Tormach PCNC 1100 Drawbar more power

bll230 · Aug 2, 2021

I have suffered TTS slip with my Tormach power drawbar. I just replaced all the items with new and very carefully installed all the parts with anti-sieze. The Tormach info says to tighten the drawbar to 30 ft-lbs. My drawbar will not loosen the collet when tightened to any more than 20 ft-lbs.

Has anyone put a stronger air cylinder arrangement on a 1100? The stock air cylinder is a 100 mm diameter, 3 stage setup. I know the cylinder is Chinese, probably not as good as a high quality assembly, has anyone tried to take two of the 3 stage units and make one 4 stage unit to get 33% more push on the drawbar?

John

memphisjed · Aug 2, 2021

Can you increase air pressure to it? Running a weak cylinder with oil rich air a few cycles can free it up a fair amount sometimes.

Djstorm100 · Aug 2, 2021

You tighten the draw bar until the tool just starts to fall out under it's own weight.

lube up the beville washers.

Yup the air pressure.

I use to own a 1100 and TTS is the weak part of the system. Same the money and go to BT30 or a used VMC.

Wsurfer · Aug 2, 2021

I had a machine that used TTS. Just a design limitation using friction based tool holding. The only way I could insure the holder wouldn't pull out was to use a full threaded R8 collet when roughing with a 1/2" end mill. If theres any chatter whatsoever, TTS will pull out. Use the smallest cutter you can use if using TTS.

trochoidalpath · Aug 3, 2021

The TTS drawbar arrangement is a weak spot in the design. Set the air pressure to the cylinder as high as you can, carefully adjust the cylinder position relative to the top of the drawbar so you get as much force as you can, and maybe add another set of Bellevilles.

I spent hours and hours tuning mine. Never got to a point where I could run a 1/2” EM reliably. You really want to stick to 1/4”-ish tools, maybe 3/8”.

Or get a BT30 spindle.

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Tormach PCNC 1100 Drawbar more power

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