Run out for lathe with speed reducer

[JPG]

Although the tail stock is not perfectly rigid, the clamp can make it worse.

A close look at the clamp will reveal if it is not adjusted correctly. When tightened, the ends of the handle should NOT touch the base casting at either end. This can not occur(one end or the other will touch the base casting) if the screws in the ends of the clamp handle do not protrude an equal amount at both ends. Those screws are what presses against the posts and clamps them in place.

To properly adjust the clamp, loosen the clamp until it will slip out of the base casting grooves. Then manually tighten both screws all the way into the clamp handle(one is right hand threaded and the opposite end is left hand threaded). Then carefully run the screws 1 1/2 turns out(6 flat edges past a fixed point). then carefully slide the clamp back into the base casting grooves. If the screws are too long to slip into the groove, run them back into the clamp handle an equal amount. If the screws are too short to extend into both grooves, run the screws out an equal amount.

Adjust the handle until you can feel the screw extend into the spt post bore. Back the clamp off slightly and insert the tailstock. Tighten the clamp snugly. The ends of the clamp should be approximately the same distance from the base casting.

Realize the clamp can be inserted into the grooves two different ways. One way will cause the clamp to tighten then the clamp is rotated up whereas if the clamp is reversed end for end, the clamp will tighten when the clamp is rotated down. Which way is 'correct' is a matter of personal preference.

[BuckeyeDennis]

Thanks for your comments, The chuck I'm using is from PSI # CUG3418CC 4 jaw utility grip. I've been using this for quite awhile with no issues. I do believe the run out problem is caused by the tail stock which runs out of round when boring even when attempting to hold it steady. I don't know if there is a way to make the this more stable The collars are tight on the tail stock post and the lock bar is secure but I still get some movement when applying spindle pressure to the forstner bit.
The response I received from Buckeye Dennis enlightened me to the issues with concentricity. I'll follow up on his observation and yours to see I can get this right on my practice pieces.
Thanks
Mikec182

Your comment about the tailstock “running out of round” spurred another thought. Mine will flex outward a bit under pressure from a large Forstner bit. I’ve never noticed that causing runout, but I suppose that it could, as the tip of a long drill would shift upward when the tailstock flexes outward. But flex aside, have you aligned the Morse taper in your tailstock with your spindle? The procedure is explained on page 19 of the Summary Owner’s Manual, at the link below.

http://www.shopsmith.com/getting_starte ... Manual.pdf

I like to use the spur drive center on the headstock (instead of the drill chuck) for this procedure, as it’s really easy to see any misalignment between the two conical points.