On Wednesday 01 July 2020 13:01:08 andy pugh wrote: > On Wed, 1 Jul 2020 at 17:12, Gene Heskett <ghesk...@shentel.net> wrote: > > My problem is getting an accurate diameter for the bolt circle. > > 1) Measure the chuck hole-centres: > Measure 1 hole with a digital caliper. Zero the caliper at the full > diameter. Measure between the outsides of two holes. The offset zero > will subtract two radiuses, so you get the bolt hole centres, ie one > side of an equilateral triangle. > Multiply by 1.1547 to get the PCD. > Re-zero the caliper to true zero before you forget. > > 2) Centre the backplate under the spindle. Use a dial indicator in the > spindle to locate the spindle directly over the centre. > > 3) Offset by half the diameter calculated above and drill, roate, > drill, rotate. > I went thru that a couple times but didn't come up with the right stuff by about a mm.
So I did a holefinder by hand, using the OD of the backing plate to find the center of the x, fiddling around till I had it zeroed within a thou. The booklet said the bolt circle was 142mm and as I was close enough to centered on y, I ran it out to -71mm, put 0.0 on the pointer and sank a hole thru it that was at least a mm undersized, ran that up about .25mm and repeated until a bolt fell thru the hole, cranked it to 120 and hit r, then 240 and hit r again. Set the chuck on it, acted like it would sink into place with some bolt tension on it. Got out a hammer and an allen wrench to fit the drive hole I'd bored in the edge and used to drive it solidly home and knocked it loose again. I'd also green thread locked it, had to beat pretty hard. Turned the chuck backside up and set the plate on it and all 3 holes aligned dead on. Put the bolts in and went in sequence around them until the gap was gone. So atm my back is ~30~ for the day, sore as can be and likely will be tomorrow too, but I'm a happy camper, no chest discomfort. Beer thirty IOW. 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-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
