BS blade jumping off

[cham-ed]

I had some 4 by pressure treated lumber to saw for my neighbor. They had a shallow arc (60 inch radius). I thought I had better get a different blade. My local store stocks 72 1/2 blades. I picked up an Olson "AllPro" 1/2" x .025 blade 3 TPI Hook teeth and raker set I thought that will be good for this material. Wrong!Four times it jumped off the wheels. Cut into my throat plate and the blade guard. I checked the tires were clean. Adjusted the blade guides and the tension. Tried being sure not to jamb or twist the blade. Cut slowly and it did seem to do a good job and then whammy off it came.
I thought it must be something I was doing wrong. But then out of desperation I put in a new Shopsmith 555196 1/2 x 020 x 6TPI raker blade. NO Problems! I cut multiple pieces with out a single problem. So now I am assuming it was the blade and not me. Am I right? Do I contact Olson and complain? It sure does encourage buying from MS and Shopsmith blades.

[lyall]

SS BS blade are 72", so have a 72-1/2" BS blade you should tighten a bit more than the SS BS blade.
If you were going by the tightening gauge for a 1/2", the blade will be loose
(not having the proper tension for the blade).

[JPG]

The 'gauge' will indicate tension regardless of the band length.* The tolerance is ± 1/2".

However if the upper wheel arm is not free to move because of excess length it could come loose.

* If upper wheel arm is binding, the gauge will not be indicating band tension.

Determine if the upper wheel arm has range of motion greater than the 72 1/2" band requires.

[cham-ed]

After the first time it came loose I remounted it and if anything the blade was on the overly tight side. It had the right "twang" when I plucked it. When I tighten the blade it is my habit to rotate the upper wheel with one hand and the other on the Allen wrench; that way I can verify the tracking on the tires.

[JPG]

Guess that leaves us with the insufficient cant possibility.

Where is the back of the blade riding on the upper wheel?