[footfootfoot]

OK, this has been bugging me so I have to put my oar in the water.

I'm all for re-designing the wheel but if you are going to do that you should improve it. The leaf spring concept is silly at best. First of all, if they are made of wood the tension on them will eventually cause them to set and ultimately lose their spring. As they are made of wood, their springiness will be forever changing with age, humidity, and sideways glances.

You can tension a bandsaw blade by ear if you need to, or use the deflection rule of thumb. The leaf springs will not break before the blade in any type of realistic scenario. If you try to over tighten a blade to the point where it snaps you'll see it isn't something that happens by accident unless you've got a 24" cheater on the end of your wrench.

If I may propose a simpler solution; replace those leaf springs with a solid bridge of steel or rock maple or anything that will not flex. Then put a proper spring in between two washers on top of the bridge. Run your threaded rod through the bridge, washer, spring, washer and up into your tightening nut. You could also replace that nut with a handle so you don't need to have a wrench to adjust it. (looking at the photos it seem that wold require re-doing the fixed nut on the bottom so maybe not worth the time.)

If you wanted to go bonkers you could even affix an indicator for proper tension for each blade width.

You can get tensioning springs like this anywhere or google bandsaw tensioning spring and order one.

That leaf spring is my only 'nails on the blackboard' moment in your truly awesome and inspiring project. And I'm an asshole.