[diyengineer]

I've seen adapters for 30 taper nmtb to mt3. Do they sell one to go to r8? I'd like to be able to use a few of my tools that are setup in tormach quick change holders without removing them and setting them up in a 30 taper holder. Would the holder adapter have a threaded screw inside for the r8?

[SCzEngrgGroup]

Just use a 30-taper ER chuck with a 3/4" collet.

Regards,
Ray L.

[diyengineer]

Way to overthink things right... Hahahah!! Thanks as always Ray.

[TurboStep]

There are a couple of reasons why I wouldn't stack tool holders but it obviously depends on your exact application:
Runout may be unacceptable - you can sometimes play with different orientations but usually Murphy ensures that components contributing to runout add up just when you would prefer them not to.
I don't see how you could ensure that the TTS collar would press against the ER nut so you'll only be clamping on the shank. This is actually a good thing when considering runout (unless you have a nut ground perpendicular to the rotational axis) but bad when considering stability. Not only is this assembly prone to flex but I wouldn't be surprised if you'd have problems controlling the chatter.
By all means try it and prove me wrong, but this isn't something that I would want to do.
In my opinion you'd be better off buying a few spare end mills.
Step

[philbur]

You don't need a collet chuck and ER collet you can buy ISO30 collets that will directly perform the same job as the Tormach R8 collet. You may have to do some minor modifications like facing the end etc. Google ISO30 Collet.

Phil