Sharpen your bandsaw blade on the mill
Through the years I have dulled a lot of bandsaw blades on my sawmill, and for the longest time, I have struggled with keeping them sharp. I have tried multiple tools and methods to get this done, but only within the last year do I feel like I have found a good solution.
The problem starts with the bandsaw blade itself. It is a finicky conglomeration of bent teeth, cut from a thin piece of flexible steel that is somehow supposed to cut a straight line, not only from front to back, but also side to side, and if it isn’t well machined and sharp, there isn’t a snowball’s chance that this is going to happen.
Early in my career, when a new saw blade dulled and started to cut waves, I would try things like adding tension to the blade, slowing down my feed rate or even adjusting my blade guides. No matter what I tried, a dull blade would still make a wavy cut. However, if I used the exact same setup but installed a new blade, the cut would be perfect again. As a matter of fact, almost every other adjustment could be less than perfect and a sharp blade would still make a good cut. From 15 years of experience, it is clear that I need to keep my saw blade sharp and touch nothing else.
My standard course of action is to put on a new or newly sharpened blade from Wood-Mizer when my cut starts getting wavy. This is a great way to live. Nothing cuts like a brand new blade, and it feels like a treat to put one on. Even the resharpened blades cut great since they get a complete factory treatment, including cleaning and full tooth grinding and setting. I have always had great results from Wood-Mizer, and I highly recommend their new blades and resharpening service. (Disclaimer: I am not being paid by Wood-Mizer and Wood-Mizer doesn’t know I’m writing this post – they probably don’t even know I exist.)
The problem for me was that time in between cutting like new and cutting like crap. I would have a blade that was cutting great, but I could feel it pulling hard and on the verge of cutting poorly. I didn’t want to pull it off of the saw because it was running so well, but at the same time, I knew my time was limited. If I could just get an edge back, I could keep cutting with the same blade and not have to mess with sending the blade off to be sharpened, and I would save $7 (by the way, I think $7 is a great price for the quality of service, but I would rather not spend it if I don’t have to). So, off I went, looking for a way to sharpen blades on my own.
In the past, I tried using a manual sharpener that came with my first bandsaw mill. It functioned like it was designed to, but the results weren’t great. Besides having to take the blade off of the mill and set it up in the sharpener, it used a stone that wore down quickly and wouldn’t maintain a flat, consistent face on the tooth (looking back, I probably should have tried some other stone options, but I didn’t).
Later, I tried a few other approaches. The first was using my chainsaw grinder, like the one below, which had a similar problem to the first grinder. The small stones would wear down quickly and the thin bandsaw blade would basically cut the stones in half.
This grinder is great for chainsaws but not for bandsaw blades because the stones wear down too fast.
The next attempt used a sanding disc on a drill. I liked the idea of using sandpaper because it maintained a flat surface during grinding – it would wear down, but not change shape. This one showed potential, but it was incredibly hard to control because the spinning motion pulled the drill up and away from the blade.
I finally gave up, feeling like I had exhausted every option cheaper than buying a fully automatic grinder like the factory has, but I never gave up on the idea of sandpaper as a good abrasive that doesn’t change shape.
Up to that point, all of my attempts focused on sharpening the saw by grinding the front of the tooth. There was nothing else I could think of that would fit between the teeth and grind the front of them. But, then I thought about grinding the top of the teeth. This surface is easier to get to and taking material off of the top will still lead to a sharp point – it doesn’t really matter which face gets ground down.
I started off with my 3″ Porter-Cable belt sander just to try things out and it worked great. I could sand the top edge of the tooth with control and the speed was slow enough to not feel like I was burning the metal (which softens the teeth). The only problem was the weight of the belt sander, which might as well have been 1,000 lbs. because there was no way I could hold it to sharpen all of the teeth on the blade.
At the time I didn’t own a small belt sander, so I took a gamble and purchased a Porter-Cable 371 compact belt sander. I figured that even if it didn’t work for the blade sharpening I would at least have another tool in my woodworking arsenal and that there were going to be plenty of times when a small belt sander would come in handy. Finding other uses for the new sander hasn’t been much of an issue though, because it works great to sharpen blades, and it is always parked (plugged in) right next to my saw, ready for the next dull one to come along.
I simply leave the blade on the saw and grind just enough off of the top of each tooth to get the edge back. I use my free hand to steady the blade and to advance the saw to the next tooth. In a matter of just a few minutes I can be back to cutting, feeling like I have beat the system.
I use my left hand to stabilize the blade and to advance it to the next tooth.
Now, there are limits to sharpening your saw like this. First off, no matter how good you get with the sander, the blade will not be as good as a new one or one that has had a full factory grind and set because this grinding is changing the geometry of the already finicky blade. And, it will do nothing to improve a blade that was just generally running badly or running badly for a specific reason like hitting a rock or metal (all of these problem blades get sent out for a full resharpening). It will, however, make a blade that was running well continue to run well and make flat, straight cuts for much longer.
Generally, it seems to work out that I touch up a blade with the sander a time or two and then send it out for full service or, for some of them, they keep working great and I keep sharpening them with the sander until they break. For all of the others, I hit something along the way (dirt, rocks, concrete, nails, hooks, cable, wire, screw-eyes, barbed wire, fence posts, screws, license plates, horseshoes, railroad spikes, chain, conduit, hangers) that either destroys the blade or dulls it enough that it needs a full regrind.
Even if I don’t use this method all of the time, it is nice to have another option to get back to cutting. If nothing else, I personally love the comfort of knowing that when I get down to my last new blade (and forgot for the second week in a row to order new ones) that I won’t be stuck cutting wavy lumber.
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