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When trying to make a drill powered disc sander, connecting the sanding disc axis directly to the drill chuck, I realised it was not a good idea. The problem is that there is always some play in the drill chuck, and that affects a lot to the sanding disc movement. So I decided to make a shaft with bearings. And I will put it between the sanding disc and the drill chuck making a kind of sanding attachment for drill. So let’s see how to make this homemade disc sander using the shaft with ball bearings.
First I have to make a new drill support. But well, instead of a drill support I will make a shaft support. So I cut four plywood strips and I glue them in pairs to make two pieces. Now I clamp those two pieces together. And I use a forstner bit to drill a hole to house the bearings. I have to drill a precise and vertical hole, so I use the drill press.
So, I screw one of those two pieces to a small plywood board. And now I can install the shaft with bearings. The hole I drilled is some smaller that the bearings, so I have to put two pieces of cardboard so the shaft fits,.
After checking that the shaft turns correctly, I can install the drill. And now I can use some epoxy, washers and nuts to install the first plywood disc to make this disc sanding attachment for drill.
I used my DIY circle cutting jig to cut this plywood disc. And I drilled a hole in the centre of the plywood circle. That hole is the same diameter as the threaded rod in the shaft with bearings. Like this I can screw it in the threaded rod.
Now it is time to rectify the plywood disc. And this is the most difficult part. I put a simple wooden table in front of the disc (this is the same table I will use when working with this disc sander), and I use a chisel, or a gauge, to rectify the disc. I try to make it be perfectly at 90 degrees with the shaft, but trying to keep it perfectly flat. I also rectify the back of this disc sanding attachment for drill so it is the same thick all around. Otherwise it will vibrate a lot.
Once I rectified it, now I glue a thinner disc. This one will hide the nut that protrudes the front of the first disc. So I had to make a hole and a wide counterbore to accommodate the washer and the nut.
Then, I glue the thinner plywood disc, and I clamp it while the glue dries. To do this it is better to disassemble the shaft with bearings so I can clamp both discs together with several clamps. And once the glue dries I use some wood paste to fill the hole in the front of the disc. I let it dry and I sand it flat. Finally I rectify the edge so both discs are identical.
Now I just have to cut a piece of sandpaper that has the same diameter as the plywood disc. And I use stencil adhesive to stick it to the plywood. I use medium grit sandpaper, because it is the kind of sandpaper I use most often. And it works well to shape the wood.
Some people ask about how to change the sandpaper of this disc sander. And the truth is that, because I use stencil adhesive, it is very easy to remove the old sandpaper. Maybe it will be even easier if I heat it with a heater gun. But I didn’t try that yet.
After some time using this DIY disc sander, I am really happy with how how works. It is very easy to sand with a lot of precision, so it is a must have in our woodworking shops.