I am not the resident expert on all band mills. My son and I built an oversized wood mizer type mill, and successfully milled Live Oak, which is the only hard wood ever used for plating the sides of a wooden military battleship, that effectively stopped cannonballs from destroying the ship.
We build the mill using a photo of a woodmizer lt40 model. I had asked woodmizer for a sample blade in our measurements of 158" length. After getting the mill running, we could never get that blade to work. We ended up with tooth marks being lagging from one side of the cut to the other, approximately 3" difference, the far side from the drive wheel being lagging. We measured, eyeballed during the cut, and simply went crazy trying to figure this out. I also has received a Suffolk "timberwolf" blade, that did work much better. However, we still had many issues. Pure luck brought us to trying a Munksforsager blade, and, it was like we had a totally different mill.
Can I assume you have "V" belts for the blade to ride on ?? If so, get new ones installed. Can you post some photos for us to help diagnose your problems ??
OK, first thing is, you have way too much downforce. 1/8" is practically what everyone runs, +/- 1/16th.
Second thing, you must have a bearing issue on the idler wheel. It should NOT have any play/sloppyness, period. If you are mechanically inclined, take that wheel and try to adjust the slack. You may need to replace the bearings. Be sure the spindle/axle is not damaged.
Once you have that taken care of, set the mill as exactly level as possible, both length wise and cross wise.
NOW, take a level and put it up against the drive wheel standing up and down. Make that "plumb". Then, do the same with the idler wheel. They have to be as near identical as possible.
Once that is done, take a string and fasten it to the complete outer edge of the drive wheel, so it can be stretched across the face of the wheel and over to the idler wheel. VERY CAREFULLY, move the string toward the drive wheel until it either touches both edges of the wheel or it touches one edge or the other of the idler wheel instead. You may need someone to help do this.
This is to see if both wheels are "in alignment" same as alignment on a car. If these are not perfectly in line, do whatever it takes to accomplish this. You may have adjustments, need to add shims, etc. to do this. It might be in the adjustment of the tension mechanism being sloppy or something.
This will also allow you to run the blade very close to the guide flanges or backing of the guide blocks. Most of us have 1/16" of clearance or less, from the back of the blade to the roller guide flanges. You do have 2 guides, correct ?? Are they solid blocks or rollers ?? You also run water on the blade, correct ??
Until you have all this done correctly, you will not be able to fine tune your mill. When someone buys a mill, it should be set up correctly, BUT, when someone builds a mill, they REALLY learn from scratch. This is why I recommend following what I posted. Others may have different approaches, but, do these things first, then we can all bang heads on how to proceed.
Do this, then, report back. We can work on last board thickness, then.
