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RE: Better blades producing less sawdust4/8
We have a sawmill with 30” wheels, which uses band blades that are 1.5 inches wide, with a 1” tooth spacing, .050 thick, and is approximately 20 feet long.
Is there a better blade than a 1.5” wide that would make less sawdust and more wood?
Our logs average between 20” to 26” in diameter, and is mostly red oak and maple.
I would say "No!" but it is not a firm "No."
Background: We need a certain thickness of the blade so that we can apply tension and so that when we hit a knot, the blade will not break. Further, we need the teeth to cut a little bit wider than the blade thickness so that the saw will not run. Note that when we cut wood, some of the wood cells are compressed slightly and then immediately springback. So, without any set to the teeth, the blade will be tight. But we do not want too cut too wide either...but too wide is better than too narrow in spots.
You specifically ask about the 1.5" width. The wider the blade, the less likely that the blade will wander...that is, the back steers the blade. However, a narrow blade can bend front to back more easily (absorbs the energy) rather than side to side, so overall a narrow blade often cuts more accurately.
You can get a blade, and may already have one, that leaves a very smooth surface on the lumber. This means less planer allowance is needed, which in turn means that you can reduce your green thickness slightly. Further, with a blade that runs true and cool due to excellent sharpening and mill set-up, you will have less variation in thickness due to the saw blade variations. Overall, an excellent blade could save 1/16" in green target, which is roughly 5% increased yield for 4/4.
Having said all this, it is exciting and unusual to have someone ask a question about yield and efficiency, rather than production speed. Keep thinking in this way.
What species are you milling? Some, such as cottonwood, need a wider kerf (more set to the teeth). A .042 thickness would save you a bit of thickness, but possibly not as straight-cutting as the .050 blade. Gene's observation that there is more to efficient milling than the smallest possible pile of sawdust is exactly right. Sharpening & setting are the most important factors. When cutting flooring, I was allowed to bring in boards 1-1/16" thick instead of the usual 1-1/8", because they were so smooth & straight. I got more boards & their planer didn't have to hog off as much wood. Look at it this way: the most you can hope to save with the thinner blade & narrower set is maybe 0.010", but a1/16" thinner allowance is .062".
From a sawdust production standpoint, theoretically the volume of material removed would be equal to the surface measure of the cant x the width of the kerf. Consider a cant 12' wide and 10' long - a surface measure of 10 sq.ft. (1440 sq.in.). If using a .042 blade with a set of .022, the kerf would .086 (.042+.022+.022) and a pass through that cant would remove 123.84 cu.in. of material (sawdust) although 'fluffed up' the volume would be slightly more. If using a blade with a .014 set then the kerf would be .070 and remove 100.8 cu.in. (18.6% less) per pass.
Of course, that is assuming a dead flat cut, any flexing or flutter would increase the kerf with an increase in volume removed. So, it would seem that the least amount of set that would perform up to your expectations would be the way to go if you want to reduce the amount of sawdust. The width of the blade shouldn't affect the quantity of sawdust. The thickness would have less impact than the set.
Perhaps, much ado about nothing.