This post is about a homemade disc sander to use on my lathe. It fits in the dovetail chuck jaws, so can be set up and removed very quickly and easily.
The disc
I attached a faceplate ring to a bit of 12 mm birch plywood, though I could just have made a chucking recess in it. I turned it to a disc of 180 mm diameter, as I have a lot of sanding discs that size. This is adequate for small work, but on disc sanders, less than half of the diameter is usable in practice. A larger size would be better, other things being equal, but would make dust extraction harder. I made sure the face of the disc was flat and running true. Then I turned a bevel on the back to thin the edge so I would be able to sand into recesses.
I covered the face with 50 mm self-adhesive Velcro hook tape from a local haberdasher’s shop. I pressed it face down under weights for a few minutes to get a good bond. After trimming the surplus, I applied the loop-backed sanding disc. With self-adhesive tape it’s a good idea to keep the disc face down when not in use to prevent the tape curling. A single sheet glued in place would be better. Velcro-backed sanding discs cling quite well to a coarse grit disc. This is an alternative to the velcro hook layer. You would have to make sure particles of the coarse grit don’t get on the face of the disc and scratch the work.
The disc sander table
Then I turned an ash dowel to a snug fit in the tool rest holder (banjo). I made a 25 mm x 25 mm tenon on one end to fit it to the table. My lathe tool rest has a 40 mm stem, so the dowel is very rigid. Finally, I drilled a 25 mm hole in a scrap of 25 mm thick MDF and fitted it to the dowel. This makes a robust sanding table, though without angle adjustment. Fine for the jobs I shall use it for. Thinner board could be laminated if necessary to build up the thickness. The dowel post is positioned off-centre in the table. This puts it close to the sanding disc, where it will give better support, particularly if the post is small in diameter.
A disc sander needs effective dust extraction. My extractor hose is there at the lathe and works quite well in its normal position. But it would be better with the intake under the sanding table closer to the downward dust stream. It should be possible to make a shroud around the lower half of the disc if necessary.
I used a 320 grit disc running at about 1200 rpm to sand the edges and faces of a batch of about 40 small items of flatwork. The disc sander worked very well and will be a useful addition to the workshop.
