I turned a core from brass on my 10K South Bend metal lathe and epoxy glued it into the oak block. I installed three 1/4" set screws in the bottom of the core for mounting in the car and I used them to mount the block on a steel mandrel so I could hold it in a 3 jaw chuck on my Mark 5.
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Here it is ready to turn with a sample knob in the background:
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Turning continues:
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Close to shape:
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Note that the Mark 5 is the one that I put the variable speed sewing machine motor on to replace the non working original.......worked great.