Snapping Kasco Woodmax blades on HM126

[gvanzeggelaar]

Good Day, 

Little history. I bought a HM126 with 11 of the Lenox blades. I sharpened them many times and between the 11 blades almost wore out the profiled CBN wheel sharpener that I had made for it. I use this sharpener here.

https://www.vieltools.com/produit/affuteuse-et-avoyeuse-de-lame-de-scie-a-ruban-viel-pour-lame-lenox-bi-metal-ou-ripper-1664559148

I did struggle a bit with the 0.035 Lennox blades and wavy lumber and decided to go with a 0.042, 4degree Kasco blade. 

Blades cut awesome out of the box. However I began snapping them immediately. A couple snapped before the first sharpening. The remainder, I would be lucky to get 3 sharpening's out of them. I try not to push the blades to far. Once I feel they are getting dull I swap out asap.

I am using the same sharpener with a custom CBN wheel to match the profile of the Kasco blade. 

I am cutting mainly poplar, spruce and ash. 

As for tensioning I am following the specs on the HM126 mill. (It is a spring style tensioner that you tighten until the spring loaded indicator sits flush.

Thoughts? 

[SawyerTed]

There's a few reasons blades break.  Some are:

On previously used blades, cracks that eventually form in the gullet  sometimes don't get ground out when sharpening.   Those cracks propagate and WHAM!  Your blade breaks (I tried my best John Madden there).  

On some mills, if the back of the blades ride against the guides blades break.

Welds break.  

Age.  Depending on the size of band wheels, amount of lumber cut, stress the blades are under, how heavily they are ground etc., blades do get past their usable life.  Wearing out a CBN wheel quickly is a sign of heavy grinding.  

Since you've been sawing fine before the blades started breaking AND new blades sometimes break, I'm thinking something about the mill changed - slight tracking or guide change is causing rubbing  on the back.