Question about spontaneous breakage of band saw blade

[Matt Zettl]

I would like to tap the collective wisdom of the band saw experts here relative to a blade breaking today. I was sawing some 1/2" thick makore on my MiniMax 16. The blade was a 1/2" Lenox Diemaster that I purchased on 2/26/2009, and put on the saw a few days later. I leave this blade on the saw most of the time, and it has currently been on the saw for about a week, without any problems.

I certainly wasn't doing any heavy sawing today, and I wasn't cutting curves. Suddenly, the blade broke. I wasn't even cutting anything at the time, I had removed one piece, and was turning to get another when the blade broke.

Upon examining the blade, I could see that it was broken cleanly at the weld. I could not determine any cause for the breakage other than a bad weld. I'm meticulous when I put a blade on the saw as far as adjusting tension (I use the FWW John White shop made gauge), and had the tension set at about 20,000 PSI. According to Lenox, their bimetal blades can be take 30,000. All of the guides were properly adjusted. I take the tension off the blade when I leave the shop for the day, and retension it the next time I use it. I should add that I probably use this saw 30 minutes per day on average, certainly very light usage. I use this blade for light resawing of woods up to about 6", beyond that I'll switch to a 1" Trimaster.

I have had this saw for about 2 years, and have never had a blade break like this. I had a Delta 14" for 25 years before the MM, and never had a blade break without some bonehead input from myself.

I called the vendor from whom I brought the blade and explained what had happened, and that I thought it was a faulty weld. They said there wasn't anything they could do, as there were too many variables involved that were beyond their control. The tech that I spoke with was not at all unpleasant, and we had a reasonable, civil conversation. He said he would check with his boss and get back in touch, which he has not done yet. He said if the blade were only a week old, he might feel differently, but since it was almost two months, he didn't see that it was their fault. I respectfully disagreed, pointing out that the blade had received very light use over the two months.

My question is whether my assessment is reasonable, or whether there may be some factor that I am overlooking. I have purchased several times from this company, and have always been happy with their courteous, prompt service and good pricing. I understand that even the best of companies will have a problem from time to time, and I try to be tolerant and understanding.

All opinions and suggestions are welcome.

Thanks,

Matt

[Gary Herrmann]

Based on your description, I'd say it was the blade. I've had my MM16 for 4 years and never broken a blade. I resaw, cut tight curves and cut wet wood.

[David DeCristoforo]

Band saw blade breakage is almost always "spontaneous". And ninety nine times out of a hundred they break at the weld. I think that in order to make an inarguable case for the weld being "faulty" the blade would have had to break sooner than two months later. 30 minutes a day for two months is the equivalent of (+/=) 30 hours of use. It really comes down to how much of a case you want to make over a band saw blade. I would agree with the vendor but I would probably end up deciding it was not worth having you turn into a "squeaky wheel" over a blade. One dissatisfied customer can cause a lot of grief even if they are not being 100 percent reasonable.

[Myk Rian]

Why don't you call Lenox, instead of the vendor?

[Alan Schwabacher]

What will it cost to have it rewelded?

[Matt Zettl]

Band saw blade breakage is almost always "spontaneous". And ninety nine times out of a hundred they break at the weld. I think that in order to make an inarguable case for the weld being "faulty" the blade would have had to break sooner than two months later. 30 minutes a day for two months is the equivalent of (+/=) 30 hours of use.

David, I appreciate what you're saying. I think I may have mis-stated my usage. I would say that I use it for maybe 30 minutes on those days when I am in the shop. If this blade has a total of 10 hours on it, I would be surprised. By " spontaneous" I mean that there is no obvious causative factor. Every blade I have ever broken, I was able to determine a cause, generally something I was doing wrong. This break totally surprised me.

Why don't you call Lenox, instead of the vendor?

Myk, I thought about that, but Lenox didn't weld the blade. This vendor buys bulk stock from Lenox, then custom welds based upon orders. I discussed this with the tech. He indicated that Lenox does do there own welding as well, and apparently some vendors sell Lenox welded blades. I may consider this the next time I buy.

What will it cost to have it rewelded?

Alan, I haven't looked into this. There is no one close by that I know of that can do this, so I would have to ship it. A couple of bends, not kinks, occurred when the blade broke, so I would be worried that it would run true if rewelded.

Matt

[Kevin Groenke]

IMO, the weld was defective: the vendor should at least offer to re-weld the blade. If the blade is damaged, the resolution is less clear. Over the years I've had welds fail a couple of times - both times the vendors (not local - Suffolk and BC Saw) offered to re-weld the blades and shipped them back after repair. Suffolk replaced damaged blades, BC blades weren't damaged.

Where do you live Matt, Any town over 50,000 probably has a business that will weld you're blade back together.

[Matt Zettl]

Kevin, I live in coastal North Carolina. The closest place that could do this would be Wilmington, 100 miles, or Raleigh, 100+ miles. Maybe there are some places I'm not aware of, but I would be reluctant to take it to some place that does not do this routinely.

Matt

[Andrew Joiner]

Iturra Design 866 883 8064. They guarantee the blades they weld for the life of the blade.

