Carbide band saw blade trouble

[Harvey Pascoe]

I just bought my first carbide band saw blade - Lennox Trimaster 1/2" 3TPI and so far it hasn't been a pleasant experience. The first blade they sent me was too short by a half inch and didn't fit the saw. Now I got a replacement and although I was told this was a skip tooth blade, it isn't.

It resaws softer woods like cherry just fine, very smooth cut. But when I do something really hard (which was why I bought carbide in the first place) the blade makes a very loud noise much like blades with bad welds do. The weld on this one is fine. When I resawed a piece of 3" cocobolo the blade went BANG, BANG, BANG with every revolution and blew large chunks of wood out the bottom, plus there was tear out in the center of the cut. This is blowing my mind, I've never had a blade do anything like this.

I suspect that the blade is not clearing the dust out of the cut, but how would that account for the loud noises? In fact, after sawing the cocobolo, the cut was packed with dust, but not with other woods. Is it just very oily woods? No, other hard rosewoods behave the same. I Normally use a Woodslicer 1/2" 3 TPI skip tooth which cuts all woods perfectly (they just wear out VERY fast). Is this just a feature of carbide blades, do I keep getting lemons, or do I need a different configuration for carbide? Supplier salesman is no help, thinks I'm full of it.

[Doug Shepard]

What size/make of BS are you using? I'm wondering if it's not tensioning the blade enough and what you're hearing is the blade slipping (in fits) on the wheels??
I dont know about the 1/2" but the Trimaster I have (1" I think) is a varitooth, not a skip tooth. It alternates between 3 and 4 TPI.

[Mike Cutler]

Harvey

Something isn't right somewhere.
I use the 1" Lennox 2/3 varipitch, Tri-master om my 18" band saw without issue. I've used it with most tropicals, including cocobolo.
The only time I got noises like you are experienceing, they were caused by the aggressive cut of the blade trying to pull the wood through the plastic throat plate. I now use an aluminum, or wood ZCI on my bandsaw.
An additional trick you may want to try is to blow air at the blade under the throat plate with a dust pickup to collect it. I had to do this with a piece of african blackwood becuase the dust wasn't clearing the gullets.

[glenn bradley]

I'm on board with the "blade slap" from inadequate tension guess as far as the noise goes. The cut inconsistency could result from that as well.

[Harvey Pascoe]

Didn't think I had too little tension but increased it anyway with similar result. One thing I am noticing is that the blade is VERY aggressive and wants to pull certain woods into it. But after sawing a bunch of cherry this AM and going back to coco, I'm noticing its become less aggressive as apparently a bit of wear takes some of the tiger out of this thing. It cut shedua and maple beautifully, but continues to be very unkind to coco especially.

Dust packing the kerf is not unusual with coco with any blade. Don't think this is a problem as the dust is not hot.

I cut perfectly straight veneers with other woods, but with coco it veers off and behaves like a haunted house. Scared to death to try it on a piece of Honduras rosewood which is both oily and hard as rock.

[Van Huskey]

First, it appears you have ruled out a poor weld. Second, be aware carbide blades like tension up around 25,000 psi vs 15,000 for a carbon blade. Given the backer cross section is significantly bigger than a thin hardened spring steel blade like a Woodslicer you are going to need probably more than double the absolute pressure on the blade to get the same tension. Third, you should be able to determine if chip packing is an issue by slowing your feedrate. A wider blade with a lower TPI and possibly variable pitch might solve that but it is no cheap fix. I have used a 1.25" 1.5/2.3 variable pitch Trimaster with all manner of tropicals with no issues. IF you saw can tension a 1" carbide blade AND chip packing seems to be an issue I would suggest a Woodmaster CT instead, it is a wood only carbide blade designed initially for huge resawing operations in the flooring industry and has deep gullets for fast automated work and does an excellent job resawing most anything.

[bob hertle]

Harvey,

I have to agree with Van about the tension, only in my testing of the same blade, 30,000 psi gave better results. The "net" area of the 1/2 inch Tri-master is a bit smaller than the normal 3T blade--.330 vs. .390 from bottom of gullet to back of blade so it will take 500 lbs of spring force to achieve the 30,000 psi. Without enough tension, the aggressive nature of this blade (it is NOT a skip tooth, rather a positive rake, probably 10 degrees) will dig in, compressing the spring further until enough downward cutting force is achieved, then releasing and repeating. This is what I think you're hearing when you say BANG, BANG, BANG! I experienced this one time with this blade when resawing about 11 inches of Osage Orange at what I think was about 20,000 psi tension. After that, whenever I use the blade, I get out the tension meter--a luxury you may not have but you can experiment around with tension til you get your best results. If you're used to a Woodslicer, this blade is a whole different ball game, not variable pitch, and nearly twice the kerf so it needs almost twice the horsepower to maintain the same feedrate. BTW, I also found it to be feedrate sensitive. Chip packing is really not much of an issue with the deep gullets and slower feedrate.

I've made peace with my Tri-master, but I cheated when I resharpened it. I reduced the rake angle to 6.5 degrees positive (a blatant ripoff of Timberwolfs geometry) and it is now better behaved. It's life is nearing the end now after two regrindings, maybe I'll go for one more. I don't use it much, as I have better luck with a bi-metal. I use both 1/2-3 and 3/4-3 hook. The 1/2-3 bi-metal may be more attractive for it's thinner (.039) kerf if you are doing a lot of exotics. Also, depending on your saw, maybe 1/2 is all you can tension. The 1/2 inch is an Olson MVP. The 3/4 blade I use is OLD. It's a Milford Marauder not made since the '80s--been reground twice. There are any number of manufacturers making 3/4-3 bi-metal. I also use Lenox 1/2-4 Diemaster 2 for less demanding resaws up to about 5 inches or so. For me, bi-metal is the sweet spot for resawing and heavy ripping on the bandsaw.

Bob