I picked up a used Grizzly 24" dual drum sander recently and finally got around to setting it up last night. Once I got the drums dialed in it produces a decent finish, but the stock is coming out with a thick layer of sawdust compressed to the surface. I've noticed when I brush it off that in areas it was particularly thick the finish isn't quite as good underneath, and it's also very, very messy. I took the shroud off to watch it in operation, and the cause is pretty clear. What I'm seeing is the drum is rotating with the direction of the belt, so as the stock passes under each drum a thick layer of sawdust is left on the surface. This passes under a feed roller which compresses it and it's fed into the second drum which makes even more, then another feed roller to compress it again. The pic shows what it looks like coming out (although to be fair there was no dust collection going for the pass where I took the photo). There's a little scraper thing that's supposed to help with the dust accumulation but it's not all that effective.
On my Woodmaster the drum spins against the feed direction, which makes sense to me as this kicks the dust out of the drum instead of under and should thus reduce loading of the sandpaper. Looking in manual, one of their 24" models rotates with and one rotates against the feed direction. Doesn't make a ton of sense to me why they'd be different, the only difference is one has variable speed and reversible feed.
So- From what I've read online I should be able to reverse the direction of the motor by switching around a few leads in the motor controller. would it be better to reverse the feed or the drums? I'm concerned about the effect of reversing direction on the bearings that have been running the other way their whole lives. Before I go mucking around with this, does anyone have any thoughts on either the nature of my problem or my proposed solution?
While we're at it, what would be considered acceptable tolerances for drum alignment? These drums are a bit of a nuisance to adjust, but I was able to get thickness variance <.005" pretty consistently across a 12" board.
On my Woodmaster the drum spins against the feed direction, which makes sense to me as this kicks the dust out of the drum instead of under and should thus reduce loading of the sandpaper. Looking in manual, one of their 24" models rotates with and one rotates against the feed direction. Doesn't make a ton of sense to me why they'd be different, the only difference is one has variable speed and reversible feed.
So- From what I've read online I should be able to reverse the direction of the motor by switching around a few leads in the motor controller. would it be better to reverse the feed or the drums? I'm concerned about the effect of reversing direction on the bearings that have been running the other way their whole lives. Before I go mucking around with this, does anyone have any thoughts on either the nature of my problem or my proposed solution?
While we're at it, what would be considered acceptable tolerances for drum alignment? These drums are a bit of a nuisance to adjust, but I was able to get thickness variance <.005" pretty consistently across a 12" board.