Thursday, August 13, 2015

Beat The Drum Slowly

Here is a drum thickness sander that I built 6 or 7 years ago. The base in an old desk that I salvaged while dumpster diving at work. Most of the remaining skeleton is 1 1/2 inch steel tube and a few pieces of 1/8 flat plate. The motor is one that I had laying in my motor pile. I bought two 3/4 inch ball bearing pillow blocks for each end of the drum assembly. The drum is a stack of 3/4 plywood discs on a 3/4 inch CRS shaft. I assembled all of the discs on the shaft with glue between each one. After it dried, I drilled and pinned the drum to the shaft. I trued up the drum on my metal lathe, though I could have used the sander as it's own lathe by rigging up a tool rest. The finished size is a sliding fit into a piece of 4 inch ABS sewer pipe. The sandpaper strips are glued to the ABS with contact adhesive. A pin at the pulley end of the drum registers with a notch in the pipe to keep it from spinning. The notch is angled in the direction of rotation to keep it from coming off. I have several of these drums made up with different grit strips glued on. Changing them requires removing two bolts and pulling off the pillow block on the free end. The drum is 24 inches long and with the open end, it has a four foot capacity. The bed assembly is 3/4 MDF and 3/4 plywood. The hood is 1/8 Masonite. The bed is raised and lowered with the crank handle which pushes or pulls on a carriage with four wheels. The two outer wheels ride on tracks that are parallel with each other and the floor. The inner wheels ride against triangular members that are screwed to the bottom of the bed. As the wheels travel in or out, against the triangles, the bed goes up or down. These pieces all needed to be exactly the same as each other and exactly coplanar. I managed to get pretty darned close. Any variance from left to right was adjusted with shims under the pillow blocks. I had envisioned some sort of feed mechanism but never got around to it. I think if I could get my hands on a belt from a large, wide belt sander, I could rig up a feed. Probably would be hand cranked rather than power feed. As it is now, I use a push board, as pictured. Though I don't use it often, It has proven to be a pretty good tool.

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