How to sharpen a hole saw?

But you asked how to sharpen it didn't you??? The best thing to do is put it in a vise, blade up and at an angle that will allow you to easily run a file over the sharp edges of the teeth. You will notice that the blades are bent back and fourth, that is the set, you have to have a set in the blade or they will be pinched by th item you are cutting and that's a b---. There is a devise that sets that angle but for a hole saw it can be done by eye easy. Just make sure that they are all out far enough, that none are flush with the flat part of the blade. Then you need to take a fine file that is small enough to get into the grooves of the blade without touching the v at the bottom and changing it's shape. Notice the angle on the cutting edge and place your file on the tooth at the same angle and push it through, only touching the surface in between the teeth on the cutting edge. Keep the file flat on that surface all of the way through. Repeat this on all the teeth and you will have a sharp $5.00 saw that you just spent 2 hours on. Hope that helps...