Need some advice regarding my Bison 6-jaw

[Mirage_Man]

Recently I discovered that somehow I must have spun a part in the chuck and welded a tiny amount of that material to the very last tooth in my 6-jaw! I've tried to very gently file it down with a green stone but I'm afraid to really screw it up. It's enough to where if you run your finger nail over it you can feel it. The thing is it's not like that on all the jaws. Any ideas on how to fix this? I need to because it will leave little dimples even in ti when I grip parts with it this way.

 

[precisionworks]

The last part of the jaw (farthest from the chuck body) is rarely used by itself ... so you will not kill the chuck, even if you mess up when correcting this problem.

Have you tried a single edged razor blade? Or a new blade in a disposable scalpel? If the weld material is harder than HSS, neither the razor blade nor the scalpel blade will cut it.

Next in line is to make a carbide tipped scraper, using a positive triangle insert that has a screw hole in the center. Something like a TPMG-3XX or TPMG-4XX or any triangle positive with a retention hole. Mount the insert on the end of a steel rod, make a handle for the rod so it can be firmly gripped, and scrape the weld off.

If carbide doesn't cut it, you may have a problem. Grinding is the next step, or last resort ...

 

[Anglepoise]

I agree with Barry. Try that first.It should work.


I have also used the following method with good results after trying the above first, that hopefully will get most of it off.

Get hold of a new automotive 'piston pin'

These are hardened ground hollow steel pins around 3to 4 inches long and around 1 inch diameter.

Make a handle on one end. Wrap black insulating tape around and around so you can grip this end.

Then you lap the chuck jaws with a very fine abrasive. I use Brasso polish.

Work very slowly and start off by hand observing as you go, Close the jaws so they are just griping the lapping pin but not so tight as to not let it revolve and move in and out.

Then if necessary run the chuck at slow speed and move the stationary laping pin in and out. Be prepared to 'let go ' if it binds. Oil on the area you don't want to polish, Brasso on the area you want to clean up.

Do not attempt in situe grinding of the jaws unless you have done this before. Its not easy.

Good luck..........

 

[precisionworks]

Get hold of a new automotive 'piston pin'

AKA wrist pin ... great idea :thumbsup:

If the pin could be held by the tailstock (like in a 3-jaw tailstock chuck) alignment would be automatic. Still, hand holding should work, as long as most of the pin stays in contact with the full jaw surface (surfaces).

 

[darkzero]

Have you tried a single edged razor blade? Or a new blade in a disposable scalpel? If the weld material is harder than HSS, neither the razor blade nor the scalpel blade will cut it.

I've had this a couple of times before & I just scrape/knock it off with a razor blade too. But is was only aluminum.

 

[Mirage_Man]

I've had this a couple of times before & I just scrape/knock it off with a razor blade too. But is was only aluminum.

Well I tried a razor blade and whatever it is laughed at it. I will try the carbide scraper idea next.

 

[Lynx_Arc]

If you have access to a flat piece of steel longer than the teeth of the jaw and some contact adhesive get some sandpaper and spray the adhesive on the metal and glue the sandpaper to the metal to make a long sanding block. if you hold the block lightly in the middle while pressing harder on the end where you want to sand off the bump it will sand it flat using the other teeth as reference to hold your sanding "block" correct. I have done this trick in carpentry and metal working to grind/sand down minor bumps flat even with the rest of the world.
You could also use a long flat fine file the same way if it isn't tapered and lays perfectly flat.

 

[darkzero]

Any luck Brian?