Thinking" for the system.

TT350: I noticed your machine pics are almost
exactly like the ones in the Tormach videos
do you work there?

Scott

[SarcasmOMatic]

Looks good. Congratulations and good luck making it that last mile.

[zephyr9900]

Mine is a 5" and some really nasty bellvieles

Scott, what force is your air cylinder applying to the drawbar when activated? This goes back to the other auto-drawbar discussions that point out that all that force is being resisted by the spindle bearings, and raising concerns to what the long-term damage to the bearings might be. Do you have a buy-in from Tormach in going this route?

Other than that concern (I'd be a lot happier with the air-wrench approach like Joe Vicars') your toolchanger looks excellent!

Best regards,

Randy