Review on Efficient and Durable NINIA Heavy Cutting Bi Metal Cutter - Superior Cutting Tools for Precision Cuts by Gary Haymon

I needed a crown to fit a vent hole through the outside wall for the stove hood. When this 6 inch beast arrived I was impressed with its depth and strength as well as the shaft design. In action, it quickly cuts through drywall and OSB. However, when I encountered cementitious hardiplank, the cutting slowed to a minimum and deteriorated when attempting to cut two partially overlapping boards. It was obvious that the teeth were rotten. When the saw wears out after about half an hour or more, the outer teeth offset is worn and all the teeth are worn down to a flat point. There was no more cutting. Although it was an inexpensive hole saw and a mandrel was included, it was too expensive to pay for a disposable tool. I don't know how long it will last unless used on a Hardi board, but the steel didn't hold up despite the saw's hefty appearance. You will need a 1/2 inch drill bit, preferably corded, to use this saw. Not suitable for 3/8" drill chucks.