This hole saw is worth every penny, if not money. metal!) and the teeth are still perfectly sharp. The first time this bore caused so much torque due to insufficient lubrication that the mandrel broke and I had to buy a better mandrel. The hole saw got stuck in an overheated piece of aluminum which I had to cool in water to get the bit out. The hole saw was fine. With the next 5 pieces I used a lot of grease at 250 rpm. Then I made some holes in the plywood. For another project. After all this,