Afternoon chaps!
I've finally finished(ish) fitting a DRO to the old Edgwick lathe - well... two of the four anyway... but most importantly I've got the cross slide one on now. Which has lead to some "interesting" comparisons....
After a bit of fettling, I think the DRO is pretty much dead nuts on; at least, cuts on a test bar agree, to within a couple of tenths, of the DRO reading... So next I figured I'd compare the DRO to the handwheel. Starting at the furthest outward position, wind in a few thou, set handwheel & DRO to zero. Wind in an inch. Handwheel now over-reads compared to the DRO by about 1 thou. Go another inch; 2 thou. Go another inch or three; 5 thou. In fact, by the middle of the travel, there's a 10 thou discrepancy. Keep going, and it closes up again to around 5 thou difference when the leadscrew nut hits its end stop.
Since the DRO *appears* to be OK, within the small range of cuts I've tried, would this rather large discrepancy across the travel suggest a worn leadscrew (and, quite probably, nut)?
If the DRO is right & the handwheel is wrong, this would go some way to explaining why I was having so much difficulty chasing down tolerances...
Oh, and while I'm here, and on a partially completely different subject: The DRO "rattles" between numbers when the lathe is running - obviously, the vibration is sufficient to cause the encoder to toggle. Now, I *could* fix that by hiding the 10ths digit
but I'm wondering, is there a better way? Maybe shim the readers with rubber sheet? Or is it just something Chinesium DROs do, and I just learn to live with it?
I'll do a build log soon, promise... I want to get the carriage readout mounted before I do the write-up.
Ooh - another question: What's the typical axis designation for a lathe? IIRC Carriage is Z, Cross-slide is X, there is no Y... As I've gone for 4-axis: Carriage, Cross-slide, Compound-slide, Tailstock, what would be the "normal" way to set those up? Won't matter once DIY-DRO is a bit further advanced, of course, as you'll be able to name the axes
