I remember when I got my first set of hole saws. They looked like this:


Little did I know I was just beginning a long relationship with hole saws. The larger ones, in particular, seemed to be good for only a very few holes before they lost their bite and stopped cutting and started smoking. Especially when doing service changes, the slightest contact with asphalt roof shingles - either side- seemed to spell instant death to the teeth.

Well, I recently had the need to try this new style saw:


It is expensive. It will NOT fit your existing arbor. It does NOT come in the exact same sizes as the ones in the usual electricians' set. Yet, for cutting through solid wood siding, a layer of tar paper, and a layer of OSB, it simply raced through. The hole was very clean, and showed no sign of gumming up from the tar paper.

I recommend replacing the conventional saws in your kit.