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View Full Version : now i need to fix my new bison 6" 3jaw



davidh
10-21-2008, 10:20 PM
after all the great help in getting my 5" bison chuck into spec, i remember someone saying that crashing a chuck will happen. . . . at least sometime in a guys life. .

my son or i, have been making simple parts on my sheldon for about a year, and i educated him as best i could about the lathe, hands, fingers, eyes, plus the fact that the machine is VERY strong and unforgiving in many cases. we discussed the sleeves and neckties from the past, and even got into the disruptions from cell calls while working.

anyway, one of us crashed a part, and now the new 6" bison 3 jaw is out of whack. i check the trueness of the backing plate, right on, and the chuck body, right on, but i know the problem is in the jaws somehow. somewhere.

the jaws are two peice and reversable, and i have just removed, inspected by eye and cleaned all the mating surfaces, but i know its more than that. its .015 out with a piece of ground round stock in it, at the jaws.

what do i need to do ? send it in for rebuilding ? something i can try to do myself ? again, use as is and get use to the 4 jaw as one of my friends told me a while back ?

im all ears here. i don;t think any pictures will explain it any better than i just have. i really love that lathe and would use it all the time except its not in the building i work in all day.

my craftsman / atlas is in there. chuck straight, pulleys straight, ready for the big clean-up and paint. were the old craftsman/atlass' really dark green ?

Bruce Griffing
10-21-2008, 10:30 PM
I would examine the spiral thread in the chuck for damage. If it is OK, then grind the jaws true.

davidh
10-21-2008, 10:46 PM
easy as that ? never woulda thought. thanks.
i guess i need to actually do more testing to see if the offset is different at different diameters. more to follow tomorrow.

Mark Hockett
10-22-2008, 12:55 AM
Remove the removable jaws, chuck the stock up in the master jaws and recheck the run out. If there is no run out on the master jaws the problem is probably in the removable jaws and you can regrind them, there are some posts in the archives about doing this. If you have run out on the master jaws the problem is possibly in the master jaws or a bent chuck body. Bison chuck parts are readily available from Toolmex, Enco and other sources.

pipeclay
10-22-2008, 01:35 AM
A question probably not required but you do have the jaws in their correct position dont you.

davidh
10-23-2008, 08:58 AM
great day. found a tiny amount of swarf actually a tiny chip that had embedded in one of the jaws. picked it out and WALLA, we have another winner.

back to the cleaning and paint prep.

derekm
10-23-2008, 09:33 AM
great day. found a tiny amount of swarf actually a tiny chip that had embedded in one of the jaws. picked it out and WALLA, we have another winner.

back to the cleaning and paint prep.

Do mean the French for "there it is" (voila) or the Indian for person e.g. Char wallah is tea person, punkah wallah is fan person :)

davidh
10-23-2008, 11:07 AM
ya, thats probably what i meant. i got no college, just hard knocks.

you gotta understand, im a swede living with the finns. . . . . sometimes surprising i can function at all. . .