On Monday 11 February 2013 11:26:56 Mark Wendt did opine: > On Sun, Feb 10, 2013 at 12:11 PM, Gene Heskett <ghesk...@wdtv.com> wrote: > > On Sunday 10 February 2013 11:55:13 Andy Pugh did opine: > > Message additions Copyright Sunday 10 February 2013 by Gene Heskett > > > >> On 10 Feb 2013, at 14:05, Gene Heskett <ghesk...@wdtv.com> wrote: > >> > So, I need a 12mm bore, 18mm OD, .2mm thick shim washer to space > >> > the center races apart far enough that when I put the end cap back > >> > on the block, pushing in on the outer races, they will > >> > >> Turn a cup shape on the lathe, part off to the desired thickness. > >> I wouldn't try for exact thickness, in fact I would shim the outer > >> races and adjust the nip with the nut. > > > > Its feels like both inner and outer races are touching each other when > > assembled in the direction they were installed. Both bearings are > > installed into the block from the nut end, with nothing between either > > set of races ATM. I could turn them around though, which would mean > > that spacing the outers would achieve the same effect, and that would > > then allow the nut to adjust the preload. In that event, even a 20 > > thou thick spacer would be fine. If it wasn't for the thin face on > > the outers when assembled that way, its only about .55mm wide on that > > side. But it should work. So, put one bearing in with the thicker > > outer edge facing left, a dab of grease to hold a formed piece of 30 > > gage kynar wire stripped, laid in the grease and push the 2nd bearing > > in to trap the angular and the nut, which has a set-screw for > > locking, brought up to put some pressure on the inners, sound like > > that would work just fine. That wire wire is too thick, but it will > > cold flow some, so if the nut is snugged up, eventually it should be > > able for the wire to support the loading for a long time. > > > > Sounds like a winner to me Andy, thanks. > > > > I'll check in later when I've tried it. > > > > Cheers, Gene > > Or maybe use a Belleville washer? > > Mark Physical size differences between the sides at contact points would seem to preclude even considering that.
What I did was to install the bearings such that pressure from the shaft nut would preload them if the outer races were prevented from touching, in this case by a single turn of 20 gage copper wire formed into a loop and placed between the wider, now in the center, faces of the outer races. The end cap is then installed and brought to so as to crush the wire between the two outer races, leaving a barely visible gap between the bearing block and the cap, 5 thou or thereabouts, then the shaft nut installed and brought up snug on those fine threads, and preloaded and additional quarter of a turn. There is a black iron spacer on the shaft on each side of the bearing pair, and an oil seal, on in the back face of the block, and one in the bearing cap. It feels like the bearings are probably stretching the outer races a small amount, but the bearing block restrains them from growing by more than .0005" as its a very snug fit, taking considerable care to walk them out of the housing, and best done by removing the cap and turning the screw in the hard to move nut, pushing them out as a package. If my preload pressure winds up destroying these bearings, I would imagine that an angled tapered roller, with half again as many rollers could probably be refitted. The measured end play is now about 0.0017", but since the bearings are now preloaded to several hundred lbs, I have no clue where the rest of it is. The bearing block itself isn't moving that my 30-0-30 dial indicator can see. At the top of the QC tool post, its a red one above 0.004, with that growth being the carriage, now tail heavy with the triple stack X motor hanging off the back about 3.5" to its front face, causing the V way up front to rise till the adjuster bars are in solid contact with the bottom face of the way. Those adjustments on the rear of the carriage are easily done although inconvenient to get to, but on the front, doing it right will require the apron (its new, big block of ALU) to be removed, and the allen wrench ground down another 1/8" shorter to gain access to those cap screws over the screw as it goes by. I suspect the cap screw on the right needs pulled up another 2 or 3 degrees, its leaving a noticeably thicker layer of vactra on the way faces back there. Overall, its doing a much better job than before. I need to reset the HOME_OFFSET in the [AXIS0] block to make it cut about half a thou smaller, and that will then be spot on. But because I am calibrating HOME against the tip of the tool, and I now have the HOME_SEQUENCE setup, I do a lot of HOME_ALL's, on purpose, so if I could do away with that (unprintable) requester that pops up when you do it again, it would be a lot less mouse work. BTW, for whoever on IRC said the keyboard combo to home was ctl+h, thats wrong, its cntl+home. :) For someone like me, it would be a boon to have two HOME buttons, A HOME_Z one that establishes the limits when the carriage is brought to a jaw face and is gently trapping a feeler gage blade and uses that to set the machine limits for Z, then a different button to use after the carriage is run back to the right, and the workpiece mounted in the chuck, then my gage is placed on the ways and slid left to contact the face of the workpiece, and the HOME_ALL then establishes a HOME for X, and a touch off offset that puts 0.000 z at the end of the workpiece, however far its actually projecting from the chuck. This touch off should not effect the software limit positions, where the current method establishes them from the workpiece offset, which is obviously going to be incorrect 99% of the time. Likewise, when changing tools, the X limits are also going to be wrong too. Another argument for real limit switches. Next project perhaps. When it starts nagging me. :) That would be the best of both worlds. :) Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> BOFH excuse #262: Our POP server was kidnapped by a weasel. I was taught to respect my elders, but its getting harder and harder to find any... ------------------------------------------------------------------------------ Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
