Handy Blade Information

After having shipped millions and millions of feet of band blades around the world for practically every brand of sawmill there is a lot of knowledge that we have accumulated.  This knowledge is the reason when new customers call to order blades that we ask some questions that other blade suppliers either take for granted or don’t know enough to ask.  These questions are often vital to success of any blade running properly on your machine.

In this article we’ll go over a few things we’ll ask you when you call for the first time to order blades and if you’re a regular customer of ours we’ll have some other info in here that will hopefully be worth your while as well.

 

1. Ordering blades - When ordering blades for the first time we often ask several questions to do our best to make sure that you get blades that will make your mill the most productive. Once you have ordered blades one time we keep this information on file so your next order will be quick and simple.

Some of the things we ask:

Brand of your mill - We do this to help confirm that the length and width is what is normal with your brand of mill.   Sometimes a new sawyer doesn’t understand that in order to use a different width blade than what the mill was built for will require some adjustments such as a change in roller guides. An 1-1/4” roller guide is not going to work for an 1-1/2” blade for example.

2.  What is the length of your blade? 

Every once in a while somebody has a sawmill built by a small company we’ve never heard of, someone local, or home built. In these cases it requires us to ask the length of the blade.  If you don’t happen to know the length and have a pre-existing blade we will ask you to measure it.

To measure:  Put the blade on the floor and make a mark at the weld and on the floor. Then roll the blade until the weld goes all the way around and stops on the floor again and make a mark there. Then measure from one mark to the other. This will give you an accurate measurement of your blade.  Note: trying to measure the blade by holding a tape and pulling it around the blade is impossible and not accurate.

Then we will ask how much tightening ability you have when you tighten (tension) the blade. This is important so that we can get the blades the right length and have the tooth spacing correct at the weld. The only time that a blade can actually be the exact length is if you plan to run it once and then throw it away.  Also, if you want to sharpen the blade, the tooth spacing needs to be correct at the weld. That means on a 7/8” tooth blade the overall length of the blade will be anywhere from exact to 7/8” short if we index back and it can be as much as 7/8 long if we index forward.  The reason this is necessary is because the tooth will hardly ever land just right on the cutting mark when we measure it out. So this requires an ‘indexing’ either forward or backwards so that after the two ends are welded together they result in a 7/8” tooth spacing.  Also part of this equation is the fact that when the welders fuse the blades together it burns off 1/8” on each end of the blade as it’s welded together.  So we have to take all that into consideration when we cut the ends so after the weld process we are left with a perfect 7/8” tooth spacing.  This is why we must know how much adjustment you have in your tension system so we can determine if we can index forward to correct cutting mark or backwards.  All this has to be taken into account so that the tooth spacing will be correct when you get your new blades so that the blades will tension up properly.

We work hard to give you the right blade for your mill every time. These questions help assure that they are correct the first time.

 3. Another question that we have found to be very important is: Which way does your band saw blade turn?

This is a question that may seem odd without knowing the reason why.  So here is the reason: We have found that nearly all blades have a curvature (hump) in them from the manufacturing process.  We have found if a blade is not completely flat it will not cut accurately.  Even just a few thousandths can give you problems.  If the curve is bad enough you can’t even hold it with your roller guide or a bottom control guide.  We have also found that because of anti-clastic curvature (when tensioned around the wheel, instead of the blade cupping around the wheel it actually does the opposite) that we are better to make the blade with a slight curve so the blade will stay up or against your roller guides.  As the blade continually goes around the band it is a natural occurrence that it will begin to take on the anti-clastic curvature. Again, the curve will be opposite of what you normally think (anti-clastic). Instead of being in the direction of the band wheel you will see that the tooth edge and back edge actually curve away from the wheel.  You can really see this by taking any band and bending it in a fairly tight circle and laying a straight edge on the backside of it.

So if you have a sawmill that runs in the opposite direction (that would be if you’re facing the teeth and the sawdust is exiting to your left) of most other mills than for you we would need to turn your blade inside out and check the flatness to ensure that your guides will not be running as a hump in the blade.

By doing this we can make the blade run straighter and run longer.

 

After we have this information there is usually a few question new customers have as well:

1. What is best brand blade for my sawmill?

We think the blade that is best for your mill ultimately will be determined by you.   However, if can give us some basic information such as your horsepower, band wheel size, and what you plan on sawing the most we can certainly give recommendations.  We have a blade for most any wood species you plan to saw.  There are just so many variables that come into play that will determine how one blade works for you over another. How clean or dirty your logs might be, the speed at which you saw, how often you change the blade or if you want to run a blade until it breaks and throw it away…etc.   So in the end we can recommend a blade but it may take more than one try to find the one you like the best.

2. What tooth spacing should I use?

This one is also personal preference but it does have some guidelines that make it easier to make a suggestion.

Typically speaking these are the most common tooth spacings:

1/2”, 3/4”, 7/8” and 1”.  There are others but these are the most common.

1/2” – used specifically in resawing pallet boards and used primarily with 1” wide blades

5/8” & 3/4”– also used in resawing pallets. We personally like the 5/8” over both the ½” and ¾” (another article later about this)

7/8” – the most popular tooth spacing in 1-1/4” wide blades. Good for pretty much all horsepower ranges and does a good job of pulling the sawdust out of the cut

1” – best tooth spacing for higher horsepower applications when they get to 40hp and greater and used for 1-1/2” and 2” wide blades

3. What bandwidth should I use?

Band width is fairly simple.  As we have stated in other articles the more metal in the blade the better it will stay in the cut up to a point. What we usually say is if you just saw occasionally use the 1-1/4”. If you saw regularly or need to go as fast as possible when you are sawing then use the 1-1/2” or 2”.  However, the wider the blade the more correct everything has to be on your mill; this is the nature of performance whether it’s the human body or machinery.  In the case of blades, one reason is because of the curvature that we spoke about earlier. The wider the blade the more the blade seems to take on the curvature.  For production sawing these wider blades can make a big difference and it is worth the little extra effort but you will need to keep your roller guides in excellent shape and keep them adjusted.  Also because the blade thickness is the same in most of the blades bear in mind that the teeth will be dull at the same time as the teeth on the 1-1/4”.  But because of more width (beam strength) the blade will stay in the cut even after the 1-1/4” will be dull and dipping in the cut.  Because of this you will need to determine a set amount of time to run these blades and take them off and sharpen them even though they are still cutting straight.  This will allow you to sharpen and reuse the blade. Also, a properly sharpened blade will out saw even a new factory blade by 25%. This means more production and your blade will last longer which means more profits. And that is what the game is about.

      There are many other things that could be said but hopefully some of this information will be helpful. Our hope by giving you this information is that we can help you help us when taking your blade orders. We want to insure that you are always getting the best running blade for your particular application.  We want to serve you the best we know how and help you make more profits.

     So let's get out there and make some more sawdust.  

 

 

Stephen Cook