My 5C collet chuck has a TIR of about 0.0002" at the nose, but different collets can be out quite a bit at 4-6".
Is that forged? The gator 8" forged set-tru I saw on fleabay was over $1100.
Yes I agree. A scroll is much more convenient and quick for set up. I have no argument there. I don't look down on anyone, or blame them for using one.Other ruminations: I know some folks almost exclusively use a four-jaw, but I have no desire to dial in every piece I chuck up. To me that's time I can better spend doing other things. Besides, this PBA once dialed in to a diameter will repeat much more accurately than any other 3-jaw I've ever owned. Even if the next piece is of a different diameter but within .5-1" or so of the piece dialed in.
But having said that, this chuck is probably a whole lot more, cost-wise, than most hobby/home machinists want to spend on a chuck to just play around in the garage.
Agree on all points, that is why I currently have a Bison Set-Tru 5C, the generic Chinese 5C brands (which I have had a few) where pretty bad. I use Lyndex 5C collets in 1/64th increments. Even with all this, collet to collet TIR can vary quite a bit based on what you mentioned. I also have an ER-40 system that was given to me, but haven't used that in the lathe. I would expect it to hold better tolerance, but a bit more inconvenient to use. I just mention the different work holding systems and chucks, that chasing a 10,000th here or there is probably not worth the effort when you factor in all the other variables at this level of machinery.The other thing that affects run-out with 5C collets is the fit of the tail end of the collet in the collet chuck. I have found that low cost imports (chucks & collets) can have a lot of variation.
Instead of using a separate collet chuck I use an ER straight shank collet holder in my 6 jaw. Works great for the smaller diameter parts and with the set-tru 6 jaw I can dial in to very good TIR. Best is I don't have to switch out the chuck from the lathe.
Yeah that could make for a really bad day! I'm looking at getting a ER32 straight collet chuck like that. Its on the never ending list.... haI don't have that particular one, but I too have a ER32 straight shank collet chuck that I grab with the PBA for really small stuff and/or working real close to the chuck (I REALLY don't like getting too close to this 8" PBA when I'm spinning it anywhere near 2k rpm. One little slip... )
I like the idea of a 6-jaw, I just don't know if I can justify another $1500 to get it.