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Widebelt hold down rollers12/1/14
Can anyone give me some idea how far below the infeed and sanding drums the pressure rollers should be? I am trying to eliminate some issues I am having with a SAC 37". I am getting uneven sanding, what feels like valleys in spots. I have re adjusted the platen which I think was too low, but now I am wondering about the feed rollers. Thanks.
I call them pinch rollers. I set mine just tight enough that he work piece doesn't get pushed back toward the operator.
We just went through the EXACT same scenario. We were getting snipe and hesitation marks on both ends.
Thanks for the feedback. I think I have everything in order. Biggest issue was the platen being way too low (the scale used to adjust the platen was off), but also the pressure rollers were set too low as well. Boards were actually having a hard time getting under the first roller.
Hold down pressure can be tricky. Some machines have strong springs and soft conveyors. I usually start with .030" on stiff springs and .050" on softer springs.
The platen should be only a tiny amount lower than the drum in a single head machine.
Raise up the platen and sand a part with just the drum. Stop the machine and run the part back under the head. You can drop the tension and slide the belt back and forth as you drop the platen until you feel good drag.
Then you can run a part and look for longer scratch. This usually nails it right away. The platen only needs to take a couple thousandths, and only on the finishing pass. I pull them out for roughing so you don't have to find the right setting each time.