south bend headstock alignment?

I've used it to turn small pieces until now. I was making a shaft about 5.25" long and .75 diameter. I kept checking the diameter and was satisfied at the tailstock end but found that headstock end was about .008" larger. I am not using the tailstock

It was 90 degrees to the work. Now I'm thinking my problem is play between the carriage and the ways. I'm taking it all apart and cleaning and adjusting it.

Consider getting new gibs. It was necessary on my Clausing 5914.

Joe Gwinn

Nope, workpiece deflection would make the free end bigger, the headstock end smaller. On most lathes the headstock cannot be adjusted, it has vee ways on the bottom that fit to the bed ways.

The remaining possible problems could be wear on the bed or twist of the bed. Wear of the front way near the headstock would cause the larger diameter near the headstock, and that is a bit difficult to fix. Twist in the bed could go either way. What you need to do is find a piece of hardened and ground shafting, or something stiff and round, and put it in the chuck. Use a dial test indicator and read at several positions from close to the chuck to about a foot away. Rotate the chuck slowly by hand and average the high and low readings to eliminate wobble from the measurement.

Now, you can shim under the tailstock end of the bed (assuming it is a bench lathe) or otherwise adjust feet on the cabinet to see if you can reduce the error. You may be able to find a compromise that even partly nulls out the effects of wear.

Jon

On my Heavy 10 the tailstock end of the bed rests on a pivot shaft within the foot. There are two opposing setscrews labelled "leveling screw" on the front and rear of the foot below the pivot. I think they press on the sides of an extension of the bed below the pivot. The round red labels are clearly visible in this photo:

I put a precision level across the ways at the head end, shimmed it with a feeler gage to get the bubble into the graduated area, then slid level and shims to the tail end which was off, but the bubble lined up with the same line when I released the setscrews.

I ran the screws in gently to contact, then tightened them alternately a little at a time.

The adjustment is similar to the one that offsets or centers the upper part of the tailstock.

Another way:

jsw

Isn't it possible for the piece to climb a bit if the too is set too far below center? We're talking what, 0.004" of deflection, not a lot.

Seems far fetched, I just don't think so. Small vertical errors make VERY small changes in diameter.

Jon

The tool can push the free end away, or (if it has aggressive rake) can pull the free end of the workpiece toward the tool. It doesn't always make the free end bigger.

While a headstock cannot be adjusted, it's possible the bearings can be shimmed or adjusted (don't know about this model in particular).

They have a shim pack under the bearing cap to set the proper clearance.