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stiff three jaw

We have a three jaw chuck ( Bison brand) on our old lathe at work. The chuck is about 18 inches in diameter. It is a brute to open and close with the chuck key. I took the jaws out and cleaned everything then put light oil the jaws. It is still stiff. The scroll spins smothly when the jaws are out. There are no burrs that I can feel in the slots or on the sides of the jaws. To put the jaws into the pockets I have to tap them in with a soft face hammer to get them deep enough for the scroll to engage. All three jaws are equally stiff in their slots. I don't want to stone anything at this stage. Do we simply have a stiff chuck??? The unit has been around a long while but has not seen much use and is in good condition. Any suggestions appreciated. Randy

Reply to
Randy Zimmerman
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I had the same problem with a chuck. We found some little dings that had displaced some metal. We stoned them out and it's like silk now.

Reply to
Tom Gardner

Look for scrape marks on the jaws and chuck itself. After you have ascertained where the problem is, do a gentle stoning with an extra fine stone and the jaws will probably start moving nice and silkily.

-- Why isn't there an Ozone Hole at the NORTH Pole?

Reply to
Bob May

Next time I have a slow day I guess I will take it apart again. I ran my fingers in the slots trying to feel a burr and on the sides of the jaws. This is after flushing the grooves with a solvent soaked toothbrush. It is odd that all three jaws are stiff right from their entrance in the slots. I will try the stoning next. Randy

Reply to
Randy Zimmerman

Hey Randy,

I've got a chuck I don't use a lot with the same symptoms, but have not tried anything yet. Mine's the same, in that the scroll works fine with-out the jaws in place. I did intend to experiment to find out if just a single jaw was the culprit by trying them one at a time. Maybe after I see the conclusion of this thread I'll give some of these ideas a shot. Please let us know how you make out.

Take care.

Brian Laws>Next time I have a slow day I guess I will take it apart again. I ran my

Reply to
Brian Lawson

You should probably stone the corners of the jaws to achieve a small radius or chamfer. It's possible the cutters used on the chuck itself were worn to some extent and some interference is occurring in that area. Use a 'sharpening stone' which will give real nice results without scratches, etc. Also, a sharpening stone when passed lightly over a flat suface will highlight any dings, etc. (You can also 'feel' them if you are using a light touch)

The same technique can also be used in the chuck slots with the correct sized stone.

Ace

Reply to
Ace

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