Sawmill blade tension?

Hey all you woodsy folk. So I purchased a mill, re powered it, cleaned it up, and installed new tires (belts) on the main blade wheels. I have noticed alot of blade wobble (oscillating). I have learned that the high quality belts which I wrestled onto the wheels which run the belt may have not been the best choice since they may not be flat?
OR do I need to deal with tensioning? or both? My mill does not have a tension guide, but rather a crank it up as far as you can go system of tensioning. HELP!

I'm not sure what type of wood your are cutting but you need to keep the blade clean. I use water and windshield washer fluid in the winter time. A dirty blade is thick and it will rub either the board or the log, or both. When it rubs it gets hot. When it gets hot it gets longer. When it gets longer you lose tension. Without a gage to look at and see that it has lost tension you may need to increase the tension once you get it running for a while.

Always back off your tension when leaving the saw, even for a short lunch break. Never leave the blade tensioned up over night.

You could/should try and see what the manufacturer of the mill recommends for band wheel belts/tires and see if they are flat or crowned. If this oscillating happens on every blade then it could be these tires/belts.

Good luck with your research and solutions.

Jim Rogers

Blade tension..... My mill doesn't have any fancy gauge to register tension. In my first year or two of use I was over tightening the band, this caused failure in the bearings of the band wheels. Since then I have had bearing failure but from normal wear. 2 years as apposed to ten. This is how I tighten my band.

Place a band on the wheels and rotate it to track the band on the wheels. I do this by cranking the engine via the key switch, I have a secondary switch to prevent the engine from starting. With that done I slowly tighten the band watching between the two wheels and the slack in the band, at the top, not the bottom due to the restrictor bearings getting in the way. You should see a clear point where the band stops movement, that is key, even though you could still tighten, at that point I simply tighten a 1/4 turn more and lock it down. This quarter turn is specific to my mill, your tighten device may be slightly different, so it should be just slightly more tight, your judgement call. I believe it would be due to the size of threaded rod the tighten device is made of, mine is about 7/8" rod.

Things to keep in mind. As the band heats up it may need to be retightened. But not usually, the band should run cool, if all is set properly, that would be set and sharpness, these are important. New band may stretch a little but not enough to demand retighting with first use, the next time you use that band you may tighten it to its new state. If you are seeing wavy cuts or dives or rises in cut it is more due to set and sharpness and tooth angle and even species of wood. Knotty wood is known to wave.

As for the v belts I can not comment my band wheels are coated in a poly material and never need tending. I hear v belts can be tricky. Have you talked to these people?
http://www.suffolkmachinery.com/index.html

What type of mill do you have collarandhames? I have a Wood-Mizer with a hydraulic gauge, so unless you have that I can't help. I run mine at 3,000 psi.

There is probably a method for tensioning from the manufacturer.

Wobbly blades eh? When my blades start the wobble i can expect catastrophic blade breakage in any second. And then BAM, scares the crap out of me every time. In my experience an oscillating blade is caused by either a warped or bent blade, a less than flat tire, or the tracking is off.
WM or at least older WM mills (like mine) use B57 V-Belts as tires. The cheaper belts have a ridge or bump that cause the blade to hop. Higher end belts are usually smoother all around (Pro-tip #1: Buy V-belts at NAPA or Carquest, not TSC) Not sure what brand you're using but a ridge can be found easily by feel. Sounds like the tires isn't the issue anyhow.
Timbeal is right about the tracking but I've found a good 3-4 seconds of full speed spinning is required to see what the blade is doing. (Pro-tip #2: take the guards and covers off for this operation, stand back and away from the dust chute. A broken blade flies outta there like an arrow)
My last suggestion would be to check how round the wheels are, especially if different blades do the same thing.
Let us know how it works out

I get my B57 belts from Wood-Mizer. $11 each, IIRC. You just have to order a bunch of stuff at a time to spread out the shipping. The WM belts are flat on the top.

Hey thanks. Jim, timbeal, dave, and Ray.! all good advice. I talked to a local supplier of blades,and he confirmed that my Gates belts that I installed may be the problem. something to do with the lap. makes sense. when it warms up I will be looking at the round of the wheels (easy enough to guage).
The board bandit mill I own is long out of production, which is a shame, since it has an awesome truss on the bottom which holds it flat. it's a lovely mill. just need to figure out the details now. Seems blade tension guages are pretty pricey no? And yes I get dull/pitched blades. I'm a professional (giggles) and I get that at the least. Will try to share pics of the set up if I can figure out how to share pics.

I'm still trying to figure this out. Anyone!?

Restate the problem with more info.

It sounds like the tires to me. Or perhaps the wheels themselves are out of round or out of wind or out of balance. Does the power wheel flutter when no band is on?

Without photos, or at least what kind of mill it is, I can't offer more.

Gabel, I replaced the tires. however I was told buy a guy who I found to make me a set of guides that I possibly have installed the wrong ones. he said that the cheapest belts are the best, and the good quality ones I got from my local bearing and belt shop might be lumpy. I spent several hours wrestling them in place. :-( next time I run my mill I will look at the roundness of the tires.

At this point, I need to run the mill and start cutting. I'll know more after a few logs.

Don't you hate that? -- you spring for the good stuff and someone tells you that the cheap stuff is better.

Tension and tracking are two different, but related, issues. Despite whatever mechanical issues may be inherent to your saw's design; you shouldn't apply any more tension than required to keep the blade running straight through the wood. Blade deflection can occur for many reasons, but most commonly it happens because the blade isn't sharp enough nor set enough to resist deflectionary obstacles in the workpiece, like knots or cross grain. Learn all you can about blade set angles and make sure you have a sharp blade pointed in the right direction first, then look to see if your tires comprise a radius equal to the radius of the wheel itself, and that the combination of wheel and tire are indeed uniformly round and smooth. Keep in mind that it's pointless to use a spring tensioning device if the spring is locked in place by a bound slide assembly. If the slide don't slide it's not a slide, it's an adjustable slot. There's a difference. If your wheels aren't round, there's not enough tension in the world to keep that blade from flapping around. Balancing the wheels on a stationary vertical pin, or static balancing, (which you can set up and do in your own shop/garage) helps to eliminate a lot of vibration also. If your wheels aren't round and crowned you'll never get your blade guides to work consistently either. If you run more tension than your motor can drive; you don't need a bigger motor, you need to lighten up on the tension. My rule of thumb is to pull the blade sideways like it was being forced off-track by an obstacle and watch the tensioner follow the movement. If there's no movement; you have a jammed-up blade-stretcher. Watch out for flying saw teeth!

Flaberg, thanks for the post, and welcome to the forum. I don't get on here often enough, and your input is awesome. tires to be a radius equal to the radius of the wheel eh? I never knew. I'll scribe it up and have a look see!I definitely don't have a spring tensioning device, only a slide. hmm, I'll come back to your knowledgeable post again!
thanks
dave