Keeping Straight-Line Rip Saws Ripping Straight
What was really happening is that long boards were rising up as they glided over the in-feed table and that changes the plane on which the laser draws the line. It was an optical illusion that he was reacting to. In any event, we taught the operator how to pull the in-feed table out from the saw to get a better balance on the longer boards, and we also taught him not to "correct" the board once it was in motion as it is pulled through.
I don't know if this is your problem, but our experience may give you some insight. Of course there are mechanical adjustments that you can make to your saws, but when you said that the problem exists on both saws I too suspected your operator - especially if the operator operates both saws.
From contributor C:
The most common cause of this problem is that the lumber is not properly conveyed behind the saw. It is imperative that the saw not have to push the lumber. A saw can usually push short lumber because there is not much weight and friction. But as the board gets longer, both weight and friction go up, and there is a point beyond which the board will lead off. The answer is to have a belt conveyor which is timed to run at the same speed or very slightly faster so that the board exits the saw with little or no "push".
From contributor G:
Lumber must be reasonably flat before ripping. We usually "skip plane" before ripping. If using roller tables, they must be exactly perpendicular to the saw blade. If not, the rollers will tug at the board and cause it to wonder off its line. The operator will naturally use his finger to help guide it. Flat infeed and outfeed tables are best. Use melamine board for a slick surface. A coat of wax wouldn't hurt either. Remember, you can't straight line cupped lumber it must be fairly flat.
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