How to know when carbide is dull
How often do you need to have saw blades re-ground? A carbide edge lasts a long time, so how do you know when it is starting to get dull? Look closely at the leading edge of a tip for signs it is dull. Focus exactly where the top meets the face. If the line of intersection reflects light, you are looking at a flattened area, or wear land. Dullness is shiny but sharpness is dark. If you can see a line, that's a sign it is worn enough. Lightly scrape a fingernail to test if it will catch and shave a little off. Don't feel the edge with your finger. The side of a saw tooth may still feel sharp after the top, or leading edge is already rounded and slick.
A pro-active strategy strives to augment the effective runtime; when work progresses at its optimal pace. Circulate bits so enough sharp ones are always ready to use while the dullest ones are out of commission.
Encourage employees to curtail the use of dull blades and set them aside. Designate a bin on a shelf, or a peg on a wall located within convenient reach to collect them. Develop a regular schedule with a sharpening service for maintenance. A methodical plan saves in the long term. This way you can recycle and save money, too. Timing is the key to making it pay off for you.
If you work with bits or blades too long, wear is exacerbated and the peripheral surfaces get rounded. Using saws in this condition brings a marked loss of efficiency. Notice signs of dullness by listening to a worn table saw blade vibrate and whine louder. It uses up more electricity; the power draw is measurable by an ammeter. Shoving the stock becomes effortful. The cut wanders and the surface is fuzzy. Sawdust turns to brown powder.
To restore saws in an extreme state of dullness requires relieving the rounding, so waste is inevitable. If the outer surfaces remain rounded after routine grinding, wear resumes at an advanced stage. It accelerates and shortens the period between tune ups. This limits the window of efficient runtime. If you delay maintenance, inefficiency along with quality control issues may ultimately add to the cost of production. Evaluate how long it takes to switch bits so you've got a realistic idea. When you need to change a blade, note the time used up by the chore and consider it relative to the potential consequences of procrastination.
How to sharpen carbide
Wet grinding by a fine grit diamond abrasive wheel on an automatic grinder maintains saws by the same method they were made. It hones them to a very close tolerance of thousandths of an inch. It will mechanically position and lock a tip in place during the procedure, then hone an identical conservative amount off each. It can maintain all the correct angles exactly and polish the facets. Wet grinding uses flood coolant to float off debris and prevent glazing. Repeated passes hone progressively lighter until the final touch is just sparking out.
It is possible to sharpen a carbide saw manually by honing one tooth face at a time with a diamond lap, but it is not often done. You can imagine how laborious and time consuming this method would be unless you use a fairly coarse grit. Each one would need the same amount of strokes rigorously controlled, skipping none. Taking no shortcuts, faces ought not to be dubbed back. The tips which see the most attention become too low to do much of the work, and the highest ones remain dull. Without a provision to equalize height, tops are better off left alone. As the circle grows slightly uneven or out of round, its effectiveness diminishes and vibration becomes undesirable. It is not recommended to hone the sides.
If you sharpen a router bit by honing its faces unevenly, eventually one side will be prominent. Honing the outside edges would really unbalance it, which makes it worse.
By any method, the object is not only to get a keen edge. To restore function like new calls for a group effort. Every tip must be aligned harmoniously in tune. Without the cooperation of precision teamwork, the result would all too soon disappoint.