Hi folks. After some design changes and fine-tuning the drum sander is finally completed. Here’s a point by point description covering some of the steps I feel important to take on this project. Pictures should help where I’m not so clear. I will post the surface sanding option, some dimensions, and final comments in Part 3. Here it goes….. hope you like it.
Main Body: Made with ¾” maple veneer plywood and solid maple for the pillow block base. Assembled first with pocket screws to check the design (without a bunch of clamps in the way) before everything was glued together with TiteBond III (the only glue I had at the time).
Everything was finished to varnish grade but decided to use enamel paint for most parts. I thought it might look more like a tool this way. Red was used for the dust cover and the belt/pulley cover to remind me of the safety hazards.
Access to the pulley, belt, and the motor is through a door-like cover held closed with a rare earth magnet.
A small drawer stores sanding belts, notes, etc. The table is made with two pieces of ¾” plywood laminated together; Formica covers the top surface and the sides are finished in Birch. I was fortunate to get a large piece of Formica (32” x 12’) for free from our local cabinet shop. It took me a while to get the guts to go because it’s a large high-end manufacture. Well, you never know unless you ask….. so they say!
The front micro table height adjustment is controlled with a 3/8” threaded rod, knob, and a wing nut to lock it. Under the table, the threaded rod is screwed in a ½” rod that swivels on two ½” copper straps.
The back height adjustment is controlled with two knobs and runs smoothly on a nylon runner.
I over-tighten the screws on the nylon runner just a bit to get a “micro-swell” to create a very snug fit without any side play. Important: The piano hinge has to be aligned perfectly with the sliding piece; otherwise the table will not be parallel with the drum. I found this out the hard way.
Pillow Blocks: The pillow blocks are held in place with 3/8” bolts attached to cross dowel quick-connect hardware. They are strong, and can be dismantled easily as often as needed without weakening the anchoring system.
A simple tool was used to keep the 3/8” bit straight and centered in the ¾” plywood side.
The dowel holes don’t have to go all the way through therefore preserving the exterior finish. I couldn’t find cross dowels locally so I made some with a ½” bolt. A bit of work, but better than taking a long drive to town.
Motor: The drum sander is powered with a 1 hp general purpose motor running at 1725 rpm. 2”diameter pulleys maintain the speed of the motor. The link belt works well; it was a bit expensive but makes the sander run smoothly without any vibrations.
I found the motor too heavy for 1” piano hinges. The hinge was twisting making the motor run on an angle. I made a motor-mount with left-over router parts and angle iron.
The motor is anchored to four ¼-20 T-nuts on ¾” plywood
Dust Cover: The dust cover (3/4” plywood) is close to the drum (+/- 1/2”) to capture as much dust as possible with a shop vac or dust collection system. It covers the drum, pillow blocks and the drum pulley. It’s fast and easy to remove; locks into place with a knob in a slot on the left side. I thought I would need something else to hold it on the right side (a magnet maybe) but its heavy enough and doesn’t even vibrate when the motor is running. Clear Plexiglas (3/16”) provides a visual of the drum, pillow blocks and pulleys. The 2.5” dust port is centered but more towards the front where dust should be more concentrated.
Final touches for the drum: The drum was made smooth, true and parallel with the table with 80 and 120 grit sand paper glued with two-way tape to a piece of MDF before installing the fences. A dial gauge showed a variation of .003” along the length of the drum mostly in the center. I will have to live with that LOL
The MDF discs were sealed with a mixture of glue and water. One part water 3 parts Titebond III and re-sanded with 320 grit sand paper. I tested the sealed MDF by sticking two-way tape on it and was surprised how well it was sticking. That part worried me a little because of the cost of the Velcro. I liked the idea of using epoxy but it was beyond my means. In any case the glue will never come off and it sealed the MDF with only one application. I tried a second coat, but it was not penetrating at all.
Applying the drum Velcro: The Velcro matting angle was calculated by wrapping a string around the drum to get the circumference. This measure was then transferred to the Velcro as shown in the picture. Then I applied the Velcro tape all the way to the end (without removing the paper) to find the exact place to angle-cut this end. The same procedure was used for the sand paper.
First Test: My first test was to sand a 3/8”x 6” very rough wood plank with the 120 grit sand paper. The sander took it down to 5/16” with about four passes. At this point I am confident enough it will perform well. Of course future sanding of doors and project parts will be the real test.
The board was very smooth and a square showed it was parallel, even and flat across the width. Then I had the pleasure to use the sander to sand the table fences. LOL
Here’s other pictures that might help.
Hope this will help LJ’s wanting to build one of these. Send me any questions you may have. Thanks for looking
-- Paul, Plantagenet, Ontario