|Project by johnhutchinson||posted 05-28-2014 04:41 PM||2962 views||9 times favorited||32 comments|
This started as a forum question where I was looking for ways to create a 30-degree chamfer on the edge of a disk. The response was overwhelming, and I settled on sanding with my drill press table angled at 30 degrees.
The steps were …
1. Glue two layers of 1/2” Baltic birch plywood together with a 3/8” hole at the center.
2. Spin-sand them to round on the drill press with a 3/8” bolt arbor and some massive fender washers.
3. Spin-sand the chamfer by slowly cranking the table, and the sanding block, up and into the disk.
3. Attach the indexing pattern to the underside with double face tape, using the end of a Forstner bit for alignment.
4. Jig the holes by eye, pointer to index line, for a perfect 36.
Things I learned …
1. This is an incredibly precise way to drill an array of holes because the index lines are so far from the center. Why stop at 36?
2. Besides tilting out, the pencils are also leaning to the side. I said some pretty awful words before I realized I want to do that! Setting the jig even more off-center will create a splayed spiral.
3. Not sure about the colored pencils. Now I’m thinking maple dowels in a walnut base. Making the base from two 1/2”-thick pieces should give it stability—two-layer plywood?
-- John - Central Ohio - "too much is never enough"