If you've been around a lathe, you're probably familiar with 5C collets. What sometimes gets overlooked is that they are a really useful way to hold small diameter bar stock to a 4th axis turntable because they are self-centering and more accurate than a 3 Jaw chuck. We've offered a lathe-style 5C collet holder for a while that works really well - our only real gripes with it were that its a bit spendy for occassional use, and it only fit on the 8" table. We recently developed our own design to address both those issues: the 5C Collet fixture.
Instead of using a chuck key to pull the collet into the taper, it uses a nut and spanner wrench that pushes the collet into the fixture as its tightened down. The two minor disadvantages of this design compared to a lathe style chuck are that it takes a little longer to set up, and you can't machine right up to the edge of the collet because the nut is in the way. You can see all of our 4th Axis products and accessories here. We also just finished a new datasheet that was long overdue. I'm stepping out from behind the camera to do a couple quick demos on the two 5C systems and also another one that is often overlooked, MT3 collet with a drawbolt and TTS toolholder.