Is there a rule of thumb for how often a circular saw blade should be replaced? Is visually inspecting the blade condition enough?
You should replace your blade when its dull. Ways to tell its dull:
- it starts binding
- it tears/chips the substance more than usual
- it burns the wood
- just a pain to use = a sharp blade should let you push the saw forward with minimum effort. If you find yourself forcing the saw forward (not ideal from a safety perspective), change the blade.
Looks for worn or chipped carbide teeth. If the teeth are merely coated in pitch, you can remove it with oven cleaner (or in a pinch windex), and old tooth brush, and some elbow grease.
Blades should be replaced when they get dull or after you hit a screw or a hard knot.Cleaning saw blades
Sometimes you're using a sharp blade and it still cuts poorly. You might be ripping with a crosscutting blade or crosscutting with a ripping blade. Just like you do with your fish hooks, run the back of a finger nail over the saw teeth: if it scrapes, the teeth are sharp; if it slips over your nail without scraping, it's not sharp.
There is a fantastic way to clean pitch off of saw blades. It is something that everyone has at home. Laundry detergent. Yeah, that's right simple laundry detergent! I put a heavily burnt/pitch covered blade in a 12"x12"x5" plastic tub with a gallon of hot water and quarter cup laundry detergent. Let it soak for three hours. Use a nylon brush/toothbrush, and be amazed. The pitch comes off like soot. Rinse off. Dry the blade thoroughly (I used a heat gun). Apply thin Coat of oil, or blade oil on carbide tips.