Posted by BillS on February 01, 2010 at 00:28:07:
In Reply to: Re: problems with Barber Colman #12 posted by Jim Pollock on January 31, 2010 at 19:57:35:
I think Ben is right about taking all endplay out of the cutter spindle, so if you have any motion there you want to remove it. This means loosening the outer support bearing (2 bolts) and, using a pry bar, gently pry against the outboard housing and tighten at the same time.
As for the index worm endplay, it sounds like there is some endplay since it's not getting warm/hot. I would loosen the lock nut at the top and lightly tighten the thrust bearing nut. Try the cut this way to see if things smooth out. Since this thrust bearing is not frictionless, this adjustment is necessarily a compromise between endplay and excessive heat generation. Running warm but not too hot to touch is probably what you want. Only after adjusting out endplay should you adjust out any backlash between worm and gear. If the backlash is 0.001, that's not bad, although .0005 would be better. Again this should be measured at operating temperature.
I don't see anything about your setup that would raise any concerns.
Here is something else you might try. Set the table at slightly less than 3d 5m. Is this the angle marked on the cutter? Try 2d 45m and see what effect this has. Offsetting the angle should assure that cutting forces are opposing workpiece rotation. If this smooths out the cut it tells me that slack somewhere has been allowing the cutter or workpiece to pull into cut. Pulling into the cut is the same cutting action produced by climb milling. If possible, you always want cutting forces to oppose table motion or workpiece rotation to keep pressure against backlash. The smaller angle should remove any climb cutting behavior. Again, if this helps, look for slack somewhere. Although you shouldn't need to always offset the table angle for this reason, a small change of 5-10 minutes should not create problem with cutter side clearance.