Troubleshooting Blade Breakage on a Bandmill

      Here's a good discussion of the various factors that could cause bandsaw mill blades to break prematurely. June 4, 2012

After my neighbor with an LT30 moved away, I bought my own mill to continue sawing the timber on my farm. Mostly white pine, but some hardwood. I bought a Keenerbuilt with a 25hp Kohler. Was the cheapest mill with power feed that I could find. Works good, except we go through way too many blades. They seem to crack from the front first.

Someone told me tracking was the problem. Adjusted that and it helped some, but still rarely get 1000 bf from a blade. Saw came with Lennox 1.5" blades. When they were gone I bought some Cook's super sharp. Lasted a little longer but not much. This spring I had a new demo blade from Timberwolf. Adjusted the tension according to the instructions with the blade. Sawed 3 moderate sized 16' white oaks and the blade broke halfway through the fourth one. Called the manufacturer and he said I was probably sawing small logs and not getting much board footage because of too much slabbing.

Neighbor with the LT30 rarely broke any blades. He sawed close to 50,000 bf for me over several years. Any suggestions for a cure to this problem? Want to move up to a hyd mill, but don't want to sell this one with problems.

Forum Responses
(Sawing and Drying Forum)
From contributor S:
The blade guides need to be 1/8 to 3/16 behind the blades. Too close and they will break. You should have 1/4" down pressure. If you have v belts, they have to be high enough so the blade doesn't touch the metal on the wheel. When a blade gets dull, get it off. A good chip deflector to keep debris from getting between the blade and wheel helps.

From contributor J:
Busted a few myself but a couple logs ain't enough. Sharpened 1/4" off before fatigue won the war. When out of the wood, the blade wanders front to rear in the guides when cracked, then bang - a pile up in the cage. Guides sound like a good place to start.

From contributor T:
The previous posts gave a lot of the reasons for breakage. Resharpen as soon as the blade feels dull or starts to wander. I am not familiar with this mill, but would suspect tracking, insufficient blade roller clearance. I also don't put more tension on blade than necessary. If you are in dirty logs, a blade will dull quickly.

From contributor A:
Are you running the blade when not sawing? I know some people will keep the engine engaged when not sawing and are moving the head back and forth or rotating the log so the power is up. This will cause the blade to break early. If not, then look at the guides.

From the original questioner:
Thanks for the tips. The mill has 19" steel wheels with small flutes crosswise every inch or so. I always disengage the blade when not cutting (over center clutch). A fellow about 40 miles away has one just like mine and hasn't had this problem, so it's got to be an adjustment or me. And I try not to push the mill. As soon as it cools down enough so the gnats and mosquitos calm down, will check all the adjustments you have mentioned.

From contributor V:
You are using the saw way too long. They need to come off the mill while they are still sharp. If they feel dull, you have gone too far.

Assume you are obtaining sharp blades for free and remove them that way. I have had saws become dull after four cuts. If those were through heavy bark, even after cleaning there is still sand and dirt that will dull a saw fast.

Measure the roundness of the wheels mounted on the mill. Use a dial indicator with a tensioned saw and manually turn the wheels and see if the diameter is constant. If it is not, your strain is not constant either, which will cause early saw failure.

From contributor B:
Make sure the blades you are using are intended for wheels of your size. The thicker blades require bigger wheels, and if you try to run them anyway, you will have this problem.

From contributor D:
My logs for the most part are clean. Farm in the summer, log in the winter, so skidding on snow and frozen ground. But I'll be the first to admit that sharpening is my weak point. There are 2 phrases that I have heard that may contribute to my problem. One is the blades are sharp out of the box. I assume they are - some millers claim they are not. And you should take them off while still sharp... I usually run till they start to cut poorly. But in the case of the Timberwolf blade I mentioned earlier, the logs were clean and the blade was cutting fine with no slowdown or wandering when it broke. The Lennox blades were .042, as were the Cook's supersharp. Not sure what the Timberwolf was. Will check out all the suggestions. Thanks to all who have responded.

From contributor M:
Feel your blade after a cut. Is it too hot to touch? How about the blade rollers? If they are, it could be a friction issue and your blade might be touching the back part of the roller flange. Running with H2O lubrication keeps the blade cooler while also keeping sap from building up on the blade.

From contributor I:
Lots of interesting ideas. I was having breakage problems with my Hud-son 28. Eventually discovered that the driving bandwheel had travelled slightly forward on the axle, causing the band to run partly on the metal instead of the belt. Apparently, alignment of the bandwheels and guides, and good guide bearings, are all very important.

From contributor N:
I remember seeing a basic rule of thumb for bandsaw blade thickness from one of the major saw makers. This was that the blade should be no thicker than 1/1000th of the wheel diameter. This would mean that for 19 inch wheels, the blade should be only 19 thou max. Your blades would appear to be too thick.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor E:
I have had this problem with my mill and the solution for me was to align the bandwheels so that they are co-planar (in the same plane). To do this, lay a flat piece of steel or a good straight edge like a level, across the front of the bandwheels over the top of the axle, and again below it. Check that all four of the contact points of the wheel are all touching the flat edge. If any are not touching then that bandwheel is not in the same plane as its partner and needs to be adjusted. Out of plane bandwheels put additional tension on the blade (much like an out of round bandwheel does) and will cause stress cracks in the gullets of the blades, eventually allowing them to snap under tensions. Before I corrected this, I was snapping blades after one or two sharpenings if I was lucky. Once I corrected my bandwheels and straightened them out, I achieve five or six sharpenings consistently.

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