Why did this blade break?

[Dan McGonigle]

Last night I uncoiled my 3/4” Timberwolf resaw blade and installed it on my 14” Rikon, something I’ve done dozens of times. I could not get the blade to track well on the wheels, but set my guide bearings anyway and made a test cut. The cut drifted badly. So in trying to get this blade to track correctly, I found that I had a split about halfway though, and a kink at the end of the break. This is my first bandaw (about 3 years old I think) and my first broken blade. My schedule is so busy I get very little time for woodworking, but this blade has been through a few hours of steady resawing. Is this just the life expectancy of the blade? Or is it defective? Did the kink cause the break or did the break cause the kink? Also I’m reading now that 3/4” blade might be overkill for a 14” saw? I just ordered a 1/2” wood slicer. Just wanted to know if this was user error (feed rate, tension, etc) or if I should expect this with blades once they’ve reached their limit. Hoping my photo attachment works. Thanks

[Maurice Mcmurry]

My guess is that sharp bends from coiling and un coiling weakened the weld. 3/4 is the max for my 14 inch. I have never tried to re-coil the 3/4 re-saw blade that I have. It is sad to see a broken blade. They can be brazed, silver soldered or welded. It is tricky. My attempts seldom last long.

[Tony Joyce]

Looks like a typical fatigue break to me. Not at the weld. Typical of thicker gauge blades on 14" saws. It just happens sometimes not all time.

Just an FYI I have forty years experience woodworking running all sizes of bandsaws up to and including resaws.

[Maurice Mcmurry]

Mine are 105 inches long when they are coiled in thirds the coil diameter is only 11 inches or so. It is a tight bend. I don't like doing it because its easy to stress the weld.

I thought I could see a heat line, I guess its glare.

477492

[Frank Pratt]

Looks like that blade has seen significant heat. Might have had something to do with the cracking.

[Edward Weber]

Is this just the life expectancy of the blade? Or is it defective? Did the kink cause the break or did the break cause the kink? Also I’m reading now that 3/4” blade might be overkill for a 14” saw? I just ordered a 1/2” wood slicer. Just wanted to know if this was user error (feed rate, tension, etc) or if I should expect this with blades once they’ve reached their limit. Hoping my photo attachment works. Thanks

3/4" blade it too large to be adequately tensioned on most 14" saws, some can barely get a 1/2" blade tight enough.
Which came first the kink or the break, doesn't really matter, if the blade isn't free of flaws, a break is likely to happen simply due to the flexing the blade undergoes during use.
I will never buy Timberwolf blades, but I digress

[johnny means]

Occam's Razor dictates that the blade was accidently damaged during handling or storage. Kinks don't happen naturally and the link is likely the cause of the crack.

[Rod Sheridan]

Kinks are normally operator error.

3/4” blades are too wide for 14” saws, try a 1/2” maximum blade.

If you had 3 hours of re-sawing on the blade you probably got 4 or 5 times the normal lifespan of a blade in resale on a small saw.


Regards, Rod

[Richard Coers]

A kink can not form in a new blade without extreme mishandling. They happen when stuck in the wood or the wood twists while cutting. Have you contacted the supplier with that photo?

[Maurice Mcmurry]

Dan McGonigle (OP) says it's been on and off the saw, and coiled, dozens of times. I think that is a nice long life and beyond any hope of warrantee. This is reminding me of a recent thread regarding What bandsaw model for Guitar Building (https://sawmillcreek.org/showthread.php?296498-What-bandsaw-model-for-Guitar-Building)

[Lee Schierer]

After I install any blade on my band saw, I rotate the wheels by hand with both doors open so I can observe the tracking. Then I adjust the guides and repeat the hand rotation of the wheels to insure that all is well before closing the doors and going to work.

[John K Jordan]

Some thoughts.

As others mentioned, a 3/4" blade might be too much for that saw. For years I used a 14" Delta with riser block for cutting thick stock. The tension indicator on the back has a mark for 3/4" blades. I think the manufacturers are optimistic and for marketing purposes want to advertise their saws have the capacity for up to a 3/4" blade. However when using a tension gauge I found the 3/4" blade could not be tensioned properly without applying more force than the spring would handle, fully compressing it. I actually bent the tensioning bracket and had to replace it. The gentleman from Iturra Design said this was a common problem - never use a 3/4" blade on that saw. He supplied a stronger replacement tension bracket and a stronger spring. Still, using a 1/2" blade I had to use most of the spring length to tension it properly, using a Starrett tension gauge to get it right. Without a tension gauge some experts recommend setting the tension indicator on a bandsaw to the next highest mark, for example set it to 3/4" mark for a 1/2" blade.

Was your tension spring completely compressed with that blade? Overtensioning with the spring completely compressed can weaken the blade since there is no "give". A wheel just a few thousandths out of round can repeated stress the blade and eventually something will give, either the blade or more likely, the saw.

I can't imagine coiling a blade causing a kink or stress problem. I've coiled many hundreds from small to the big blades on my Woodmizer sawmill. A kink is usually from a traumatic incident from an unsupported cut. I also understand that the smaller the radius of the wheels, the more the blade is stressed simply buy running. I've read that three-wheeled saws with small radius wheels are particularly hard on blades but I've only had one for a short time before I decided I didn't like it.

One thing not mentioned is the thickness of the blade. A thicker blade of the same width will require more tension force. If interested in the math, here is some info by the wonderful John TenEyck:
https://sawmillcreek.org/showthread.php?290973-Bandsaw-tension-new-math&p=3113838#post3113838
The entire thread may be interesting.

Guides too tight can cause overheating.

All in all, I think insuring the tension is correct is very important.
BTW, here are some tension gauges, the commercial one I use and some others have made:

477553 477554 477555 477556

JKJ


Last night I uncoiled my 3/4” Timberwolf resaw blade and installed it on my 14” Rikon, something I’ve done dozens of times. I could not get the blade to track well on the wheels, but set my guide bearings anyway and made a test cut. The cut drifted badly. So in trying to get this blade to track correctly, I found that I had a split about halfway though, and a kink at the end of the break. This is my first bandaw (about 3 years old I think) and my first broken blade. My schedule is so busy I get very little time for woodworking, but this blade has been through a few hours of steady resawing. Is this just the life expectancy of the blade? Or is it defective? Did the kink cause the break or did the break cause the kink? Also I’m reading now that 3/4” blade might be overkill for a 14” saw? I just ordered a 1/2” wood slicer. Just wanted to know if this was user error (feed rate, tension, etc) or if I should expect this with blades once they’ve reached their limit. Hoping my photo attachment works. Thanks