I am just wondering if these tools would be we suited for small spaces and sanding in corners.
I've got a corded and a cordless oscillating multi tool, and they're amazing for corners, since the sanding pads for them are triangular with 60° corners.
There are a few drawbacks that will keep you from using it as your default go-to sander though:
- They have a relatively small surface area.
- They usually oscillate in a 3° arc, which will be more likely to leave noticeable cross grain scratches than a random orbital sander.
- They don't have holes for dust collection, but this can be remedied since you can buy a dust collection adapter for many of them.
It's ok for getting into really tight spaces where a normal mouse sander won't fit, but as Doresoom mentioned, it produces an arc-shaped scratch pattern. Also because of the tool's shape and the tiny surface area of the sanding pad, it can be difficult to keep it oriented flat against a surface.
Be sure to run the tool at a lower speed (and use a dust collection adapter if possible), otherwise the hook-and-loop sanding pad's hooks will melt.
Not to suggest that an oscillating multi tool is not good for this type of sanding but small spaces and sanding in corners can mean different things.
Just to have another suggestion for these types of scenarios there are such things as contour sanding blocks/grips that are designed to hold paper to a shape. Depending on how tight your corner is you might have more luck with something like this.
Image from LeeValley
Sure there are commercial products which work well. I find myself wrapping sanding paper around scrap wood all the time albeit mostly for right angles.