Homemade 12" Disc SanderOne of the things I use most in the shop is the little disc sander on my combo 4x36" belt / 7" disc sander. It's pretty lightweight and when I seen some examples on YouTube of others making a 12" size out of wood, I started thinking about my scraps and wondered if I could put something together for cheap.
I bought a 1/2 horsepower 1750 RPM motor at a garage sale for $5. The shaft is 5/8" and I'll have to rig something to mount the disc. A steal for $5, but then both the seller and I never knew if it worked at the time. It works!
I had to swap the starter capacitor leads to get the motor to run counter-clockwise (when looking at the shaft).
I bought a piece of 1/4" thick aluminum from the metal supermarket. This is probably going to be the most expensive item in the build. I cut it down to 12-1/2" x 12-1/2" with a jig saw. I used some masking tape and clamped the piece down good before cutting. It's slow going but doable.
portable band saw I cut the circle out. This was done in 8 small sections. I am staying outside the line as I will true the circle after it's mounted.
I used a little nail polish for thread locking of the machine screws to keep the nuts from working loose.
Now the motor and disc are looking good, it's time to build a frame to mount the motor and allow for a table mount.
In the scrap pile I have some salvaged 1-1/2" channel. It comes as bracing for large cardboard shipping boxes to keep them rigid. It's folded up 18 gauge so not the strongest thing, but when it's tacked together in a web it will be quite strong.
This is a photo of the rod with the motor and disc sitting in place.
For the table I had two things in mind--an adjustable angle and easy to remove. Removing the table is necessary to change a sandpaper. In order to get the table to swing I need to get the pivot in the right spot. I played in AutoCAD to see where the pivot should reside. I determined that dead centre on the disc would be good.
The table can be made from anything flat. I chose some 3/16" steel that I had bought for some other purpose and cut it to 16" x 8".
To build a hood I opted for something simpler to work with than steel. I had some 1/2" plywood and cut it to 12-5/8" x 12-5/8". I drilled a 3/4" hole in the centre drew an arc with a radius of 6.25" This will give a nice round curve. I cut on the band saw and smoothed on the sander. From the bottom, I cut out up to the hole so this will slip over the motor shaft.
Test fitting over the motor shaft.
Once the glue is dry I cut a strip of 1/8" hardboard at 2-3/8" wide and 19" long. It's glued and screwed. Starting at one one and working around the curve. Any little excess is trimmed off at the finishing end.
I used some #10 pan head wood screws to secure the hood.
This is the hood and table installed.
The electrical is a basic switched circuit. I've included some photos to show what I did, but as long as you're safe, go for it!
Mount the switch in the 1110 box and put the plate on it. I made some red and green rectangles out of duralabel and red and green sharpies.
The clearance is close at 90 degrees. If the sandpaper disc isn't adhered properly it ticks on the way 'round.
This thing is really useful. I made a few videos which I will post on YouTube.
Bill of Materials
Miscellaneous (cable ties, wood screws, paint): $5
Electrical box and switch plate: $5.99
1/2" plastic bushing: $0.49
Running total: About $71.00