[bobeson]

I believe that the particular dynamics of the PCNC1100 do in fact contribute to the pullout problems that I have experienced with TTS on my tormach mill. It is quite possible that the machine dynamics of a different design, such as the Torus Pro, would not experience chatter conditions in the same manner as the PCNC does. My pullout problems are significantly reduced (nearly eliminated) when I change out my power drawbar springs for a solid bushing, for example. I believe you are using a screwthread-tensioned drawbar arrangement on your machine, is that correct Ray?

In any case, I don't believe you can accurately state that TTS works the same on any machine, at least as regards this issue of chatter-induced TTS toolholder pullout, using a typical R8-collet TTS setup.

[SCzEngrgGroup]

I believe that the particular dynamics of the PCNC1100 do in fact contribute to the pullout problems that I have experienced with TTS on my tormach mill. It is quite possible that the machine dynamics of a different design, such as the Torus Pro, would not experience chatter conditions in the same manner as the PCNC does. My pullout problems are significantly reduced (nearly eliminated) when I change out my power drawbar springs for a solid bushing, for example. I believe you are using a screwthread-tensioned drawbar arrangement on your machine, is that correct Ray?

In any case, I don't believe you can accurately state that TTS works the same on any machine, at least as regards this issue of chatter-induced TTS toolholder pullout, using a typical R8-collet TTS setup.

The OP is not using a power drawbar at all, so his environment is much closer to mine than to yours - we are both tightening a drawbar, with no Belleville springs. Mine has never slipped, even under conditions of pretty significant chatter.

Regards,
Ray L.

[bobeson]

The OP is not using a power drawbar at all, so his environment is much closer to mine than to yours - we are both tightening a drawbar, with no Belleville springs. Mine has never slipped, even under conditions of pretty significant chatter.

I think I did a poor job of expressing myself regarding the effects of machine design and drawbar style on chatter-related pullout. You are correct, the OP and yourself have more similarity between your drawbar configurations than my default Tormach spring-loaded power drawbar does. However, the overall machine construction and configuration of any TTS-equipped machine (including work clamping, etc.) will affect how frequently TTS holders will pull out during chatter conditions. I used my spring-loaded vs. screw-tightened drawbar configuration difference anecdote as a poorly-executed illustration of the effects of differing machine configurations affecting TTS pullout. My question about your setup was motivated more by curiosity and was somewhat tangential, and not intended to support my main point by inference, although it does read that way in hindsight.

I am speaking of this because I spent quite a bit of time attempting to characterize and understand the conditions that were causing pullout on my machine. I came to realize it was all a function of the dynamic loading of the toolholder interacting with the machine's motion and drawbar tension. I can easily see how you might never experience TTS pullout with your machine, setup and tooling, whereas various Tormach (or other mill) owners may experience it relatively often if they are doing deep profiling cuts in steel with a standard end mill, for one example. (My worst case example, btw).

For the OP, I would recommend checking your gib adjustments for all three ways, and also your lubrication effectiveness across all of the ways. I have had problems crop up with pullout when my gibs are too loose or when inadequate way lubrication is causing extra chatter. Also, make sure that your spindle is trammed well. This is easy enough to check, but not particularly easy to correct if you are out of tram. Since you mention slotting and not profiling as being the operation that causes your pullout, I would check the tram first, in fact. You should be checking and adjusting your gibs fairly regularly anyhow, so do this too if you haven't recently.
Good luck! I know how frustrating it can be to wrestle with this problem.

[SCzEngrgGroup]

I think I did a poor job of expressing myself regarding the effects of machine design and drawbar style on chatter-related pullout. You are correct, the OP and yourself have more similarity between your drawbar configurations than my default Tormach spring-loaded power drawbar does. However, the overall machine construction and configuration of any TTS-equipped machine (including work clamping, etc.) will affect how frequently TTS holders will pull out during chatter conditions. I used my spring-loaded vs. screw-tightened drawbar configuration difference anecdote as a poorly-executed illustration of the effects of differing machine configurations affecting TTS pullout. My question about your setup was motivated more by curiosity and was somewhat tangential, and not intended to support my main point by inference, although it does read that way in hindsight.

I am speaking of this because I spent quite a bit of time attempting to characterize and understand the conditions that were causing pullout on my machine. I came to realize it was all a function of the dynamic loading of the toolholder interacting with the machine's motion and drawbar tension. I can easily see how you might never experience TTS pullout with your machine, setup and tooling, whereas various Tormach (or other mill) owners may experience it relatively often if they are doing deep profiling cuts in steel with a standard end mill, for one example. (My worst case example, btw).

For the OP, I would recommend checking your gib adjustments for all three ways, and also your lubrication effectiveness across all of the ways. I have had problems crop up with pullout when my gibs are too loose or when inadequate way lubrication is causing extra chatter. Also, make sure that your spindle is trammed well. This is easy enough to check, but not particularly easy to correct if you are out of tram. Since you mention slotting and not profiling as being the operation that causes your pullout, I would check the tram first, in fact. You should be checking and adjusting your gibs fairly regularly anyhow, so do this too if you haven't recently.
Good luck! I know how frustrating it can be to wrestle with this problem.

Personally, pullout under chatter would not really concern me too much since, pretty much by definition, if you're getting significant chatter, you're operating outside any proper operating area for the combination of machine, toolholder, tool, and workpiece. Chatter is the result of exceeding the rigidity of the machine and/or toolholder and/or tool and/or workpiece support.. It is brutal on the tools, creates lousy surface finish, and poor dimension. So, you simply shouldn't ever be operating there.

Regards,
Ray L.