[Gravelleknives]

Hey everyone, Ive been a lurking here a long time but I never post. I just wanted to say i get a lot of good info here and enjoy the tormach forum here.

I have gone from knowing nothing about machining to knowing very little but I am enjoying using my tomach. However the last few months as ive gotten more comfortable with pushing my cutters hard I've started having a bad problem with pullout.

this morning I was cutting A2 tool steel .25 doc .075 woc with a .25 roughing endmill at 16ipm and in just a about 30 sec it had pulled out about .25" out of the spindle. the material was cutting fine, no chatter but it started bogging down and I realized it was pulling out so i hit the e stop. Is this normal, am i just cutting to heavy? or do I maybe need new spring washers to tighten up the collet? It has pulled out several other times too under a similar load. I had a .1875 rougher pullout while cutting Ti which really surprised me, I didn't think a .1875 bit would be able to pull out. Any input is appreciated.

totally off topic but has anyone ever heard of someone installing something like this on their tormach?

[MetalShavings]

I've never had this happen to any of my cutting tools so I'm not really clear on what exactly is "Pulling Out." Is the tool holder pulling out of the R8 collet in the spindle or are you using Tool holders with ER collets that your cutting tools are "Pulling Out" of?

If your tool holder is "Pulling Out" of the R8 collet in the spindle, you might try a different 3/4" R8 collet. I could be that your present spindle collet is just not clamping down tight enough when your draw-bolt is torqued down.

If it's the cutting tools being held by your ER collets that are what's being "Pulled Out" of, perhaps the tool holder itself is defective in some way. It could also be that if you have even a slight film of lubricant on the tool holder or the cutting tool, that may be enough to allow for slippage.

MetalShavings

[popspipes]

https://www.youtube.com/watch?v=Imu1jhMJBZc

This video is for cleaning and lubing R8collets.

It works well for me greatly reducing cutter pullout

[pickled]

Hopefully you didn't get to machine your table when that happened. There has been some good info presented in this thread so far for you to follow up on. I use the "armstrong" method here for both of my machines so I don't have much to offer from the power drawbar side of the equation. You shouldn't have had pull out on the Ti or A2 unless something was truly amiss. Pull out typically only happens for me these days when I'm either bouncing into the RED repeatedly and bogging down the spindle (hitting hard spots from flame cuts, or poor toolpath geometry can get you in trouble quick on tool steels), or taking very heavy interrupted cuts.

Cleanliness and basic mechanical inspection are extremely important in my book these days. I wipe my tts holder shanks with denatured alcohol and/or acetone frequently and check for any obvious linear scratches or signs of wear. I experienced pullout on a 1/2" 6 flute tool that I was pushing really hard on steel a few months ago and it actually marred the TTS set-screw holder shank so badly that it is now sadly retired. Amazingly it didn't "injure" the collet. The prussian blue wipe is a good way to make sure that you are getting a good contact pattern with the collet and it doesn't take very long to buff the surfaces into a high degree of engagement either. FYI A build up of any gunk in the reliefs of the R8 will screw you up too. I had wood fibers and carbon fiber dust get up into mine and cause me some troubles a while back so I now drop the collet out and give it a good cleaning before I start a new project. That is also an excellent time to service the threads and washer contact areas as well. Good luck!

[Don Clement]

I found that applying LP250 anti-seize on R8/TTS external mating surfaces and threads really helps to prevent pullout. LP-250 & LP-250F Anti-Seize Thread & Sealing Compound

Don

[shred]

Check your Bellville spring stack if you have the PDB. They do wear and crack over time and a cracked Bellville causes all kinds of havoc.

[SCzEngrgGroup]

The Bellevilles also need to be coated with anti-sieze, and tightened to the point that the air cylinder is JUST BARELY able to release the toolholder. Even so, with a larger tool, and aggressive cutting, pull-out is not particularly unusual.

Regards,
Ray L.

[sansbury]

I haven't cut A2 so I could be wrong but your cutting parameters sound pretty aggressive to me, particularly the .25DOC with a .25" tool.

For comparison I will run a .25 2-flute in 6061 using a .1 WOC, .05 DOC at 5k RPM and 40IPM. Beyond that I get chatter.

[Steve Seebold]

I have tightened the PDB on my 1100 like Ray L says to do and I have no pullout issued with MOST materials, but I have never tried cutting A2 steel.

I cut all kinds of other stuff like Inconel 718 and 6AL4V titanium with no pull put issues.

The material I like the least is delrin. I don't have any pull out but it makes a HUGE mess in the machine.