I can offer some potential reasons:
- the threads in a typical TS may not be of same quality as say a leadscrew. Its not really considered the precision end of the lathe. Especially if it seen heavy drilling use (wear) which may be showing up as backlash. Now that you have an DRO on it, put the dial on a number so it stays put. (Don't lock the quill). Pull & push the quill & observe - do you see any displacement on the digital display?
- my dial can be nulled or set by rotating into a position. its a friction thing, not a thumbscrew lock. But it had this irritating habit of scuffing just a tiny bit so was 'losing time' every rotation. I thought some debris got in the crack but it was actually not turned with parallel thickness. QC issue that can probably be fixed.
- you might have something goofy although I thought most of those metric/inch bastard hybrid lathes were behind us. I have seen some dials with a truncated graduated scale. Like 0.100" increment on the IMP side of dial & a 'stubby ruler' scale on the metric side. Works dandy as long as you only turn it < rev. And sometimes they got the dials mixed up, IMP bastard on IMP pitch lathe when it was supposed to be MET bastard. Hope this makes sense. Yes DRO takes away some of this bygone fun & games.
- the threads in a typical TS may not be of same quality as say a leadscrew. Its not really considered the precision end of the lathe. Especially if it seen heavy drilling use (wear) which may be showing up as backlash. Now that you have an DRO on it, put the dial on a number so it stays put. (Don't lock the quill). Pull & push the quill & observe - do you see any displacement on the digital display?
- my dial can be nulled or set by rotating into a position. its a friction thing, not a thumbscrew lock. But it had this irritating habit of scuffing just a tiny bit so was 'losing time' every rotation. I thought some debris got in the crack but it was actually not turned with parallel thickness. QC issue that can probably be fixed.
- you might have something goofy although I thought most of those metric/inch bastard hybrid lathes were behind us. I have seen some dials with a truncated graduated scale. Like 0.100" increment on the IMP side of dial & a 'stubby ruler' scale on the metric side. Works dandy as long as you only turn it < rev. And sometimes they got the dials mixed up, IMP bastard on IMP pitch lathe when it was supposed to be MET bastard. Hope this makes sense. Yes DRO takes away some of this bygone fun & games.
