I don't know much about bandsaw blades, but this seems like a good idea. I believe the same concept was used with some treads on German tanks in WWII.

Great idea. Why hasn't anyone done this yet? How about double-sided sandpaper too?

On my bandsaw the wheel is slightly beveled so the blade stays on. The back (non-cutting) side of the blade presses against an edge cut onto the wheel. This is what holds the blade in place when you begin to cut something.

If the blade had teeth on both sides the teeth would likely cut into the ridge or, in the case of the longer teeth on wood cutting blades, ride up on the ridge and bend or break.

Either way the wheel needs a redesign or the blade life would be shortened.

So in place of the typical metal or ceramic blade guides, you'd use these sprockets to keep the blade tracking properly? Ouch, this could be a long one, but bear with me.

Bandsaw blades must be in tension to work. It helps them track the center of the upper wheel which is vital for straight cutting, and it also helps control blade deflection resulting from the spinning of the blade (this deflection is 90 degrees to the flat side of the blade, away from the center of rotation). Blade tension must be variable, due to differences from one blade to the next, and also due to different requirements for different cutting tasks. Varying the blade tension will cause slight variations in the blade length as it stretches in reaction to the tension. This will change the required pitch on the sprockets, or require that they fit the holes in a very sloppy manner.

Blade guides, whether metal roller bearing style, or metal or ceramic rub guides, must be significantly harder than the blade in order to stand up to the abrasion of the blade. So your sprockets would have to be very hard metal, which as I'm sure you know tends to be rather brittle. So even if you could solve the tension/length problem, I think you'd wind up with a bunch of sprocket teeth on the floor after a couple weeks of use.

The other purpose the tensioner is used for is taking up slack in the length of the blade. On my saw the blade length can vary between 108" and 111". This means I can buy 100' rolls of blade stock, cut it into pieces between these two lengths (using two crescent wrenches rather than a sophisticated saw), clean up the cuts with a bench grinder and file, and braze or weld the ends together. Takes about an hour to make 10 blades, total cost per blade is around $10 if I figure my time at $60/hour (typical shop time charge in small production shops). If I then figure it takes me 10 minutes to change a blade, thats another $10, total cost for a blade change $20. With those sprockets you've come up with, the blades would have to be factory made, lengths repeatable down to the sub-milimeter, and of very consistent metalurgy to ensure the same amount of engineered stretch under exactly specified tension. I'm guessing that total blade cost would be around $30 for the cheap carbon steel blades I use and a lot more for some of the fancy blades on the market. Add in extra fussing time with the machine due to increased complexity of the guide system, and I'd estimate the total cost of changing the blade at more than $40, which takes care of the 2x savings in blade use.

I agree with the last post completely, not to mention can you imagine the sound it would make? a bandsaw is pretty loud to begin with. Imagine tiny gears travelling at that speed instead of the bearing roller backstop. sure wouldnt want to use it for long periods of time. Plus having teeth on the backside of the blade when cutting tighter corners wouldnt leave as tight of a curf. the Backside teeth would widen your cut making it less percise.

I surrender.

Everyone here is a little bit off.

Double sided blades are already in use on large (4"-16" blade width) saws, and have been for a very long time. Could the tensioners and saws be scaled down? Absolutely.

The problem is that blades wear in more ways than just dulling. They accrue various deformities over time that lead to poor cutting, and are mistaken in the majority of cases for a dull saw. And why should anyone but serious production mills care? If the saw isn't cutting right, it doesn't matter to you since the sawblade is disposable. The solution is the same no matter what defect the saw has developed.

Production sawmills employ sawfilers to maintain the larger bandsaws, precicely deforming the saw's surface so that the blade does not wander during a cut under tension. Anyone using a bandsaw that comes in 100' coiled lengths is better suited to throw the blade away, rather than attempt to maintain it.

So, to you naysayers who don't think it's practical: It's already in production use.

But, to those who desire a longer-lived saw: Better throw it away when it starts to act funny than spend five years in a sawfiler apprenticeship.