You will need a piece of ½” aluminum tubing as long as your lathe bed or a bit longer. You will also need some 1/8” thick aluminum sheeting or you can buy some aluminum cookie sheets. Purchase a box of 10-40 bolts 1 ½” long and a wing nut and washer for every bolt. Buy a second box of 10-40 bolts 1” long with nylon-lined lock nuts for every bolt. You will need (4) 3” angle irons with screws, as well. The rest of the parts can be made out of any scrap wood you may have laying around the shop.
The design of this apparatus incorporates multiple feeler “fingers” suspended behind the lathe along the aluminum pipe. These fingers are adjusted to match the exact depth of the cuts in your original turned spindle. When you place a new spindle blank on the lathe, all of the fingers you adjusted will be laying on top of the blank. As you cut into the blank, prepare yourself to stop cutting as soon as the fingers relating to that cut drop down and through the cut.
Make two, vertical support posts about 6” higher than the top of the largest spindle blank you can turn on that lathe. Note the outside diameter of the aluminum pipe and drill a hole of that size near the top of each support post. Mount the posts using the angle irons on the lathe table immediately behind the lathe. Insert the pipe through both holes to make sure it fits.
Make a bunch of wood blocks ¾” x 1¼” x 6” long. Drill a pipe sized hole in one end of each of them through the ¾” thickness. With the blocks laying flat, cut through from the end into the hole with a 1/8” table saw blade. With the blocks standing on edge, drill completely through each block between the hole and the end of the block. Use a drill diameter slightly larger that the shaft diameter of the 10-40 bolts. Insert one 1 ½” 10-40 bolt through the hole you just drilled and place a wing nut and washer on the end. The idea is that the wooden blocks will slip onto the pipe and the bolts and wing nuts will hold them in place by closing up the 1/8” cut you made on the table saw.
Drill another bolt hole of the same diameter about ½” from the other end of the block, centered with the block laying flat on the drill press table. Cut another 1/8” slot, 1” deep and centered through the 1¼” dimension, at right angle to the bolt hole. Remove one end of the pipe from the vertical support posts. You can now mount the blocks along the pipe before replacing the pipe in the vertical support post.
Cut aluminum fingers out of the flat stock using a ¼” blade on the band saw. The fingers should measure 6” long and ¾” wide. Both ends should be completely rounded (3/8” radius) on an edge, belt or disc sander. Drill a 10-40 bolt hole in one end of each finger centered ½” from the end. Sand the fingers smooth, removing saw marks and burrs.
Mount the aluminum fingers onto the ends of the wooden blocks, securing them in place with the 1” 10-40 bolts and lock nuts. The aluminum fingers must be free to move up and down.
Now place your original spindle on the lathe. Set the fingers to just drop through, barely touching the depth of each cut. Place the first blank on the lathe with the fingers you just adjusted resting on top of the spinning blank. Start cutting and stop as each finger falls through.
Bob Gillespie
Woodworker
For similar articles and tool reviews, see:
http://www.finewoodworking.com/
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