Gallery, Projects and General > How to's

Grinding the jaws on my three jaw chuck

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mattinker:

--- Quote from: awemawson on January 20, 2018, 09:11:49 AM ---Matthew,

The small internal stones I use in my J&S 1300 EUIR cylindrical grinder are supplied as cylinders with a central hole, and can be mounted on an arbor as long or short as you wish.

For a 3" long chuck jaw you need a stone that is relatively short  say 1/2" or so so to meet my criteria would be mounted on an arbor with marginally more than 3 1/2" protrusion from the collet.

White aloxite 46 grade probably be my first choice

--- End quote ---

Thank you Andrew, it's done now! I can't see me having another chuck to grind! I'll certainly keep it in mind!

mattinker:

--- Quote from: hermetic on January 20, 2018, 10:14:40 AM ---Hi Matt, on the flange where the chuck fits, is there any indexing marks, or odd bolt spacing or alignment pins,  in order to get the chuck on to the flange in the same orientation every time?

--- End quote ---

Hermetic,

I have marks on the flange and the chuck.

Matthew

krv3000:
a job well dun

mattinker:
Thanks Kev!

vtsteam:
Glad that worked out for you Matt.  :beer:

Since this is a How To and others may be learning, I just wanted to point out a few additional things I think about when I do this operation.

I want to take as absolutely little off of the jaws as I can, because it increases the minimum diameter you can grip with the chuck. I'm mainly interested in removing a small amount of run out by this operation, Nothing more.

It can't correct for an unevenly worn scroll, except for workpieces of the same diameter that the jaws were ground at. Different diameters will again show run out on a worn chuck.

I've had good luck using centrifugal force to keep the jaws out against the scroll, rather than gripping a set of spacers or rings. I just run the chuck at a reasonable speed and it seems to work, for me. Jaws have mass and they do want to move outward on the chuck

My process: I take VERY little meat off at a time, I just feed the stone outward a tiny amount until I just see a few sparks -- not a shower. I make passes completely through the jaw bore and I wait until all sparks stop, and then I stop the lathe and look at the jaws to see which ones are hitting. If all three hit over a reasonable length, I'm done. If not I'll take a tiny additional amount off. Generally the last pass my produce only an occasional spark, until they stop altogether.

I don't try to get a perfect clean face. This takes the minimum off needed to achieve the least run out possible with this method. Just personal preference -- and I don't have really rough chucks to deal with.

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