Chuck For Mill

I do have an idea though. Clamp the chuck on a piece of 3/8 rod stock. Put the rod stock in the collet. Turn the whole think to get a nice straight shaft on the chuck. Reverse the assembly and drop out the rod stock. I would need to buy a piece of rod stock that was machined to pretty good tolerance, and I would have to accept the imperfections of the jaws since I would not be able to turn them to be perfect before clamping the rod in them, but it should be ok for some crude parts.

My big concern is whether or not my Z-axis stepper motor would flake out with the extra weight. I have to keep my Z-Axis lead screw well lubricated now to prevent lift fails in some ranges.

There will be cumulative error from this method, but I should be able to turn stuff within 5 thousands (plus the any slop in the mill head) if I start with a purchased piece of precision rod stock. Of course this sets off a-whole-nuther chain of ideas. LOL.

The arbor screws into a 12mm x 1.0 tapped hole in the back of the chuck.

jsw

I wonder if you could bore out that hole and tap it to mm 22 x1.5. Then you could use the chuck in place of the ER16 collet nut. Still you might have problems turning the chuck. I'm not sure how robust the Taig mill head is.

The boss on the back of the chuck is 23mm diameter with a groove for the snap ring that retains the scroll, the black knurled ring. The hole is 15.8mm deep to the back of the chuck jaws. The arbor extends

I'd look for a 12mm-1.0 tap with a shank that fits the ER collet and use it as the arbor. I doubt you can find or make anything as straight and concentric as a ground tap, especially without a lathe. Tap the lock nut, then cut the tap off short to reduce overhang.

jsw

Bob,

I could make you an ER32 chuck to thread onto that... But the runout might not be lathe quality... Maybe a few thousanths at worst. Probably not terribly cheap either, but worth looking at if you are interested as it's a no risk talk, eh?

Call and ask for Joe Jr. if interested.

Regards, Joe Agro, Jr. (800) 871-5022

Bob,

I could make you an ER32 chuck to thread onto that... But the runout might not be lathe quality... Maybe a few thousanths at worst. Probably not terribly cheap either, but worth looking at if you are interested as it's a no risk talk, eh?

Call and ask for Joe Jr. if interested.

Regards, Joe Agro, Jr. (800) 871-5022

I'm less concerned with the head being able to spin the chuck as I am my stepper motor being able to consistently lift it with out skipping steps and going out of calibration with my software.

The tap is not a bad idea if I could find one with a 3/8 shaft. Given its nature I'ld probably want to lock it in place with green sleeve locker and make it permanent. I suspect this is one of those things, I'm just not going to be able to do to my satisfaction until I already have a lathe. LOL.

I dunno. I think the taper inside the head meeting with the collet is how a bit centers. The outside locknut and threads do not have to be as perfect. May be compounded error there. Did I misunderstand how this stuff works? Something screwed to the outside I think would not be as perfectly centered as something clamped in the collet?

Your solution is probably the best. I understand the difficulty of getting the threads perfectly straight, but it's much more preferable to have a thru hole in a lathe chuck and threading the chuck on the spindle avoids the problems of having the chuck slip. Sherline chucks have 3/4-16 threaded backs, which is close to the mm 22 x 1.5 size. I found an odd fact in that both 3/4-16 and mm 22 x 1.5 are both automotive oil filter threads. Maybe Bob could use oil filter parts for a faceplate (although tolerences might again be an issue).

Right now, how do your chucks mount?

I thought it was a 12mm X 1.5 male thread sticking out of your unit.

In that case you could thread the outside of the chuck boss 22mm-1.5 and make a simple inside-threaded sleeve adapter. Then the bores of the spindle and chuck would be open to accept long work pieces. The Taig site says the ER-16 spindle has a 0.406 thru hole.

The boss extends 3.2mm beyond the snap ring. If you don't mind a little adjustment when installing the chuck the sleeve could replace the snap ring as the scroll plate retainer, this would allow longer threads on the boss.

jsw

There's a reason for that; it self-centers when mounted. Can you get a chuck with the same taper as your ER-16 collets' exterior? Use the collet-holding taper to center the chuck, would be my preference. Chucks with R-8 taper, for a Bridgeport mill, are a common item.