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.
Using a small belt sander works great to touch up bandsaw blades.
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.
The Best Outdoor Wood Finish
Cetol Door & Window can be found under a new line name of ProLuxe by Sikkens. It retails for about $70 per gallon.
I often get asked, “What can I put on wood that will protect it outside?” My follow-up question is, “Do you want a finish that builds up to a film or just something that soaks in, like an oil?” If the answer is a film finish, I recommend Cetol Door & Window, from the Sikkens Proluxe line of wood finishes. It holds up better than any other outdoor finish that I have used, and every painter that I know and trust uses it too. I have found Cetol to last almost twice as long as the next class of film finishes.
In my teenage years, I tried regular ol’ Minwax polyurethane on the wood bed of my restored ’63 Chevy pickup truck, and I couldn’t believe how fast it started to peel. One St. Louis summer of constant heat and sun made it look like it had a bad sunburn with lots of dead skin.
After that, I moved on to other products like spar urethanes (Minwax also makes one of those, called Helmsman’s). Yes, it lasted longer, but not LONG. It started to look bad after a little more than a year. It didn’t totally fail all at once, but enough areas were falling apart that it didn’t really matter – it just looked bad.
In defense of these two products, the bed of a pickup truck is a tough environment. It gets direct sun, extra heat with no breeze, and the surface is horizontal, so water has a much better chance of nosing its way under the finish. It really gets no more demanding than this for a wood finish.
With yearly maintenance, the spar urethane could be kept looking reasonably good, but eventually the maintenance gave way to submission and the weather won. The boards still looked alright (nothing rotted through), but there were always spots where the finish failed and the beautiful clear-coated lumber had cracked finish and gray spots of raw wood.
It wasn’t until much later that I was introduced to the Sikkens brand name from a friend in the St. Louis Woodworkers Guild. He had great things to say about their products, and then I started noticing them being used by different painters on different jobs around town – and consistently. Nobody was using anything else, at least not anyone that I trusted, so I started using them.
Originally, Cetol only came in various forms with added stain. Some of the colors were pretty light, but none were clear. I believe the color is added to help with UV protection, but it does nothing to help color matching or achieving a clear finish. Now, with the name change to Proluxe, a colorless version is available, and it is the one that I use.
The can says that Cetol should be applied with a brush and not rolled or sprayed. I haven’t rolled it, but I have brushed and sprayed it, and both worked fine. Spraying is more difficult, and probably not recommended by the company, because the Cetol has a long working time and tends to sag if applied too liberally. That same working time is great for brushing and allows large areas to be worked and reworked to blend brush strokes. If you do try to spray it, start with a light application and allow it to settle for a second so you can get a feel for how it is going to sit down. Keeping a wet edge isn’t critical because it doesn’t even start to get tacky for a long time and the following passes will easily blend together. If you do spray the Cetol be vigilant about finding areas that start to sag or run and simply blend them in with a brush.
Cetol, like many other finishes, takes three coats to build a good protective barrier. A fourth coat will add a bit of extra protection, but isn’t required. I would opt to skip the fourth coat on the initial application and put that energy to a maintenance coat later down the road.
Regular maintenance is critical to keep the finish from failing. Keep an eye out for areas that start to crack and get another coat on as soon as they appear. If you wait too long it will be necessary to completely strip the finish and start over.
Cetol should last for several years without maintenance on vertical surfaces and even more if they are protected from the sun. Horizontal surfaces in the sun will probably last a maximum of two years before they require attention. Both of these time-span numbers are not great, but they are at least twice as long as the spar urethanes. If you jump around the internet and read about other choices or recommendations from other woodworkers, you won’t find anything that lasts longer.
Unfortunately, three years is really the maximum for an outdoor clear finish with sun exposure. Of course, if you know of a finish that lasts longer please let all of us know about it. But, do watch out because the world will beat a path to your (long-lasting, clear-coated wood) door.
General Tools MMD8P Moisture Meter Is Good On The Outside
The General MMD8P features a bright OLED display, built-in species correction, displays ambient temperature and humidity, and stores multiple readings.
When the General Tools & Instruments MMD8P moisture meter ($199) showed up to be reviewed, I was excited. I have moisture issues with wood – it seems like it’s always too wet to use and I don’t want to wait. Waiting takes all the fun out of opening up a log, and the longer I have to wait for wood to dry, the less of it I can sell. That is where the ol’ moisture meter comes into play. Much better than just guessing how wet the wood is, a moisture meter should tell me exactly how wet the wood is. It sounds simple enough, just put the meter on the wood or at most push two pins into the wood and take a reading, but it isn’t always that simple.
There are a range of moisture meters out there and they don’t all work the same and they don’t all read the same. I was hoping that the MMD8P from General that just showed up would be the meter of my dreams and for once make me feel confident that I knew just how wet my wood was. And it appeared that is just might.
Though I wasn’t impressed with the light, toy-like feel of the unit, it has more buttons and obviously, more features than I am used to in a moisture meter. It shows the relative humidity and temperature of the environment, which is pretty cool and has a menu for selecting different wood species, which is also cool. My first moisture meter (that I still own) has paper charts for species and temperature adjustment. I don’t bother with the charts, but I will gladly allow the meter to make the adjustments for me, and the General MMD8P does just that.
The first thing I did was play with the species correction. The interface, while obviously not from the great designers at Apple, worked fine and I was able to get to the species I wanted after a quick perusal of the owner’s manual. There are more than enough species to choose from and they are accessible by just pushing the up or down arrows until the desired species appears. It took only a few seconds to quickly flip through the alphabetical list, pick a species, and start jamming the pins into some boards.
