I built this sander loosely following Ronald Walter's, but with a lot of changes. It was built with the main intention of sanding veneers to thickness, but it's already come in useful for planing some objects too big to fit in my rubbish jointer/ planer combo (don't ever buy one! I should've known better and got a regular planer).
I built the conveyor belt first since I'd read a few things online of people having trouble getting them to work.
The rollers were made from 18mm plywood stacked on a 12mm steel shaft. People seem to be using PVC pipe for the rollers in other sanders I've seen, and I'd imagine (although I haven't checked) that the pipe won't be fully round. Plus, on top of that it'd be harder to get it fully concentric than just turning wood round. They didn't track so well at first, so I ended up giving them a bit of a crown. I find it kind of funny that crowns work on rollers so wide.
I was pretty pleased with getting the conveyor to work. I didn't imagine it'd work after reading about other people's trouble.
The sides were cut out with paper templates printed 1:1 using BigPrint. I really think paper templates are ideal for this kind of thing.
The drum itself was made from 18mm birch plywood, similar to the rollers but bigger. Using fancy plywood might've been overkill but after having trouble with MDF when making the rollers I didn't want to take any chances. The two disks on either end of the drum are only screwed on and can be removed for cutting the sandpaper retainers, and for lining them up with the edges of the sandpaper once it's wound on.
The table pivots on these bearing flanges to change the depth of cut.
The drum was slightly narrower in the middle after turning, and was sanded flat with this setup.
The first thing I sanded caused a kickback. I think the small part just had a chance to be easily pushed over by the sanding drum. To sand small parts in the future I'll probably have to attach them to a longer board first.
The 80 grit paper left a fairly rough surface. I'm using this sander for leveling surfaces and thicknessing mostly, rather than for finishing. I think finer sanding could just as well be done by hand.
More homemade machines by Simon Heslop: