Chuck Radial Runout Standards

[mksj]

Had a recent email flyer from Shar's that outlined the chuck radial run out and the different standards. I thought it would interesting to post, as there is often the discussion about expected TIR of different chucks. The TIR is dependent on the manufacturer guaranteed specs (QC), size/type of chuck and if it uses some form of Set-Tru type system. One also needs to factor in the back plate and if it is trued up on the machine. Given that Enco is gone, and a few of the other vendors that sold chucks, the options seem to be more limited these days. I have had my share of generic Chinese chucks, most either where returned or sit on a shelf because of TIR or clamping alignment issues. They probably could be fixed with some TLC, but I do not have the inclination to deal with them.

Anyway, the new Shar's chucks seem to offer decent quality and some pretty tight tolerances at decent prices, the Gator/Feruda can be hit or miss but seem to work well, and I have read a few older posts where there have been an issue with the Bison chucks. I do a lot of repeat turning and currently run the Bison Set-Tru 5C, their 8" combination 4J and have been very happy with both of them, also have a Pratt Burnerd SetRite 6" chuck. The PB is also great chuck, The adjustable chucks hold a repeat TIR of better than 0.0004", the combo chuck can be zeroed in less than a minute with repeat parts. The new Shar's FS and CS might be worth considering at a lower price break, they also have their Zero-Set adjustable chucks. I also have a 4J Taiwanese independent from Quality Machine Tools, which has excellent specs/finish.

 

[wrmiller]

My PB works so well I have been afraid to remove it from the spindle.

Recently I've been doing some pistol barrel work and fixtures for said. While my chuck will repeat almost perfectly on a re-chuck of the same diameter, it is off a bit, maybe 1-2 thou (it looks like a lot on a .0005 dial) if I'm going from say a .5" part to a 2" part, but it only take a min or so to adjust it out. I have the same 4j chuck from Matt and it looks really well made. I've just been able to do everything I need in the set-tru so far.

 

[wrat]

My PB works so well I have been afraid to remove it from the spindle.

There's a lot to be said for that!
Because not even the spindle is perfectly concentric and hanging the right chuck in the right way can, on rare occasion, cancel resulting errors.
If you PLANNED it that way, a guy wouldn't have a chance. But if it just happened to work out that way, I'd be keen to leave well enough alone.
And don't go to Vegas, because you done used up all your luck

Wrat