I was having some chatter issues with the Tormach even at pretty conservative feeds and speeds, so I was troubleshooting and found out that the 3/4" R8 collet used in the Tormach actually matters. It turns out that the R8 collet that Tormach sells for use with the TTS system is actually a slightly modified collet compared to the standard taper, so it sits further up into the spindle when the drawbar is tightened. That allows the shoulder of the TTS holders to sit flush against the spindle face, providing a lot of surface area and rigidity to oppose the moment on the tool.
The collet that was installed in our Tormach was a standard 3/4" R8 collet, and when the TTS holders were inserted, the shoulder still sat ~0.050" below the spindle face instead of making contact. In that configuration, the TTS holder basically just adds an extra couple of inches of length to your tool, so it’s no surprise I was having rigidity issues.
We had what looked like a brand new Tormach branded R8 collet sitting in the TTS holder tray, so I went ahead and installed that one. The TTS holders sit flush against the spindle face now, and it helped tremendously with rigidity. I’m pretty new to using the Tormach, so I have no idea how long the other collet had been in the machine, but it looked pretty beat up so I’d guess quite a long time. Just thought it would be useful for everyone to know, and you can make sure to check that the TTS holders sit flush against the spindle face when tightened. Hopefully if anyone else has had rigidity issues with the Tormach recently, they’ll give it another go with everything working as it should. Happy milling!