It uses a right angle drill chuck to adapt the drill press’s axis of rotation, and a lazy susan bearing to support the sanding disc. Now as you can see it’s a very crude prototype – just a few pieces of wood held together with clamps, but it’s a successful proof of concept… so let’s take this to the design tool and see if we can make it any better. I’m drawing this up in my new favorite 3D CAD program, Fusion 360.
Looking at the drawing it’s not long to realize that the extended standing platform makes the unit bulky to store. It would be nice to get rid of it, but the extension is currently used to secure the sander to the drill press table.
I explored an idea of making the platform fold up, sort of like this. It looked really nice in theory, but it would introduce an entirely new set of design challenges.
Eventually it occurred to me that drill press tables can tilt. So I can move the drill press table over here, and clamp the disc sander from the side.
At first it didn’t look like the 9″ sanding disc I have would fit in the available space – but thanks to asymmetry of the drill press table, I can turn it around, and now it should fit.
The philosophy was to keep this project as simple as possible, so everything is cut from one material and all parts share a common side length in order to make construction faster. The material is 3/4″ birch plywood.
Now the million dollar question: how will this right angle adapter that only accepts a 1/4″ hex shank connect to the sanding pad? Well, it’s only logical to begin with a 1/4″ hex bit – yes, I insert it into the adapter backwards. The hole is deep enough that it still grabs a good hold. On the other side a 1/2″ set screw will accept the 1/4″ hex shank perfectly. The set screw will be driven into the plywood sanding pad, and that’s how it’s going to spin.
If you’re making a drill press disc sander, I figure you’d probably have a drill press. So I use it to make sure the set screw goes into the pad perfectly square. A 7/16″ diameter hole is drilled 1/2″ deep.
To insert the set screw, I’ll chuck up the 1/4″ hex bit, and manually run the drill while applying pressure with the drill press table. It’s very important that the sanding pad spins true, and this is the way to guarantee that the set screw does not go in on an angle.
At this point the screw got too tight, and the pad started slipping… so I took it off the drill press, and drove it home with a hex key.
Before this machine goes into service I’ll get a bit of silicone spray into the bearing to minimize friction. UPDATE: it turns out silicone spray should not be used for metal-on-metal contact, try lithium grease instead.
The sanding platform is designed to overhang the edges in order to help align the unit on a drill press. A single clamp should be good enough to hold it in place.
It’s working really well, but if you don’t like a lot of fine dust in the air This tool could really use some dust collection. We’ll save that project for another time.