On Friday 26 January 2018 14:22:10 andy pugh wrote: > On 26 January 2018 at 16:56, Gene Heskett <[email protected]> wrote: > > Moving the dial with the carriage also tells me the head on this > > thing isn't well trammed. The error, assuming the A2 isn't tapered, > > is about a thou/inch. > > > > What sort of a measuring setup does it take to measure that? > > Comparing the results you get when turning work between centres and > turning work in the chuck can probably indicate whether the head is > set over or twisted (or both). > As a first measurement, try a dial indicator in the chuck around a > good MT adaptor in the tailstock (assuming a set-over tailstock).
That, even with the tailstock that close, is going to be off a good 50 thou as I've yet to get shims (and shim stock enough) to get it true, its off vertically, and I've also bought 2 more triple bearing MT2 centers only to find their NT2's ground off center. Rotated in the barrel, the major diameter of the dead ones cone can be seen to have a pronounced wobble at the major diameter. So I am still looking for a center claiming .0005" or better accuracy before I fight any more trying to align the tailstock in any direction. The marketplace at ebay is loaded with junk. But I expect you knew that too... The only choice I may have is to make another MT5-MT2 adapter which at the size for boreing, will be a major project in itself, and regrind the badly worn/scored dead center I got with it. The live centers I've bought, look "purty" but the MT2 on the rear isn't even close to being concentric with the tip. 2 brand new ones are at least 20 thou out. But for a $20 and change, I guess I got what I paid for. :( What I just thought of, is to pull the barrel out, put it in the 4 jaw and make it run concentric at its ID, then put the worn dead center in it and grind it true. Does that sound like it would work well enough for this? Seems like it ought to. Then I can worry about sourceing some shim stock to jack it up. Mostly at the rear IIRC. Thanks Andy. -- 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
