Q. This woodworker is using a carbide forstner bit and having trouble with the speed. He's getting burning if he runs it faster than 600 rpm (on pine) and chipping if he runs it slower. What's up?
A. (Simon Watts)
"Forstner bits are notorious for this: the cylindrical cutter head is not relieved, so it tends to heat up because of friction with the wood. I'd suggest experimenting with different rates of feed. Usually, the faster the feed, the rougher the cut but the less heat generated. Try to find the best balance."
A. (Rob Johnstone) "While Forstner bits are wonderful for boring large diameter flat bottomed holes and drilling accurately at an angle, they are really fairly complicated cutters. However, the problem discribed seems to simply be a dull bit. Carbide cutters stay sharp longer, but in my experience, do not take as keen an edge as high speed steel. Once dull, a carbide bit burns and chips with the best (or worst) of them."
Q: Can I burn scrap plywood in my fireplace, or is it toxic?
Andy Rae: Burn away. It's as safe as burning solid wood — assuming you don't put your head in the firebox and breathe the fumes. The fierce heat of the fire destroys all suspect ingredients. The only toxic items in your fireplace will be all the normal carcinogens found in the smoke of a typical log-burning fireplace.
Carol Reed: Sure, but it smells awful!
Q. My Craftsman contractor-grade table saw has been a pretty good saw, but lately I've had trouble with it burning the right side (fence side) of boards, but leaving the left side smooth. The fence got knocked off my workbench one day, and I suspect that may be the sources of the problem. If I replace it with an aftermarket fence, what's the best for the money?
A. Michael Dresdner: "I suspect you are right. If you can, realign the fence so that it is parallel to the blade. At present, it sounds as if it is not. The burning is the smallest problem. More important is that you are creating a potential for kickback, the most common cause of accidents on the table saw. If you can't adjust the fence, replace it. What's best for the money? That's a matter of opinion. I like the HTC fence, (sold through JET tools, and direct from HTC), and that is what is on my saw."
A. Rob Johnstone: "Your saw needs a tune-up. An aftermarket fence would be cool, but I would start with making sure that the table and fence are properly aligned with your saw blade. There are many articles and books which can walk you through this process."