A disc sander is a must for any shop! They make quick work of shaping and smoothing stock. Getting the most out of your shop tools can often take you down paths you didn't know existed. If you can't afford a disc sander or dont have the means to make your own, this simple table saw version might be for you. The usable space on the disc is less than a standard disc of the same size, however if you are limited on shop space this may be just what you need.
Step 1: Tools and Materials
Step 2: Draw Circle
On a piece of scrap sheet metal, mark the center of where your circle will be. I have a 10 inch table saw so I made a 10 inch circle. Punch the center of the hole. With your compass, scratch the circumference of the circle.
Step 3: Cut Circle
Using an angle grinder, cut the circle out. Be careful of the sharp edges.
Step 4: Drill Center
Secure the disk to the drill press and drill a pilot hole through the center of the disc (where you marked with the punch). Drill the final hole size of your arbor (probably 5/8 inch in the US). Be sure that there is clearance under the disc for the drill bit to go without drilling into the drill press table. Depending on the thickness of your plate, you may need to flip the disc over to drill the other side.
Step 5: Grind the Disc Round
On the lathe, turn a support to hold the disc on the bench grinder. Turn one end the same size as the hole through the middle of the disc.
Cut the support so the shoulder of the support is the same height as the tool rest on the bench grinder.
Unfortunately I never made an instructable on my lathe tool sharpening system which is what makes this step work. You could probably set up a holder of some sort to clamp down to your bench next to your bench grinder. All it needs to be able to do is be adjusted to grind more or less off the outside of the disk.
Once mounted, turn on the bench grinder and rotate the disc grinding off more and more until it is perfectly round.
Step 6: Smooth Edges
The edges of the disc are going to be rough and sharp. Using a metal file, break the edges to prevent possible cuts in the future when handling the sander.
Step 7: Paint
Degrease the disc and apply a coat of paint to prevent rust.
Step 8: Apply Sandpaper
Remove the paper backing from the sandpaper and place the disc on it. Cut the outside of the sandpaper off with a utility knife. Trace the outside of the arbor washer and cut on the outside of the mark. This will give clearance around the arbor. Test to verify that there is clearance around the entire washer.
Step 9: Mount Disc Sander
Insert the disc just as you would any saw blade following your manufacturer's instructions and connect your dust collection.
You can mount it with the sandpaper facing either direction if you are using it at 90 degrees. If you plan on using it at an angle, be sure that you are sanding on the upward facing side. You do not want to trap your piece between the table and the sander.
Always sand on the downward cutting side. This will be the side closest to you when using the table saw normally. This will keep your workpiece firmly on the table.
Step 10: Get Sanding!
This is a fairly easy project that can save some space if you don't have a dedicated disc sander. Clearly this will never be as good or versatile as a stand alone sander, but will work in a pinch. With the higher RPM (3600 for my table saw) be careful to keep fresh sandpaper on it as worn out paper can easily cause burn marks. If you do not have the tools or time to make this, you can purchase one instead for around $20, but what's the fun in that? :)
Share a picture of your homemade disc sanders in the comments. What strange and interesting uses do you have for your shop tools?