The spinning jaws of the 3-jaw chuck are stopped in motion in this
view. I make my boxes by cutting off the
bottom and then coring out the center plug in the body with a process known as trepanning. A 1/4" square
tool bit is fed slowly into the workpiece cutting slightly over half depth from both sides until the plug is cut
free. This process saves wood, as the plug can be used for a smaller box or other purposes, and also
eliminates the tedious process of turning away all the wood in the center of the body.
The bit must be properly ground with side clearance for the size of
circle it is cutting so only the cutting
edge contacts the wood. It must be fed slowly and carefully as there is danger of breaking off the bit. Done
properly, when the plug cuts free, it simply drops into the bottom of the cutout and does not catch on the bit.
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Last revised 12 February 2004.