I'd imagine your drum should be running against your feed direction so that doesn't shoot the wood through. I can't remember what my homemade one did, but I think it opposed it.
So I've almost got a diy drum sander built, similar to many you've probably already seen before, but I have an issue with the bed (part that the wood rides on...there's no conveyor, I'll just push the wood through).
So the was flat...and now it's not lol. I built it with 2 pieces, piece A = .75" particle board, piece B = 1/4" MDF. I glued it up on a flat surface with Titebond 1, and it remained flat for a week as it sat indoors.
Then I left it out in the shop overnight with the hurricane IDA storms rolling through. I'm guessing humidity got to it and now it is bowed ever so slightly.
Any suggestions about trying to fix this? Or maybe building a sturdier bed?