Ok, I'm reviewing my own home made tool, so I supposed it might be biased :-). But honestly, I think this is for everybody's interest:
This unit has a 1.5 HP motor, single belt, which turns a drum that is approx 5.5" in diameter, with a total speed of about 2000 linear feet per minute. I have 100 grit "paper" attached right now, and it's easy enough to change since it's velcroed on.
This unit is heavy, and doesn't budge at all. Right now there's no on/off switch, so I need to add that. Height control could be easier to get at, as I have to bend over and reach under the table to change it. Something with a knob at the top of the table that perhaps moves the main screw drive with a chain. A depth indicator would be quite helpful as well. Right now I just set the initial depth by putting the board under the drum while, and raising the table til it hits. Then I turn it another 1/2 turn or so.
Only about 1/8 of a turn is needed per pass. Sometimes that's even too much, and I'll run the board through at the same height to remove more stock.
How is that you ask? Well, the velcro matting and the paper itself has some give to it... like a cushion. So it's possible to run a board through and the board will come out thicker than the height of the table.
My push board works pretty well. It's basically a 20" wide board, about 10" deep, with some hard wood "handles" on the front of the board. Feeding at a constant rate has NOT been a problem at all, and that was one of my two main worries about this unit. I think the fact that the drum is a larger diameter than most means that the pressure of the roller is distributed onto a wider area, so gouging into the board just has not happened at all!
Speed wise, I can flatten an average glued up panel in about 10 minutes for both sides. I just mill all stock maybe 20 thous oversize. When I begin to run the board through, I scribble all across the board with a pencil so I can see high and low spots. Once all the pencil marks are gone, I know the board is flat.
I've run some doors through this, and while 100 grit scratches the cross grain, I can easily finish sand these out pretty quickly. I'll have to try some 150 in it and see how it works. What would also be cool is to have a wider drum, and put half at 150, half at 100.
Dust collection works pretty well, although it does miss some dust on the edges since the only opening is at the center. If I were to do it over, I'd split the dust fitting, or maybe even make a slot along the entire width of the cover.
You can't beat the cost of this unit. I'm averaging the cost to be about $150, but I already had the table built from a project 2 years ago. Probably add another $30 or so for the table.
If I were to do it over again, I'd make the table 36". While I haven't had a board over capacity yet, I'm sure it will eventually come up, and now that I've proven the method works, I feel VERY confident that I could run something that large through the table.
I really recommend any shop that has the room to make one of these, as it's so much more forgiving than I ever thought. The time it has saved in sanding is immeasurable, AND the quality of the final product is unbelievable. DEAD FLAT. I can already see a quality of my work that I haven't seen before. It even seems to take any slight cupping or twist in a door out.