Sharpening circular saw blades – do it yourself – mother earth news
To clean the blade, drop it into a pizza pan and soak it in mineral spirits for a half-hour. Some workers prefer a commercial pitch remover, and some advocate using oven cleaner, but ordinary mineral spirits usually softens it up enough for easy removal. Then attack the crud with a brass-bristle brush and a small sharp knife. Get it all off.
After you clean it, inspect the whole blade. In most cases, a good cleaning all you need to restore your well-used blade to near-new performance. However, carbide is brittle and you may find some chipped teeth or even missing teeth.
Some woodworkers like to touch up chipped teeth with a small, flat diamond hone. If you try that, be sure you maintain the original angles and surfaces, and don’t round over the cutting edges. Once in a while you’ll find missing teeth. While the manufacturer may be able to replace them, it’s liable to be expensive, so unless that blade cost a lot in the first place, you’re probably better off to toss it and buy a new one.В В (see illustration).
Sharpening BladesCarbide-tipped blades are best sharpened professionally, but high-speed steel models can be sharpened in the shop.
Jointing the Teeth. To sharpen the teeth of a non-carbide-tipped circular saw blade, install the blade in a commercial saw-setting jig following the manufacturer’s instructions. For the model shown, the blade teeth should be pointing counterclockwise. Install the jointing head on the jig, butting its file up against the saw teeth. Then tighten the thumbscrew until the teeth drag against the file. To joint the teeth so they are all the same length, clamp the jig in a bench vise and rotate the blade against the file clockwise (see illustration). After each rotation, tighten the thumbscrew slightly and repeat until the tip of each tooth has been filed flat.
Setting the Teeth. Remove the jointing head from the jig and install the setting head. Also remove the jig from the vise and set it on top of the bench. Adjust the head for the appropriate amount of set, or bend. Using a pin punch and ball-peen hammer, lightly strike every second tooth against the setting head (see illustration). Remove the blade and reverse the position of the setting head. Reinstall the blade with the teeth pointing in the opposite direction, and repeat for the teeth you skipped, again striking every second tooth.
Sharpening the Teeth. After the saw teeth have been jointed and set, file them using a commercial saw-sharpening jig. Mount the jig to a workbench and install the blade loosely on the jig so the blade turns. Following the manufacturer’s instructions, rotate the triangular file in the file holder and adjust the guide arm to match the required pitch and angle of the saw teeth. Starting with a tooth that is pointing to the right, file the cutting edge by sliding the file holder along the top of the jig (see illustration). Rotate the blade counterclockwise, skipping one tooth, and repeat. Sharpen all the right-pointing teeth the same way. Adjust the triangular file and the guide arm to work on the left-pointing teeth and repeat, sharpening all the teeth you skipped.