An expert tells you how to drill large holes in wood and metal faster and better with carbon steel or bi-metal hole saws. Choose the correct hole saw for the job at hand; it doesn't have to be the most expensive.
The best way to cut holes faster is to drill relief holes to exhaust wood chips and keep the blade cooler.
If you hate to use a hole saw because it's slow, dulls quickly or burns the wood, take heart. We talked to Matt Savarino, the hole saw expert at Lenox Tools, to get to the bottom of your dilemma. Matt told us that most DIYers don't need expensive hole saws. In fact, for occasional cuts in wood, he says the cheapest carbon steel saws work just fine (see Photo 1). But don't try using them in metal—that'll destroy the saw teeth in seconds.
Even if you drill relief holes, hole saws take forever to drill through thick wood. If the holes are less than 1-1/2 in. in diameter, don't bother with hole saws; use spade bits.
In metal, always use bimetal hole saws and keep the teeth sharper longer by using lubricating oil.
But if you're cutting a hole in your steel door for a dead bolt, or cut lots of holes, step up to a bimetal hole saw. The teeth are made from a harder steel than the shell, so they last longer. But that doesn't mean they're indestructible. Always provide lubrication when drilling into metal. Cutting oil is best, and even ordinary motor oil is better than nothing (see Photo 2). You can use bimetal saws to cut through all types of materials except ceramic, porcelain, granite and the like. For those, you need a carbide-grit hole saw.