# Band Saw Blade Wandering Through Knots



## Drew Pavlak (Aug 21, 2010)

Hello all,

Had a pretty interesting Sunday. Decided to try and split one of the larger Red Oak logs I had posted some pictures of, and my dad and I ended up getting it into 3 pieces. Took us about 3 hours of chainsaw work and swinging a sledge to wedge it apart the rest of the way. We got it apart though and I guess that is the most important thing.

Anyway, one of the split pieces had another trunk that was cut off from a long time ago that had grown over. When we started to get into cutting it and taking some slabs the blade was wandering up and down. I will admit that the blade was not the sharpest. The part where the other branch was taken off was rotting and had some grubs in it and we didn't want to send a new blade through that stuff. Also the wandering started when we were cutting through some of the more solid knot. Is this the cause of a dull blade? Just curious, you guys have way more experience with this stuff than I do.

Thanks,
Drew


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## jeffreythree (Jan 9, 2008)

My first thought is your blade tension right? Maybe need to increase it some. Sounds like it is going up and down, if it were trying to go one direction mostly I would say something knocked the set out of one side of the teeth. I tend to run a blade to long(rookie mistake) and pushing a dull blade tends to cause it to wander since it just doesn't want to cut through the wood anymore. 

And sometimes cutting from the other direction lets the blade cut through knots better, I always cut cedar with its soft wood and hard knots from the small end to keep the blade from moving around when it hits one.


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## Mizer (Mar 11, 2010)

As long as your mill is aligned properly it more than likely has to be the blade. It is not uncommon to get some dipping and dooing when you are sawing through punkey wood then into something like a limb knot if you do not slow your feed rate down particularly if the blade is not sharp. It would be your call if you wanted to change the blade or keep on cutting through the trouble spot. More than likely you are not going to be using that part of the lumber anyway so it shouldn't matter if it has a small dip.


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## Drew Pavlak (Aug 21, 2010)

The blade tension is as tight as it will go and that is where the scale on the side of the mill says it should be for the size of the blade. So I don't think it is blade tension. I think both you and Mizer are correct. I think I need a new blade. There was also some burn marks when it went through that knot.

Drew


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## TexasTimbers (Oct 17, 2006)

Plenty of good advice from just two posts. I don't have the experience level Mizer does he has sawed no telling how many gazillion BF. So I cheat when I have a blade issue - I use this chart at least as a starting point. I don't use their blades so it's probably not fair. I bookmarked it several years ago when I switched to Munkforssagar blades, and it hasn't let me down yet. 

I don't know if it applies equally well to all blades in general, but Munks and Timberwolf have the same profile. But like Jeff I allow them to get too dull before I change them. Here's what Timberwolf says about that bad habit (I added the underscore):


_When a TimberWolf blade is new or has been properly sharpened there is about 5 pounds of pressure per square inch applied to the face of each tooth. Friction, impact and heat will dull the teeth during use. As the edge and tip of the tooth erode, the pressure on the face of each tooth increases dramatically. If this pressure exceeds 15 pounds per square inch, the gullets of the teeth will start to stretch and will be literally ripped apart over time. If the blade is run to this same point of dullness each time, the steel will fail and you will lose 50 to 75% of the life of the blade. That equates to 2 or 3 sharpenings as opposed to 8 or 10 sharpenings over the life of the blade._​




.


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## TexasTimbers (Oct 17, 2006)

I just went to the Munkfors site to see if they had a troubleshooting chart as well - they do but it isn't nearly as good as Suffolk's. In fairness I guess I should link it also. 

Munkfors Troubleshooting Chart. 





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## Daren (Oct 14, 2006)

Drew Pavlak said:


> Is this the cause of a dull blade?


You got a yes from others..and now from me. :yes:







.


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## Mizer (Mar 11, 2010)

TexasTimbers said:


> I don't know if it applies equally well to all blades in general, but Munks and Timberwolf have the same profile. But like Jeff I allow them to get too dull before I change them. Here's what Timberwolf says about that bad habit (I added the underscore):
> 
> 
> _When a TimberWolf blade is new or has been properly sharpened there is about 5 pounds of pressure per square inch applied to the face of each tooth. Friction, impact and heat will dull the teeth during use. As the edge and tip of the tooth erode, the pressure on the face of each tooth increases dramatically. If this pressure exceeds 15 pounds per square inch, the gullets of the teeth will start to stretch and will be literally ripped apart over time. If the blade is run to this same point of dullness each time, the steel will fail and you will lose 50 to 75% of the life of the blade. That equates to 2 or 3 sharpenings as opposed to 8 or 10 sharpenings over the life of the blade._​
> ...


This is what we do. When the blade starts giving signs of being dull (rising in the cut) or any symptom of not running good we snatch it off and throw another one on. We will generally sharpen a blade no more than two times before we throw it away.


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