Watching the band

[Larry]

 When I'm sawing I keep one eye on the band at all times as it will tell me a lot. Yesterday I noticed as the the band exited the cut I would see a change in the sunlight reflected from the band. I was making 32" wide cuts for live edge slabs so the wide cuts were contributing to the change in reflected light. This normally means the band is dull, set is off, a crack starting in the gullet, or the blade has a tilt from the guide rollers. Change bands and saw the same thing.

I suspected guide rollers were tilting the band. Got out my trusty aluminum straight edge (36" yardstick). I centered the the band between my bunks and balanced the straight edge on the band between teeth. I keep the straight edge on its edge by placing a magnet on both sides. My bunks are 36" apart so I make a measurement from each end of the straight edge to the bunk. I had a 1/4" difference between ends so that confirmed my suspicion the roller tilt was off.

The next question in my mind is why is the tilt off. Usually two reasons. The adjustments are off because they are loose or I hit a log while sawing. The second reason is the guide bearing is wearing out. Put the calipers on my guide roller and the front was .040 smaller than the back of the roller...to much for me. Probably a little misalignment in the adjustments also. Checked my parts and didn't have a couple of new rollers. Tweaked the adjustments to make up for the roller wear to get going again. Put rollers on my order list. This morning the band exited the log perfect, with no change in reflected light so I did good.

When the tilt is off you will see cupping and the wider the cuts the worse it will be. If you use a straight edge similar to what I use, make sure it is truly straight.