On Sunday 28 January 2018 12:39:48 Jon Elson wrote: > On 01/28/2018 01:36 AM, Marcus Bowman wrote: > > I have a TOS 4 jaw self-centring chuck for my mill (lives on a > > plate, and faces upwards, for use holding cylindrical stock facing > > upwards. That's Polish, > > Actually, TOS is Czech, but supposed to be VERY good stuff. > Their high-end chucks go for several thousand $. > > Jon > I have come to the conclusion, after taking this chuck apart, that its possible it is a Bison, but well aged, made before they started inlaying a brass logo disk in the face. Its a 6.25" chuck.
The grease in it was much like cold crayons for consistency unless there was a big gob of it that apparently settled to the bottom over several decades without motion. Had a heck of a time getting the scroll disk out as it fit so tight it bound in the hole if tilted 10 thou. Had to put a bar of poly in thru the jaw slots, and drive it out 10 thou at a time with a small hammer. Turning the striped body over, I noted the serial number, 4670, was splashed up 3 or 4 thou around the numbers, I knocked them down with a smiths diamond plate, then cleaned the mill table and put it face down on the mill. Lowered my CBN cup wheel down to pinch a sheet of 20 lb under it, wrote a quick loop to drive it in a circle, dropping .0001" for each pass around the circle. Then realized that the head likely wasn't perfectly trammed, so I dropped a plug in the bore hole so it could only move a quarter inch, then restarted the wheel and turned it by hand, dropping it .0001" about every full turn. And I was right, tram was off so it did all the kissing at about the left third of the wheel. Kept that up for about a half hour, until the back face was clean all the way around. Some of the bolt holes were pulled up around a thou for a 1/4" around them. Washed it out clean with paint thinner, using a good bit of a box of Scott towels, smeared some lithium based chassis grease into the scroll's resting place, and had just as much fun re-seating it. That fit could only be achieved useing chalk for the final abrasive, I've done it on $8000 camera lenses. Cleaned up the pinions, greased the scrolls teeth and the pinions and reinstalled those. Feels like well greased fine machinery now. Put the scroll catcher rear center piece back in, (I should mention I found one of those 3 bolts about a turn loose when I took it apart), and it still turned sweet and smooth. Cleaned up the jaws and reinserted them. Jaws can move maybe 5 thou before running into the scroll, so there's no drag there. Put some of that chassis grease in the face of the scroll while I could, then ran half a teaspoon of stp into the ball oiler. Smooth and silky. Looking at the backing plate, wishing I had a thicker one, I'll go see TSC about 3 more bolts tomorrow so it will have a bolt in every hole. They are spaced evenly, or at 60 degrees, but I'll have to use the mill and holefinder routine to find the exact diameter of the circle, cutting all the holes 15 thou bigger as I go. This will have to be done while its clamped face down so I can use the holefinder.ngc to find the x,y=0.00000 center of the bolthole circle by referencing the inside edge of the smooth rear spindle hole. And find a flat, sacrificial to lay it on letting the holddown clamps do the grounding. If I do the math right, it ought to Just Work(TM). ;-) We'll see how my luck holds out, as it will probably be Tuesday before I can mount and try to adjust it. At the pace I work, I'll be doing good to get all the holes milled to the new size and the bolts test fitted tomorrow. Thanks for reading this far, comment if you like. :) -- 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
