Circular Saw Blade Sharpener

Four years ago I built a simple saw sharpening jig from wood from another Instructables post. I couldn’t find it this year, so I decided to make a more sturdy one from metal. If you don’t know how to weld, just stick with the wooden design. The wood design uses a separate angle grinder shield to fix the grinder to the jig. I used a fixed bolt that screws into the angle grinder handle holder in my metal version and do not need to remove the existing guard.

The base was made from 1-1/4” angle iron. The base supports are 14” long and the movable supports (rails) are 10” long. The long pieces are connected with two 5” pieces with the a flat face up to support the angle grinder. 1/2" wood 6" x 8". 1" wood screws, 1/2" x 8" rebar, 4 1/2" shaft roller bearings.

A wooden blade support is attached to the upper slide rails with screws through drilled holes in the metal. The support is first drilled through in the center with a 1” hole saw to make the holder for the blades. Another piece of wood is then screwed to the bottom of the support plate to form a base for various sizes of blade arbors.

The blade arbors are made by drilling a 1” plug with a hole saw, and then drilling that down with a 5/8” and 7/8” hole saw to make arbors to fit my common circular saw sizes. The use of the 1” holding bore allows the other sizes to be put in place easily and interchangeably.

The angle grinder is attached to the jig by a bolt secured to the jig. A lock-nut is used to position the grinder at the correct angle. I also use a simple C-clamp on the jig to mitigate any movement by the grinder due to vibrations. A fine-grit diamond grinding wheel is used to sharpen any steel or carbide-tipped saw blades.

When the alignment of the grinding wheel and the saw blade is correct, everything is tightened into place, with continuous checks to insure that nothing gets moved during the tightening. NOTE that the angle WILL change with different diameters of saw blades, but it usually does not need any adjustment as long as the diameters are the same, even with different numbers of teeth.

Back the blade away from the grinder before starting. Wear safety goggles as stuff can fly out from the grinding. Mark your blade at the starting point with some chalk so you know where to stop. Start the grinder and then gently move the blade tooth next to the grinding wheel and then against it with moderate pressure. Back it off just a bit, withdraw the blade support just enough to clear the grinding wheel for the next tooth, and repeat the process until all of the saw teeth have been resharpened. NOTE that it does not take a lot of pressure or time to retouch the sharpness! Don’t take too much off, and keep it even for all teeth.

Some fancier jigs have precise advancing and locking mechanisms for consistency. You may prefer to just buy a commercial sharpener for all that. Resharpening is just a touch-up and blade life extender. It will not usually match the factory delivered precision. If you do a lot of fine cutting, it may be best to just buy new blades occasionally. I do a lot of rough lumber trimming with hardwoods, so the blades dull more quickly and don’t need to have a super-fine finish. I still use factory sharpened blades for my finished carpentry cuts.