Band breakage

[Dan_Shade]

I broke 5 bands this weekend sawing probably a bit over 2500 board feet or so. 

Blades may have been sharpened several times, 3 have a tooth height of 1-1/8, 2 have a tooth height of 1-3/16.

The belts were old, but not bad, I changed them after the last break. 

Any ideas on what I should check? 

[barbender]

Were your wheel belts worn enough for the band to contact the bandwheel? How about your idle side band wheel bearings? Those are 2 items that broke a lot of blades for me.

[Southside]

You already did. Belts that let the band touch the wheel will result in breaks and bands just have so many rotations in them before they go. Broke a few last week myself, had 3+ sharpenings on them. It was their time.

[Dan_Shade]

Thanks for the input.

[dgdrls]

Where did they break?
Each in the same place or a variety of locations?

Wheel belts being worn will not help

D

[Dan_Shade]

Not sure.

I did not check to see if they broke at the welds. 

[ladylake]

 
Depending on who is sharpening them, when mine get down to 1 1 /8" they have 10 sharpenings.  Keep the flange on the guide wheel 1/4" behind the blade when tensioned if you want good blade life, plus belts and bearings .  Steve

[Walnut Beast]

Hey Steve you like 1/4 inch clearance from the back of the blade to back of guide wheels also ? On the drive belt what do you like for tension 1/2 inch 

[ladylake]

 Yes 1/4" back, any closer it will break bands fast. I never measure the drive tension, if it starts to squel at the end of a log where it's dried out I tighten it a little.  . Steve

[Dan_Shade]

1 broke at the weld

[Mountain_d]

I am breaking bands also (1995 LT40). Broke 2 on Friday but chalked that up to older blades. Those cracks started at the back of the blade. Today I put a brand new Kasco band on and took it off after 5 machine hours and noticed crack starting on 2 adjacent teeth but these cracks were starting from the gullet. Disappointing to see that! Does cracking from the back vs cracking from the gullet point to a certain are that needs fixing? Any ideas other than those already mentioned above would help. My tension was set properly.  Wheel belts are not worn. What does an idle side bearing feel like when it goes? Mine turns fine without noise but it has a little in and out movement when I rock it from the bottom of the wheel (1/8 to 1/4 inch movement on the bottom of the wheel). 
Thanks in advance.
Mountain D 

[Dan_Shade]

5 hours may be a bit much for a band

I'd be concerned about the break from the back. 

The place most bands break are the bottom of the gullet. 

[KenMac]

I am breaking bands also (1995 LT40). Broke 2 on Friday but chalked that up to older blades. Those cracks started at the back of the blade. Today I put a brand new Kasco band on and took it off after 5 machine hours and noticed crack starting on 2 adjacent teeth but these cracks were starting from the gullet. Disappointing to see that! Does cracking from the back vs cracking from the gullet point to a certain are that needs fixing? Any ideas other than those already mentioned above would help. My tension was set properly.  Wheel belts are not worn. What does an idle side bearing feel like when it goes? Mine turns fine without noise but it has a little in and out movement when I rock it from the bottom of the wheel (1/8 to 1/4 inch movement on the bottom of the wheel).
Thanks in advance.
Mountain D

I'm not familiar with your mill, but I'd think any play in wheel bearings is too much. That's my thinking from years of commercial HVAC work and 3 years of sawmilling, but on a Cook's mill.

[barbender]

There shouldn't be much play in the bearings themselves, but it is a bit difficult to feel because there is a fair amount of slop in the blade tracking mechanism. The slop in the mechanism is ok, slop in the bearings is not.

[Deese]

Improper vertical tilt on roller guides.(major breakage issues)

Improper horizontal tilt on roller guides. Ever had a heavy slab/cant literally slam into the horizontal adjustment bolt for the inside roller guide when your blade exits the cut? Be sure to check adjustments often. 

New bandwheel belts (B56 strongly preferred)

Proper spacing b/t blade & roller flange. Otherwise guaranteed premature band failure.

Change blades often. I change often and sharpen/grind gullets heavily through several light passes because I'm running 055's on 18" bandwheels. Also set teeth about double thickness of your blade. I set mine close to .030" You know how a sharp sawblade feels like it's cutting through hot butter? I change mine shortly after I notice that smoothness is gone. If not, I'll start getting tiny cracks in gullet. 

Use a blade lube that keeps your bandsaw blade and roller guides nice and clean. I use diesel fuel. Who cares if it prematurely wears your belts. Buy a box of'em so you won't get stuck without a new one when you need it.

You shouldn't see flutter in your blade when it's spinning. If you do, you're prematurely breaking blades. 

Adjust the bolt that acts as a shock/vibration absorber. You know, the one inside middle blade cover that swings down. In fact, I need to check mine. Can't remember last time I even looked at that thing.

Bearings--You'll know when one fails if you regularly use and learn the feel of your machine. 

[Brad_bb]

Woodmizer will replace bands free that beak at the weld.

As most on here know, bands fatigue based on the number of rotations they've seen.  As they go around the band wheels they bend and over time fatigue like bending a coat hanger back and forth.  

5 bands seems like a lot in a cluster but sounds like you were cuttng a lot.  I had a cluster of 3 in 3 days once.  One was at the weld.  Two were just fatigued.  Broken bands doesn't happen all that often with me, but I have Woodmizer resharp sharpen my bands, so I think they may catch some of my bands before they actually break.

[Crossroads]

Dang, the outfit I have sharpening my blades must be hitting them hard. I'm under 1 1/8" after 3 grindings. I pick up my own grinder Monday, so hopefully I'll see better blade life. 

[Dave Shepard]

Wood-Mizer will inspect bands broken at the weld and make a determination. I've pushed mine too far and had a couple break there, but I don't think it was a bad weld.

