On 17.09.17 10:07, Gene Heskett wrote: > I also have a good level, actually > 2 of them now, of that fawncy Starrett, except this one is still factory > calibrated, I can set it, read the bubble, turn it end for end, and the > bubble settles at exactly the same spot. The one I had been using I'd > found in the BiL's garden shed after he'd passed, sitting bare on a > wooden shelf and was quite rusty on the bottom. Enough it had a > detectable end to end rock when placed on a sheet of glass or on my > surface plate. I lapped it wet on a sheet of 600 wet-r-dry on that > surface plate, took the rocking out of it but would have had to motorize > it and let it run for days to clean it all up proper. Readjusted the > bubble cartridge until I could turn it end for end without any change, > but I still don't trust that bottom.
ISTM that for "levelling" a lathe bed, neither adjustability nor a pristine base are big assets in a machine level. Just flat enough to sit solidly, and a large arc vial, so that it can detect minute inclinations, in the order of 0.1mm/m = 0.006° will do. With one of them sitting solidly on the top of a flat cross-slide, bubble set to pretty near the middle of the vial graduations by winding the jack screw at that end, it's just a matter of winding the saddle to the other end, and jack to the same setting. That left the middle of the 1 metre bed off by 0.1mm/m = 0.006°, which is within spec, IIRC. Mine set me back around A$200 or so, but it was worth it. > So when I find that famous round tuit, I'll check it, and if off, will > loosen the lock nut and let it adjust itself. My problem I suspect, will > be the beds swaybacked wear over the years. It's past midnight here, so I'm not recalling the name of that tabular axis error compensation, and can't remember whether it's just for screw pitch error, or could also tweak x as a function of y. But that ought to be able to undo the effect of a bit of saddle tilt, you'd think. Sleep beckons. Erik ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
