Band breakage

Dan_Shade · May 01, 2022, 05:46:23 PM

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 · May 01, 2022, 06:51:58 PM

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 · May 01, 2022, 06:53:14 PM

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 · May 01, 2022, 08:46:37 PM

Thanks for the input.

dgdrls · May 01, 2022, 09:27:15 PM

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

Wheel belts being worn will not help

D

Dan_Shade · May 01, 2022, 09:31:07 PM

Not sure.

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

ladylake · May 02, 2022, 03:20:23 AM

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 · May 02, 2022, 03:54:02 AM

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 · May 02, 2022, 06:04:08 AM

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 · May 02, 2022, 08:48:38 AM

1 broke at the weld

Mountain_d · May 02, 2022, 07:05:26 PM

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 · May 02, 2022, 08:05:36 PM

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 · May 02, 2022, 08:28:19 PM

Quote from: Mountain_d on May 02, 2022, 07:05:26 PM
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 · May 02, 2022, 10:57:42 PM

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 · May 03, 2022, 02:03:19 AM

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 · May 03, 2022, 10:29:26 AM

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 · May 03, 2022, 12:02:07 PM

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 · May 03, 2022, 01:20:57 PM

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 · May 03, 2022, 02:36:06 PM

Quote from: Crossroads on May 03, 2022, 12:02:07 PM
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 · May 03, 2022, 06:31:57 PM

Thanks for the info Steve

Mountain_d · May 04, 2022, 06:34:21 PM

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 · May 04, 2022, 07:37:42 PM

Quote from: Mountain_d on May 02, 2022, 07:05:26 PM
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 · May 04, 2022, 09:51:11 PM

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 · May 04, 2022, 10:15:51 PM

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

Brad_bb · May 04, 2022, 11:19:19 PM

Quote from: Stephen1 on May 04, 2022, 10:15:51 PM
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.