[ladylake]

Dang, the outfit I have sharpening my blades must be hitting them hard. I'm under 1 1/8" after 3 grindings. I pick up my own grinder Monday, so hopefully I'll see better blade life.

I take off 10 to 12 thousands per grind, at 12 thousands 1/8 " would be 10 sharpenings.  Steve

[Crossroads]

Thanks for the info Steve 

[Mountain_d]

Today I put 4.5 hrs on a brand new blade and no cracks. I slowed my feed rate down a bit so that may have helped. I noticed my blade guides wiggle a little bit so I will order bearings for those tomorrow. That may be part of the problem. I will also try keep my time around 4 hrs per blade before I take them to be sharpened ($12 Canadian per blade to sharpen and set). I guess it is a pay me now it pay me later thing. 
Mountain. 

[dgdrls]

I am breaking bands also (1995 LT40). Broke 2 on Friday but chalked that up to older blades. Those cracks started at the back of the blade. Today I put a brand new Kasco band on and took it off after 5 machine hours and noticed crack starting on 2 adjacent teeth but these cracks were starting from the gullet. Disappointing to see that! Does cracking from the back vs cracking from the gullet point to a certain are that needs fixing? Any ideas other than those already mentioned above would help. My tension was set properly.  Wheel belts are not worn. What does an idle side bearing feel like when it goes? Mine turns fine without noise but it has a little in and out movement when I rock it from the bottom of the wheel (1/8 to 1/4 inch movement on the bottom of the wheel).
Thanks in advance.
Mountain D

as @ladylake noted, back of the blade breaks are often due to improper guide bearing clearance,
Gullet cracks on a new band are either caused by being run too long and/or are under-set
D
 

[Brad_bb]

The worst part about breaking a band is that sometimes it can cut your belts.  Last one cut my idle wheel belt, not all the way though, but a good nick such that I replaced it.  Also having to fish it out.

[Stephen1]

2 hrs of run/saw time is all WM recomends you run a blade before pulling for resharpening. 

[Brad_bb]

2 hrs of run/saw time is all WM recomends you run a blade before pulling for resharpening.

And I often pull them well before that.  I figure I'd rather keep the teeth sharp while cutting even if that means I sharpen it 2 extra times before it cracks.  Sometimes i get a band that will keep cutting in Ash or Walnut for 2 or 3 logs.  But I'd rather stop earlier and get it sharpened than go until I start getting waves because it's not sharp enough.
You should not "expect" a certain run time from a sharpening as you can easily hit a stone or some dirt you don't see which will dull it right away, enough to negatively affect cutting.  If you have a de-barker, you probably get more reliability with how long you run a band.

You really have to read your band/cut as you go and learn when it's time to change.

[barbender]

Going by hours used is a good way to break blades in the first place, imo. It kind of reminds me of the little product that was sold in the 60's and 70's as a chainsaw accessory, it was a sieve that you would put some of the chips your saw cut into. If the chips were fine enough that they went through the sieve, it meant your chain was dull🤦‍♂️ Change your blade when it starts to get dull! That might be after 1 cut, or 5-6 logs. Honestly, without a debarker I think a blade is usually best switched after about 3 logs. If you have some dirty bark, that changes things quick. 
 Probably the main two ways I pick up on a blade that is starting to dull is, first- any waves at all, and second- when I get to the end of the cut, I watch the blade on the guides and see how much it jumps forward when it exits the cut. You can also feel how much of a load the carriage drive is under when the blade pops out (especially if your mill is manual feed!😊) If you can see that the blade is pushing back a good 1/8" and feel the surge when the blade comes out of the cut, time to change the blade.

[Southside]

Look at your sawdust, if it's fine powder then the band should have been changed before that point. You want to see corse material coming out of the chute.  Also look at the band as it exits the cut, the sawdust on a sharp band will be a fine, tight, stream still in the gullet pocket.  If it's a fan or spray coming out of the cut - your band is already dull.   

[Peter Drouin]

If the blade guides are not off set some and the back of the blade is being push down by the back of the guide. That where the crack on the back of the blade comes from.
I run mine until they're dull. Riding the chair on the way back with my hand on the log will tell me everything.
Most times I sharpen  6+ times and the hard part of the tooth is gone long before they brake.
WM 1 1/4x55 T7
cutting slow will dull them faster.
Load the motor down when cutting.

[Mountain_d]

Thanks to some comments on this topic I check my blade guide bearing on the idle side and found the bearing was coming apart. One of the double bearings was missing a ball bearing or 2. I was surprised to see that as it rolled fine when I rolled it by hand. It had a tiny bit of wiggle but I guess it does not take much. There was a tiny bit of vibration when sawing and I think that may have been adding to the blade breakage. I also slowed my feed rate down a bit. So far, no more broken blades. Thanks to those that shared their knowledge. 
Mountain

[WV Sawmiller]

   I have been breaking more bands lately also but in just about every case, while the blade continued to cut smooth cuts, I could feel the extra strain and several times I'd tell myself "When I finish this cant I'm gonna change blades" then a cut or two later "Wham". I don't sharpen my own or try to keep up with how many tines they have been sharpened so I've been writing it off to normal wear and tear. The WM Service team visited me on their loop a few weeks ago and checked and aligned everything back to factory specs and the mill has been cutting great. I did my 1150 hour service today and am ready to go again.

[Magicman]

Some blades get mixed from box to box, but generally all of the blades in a particular box are the same approximate age so I may have 3-4 to break within a week of so of sawing.  Within the past couple of months, I have probably lost a box due to breakage. 

It's no big deal because blades are consumables.  I keep about 50 blades in rotation and at times I may have three boxes of 10 at various stages in the Resharp cycle.  I have an unopened box of 15 that may have the "seal" broken very soon.