On Sunday 17 September 2017 09:10:11 Erik Christiansen wrote: > On 16.09.17 16:37, John Bald wrote: > > Have a few options for used stands and cart that I might be able to > > modify that could work for the mill, but haven't found anything that > > could be made to work for the lathe. Used to buy used steel from > > local scrap yards for projects a lot, but they won't sell it any > > more because of liability concerns. > > Cross-grain wood movement with changing humidity has always been a > concern of mine w.r.t. a lathe base. My Taiwanese "Toolroom quality" > 3/4 tonne lathe had massive bed twist (something like 0.4mm/200mm > IIRC) when first plonked on the concrete floor. Very fine adjustments > of the jacking screws included in the twin pedestal base, with a > machine level on the cross-slide, fixed that. But the ease with which > 0.1mm/m of twist can be inflicted, admittedly using the pedestals as > levers, makes me shy away from wood as a base. > This is something I haven't checked on my Sheldon. The right end bed foot on the Sheldon's can pivot of a ball joint like connection, but I had not found, until I redecorated my driveway with a newer pickup, which meant I had to clean out the 99 GMC, and found my biggest 3/4" socket set under the back seat, so now I think I have the tools to loosen the clamp nut and let it adjust itself. 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.
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. I redid the rear gib, it was a miss-machined mess, nearly 20 thou tapered, now zero clearance but not a noticeable bind near the tailstock, around 4 thou clearance at the headstock. And I've no clue if its all wear, or leftover paint tightening it at the tailstock. Much the same on the front of the saddle. Removing that paint with acetone for solvent is maddeningly slow work. I spent days scrubbing, even filing it, and haven't got it all cleaned off yet. > OK, wood generally doesn't move much lengthwise, so wooden legs > wouldn't be a big worry, but I'd run them through any connecting > planking, so loads are only on end-grain to the floor. Then I'd check > regularly with the machine level, at least for the first four seasons, > adjusting the jacking screws as necessary. > > 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 > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
