(Online-only images of Milwaukee's SwitchBlade Selfeed bits appear below)

As the owner of a plumbing and heating business, I am also the fixer of tools and the sharpener of blades, and it's up to me to make my equipment investments last. One of my most onerous duties is sharpening the Selfeed bits we use. I've gotten good at it, but it's a time-consuming chore. So it was with great optimism that I tested Milwaukee's SwitchBlade Selfeed bits with replaceable blades. I got the plumber's kit with four commonly used bit sizes and a handy snap-in extension (which I can no longer live without). Besides spare blades, the kit has four spare feed screws and their set screws, all contained in a durable "lunchbox" that is one of the few plastic tool cases I haven't tossed out for being oversized.

In daily use, the blade inserts stay sharp for a long time and are easy to remove when dull. And even though they are disposable, I got a lot more life out of each blade by touching up the flat side with my stationary belt sander. With the outside teeth of the bit not in the way, it's a breeze to sharpen the inserts. Just make sure to remove material from the flat side of the blade only; otherwise, the blade height will be too low to cut. When the side teeth get dull, they have to be sharpened the same way as conventional Selfeed bits: I use a mini cutoff wheel on a Dremel tool for the job.

The Verdict

Milwaukee has come up with a welcome revolution in quicker and easier maintenance of these expensive bits.

John Myrtle owns JM Plumbing and Heating in Hotchkiss, Colo.

Price: $249