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Chuck Key for a 4 Jaw Chuck |
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Mid way through the design of an XY drive for a micro-mill
(see the other section in cad/cam projects), I remembered that I had wanted
to buy an additional key. I kept forgetting. Time to take time
off and go make one. |
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First
thing was to take a piece of half inch tool steel rod a little longer than
the original chuck key. I'm arbitrarily making the size of the key a
bit under 1/2 inch, that's a 1/2 inch mill sitting there.
You can see the 5C collet in the spin indexer. I
took off about 0.030 each pass, rotating to keep the sized symetrical. |
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The
completed key end, but it's time to make it neater. |
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A
completely arbitrary cut about halfway up the barrel gave me the cleanup of
the edge I wanted. The spin indexer was used to hold the blank to
drill a hole for the cross bar. The cross bar was a piece of steel
from an old floppy drive. |
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The
only drill I had was a bit too large for the shaft, so it was a bit loose.
I tried knurling the shaft to deform it a bit. It's not enough.
I think it's either time for locktite or I will drill and tap a hole in the
end for a setscrew. Elaborate, but ok. |
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The
original and the copy. I need to bevel the ends of the key just a
little to make the adjustment procedure a bit easier. I'll
probably drill and tap the end to hold the cross bar in place.
You really want two of them to adjust the jaws on a 4 jaw
chuck. |
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OK, I
got tired of the handle falling out. This is the fix. Works,
too... |
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That's it. I just polished the key a bit with
sandpaper, and that also rounded the edges, so there's nothing rough there
that I needed to worry about. This is a bit of a
beginner project, the only thing you'll have a problem with is the square,
which needs a spin indexer or something to make the angles 90 degrees.
Be sure to mill the top and bottom before checking thickness. |