[Thomas S Stockton]

I think in the last 20 years I've had one weld break on a 1/2" lenox bi-metal blade and usually when a blade breaks it gets so mangled that it is not worth getting fixed. I used to work for a place that used 1/4" blades on 14" delta saws and we used the saws about 6 hours a day and a blade would break at least once a week, luckily the blade is mostly enclosed and nobody ever got hurt it just makes a big racket. As David said they just let loose with no warning at all.
If your not happy with the vendor I would find another one especially if your not happy.
I use www.hastingssaws.com and they ship everywhere so distance doesn't matter.
I once tried someone else for a bunch of 1/4" blades and the welds looked fine but each blade only lasted about 15 minutes before breaking.
Tom

[Wes Grass]

If there are any machine shops in town they may have a bandsaw with a welder on it. Much more common to find in metal working.

They can also be brazed. Might be easier to find a fab shop that can do that.

[Ben Cadotte]

I am not expert in metalurgy but the blade failed becasue of heat! Now the weld may not have been properly done, that I could not tell you without magnification of the actual weld. But the failure of the weld while the saw was running but not being used was caused by heat damage. Basically the blade / weld work hardens everytime it goes from straight to curve around each band wheel. Now obviously the bend is not that sharp, but by the metal having to conform to the curve a little heat is created. Now normally the strength of the weld can put up of with this. But say 2 weeks ago you did alot of cutting and the blade got hotter than normal. It didn't break then, but because the blade did get hot, maybe the temper of the blade / weld was changed slightly. This adds up as the blade / metal keeps getting used. Eventually it will break even if no sawing pressure is put on it. And of course the quality of the weld deppends on how much heating it can take before it fails. Basically even a 100% propper weld can break over time if heated repeadily.

Think of it like taking a thin piece of metal and bending it back and forth. Do it a couple times and the metal seems fine, nice and strong. Do it a couple dozen times it seems to get easier to bend (metal is work hardening and starting to fail but still remains intact). Keep doing it and the metal finally fails and breaks at the bend.

Not saying you were / have been using your saw incorrectly. But the blade may have been exposed to some over heating on a prior use. And since that type of damage can accumulate. That could be the reason the blade failed even though it was not currently cutting anything or being used incorreclty in the most recent use.

Or it was a bad weld, or a combination of the two! Heat is the enemy with metal cutting tools. Too much heat you loose your temper or strength. And of course if there are any errors in the welding / brazing, that just means it can take even less pressure before failing.

Work as an aircraft inspector and deal with stress cracks on airplanes all the time. The current plane we have in maintenance had a stress crack on a web in a leading edge slat. The crack was dead center in the end web. No other damage to it other than the crack. Was caused purely by the metal web bowing in and out over the years as pressure from flight loads was placed on it and then released.

If the blade is not kinked you should be able to have a local welding shop reweld it for you. Also if it is kinked you can have the kink cut out and blade rewelded slightly shorter (blade will run truer with the kink cut out and shortened blade, than leaving the flattened kink in, the kink will be a stess area and blade may fail there). Being a 1/2" blade, you should have enough adjustment on the saw that the blade can be shortened and still be used. The larger the blade the more room you have to shorten it. IE a 1" blade could be shortened slightly more than a 1/2" blade. The only limit on how much a blade can be shortened, is getting it on the wheels with tension full off.

[Paul Atkins]

Blades break. I got tired of having mine break at the weld so I now silver braze my own. My saw has a welder on it, but I haven't got the knack yet to get perfect results. My blades last much longer now. They are alot cheaper too buying a 100' roll.

[Matt Zettl]

Ben, thanks for your input. I understand what you are saying. I guess the reason that I am perplexed is that I've never had a blade this new break like this before. One of the reasons that I got this bimetal blade is because they stay sharp longer, and should outlast a standard steel band. Maybe it's just one of those things that happens on occasion, and I need to get over it. I would really be upset if it were the Trimaster, given the price of one of those.

Also, I want to say that I ma not unhappy with the vendor. I understand their reasoning. I've never had any problems with them before, and the situation is certainly not self evident. However, I think that as I stated previously, I'm going to consider using someone in the future who either will warranty the weld for a reasonable period of time, or sells factory welded blades. According to their website, Lenox has a 90 day warranty.

I appreciate everyone's input.

Matt

[Matt Zettl]

I thought I would post the resolution of this problem, as well as some additional information that I have obtained since my original post.

I had two experienced machinists look at the blade independently. They both said immediately after examining the blade that the weld was defective. They each pointed out that the metal at the site of the break was two different colors. About 1/3 of the surface of the break was shiny metal, indicating a fresh break. The other 2/3 was dull gray, indicating that this was either cracked well before the blade broke, or that it was never completely welded to begin with. In either case, both of them said that the company should replace the blade.

I had the blade all boxed up, ready to ship back with a letter requesting a replacement, when I received a call from the company saying that they were going to replace the blade. This was before I had given them the above noted opinions. Ulitmately, they came through and did what I thought was the right thing. They did ask if I would return the original blade so that they could have a look at it, and I gladly did that.

I learned a few things in this experience, so I thought that others here might benefit from it as well. I think that being reasonable and understanding when talking with suppliers and mafufacturers is usually more helpful than being confrontational and accusatory. Getting opinions from independant knowledgeable people elevates your level of understanding of the problem.

Thanks to all who offered an opinion.

Matt