A notable difference between this meter and other pin meters that I have used is the thickness of the pins. These are stout, less like pins and more like cones. My first thought was, “Now, these pins won’t break. Finally, pins that won’t break.” They are built like a tank compared to the pins on my Delmhorst (which often break), but after using them, I am not sure that it’s an advantage. I felt like the pins didn’t penetrate very deeply, which made my readings feel even more like surface readings instead of core readings. It also seemed like the pins wanted to eject themselves from the wood, and any difference in pressure while taking a reading resulted in a variance on the readout. If I pushed hard, the reading might be 9% and when I let up a little, the reading could be 12%. Unfortunately, there is no way to know which of those numbers is accurate. In my head I want it to be the drier number, but my heart knows it’s the wetter number, or even worse.
The display on this unit, which is touted as a major selling feature is big and bright and can be configured to display critical information in a few different ways, though I imagine that most users will pick one option and just stick with it (most likely the one that shows all of the information and not a truncated selection). I chose a display option which shows the moisture content reading very large, which seems to just make sense. After all, that’s what it’s for.
I moved around my shop from board to board checking to see how it worked and finding the moisture content of random boards – most of which were around 10%. That is fine if it is accurate, but at the same time very disheartening, and here is why, in the form of a little more background.
As I mentioned, I have a moisture meter, a Delmhorst J-lite, which was the first meter that I purchased. It is a pin-type meter, just like the General MMD8P and it always reads 9-10% or drier. Maybe not always, but it feels like always. I think it is a lazy meter and doesn’t try very hard. It says in a very monotone and cubical job sort of way, “10% boss. Next reading, 10%. The wood that you cut just a few weeks ago, 10%.” If it doesn’t read 10%, it will only read lower (even painfully low), unless I just cut the wood, where it may possibly read higher. I was so sure that the meter wasn’t working properly that I called Delmhorst. Officially, it checked out OK, but I still don’t trust it.
Since then, when I really check for moisture I like to use a Wagner MMC220 pinless meter, which takes readings 3/4″ deep using electromagnetic waves. The numbers go up and down like I expect in different woods and even in different spots on the same board. It will read 10% too, but it can do 9% and 6% and even 13%. Heck, sometimes it even does 17% (crazy, I know). I am still not sure of its absolute accuracy, but at least there appears to be movement in the numbers, and in a logical fashion – wood that is newly cut is wetter than wood that has been on sticks for a while. It will even read accurately on rough cut wood and won’t leave holes when you are checking surfaced lumber or finished projects.
So, back to my review.
I used the General MMD8P meter, and seemed to get the usual 10%ish measurement. I was testing wood that had been dried and had been in the shop awhile, so 10% or somewhere from 9-11% made sense. Then I tried an 8/4 chunk of walnut that I had cut only two weeks earlier. Funny enough, I didn’t get 10% like I expected, but I apparently pushed the meter a bit and got it to go to 13%, which at least told me it was wetter than normal (for reference, it should have read off of the scale, or at lease 30%). I thought, “Here we go again – another ten percenter!”
Now it was officially time to get to the bottom of this, once and for all. This new meter has the right look, it has all the extra buttons, it has a fancy display, but why must it always read 10%. I knew the walnut that I tested was soaking wet on the inside. Sure, the surface was perhaps 10%, but if I was strong enough, I guarantee I could ring water out of the middle of that board. I grabbed the $8 per board foot wood and threw it on my chop saw to expose some of the wood in the middle and took some new readings.
The very center was very wet and read as very wet, above 40%. As I moved towards the outside of the board it got drier, and in logical increments, until the outside reading of, you guessed it, 10%. That was good news. At least this meter had the potential to read something other than 10%, and it seemed to be accurate.
I took it with me to check on the kiln progress and went through the same process with 8/4 walnut in the kiln that was nearly dry. The shells were reading dry, around 6-8%, so I trimmed an end to test the inside. The General MMD8P meter did a good job of showing me the moisture content in the middle of the board and the moisture gradient as I moved towards the outside, just like it did in the shop. The numbers read as I would expect for how long the wood was in the kiln with a high number of 13%, and did a good job of telling me that the inside was still a little wet. So far, so good, for a pin-type meter.
I continued using the General MMD8P meter for the next few weeks. If I found myself wondering about the moisture content of a piece of wood, I checked it with the meter. It turns out that it isn’t just a ten percenter. In the shop, I got a full range of readings, and in a logical fashion. Shells were drier and when I cut into boards, the centers were wetter. The drier shells even showed a wide range of readings, again, all that seemed accurate.
The only problem is that I had to cut into the board to get an accurate reading. I know (and everyone else reading this knows) that the outside is drier and probably around 10%, but I don’t need a meter for that. I need to know the moisture content inside the wood and therefore, the overall moisture content of the wood. I need to know if the wood is still shrinking and how much shrinking it has left inside it. This is especially true in a species like white oak, for example, that doesn’t give up water and can be completely wet in the middle for a long time, even when the shell reads as dry.
The question that was continually in my head as I was reviewing this meter was, “Why would I use a pin-type meter that punches holes in the wood and only gives me a reading near the surface?” Unfortunately, the answer is I wouldn’t. No matter how bright the display, no matter how big the numbers, no matter how many corrections are built-in, no matter how many readings it can store, I wouldn’t choose a pin-type meter and I wouldn’t recommend one, not even at half of the price of a pinless meter. I think the General MMD8P meter is good for a pin-type meter with all of the controls that I could ask for and more, but it just doesn’t do the job that a pinless meter, with quick, accurate and deeper readings, can do.
What’s Going on at WunderWoods
Everyone always asks what I do. Here's the answer. Click on the photo above for a short video tour and see all of the steps it takes to go from a tree to finished furniture.