Q: What blade do you suggest for a radial arm saw so the saw does not pull into the wood being cut so much?
A: If the saw is pulling into the wood,then you are using an incorrect saw blade for this saw. I suspect you are usinga saw designed for a table saw; you need a blade designed for a radial arm saw.Using the wrong blade is a safety issue indeed.
Let me give you a littlebackground information. Start by drawing a straight line from the tip of thetooth to the center of the blade (we would call this line a radius). Then, lookclosely at how the bottom of the tooth (about ¼ inch below the tip is located with respect to this radiusline. Is there a slight gap between the bottom of the tooth and the line? Ifso, then we say that this saw has a positive hook angle. The hook angle is theangle between the tooth and the line, which might be on the order of 10 degreesor more. If the line and the tooth do not have a gap but line up togetherperfectly, then we say that the tooth has zero degrees of hook. Finally, if thebase of the tooth protrudes beyond the radius line slightly, then we say thatthe saw has a negative hook.
A saw with a positive hook will betrying to pull itself into the wood (or pull the wood into the saw). We woulduse a positive hook blade on a table saw for example or a rip saw. If we used anegative hook, the saw is pushing the wood away from the saw. On a table or ripsaw, this negative hook design means that the wood will come flying back at theoperator.
Now consider the radial arm saw. Ifthe saw has a positive hook, it will pull itself into the wood as you cut,which means the operator has to use a lot of effort to keep the saw fromfeeding too fast. But, if we had zero hook, then the saw could be pulled intothe piece being cut by the operator and when halfway through, the operatorcould take his hands off the saw (Do not dothis—this is justa visual example) and the saw wouldjust sit there. However, we know from experience that a slight negative hookfor the radial arm saw (maybe 3 to 6 degrees negative) will actually work thebest. The operator will have to use a little effort to pull the saw into thewood, but the saw will not pull itself. This is indeed a safe procedure. Butlet me repeat that such a saw blade used on a table or ripsaw will push thewood away from the blade toward the operator, so do not use negative hook forthose saws.
Consider the “portable” electricsaw (often called a Skil saw, but that is actually a trademarked name). Do wewant the saw to pull itself into the wood (perhaps it would be out of control alittle bit)? No! So again, zero or negative hook, but not too much negative asthen the saw will be hard to feed and will jump back.
Consider a bandsaw—if the saw has a positive hook, then it is pullingitself toward the wood and it might pull itself off the wheels as it grabs intothe wood, which is a disaster. So, a bandsaw will have zero or slightlynegative hook. Questions?
Gene Wengert, [email protected]
Gene Wengert, "The Wood Doctor," has been training people in efficient use of wood for 35 years. He is extension specialist emeritus at the University of Wisconsin-Madison.
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