On a 25 HP diesel timber harvester with 19" band wheels, what thickness blade should I be using. I tried .41 brand unknown and .45 from wood mizer. It seems as though the mill works a bit harder with the .45 thickness. For cutting popple, spruce, etc. what is the best thickness?
A thinner band, in the neighborhood of .042 seems to work best on a 19" wheel. There is a bit of effort spent bending the band around the wheel and it equates mostly into band-life. Bands of .041 to .045 probably arent different enough to notice, but you will see a difference in thinner bands of .035, or thicker bands of .055.
So many people today go to thicker bands because they are more forgiving to a mill that has a set-up problem, or is cutting difficult wood. Because of this, we are forgetting the advantages offered by using thinner bands. Thinner bands don't require as much horsepower and don't require as thick of a kerf. They can run cooler, don't take the effort of a thick band to get around the wheel, but may need sharpening more frequently in difficult sawing situations.
If you are good at aligning your mill, and you have a mill that will hold the alignment, you may, not only get away with using a thinner band, but might get good results for less money. That always helps a bottom line.
Good advice from Tom as usual.Thick,wide over tensioned bands tend to be a crutch for a less than perfect setup or worn parts.A sharp well set thin band on a well adjusted mill will slither through as slick as any.Call and talk to band manuf. most are very helpfull and many will send you a band to try for free.Frank C.
What type of setup problems will a thicker, overtensioned blade cover up? Is it actual blade alignment in to the log or something else. I haven't experimented on my mill with that many different blades but just wondered how a thicker/tighter blade could make a problem less obvious, thanks.
I like thinner.
Ironwood
davemartin88,
Wider bands provide greater beam strength and help to combat distortion between the guides. This distortion on narrower bands must be controlled with sharpening procedures. Balanced set, Sharp tips, correct rake or anything that would affect the speed of the cut are more critical in a thinner or narrower band.
A wider or thicker band might also help to cover up minute guide alignment problems because of the increased difficulty in errant forces being able to twist the band and also the increased control by the kerf on a wider band. Thinner bands must rely more on the accuracy of the sharpening and the accuracy of the alignment of the band wheel. Stationary guides must react a lot quicker to deviation on a thinner band, making these adjustments more critical as well.
Other stresses on bands that we don't see happen are on the band wheel with the wearing of the crown and co-planer band wheels. Tension may cause misalignment of band wheels by stressing them out of parallel (co-planer). A mill that is not built to handle this over-tensioning may suffer in blade longevity as well as cutting problems.
Setup isn't just about the squareness of the mill, it also includes the accuracy of the bands. The more perfect the band runs and the more perfect the cutting edges are engineered, the more accurate will be the cut and less stress put on the band and mill.
Thicker bands running on small band wheels are work stressed more than a thinner, more flexible band. Thicker bands require a wider kerf. That means more wood removed and more work the teeth must accomplish.
Narrower bands can't rely as much on the kerf for controlling their horizontal travel (twisting). They are much more dependent upon the accuracy of setup and require much more finesse'.
That's not to say that wide and thick bands don't have their place, but it's folly to try to remedy a cutting problem by "getting a bigger hammer", so to speak. The difference in blade and mill longevity is a realism when you measure the bottom line over the life of the mill. The argument being, of course, that the more finesse' may lead to the use of more inexpensive parts and that adds to the bottom line.
Great reply Tom, Everything you mention, I found to be true on the first band mill I built. I tried 1", 1.25" and, 1.5" bands each a little thicker. With that mill having everything hand/ stick built and stick welded with old mobilehome tires as bandwheels, I found the thicker wider blade did a better job, if I spent the time to very carefully true everything the thinner blade would cut faster till something got out of wack.
My mill has 26 inch wheels and is set up to use 1 1/2 in. bands. I had been using .050 bands on it , and it has plenty of hp to use them, but I tried the .042 bands on them and they cut great, I actually think they throw the sawdust out several feet farther than the other bands did. The gullet seems to work better IMO. And as an added bonus, I can now roll a band back up. I had tried and tried on the .050 's and just could not roll one back up. The thinner blade rolled right up no problem. Now I can get the .050 's to roll up as well. 8)
And as to what Tom said: If he tells you a chicken dips snuff...look under its wing, and you'll find the box. ;) Tim
Tom, thanks a lot for the reply, great information and helps me to understand more what's going on. It's easy to just get focused on milling without really understanding but when you have a problem, really helps understand what is going wrong, thanks again.