Lathe pattern copiers are pricey and are not manufactured for many wood lathes. Pattern copiers are used to make copies of turned spindles from an original. Here’s how to build your own.
You will need a section of 1/2" aluminum tubing as long as your lathe bed or a bit longer to make your lathe pattern copier. You will also require some 1/8” thick aluminum sheeting or you can obtain some aluminum cookie sheets. Acquire a box of 10-40 bolts 1 1/2" long and a wing nut and washer for every bolt. Get 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 remainder of the parts for your lathe pattern copier can be made out of any scrap material you may have laying around the shop.
The design of this lathe pattern copier incorporates multiple feeler “fingers” suspended behind the lathe along the aluminum pipe. These fingers are adjusted to equal the exact depth of the cuts in your original turned spindle. When you place a new spindle blank on the lathe, all of the lathe pattern copier fingers you adjusted will be laying on top of the blank. As you cut into the blank, prepare yourself to end cutting as soon as the fingers relating to that cut fall down and through the cut.
Make two, vertical support posts about 6” taller 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 measurement near the top of each support post. Install the posts (using the angle irons) on the surface immediately to the rear of the lathe. Insert the pipe through both holes to make sure it fits. This will help locate the aluminum fingers of your lathe pattern copier so that they can reach the spindle you are turning.
Make a quantity of wood blocks 3/4" x 1 1/4" x 6” long. Bore a pipe-sized hole in one end of each of them through the 3/4" thickness. With the blocks lying flat, cut through from the end into the hole with a 1/8” table saw blade. With the blocks standing on edge, bore 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 1/2" 10-40 bolt through the hole you just bored and place a wing nut and washer on the end. The concept 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 size about 1/2" 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 1 1/2" 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 of your lathe pattern copier.
Cut aluminum fingers out of the flat stock using a 1/4" blade on the band saw. The fingers should measure 6” long and 3/4" 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 1/2" from the end. Sand the fingers smooth, removing saw marks and burrs.
Install the aluminum fingers onto the ends of the wood 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 pattern 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 finish as each finger falls through.
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© 2010 Robert M. Gillespie, Jr.