On Wednesday 27 November 2019 05:23:56 Darren Conway wrote: > Hi > One way to measure diameter errors to get the corrections is to fit a > dial test indicator gauge so it measures a point 180 degrees from the > cutting tool. Any errors in the turned diameter will be doubled. > > For example, if the cutting tool path has an error of 0.01mm, then the > diameter error will be 0.02mm. A DTI mounted opposite the cutting tool > will see a 0.02mm error. > > This method assumes the cutting tool path is repeatable.
Interesting. I visualize the DTI on a mag base sitting on the cross slide reading the back side of a skim cut. I have a virgin extruded alu rod about 1.5" in diameter, chucking it on a dialed center in a 4 jaw to make a dead center socket, faceing that end about 2 thou deep hollow so that it would sit straight on the clean mill table, then re-chucking it true but running on the dead center, with just enough of it in the jaws to get a good grip, then a skim cut with the DTI sitting on the cut ought to show what the lathe can do. Keep notes! Then move it to sit that square end on the clean mill table and run the DTI up and down all 4 sides with the z motor ought to give a pretty good indication of just how crooked the post is. Keep notes! hang the post on a sky hook and scrape accordingly. Wash, rinse and repeat till its square to the table, showing the same errors recorded on the lathe, ought to be a lot closer than it is now. Perfect of coarse depends on any room temp changes. Since thats a bolted connection, left/right errors can be pulled with temp guy wires to the ends of the centered table while tightening the bolts. If the x gib is zero clearance of coarse. It will take time I won't have till my lady is done. > > > On 27 November 2019 at 12:00 andy pugh <bodge...@gmail.com > > mailto:bodge...@gmail.com > wrote: > > > > On Tue, 26 Nov 2019 at 23:46, Gene Heskett <ghesk...@shentel.net mailto:ghesk...@shentel.net > wrote: > > > > On Tuesday 26 November 2019 13:59:39 andy pugh wrote: > > > > > > On Tue, 26 Nov 2019 at 16:42, Gene Heskett > > > > > > <ghesk...@shentel.net > > > > > > mailto:ghesk...@shentel.net > > > > > > > > > I'd expect a better cylinder, but not perfect on a > > > > .0001" dial. > > > > You can't use a dial. That depends on your (known flawed) lathe > > to support it. > > > > A lathe exists to make accurate diameters. So measure the actual > > diameter with a micrometer. > > > > Start with what you are _trying_ to make, and measure how far > > from spec it is. > > > > > > -- > > atp > > "A motorcycle is a bicycle with a pandemonium attachment and is > > designed for the especial use of mechanical geniuses, daredevils and > > lunatics." — George Fitch, Atlanta Constitution Newspaper, 1916 > > > > _______________________________________________ > > Emc-developers mailing list > > Emc-developers@lists.sourceforge.net > > mailto:Emc-developers@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
