Hi, I purchased the bone on ebay thanks to a response from an NAWCC member. He told me to look in guitars because they use bone for the bridges. I ordered 10 pcs. for $10.00 they were 1/8" thick 3" long and 3/4" wide. The thickness was perfect for the hole depth I needed. The original plates are a little over 1/4" allowing me to drill down to 1/8", half the thickness of the plates. Making them was not as difficult as I first thought. I purchased a 3/8" plug cutter to match the hole dia. that was already there. I installed the cutter on in my drill press and was able to get 5 out of each borne piece. The trick here is to use the right speed in cutting. I ended up setting the speed at 900 rpm. At first I went to fast and then to slow. The bone will smoke when cutting and it does not smell good!! After I cut the disks I a simple jig out of a flat 1/8" thick piece of metal with a 3/8" hole drilled in it. I placed the discs in the drilled whole and hand sanded them until they were all flush with the plate. After that I made a second jig out of wood. I used a 3/8" fostner bit drilled a hole in the wood to a little under the thickness of the bone. That way I can pry them back out. I use the center mark from the fostner bit as the location for the 1/16 hole that I drill through the wood. Then I placed the disc back in the hole flip it over and use the exit hole from the 1/16" hole as a guide to drill through the discs. The idea for drilling the center hole in the discs came from Al Takatsch's dvd on repairing wooden movements. He also answered many questions I had as well. One issue I had which he made me realize there was a simple fix for was the dia. of the fostner bit was a little over size resulting in a loose fit when I tried my first samples on scrap wood. He told me an option was to grind down the fostner bit. I did it and that solved the problem. If you have any questions let me know.
Thanks for the detailed response. Sounds like a winner! I think Al's solution on getting a perfectly centered pivot hole is great, yet such a simple solution. I too have used this for re-bushing wood movements and it works perfectly for centered pivot holes.
Regarding the problem you had with the plugs not fitting- you really need to get good plug cutters. I have a set that I bought from W.L. Fuller, here in Rhode Island. They make what are perhaps the finest plug cutters available, and the resulting wooden or bone plugs fit holes made by Forstner bits perfectly- just a slight interference fit. These cutters are actually manufactured here in RI, and are available through Fuller's website, as well as from other suppliers. Don't bother fooling around with ordinary grade hardware store cutters. Like any good tool, they are a bit expensive, but worth their weight in gold.
I like to make tools that provide solutions to little problems like making bone bushings. The following series of photos show the cutter I made and the results in using it, as well as a modified “bullet” drill I use to bore out plates for the bone bushings. Both the cutter and the bullet drills can be made in pretty short order with a lathe and a Dremel tool.
The cutter is made using tool steel bored to the needed bushing size, fitted with a center drill for the hole in the bushing and teeth cut using a Dremel, or in my case a 45 degree dovetail cutter indexed and cut like a wheel.
It makes for a pretty decent cut in the bone, wastes very little material. Down side is I didn’t put any relief in the teeth so they tend to clog with bone dust and needs a bit of clean out between bushings. The hole in the side of the cutter is to allow me to lever out the finished bushing…they tend to be very tight in the cutter when finished.
The bullet drill can be done with any old drill bit of the proper size and a couple of minutes with the Dremel…