A carbide tip

I go through a lot of steel circular-saw blades remodeling and building additions. I hate to pay $2 a blade for sharpening, and then wait a week to get the blade back from the shop. But doing the sharpening myself takes more of my time than I'd like.

The answer for me is to use carbide-tipped blades and sharpen them myself with a diamond whetstone. Unlike the teeth on a steel blade, the carbide teeth on my blades are a simple series of flat planes that are easily reached with a small, flat stone.

The stone I use is a plastic block 4-1/2-in. by 13/16-in. by 7/32-in. Diamond crystals are bonded to a nickel matrix that's embedded in the plastic. Mine was manufactured by Diamond Machining Technology, Inc. (34 Tower St., Hudson, Mass. 01749) and cost $16.50 when ordered from a tool catalog. These diamond whetstones come in several sizes and are also just the ticket for those impossible-to-sharpen stainless-steel kitchen knives.

Although I take my blades to be professionally professionally sharpened every third time, the touch-ups have paid for the stone many times over.

Angelo Margolis, Sebastopol, CA