Sharpening of band mill blades

A primer on sharpening band-mill blades. March 2, 2000

Q.
I just got my new Cooks sharpener today. Prof. Gene, it kisses the face of the tooth, slides just about to the bottom of the gullet, and then just kisses all up the back side of the other tooth, in a gentle sweeping motion. Is this good for the blade? It hardly grinds any steel away, but it seems like a lot of grinding. Is there a book that gives all the thinking on blade sharpening?

A.
There was a whole insert in one of the latest editions of Sawmill and Woodlot Magazine dedicated to saw blades and sharpening.

The gullet has to be sharpened along with the tooth, to keep the proper relationship to tooth height for proper feed rate and sawdust removal.
Gene Wengert, forum moderator

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I'd call Cooks and ask if they forgot to include the instructions. I have a Wood-Mizer sharpener and it came with considerable documentation. The first half-day of our new-mill-owner instruction session dealt with blade theory, and how to use and adjust the sharpener and setter.

Here are a couple of suggestions:

You may look for a maximum-depth adjustment. The Wood-Mizer has one, but they recommend setting it all the way out so it's not effective. One way to see if it's not letting the grinding wheel all the way down is to watch the roller going around the cam. If it contacts all the way around, everything is fine. If it rises off the cam, something is keeping the grinding wheel from coming down as far as it should.

If it's not the depth adjustment, then it sounds to me like you need to dress down your grinding wheel on the face that rides up the back side of the sawtooth. Then you can adjust your grinding depth down so it will grind the bottom and still hit the upslope of the next tooth. Try this a little at a time until it will uniformly follow the tooth contour, or give you the desired depth. At least that's what I'd do with my Wood-Mizer sharpener.

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It sounds about right (although it would help to see it). The idea is that you grind very little so that you do not overheat and soften the metal.

The original profile of your tooth is apparently not exactly the same as what the grinder is using -- it will take a couple of passes to get it the same. Remember that the grinding wheel wears a little, too.

One trick is to trace the tooth (and gullet) on a piece of very fine graph paper. This gives you the profile and if you count the squares, you can determine gullet area, which, as previously stated, is critical to maintain.

Again, remember that the points and side of the tooth are probably more important than the top of the tooth -- the sides contact the face of the lumber.
Gene