On Sunday 20 May 2018 09:57:29 Erik Christiansen wrote: > On 19.05.18 21:41, Gene Heskett wrote: > > I have all these brass slugs fixed so they are keyed into a scallop > > in the edge of a 7/8" R8 collet that fits the head of a 4mm capscrew > > in the lower end of the slug. So the next operation is to set it > > into the spindle, and position it so the rotation center is directly > > over the drill bit, chosen to be a fairly wiggle free fit on the > > shank of the tap that will be held in this one. > > > > Good idea but the drill bit doesn't seem to want to self center, > > despite moveing the table and the drill bit around looking for the > > magic spot. I haven't tried a small center-drill yet. Is that the > > fix, or do I need to treat the bit in a drill doctor? Or both? > > Aligning the tailstock on the lathe seems worth doing, Gene, but if > you need some taphats beforehand, then a small center-drill is the > answer. I don't drill a hole on the lathe or mill without > center-drilling first. It's not worth it as a .243 aimed from across > the street is more precise. > > ... > > > But how best to prevent the drill bit from doing the sailors > > hornpipe dance when the brass first touches it? Thats the $64 > > question. > > You can get quite a few small center-drills for $64 - a lot less of > the medium & bigger ones. But ISTR that the good ones are cobalt > steel, and that's why they do fine even in SS, I find. > > Erik
I think its off with a vertical tilt. I can shift it left right, and get it close enough to hold a center drill, but needs some shimming to level it and bring it to the correct height, thats off about 15 thou. But with the condition of the barrel, I only have the idea of grinding a 3/4" rod to the same taper so it projects out far enough to measure the barrels shift as it move in and out. I really think it could be bent or worn so its not on axis. But I need to invent a way to verify its alignment thats better than my eyeballs. I bought a couple ball bearing centers, but neither ones point is anywhere near the axis of the mt2, I can rotate them in the barrel and see the points shifting on a dial, a long ways, 20 thou on the worst one. ebay crap, less than a $25 bill. The worn, chipped tip live center I got with it is much more accurate. And the solid but somewhat oxidized plain one is the best I have. Don't know if I'll have time today, the local AM stations nighttime low power transmitter took a dump last night, so I need to go see what smoked this time. Trouble is, its old enough to legally smoke in public, some POS that LPB made decades ago, and of course LPB is gone 20+ years ago. Just barely transistorized. And definitely built by the lowest bidder. Sigh... Such is the life of a dying breed, me. -- 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
