[bobeson]

OK, once again my poor choice of words has derailed my point. You can substitute "vibration" for instances of "chatter" in my description of the pullout problem areas, because that is more what I was attempting to imply than conditions specific to the traditional machinist's definition of tool chatter. Of course we should not be operating under chatter conditions under normal circumstances. Chatter is a specific condition that is a problem by definition, yet it correlates with cutter-induced machine vibration and TTS pullout conditions, but it's not the whole story about TTS pullout by any means. Steve, if you aren't cutting steel, I'm not surprised that you aren't getting chatter. I'm interested in cutting mild steel, and while I have had plenty of successes, along with them I've had plenty of struggles to avoid chatter and pullout for some operations, such as profiling with a reasonable DOC and shallow WOC. This is where machine design and setup differences are most pertinent, when intermittent high loading forces are imposed in repetitive and complex radial and axial loading directions. First vibration starts at light loading, then you get chatter at higher loads, and maybe you get TTS pullout somewhere in there too, or maybe you don't.

[LSM]

How tight not supper tight the cheapo wrench that came with the machine will do it
snug then about 1/4 to 1/2 turn.
but the threads on the drawbar and the collet have to be lubed

it will cut steel with out chattering but using a rougher mill helps and 3/8 is the max tool for a finisher
and it's better with 5/16 .
Like Steve points out it's all in knowing the limitations of the machine and the tool

a good carbide endmill also makes a difference when cutting steel 1/4 and 3/16 were my work horses in steel usually a ghuring variable helix.
close to the same price as a decent hss tool in steel the tool smf is the limiting factor in aluminum it's machine spindle speed

[Don Clement]

I have had no pullout issues with my Tormach PDB. I use at least 120psi with the PDB and adjust the drawbar on the Bellevue washers so that 120psi will just release the TTS toolholder. Also lubricate the Bellevue washers , drawbar threads, and R8 collet with LP250 antiseize LP-250 & LP-250F Anti-Seize Thread & Sealing Compound Bellevue washers are not a true spring and have sliding surfaces with friction so good lubrication is really required.

Don Clement

[IMT]

I have had no pullout issues with my Tormach PDB. I use at least 120psi with the PDB and adjust the drawbar on the Bellevue washers so that 120psi will just release the TTS toolholder. Also lubricate the Bellevue washers , drawbar threads, and R8 collet with LP250 antiseize LP-250 & LP-250F Anti-Seize Thread & Sealing Compound Bellevue washers are not a true spring and have sliding surfaces with friction so good lubrication is really required.

Don Clement

Don,
Thanks for the input. I never thought about lubing the belleville washers. I run my PDB as tight as I can get it and still have my it release at 100psi, where my compressor kicks on. Keep the outside of the R8 collet lubed with antisieze and the inside clean, also keep the tool holder shanks clean. I have only had pullout when there was chatter.

Dan

[LeeWay]

One other area to check is the nose of the spindle itself. TTS seats there and if it is not true, it can bind a bit and require higher pressure to release cleanly. It's an easy spot to check and fix if actually needed.
Before you remove any material from there though, make sure that it is trammed good.

[BAMCNC.COM]

It's funny we have 3 threads on basically the same thing going on at the same time.

Uploading a video now, which will be part 2 of my test for collet pull out - My video is posted in the other 2 conversations, so I won't post it here too.