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I figured some folks might like to see this, since I've received quite a few questions on it. This is the setup I made for myself not too long ago when I realized that the 3.5" abralon discs just weren't cutting it.

I made this using my wood lathe and drill press - no metal lathe involved. I did have to buy a size I and #29 drill bit for the threaded holes, as well as the taps to make the threads. It didn't come out too expensive, however.

In this first photo the business end is visible. The DA disc simply threads right onto the end there.


Here's the other end of the mandrel. This is a 5/8" hole finished using a regular old 5/8" Silver and Deming bit. I went from 5/16" to 3/8" to 1/2" to 5/8". Possibly it wasn't necessary to hit all those steps, but I decided to play it safe. The holes for the set screws were done on the drill press. It slips right on to the shaft of the motor, and the set screws are tightened down.


Here's the thing all put together. I have half a dozen of those DA backup discs so I never have to remove the sanding disc once its on there. When I want to change grits, I just spin the current one off, and spin the next grit on.


Now comes the fun part - unless you have some sort of precision vise setup, I don't suggest you try and make one of these on a drill press. You need those holes to be perfectly axially aligned, otherwise you're going to get some pretty strange off-center rotation. You really need a lathe to make this - even if it's a wood lathe.

If I can make this, anyone can. So now none of you have any excuses for not using your eBay-bought Baldor motors to do finish sanding.

Kurt, that looks great! Where did you get the DA disc? What type of git do you have on it?

All my materials and supplies for this were bought from McMaster-Carr. They have, literally, one of every tool. Even the aluminum rod was bought from them.

There's no sanding disc on that in the pic, just the hook that the loop backing on the discs slaps onto. I typically use 6" Abralon pads (also from McMaster-Carr).

The same DA pads are available with a 5/8-11 threaded socket, which will spin right onto the threaded shaft of a Delta 1725-rpm 8 inch grinder.

Yep, Woodcraft has a pile of those discs. There seems to be slight differences between Delta, Porter Cable, and Dewalt though - either that or it's slick marketing.

I chose the 5/16-24 route only beacuse it's easier to drill a hole on a wood lathe than cut a piece of metal to the right diameter.

are those discs rigid backed or flexible?

android wrote:are those discs rigid backed or flexible?

They're fairly rigid. There is a plastic and aluminum backer on the disc. That said, the foam/whatever they used to construct the discs is very soft, so they do flex.

What diameter is the aluminum rod you made the mandrel from? I could probably turn one of these guys out on my metal lathe.

hazmat wrote:What diameter is the aluminum rod you made the mandrel from? I could probably turn one of these guys out on my metal lathe.

Buh... I forget. I think it might be 1.25". I don't think I would have gone larger than that.

If I can make this on a wood lathe, a trained helper monkey could do it with a metal lathe.

KurtHuhn wrote:

hazmat wrote:What diameter is the aluminum rod you made the mandrel from? I could probably turn one of these guys out on my metal lathe.

Buh... I forget. I think it might be 1.25". I don't think I would have gone larger than that.

If I can make this on a wood lathe, a trained helper monkey could do it with a metal lathe.

Nice. I'll get my trained helper monkey on it...lol..

hazmat wrote:What diameter is the aluminum rod you made the mandrel from? I could probably turn one of these guys out on my metal lathe.

It would only need to be big enough dia to drill the mounting hole for the motor shaft and still have enough wall thickness for the length of the set screw(s).