Description of Stone Tools ST 63 Variable Bi Metal
Uses M-42 tool steel as it's cutting edge. M-42 tool steel contains 8-Percent cobalt and 5-Percent tungsten for tough wear resistant teeth. Aggressive cutting action, especially for hard materials. Fast, smooth cuts with less vibration. Made in U.S.A.
After I put it to the test, I was highly disappointed with this hole saw. Despite its claims of being bi-metal and variable, it failed to cut through even relatively thin materials and dulled quickly..
Very disappointed with the quality. Although the teeth appear to be sharp, they only cut through a small portion of the 2x6 before starting to smoke and burn the wood. I had to constantly take off, clean and cool down. I took my time cutting - didn't force it, and there were no nails or screws in the 1-1/2 lumber frame. For comparison, I've used another manufacturer's hole saw for over 40 holes with no problems!