Tormach R8 Collet

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!

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Thanks, Matthew.

We should add that information to the documentation.

Sorry to revive a dead thread, but I noticed yesterday this was the same problem again. A non-TTS R8 collet was in the spindle and not letting tool holders sit on the spindle nose. I replaced it with a correct collet that was in the drawer, problem solved…again.

Can we just dispose of the non-TTS R8 collets then? It seems like this is an accident waiting to happen over and over …

The RonFu uses R8 collets; the new mill might also. They are standard; the Tormach’s system is proprietary.

But we should definitely remove all the regular R8 collets from the Tormach tool box. What size was it? Was it taken from the RonFu’s collection?

There are a couple people who prefer a nicer 3/4" R8 (I believe the one in there is a Hardinge or similarly high quality) over the Tormach R8, despite the downsides.

That 3/4" R8 in there was bought specifically for the Tormach.

I personally still prefer using the Tormach R8 as it was intended, but :man_shrugging:

Using a non-Tormach R8 would only make sense if you’re not using a TTS tool holder and you’re using the collet directly and touching tools off on the workpiece. Otherwise it completely defeats the purpose of TTS. But as you said, to each their own. We should probably have a guideline that the mill should have the TTS collet in it when you’re done using it, as it’s not entirely obvious to the untrained eye.

All that said, the standard R8 that was in the mill is in the Tormach drawers still, not mixed in with the manual ones.

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