My brother has asked if I can make him a tiny little hand-held belt sander. My current prototype is about 3" x 1". Can anyone suggest a good high speed, relatively high torque motor (if there is such a thing)? Smaller is better. It will be powered by a wall wort.
Thanks
Do you have a source for sanding belts of that size? Belt sanders aren’t super useful without the belts!
Do you have a picture of what you have rigged up so far?
The belts have to be made. I’ve cut up some 18" x 1" belts and sewn them together. I think they’ll be fine.
I have it all apart again, but I have to put it back together to test out my belts anyway. I’ll snap a few pics. Current DC motor is not going to work at all, but it’ll give you the idea.
You could use an RC brushless motor, maybe with a gearbox.
Or you could build one of these 
A dremel, if at all possible. You can get a cheapo for less than $20, and
they’re designed for sort-of this kind of thing. Any discrete motors are
going to be similarly priced on their own. Harbour Freight is great for
stuff like this.
Related:
If you think a cordless drill will go fast enough, I can give you one (by
way of @funvill last year). I suspect they are too slow though.
Actually, you don’t really want a belt sander to spin too fast otherwise the sanding belt heats up too quickly. Princess Auto usually has a good selection of small, torquie, DC motors in their surplus section.
Mathias Wandel did a video related to this recently, Where I get my motors from
tl;dw: Matthias’s motors are mostly AC and mostly much larger than I think is wanted for the tiny belt sander.
Hey, look what just popped up on Make!
I saw that! Very nice, but not trivial to build. Do we have a metal brake at the space? That would almost tempt me!
Regardless, I’m working on a tiny little palm held one. This week I got my skate bearings in. I had to discard my aluminum chassis because it wasn’t stiff enough. Now I’m thinking of building a simple frame from makerbeam or 8020 or something.
Just a little project that I pick at as time permits…
We do have a metal brake!
It’s a little old and junky and clamps onto the table, but it works okay! I
have built a sheet metal box with it.
I have very small sanding belt, used with a hand tool, for modelists. The brand was “Flex-i-file”, and I bought that eons ago at MagicBox Hobbies, in Kerrisdale? See www.flex-i-file.com
Also, I used an air tool that was using industrial grade miniature sand belts. My guess is that came from Hansen Tools.