LeeB stopped by yesterday afternoon on his way home from a sawing job. We was a talking about blades a breaking. It seemed to us that most of the time they busted over around the driven wheel. (the one on the right as you are putting the blade on a WoodMizer.) Well last night I was a sawing along when the blade broke and sure enough it broke on the driven wheel side.
So I was a wondering if everyone else noticed the same thing? I know 4 poster mills do not break blades or even hardly dull one.
Where do the break the most? ???
I've had them break when just spinning and not even in a log. I don't know where they break like that 'cause I'm too busy running away.
I do have a theory as to why they would break in front of the driven wheel. That is where the pressure is applied. The wheel is pulling the band and the teeth are braking it by digging into the wood of the log. The rest of the band is pretty much just along for the ride. As a matter of fact, you can't push a band too good, so that length between the top of the driven wheel, where it leaves it, and the area where it enters the log, may just have less tension on it than the little spot where the band is leaving the log to the driven wheel.
My Baker dogs the log on the idle side and that distance between the log and the driven wheel is pretty long. The blade almost always breaks on that side of the log, usually as the wheel takes it up or as it passes a guide. If it breaks close to the wheel, it shoots out the chute. If it breaks close to the log, It causes a real mess by tangling up with every moving part in the shroud, including the drive belts.
Most of the time when I break a blade on my mill, it breaks after it comes out of the operator side of the log and before it starts up around the drive wheel.
Once in a while a band will break while it's still inside the log.
Very rarely, one will break after it goes up around the drive wheel and before it gets to the log.
I have to agree with Tom. Most of the pressure is on the blade when the drive wheel starts to pull the blade through the log!
Most of mine pop anywhere from the drive side guide roller to about half way around the driven wheel. Had one punch a hole completely through the sheet metal sawdust chute. I'm with Tom, the real scary ones break when I'ts up to full speed but not yet in the log. Pieces likely to anywhere.. I never thought too much about the energy involved until I put a bicycle speedometer on the drive wheel. It normally reads in the neighborhood of 50 MPH, not something you'd want to stop with any part of the ole bod.
I had one break yesterday while I was sawing for the customer, the one that started the conversation between Arky and I. I didn't think a whole lot about it. I flinched of coarse, but the customer, who was tailing for me, about ran all the way to the other side of his property. Guess it got his attention.
Most of mine break between the log and the drive wheel (but some make it part way around the wheel before they stop moving). Once in a while one'll break entering the log and that get's pretty hairy.
I never thought much about breaking a blade. When I started sawing next to the timber framing shop, I noticed everyone would stop and stare when I broke one -- even the guys running planers and such. Folks tell me it sounds a bit like a gunshot. Never noticed with the muffs on.
Tom has the stress issue well defined. (The saw is under stress from the time the saw enters the cut until it is half way around the drive wheel) The mills that clamp the log to the same side as the drive side create a situation where the saw is under stress longer then the mills that clamp the log on the idler side.
The point of greatest stress is just before the drive wheel. When a saw has a crack developing this is where it will open up the widest. The area leaving the drive wheel and before it enters the cut is under compression and a crack will close up in this area from the push of the wheel.
I found a new way to break a blade today. >:( Anybody else ever manage to break one thats not even spinning? I finished up a log and the blade was getting a little dull. This had been a real good blade so I decided to sharpen it and put it right back on being as how the mill was set up right next to the shop. On the sharpener it went and off I went to pull another log up to the mill. Got the log in position and went to finish the blade. Everthings looking good. Put the blade on and start back to the contact strip so I can put on the next log. BAM!! Broke blade. If your gonna leave the stops up for the next log, make sure you raise the head enough to clear them. >:(
i got a 4 post Kasco saw 2B in 41/2 years only broke 1 blade. when i hit some thing in a log
i have bent a few knocking them off while backing i use lenox & simmons blades
some of them been sharpned 10 times
Yes, LeeB, I have broken blades that way, not once but twice. :-[ I am just a slow learner. It was not my fault, someone was distracting me. ;)
Quote from: pigman on January 12, 2009, 10:05:33 PM
It was not my fault, someone was distracting me. ;)
Put down the cell phone to drive.
Everyone breaks blades probably but has anyone made a wood rasp out of them? I took about 8 chunks about 20" and welded them up as one. I stagered the points so it would cut better. The rasp worked pretty well,,I gave it to a friend that does a lot of trail bridge work.
Any broken blades that I have had ,I send them back to resharp and at a discounted price, get a new blade smiley_clapping
Any one have any uses for broken blades? Ever have one just de-rail (wheel) without gua rd on and take off cross the millyard (woods)? scarry! :-[
That begs the question.... ???
I use them for re-bar when I pour concrete.
Quote from: Papa1stuff on January 14, 2009, 06:55:29 AM
Any broken blades that I have had ,I send them back to resharp and at a discounted price, get a new blade smiley_clapping
What discounted price? I thought the resharp replacement price was the same as a new blade. Besides, it's costing you money to ship the broken blade. Mine go in the trash.
Dr_Buck When I was using re-sharp the discount was 10% and when using the pre-paid mailer it didn't cost any more to send the broken blade back. Also they would examine the blade and if they determined it had failed prematurely it was replaced free. I had several replaced over a span of 5 years.
Bill
i think that resharp replaces any missing bands at the discounted rate if you are on that plan.