Broke My Lennox Trimaster

[Harvey Pascoe]

I just broke my Lennox trimaster after two months and I know why it broke. Frequently I slice veneers from small pieces of burl and other highly figured woods and this time it was a 6" x 8" square of Masur birch. The workpiece tilted into the blade due to the extremely aggressive hook on the teeth even tho I try to hold it down hard. The piece tilted and the blade dug in deep and jammed and WHAM. It even punched the throat plate right through the table. Obviously, the drive belt was not loose!

I've also had trouble with this blade (1/2" x 3tpi) blowing out hunks of wood out the bottom of the cut in cocobolo and one or two other exotics. The reason I think is that the teeth are not clearing the dust out of the cut and is often impacted hard enough that it has to be scraped off. I use this saw every day and anything more than two months use is good for me. Prior to Trimaster I was going through at least one Woodslicer per month, sometimes two.

Does anyone know if Lennox makes a less aggressive blade that won't grab small pieces of wood and try to jam them through the table? I checked several suppliers and the answer seems to be no. I can veneer any size block with the WS, but damn, that Lennox gives me the willies!

[David Kumm]

Harvey, I've had lenox blades break as well, especially the 1/2" ones but felt it had more to do with my technique. I usually pushed too hard and the blade spinned the back bearing, heated up and wham. I run a 3 tpi trimaster on my Oliver 217 which runs at 6700 fpm and don't have your problems- although I now run a 1" blade that has more beam strength. What type of saw and at what speed are you running? The trimaster takes a pretty good kerf so it should clear the dust unless the blade is not parrallel to the fence and binding if you use a fence. Do you freehand resaw as well and do you seem to have the same problems when you take the fence and drift out of the equation? Dave

[bob hertle]

This is why when I regrind my Trimaster, I reduce the hook to 6.5 degrees. I tried 5 degrees, but I like 6.5 better. A blatant ripoff of Timberwolf's PC geometry. I've found the less agressive hook angle to be a lot better behaved. I've gotten 2 sharpenings, and can probably squeeze one more. I grind only the face of the tooth, and only enough to remove the wear land (when viewed with a 10X magnifier). To be fair, over-aggressive behaviour is not unique to Trimasters. Almost all hook tooth blades are made with 10 degree positive rake, and tend to want to cut too fast and leave a poor finish. I also regrind my brand new bimetal blades to 6.5 degrees, and they cut better than the Trimaster, in fact the finish is better than what I got when I tried the short-lived Woodslicer.

Bob

[Harvey Pascoe]

First, this wouldn't have happened with a longer piece of wood because it wouldn't have tilted, so its hard to blame the blade. Yeah, its way to aggressive for me when its new and supersharp but as it "breaks in" it becomes less so. I'm running the modified Delta 14 and I've no idea of the speed. At times the blade is so aggressive it "self feeds", that is pulls into the work piece with almost no feed pressure, but this is not a constant, only momentary. But when I have my fingers close to it, this is scary as hell.

I got no complaints with finish at all, as good or better than woodslicer. And when Woodslicers start to dull they start to go off track so that I end up with shims instead of veneers. So far the TM hasn't done that.

Seems my only solution is to change blades whenever I have to slice short pieces which is a major PITA with my DC apparatus on the saw. The TM is just too good for veneering wide boards to be without one and the WS is not.

[David Kumm]

Harvey, Do you know the tension you run at? I have found - and I don't want to start tension wars again- that high tension on carbide blades isn't just about cut quality but also helps with a binding problem like you are having. The tension sort of doesn't allow for the piece to tip into the blade. Doesn't help your situation as you are limited to what you can tension but may be an explination. After years of experimenting and breaking blades and all of that, I settled on 25000psi for the lenox trimaster and 30000psi on my 1/4 bimetal blade in the smaller saw. Dave

[Harvey Pascoe]

Well, Dave I have no idea about tension as I'm pretty sloppy about that because I've never had a problem like this before, never broke a blade. I have a hard time seeing how tension has anything to do with tilting the workpiece. Seems to me the 6" x 8" work piece is the culprit as the tendency of any blade is to tilt it, whereas a 4 ft. board has the leverage to prevent that. I do all fence cutting veneers, a major factor in not breaking blades. Don't most broken blades result from freehand cutting and twisting of the blade?

If I ever get scalloping on the veneers, I then know the tension is too low.

After thinking about this for 24 hrs. I think the solution is: Don't veneer small blocks of wood with an aggressive blade. I'll have to change to the Woodslicer which is much less aggressive. Ugh, blade changes, what a time waster.

[David Kumm]

I was thinking that the blade might be twisting or deflecting inside the cut enough to bind up. Really just thinking out loud but I just haven't had that problem and cut short pieces on the bandsaw all the time. Does your blade move in and out at all when spinning? I have seen that and it can pull a short piece into the cut as well. It doesn't take much to break lenox blades though. They used to be even more brittle but have changed the steel over the years to help that. Dave

[Will Blick]

Lenox suggest you always follow the 3-6-12-24 rule for re-sawing wood...

min. 3 teeth in the wood

ideally 6 - 12 teeth in the wood (sweet spot for chip removal and min. heat build up)

max. 24 teeth in wood

So if you were cutting 8" height, that would be 24" teeth in wood, not ideal...
Ideal height wood for triMaster is 2 - 4" high.

Suggested for higher re-sawing Woodmaster CT 1", which is 1.3 TPI

sweet spot is 8" to 16" re-saw height.

[Harvey Pascoe]

I was thinking that the blade might be twisting or deflecting inside the cut enough to bind up. Really just thinking out loud but I just haven't had that problem and cut short pieces on the bandsaw all the time. Does your blade move in and out at all when spinning? I have seen that and it can pull a short piece into the cut as well. It doesn't take much to break lenox blades though. They used to be even more brittle but have changed the steel over the years to help that. Dave

Well, my veneer cuts are pretty even so, no, no twisting or uneven loading of teeth. But yes to the fore and aft movement, I can see it slightly against the rear bearing but I think all my blades do that.

One thing I noticed just before breaking was that suddenly some deep scoring was appearing on the sawn surface. This was on perhaps 3-4 pieces cut on larger stock before the break. These vertical scores were intermittent but fairly regular. Was baffled at what might have caused that, but it was so near to the time of breakage, I had little time to think about it or investigate. However, I can't seem to correlate that to what happened, but does this suggest the blade was already in failure mode?

Looks like I'm going to have to do more blade changing in consideration of stock size. Thanks for all your input guys.

[james bell]

Harvey, I did the same to 3/4" Lennox trimester, short piece of wood knocked through the throat plate. Blade then worked like a drunken sailor. I "think" a couple of teeth are out of kilter, pretty regular and pronounced teeth marks to each side. Changed blades and one of these days will try and determine which teeth are the problem ones. But no more cutting short pieces on my mm16!

[Harvey Pascoe]

Harvey, I did the same to 3/4" Lennox trimester, short piece of wood knocked through the throat plate. Blade then worked like a drunken sailor. I "think" a couple of teeth are out of kilter, pretty regular and pronounced teeth marks to each side. Changed blades and one of these days will try and determine which teeth are the problem ones. But no more cutting short pieces on my mm16!

Thanks for that. Yep, I concluded this blade is just too aggressive to cut small stuff so I ordered a bunch of woodslicers today and a replacement trimaster for the long stock. If nothing else I will feel much more secure with my pinkies a few inches away.