Bandsaw Blade broke

[Herr Dalbergia]

Hello,

After having some issues with my Resaw King, I went back to the Woodmaster CT. Took a fresh, brand new blade out of the box on friday afternoon. Put it on my saw, adjusted everything and started resawing the sides for my current BRW resawing project. Everything worked perfect, I resawed about 50 side sets, working friday evening, the complete saturday and this sunday morning.

What better than resawing some BRW on a sunny sunday morning....I had one billet still left over for resawing, so I started this morning. The blade was still working perfect, the cut flawless, no drifting, no strange noises, the surface quality very nice, no wobbling. Al systems go.

I had just done the last cut for the last side of BRW, really the very last side had just came off the saw, I took it and turned around for putting it away on the stash, also having a small fast look at it. I did not turn off the saw immediately, but luckily I was away from the saw, only 3 or 4 feet, but at least not next to it.

Suddenly out of nothing there was a big bang and actually I realized quite fast what probably had happened and - just run outside of the room around the corner.

For a sunday morning this was quite exciting...

What do you think? Me and my brother have the same opinion, since the blade broke where it broke, we somehow assume there was a mistake in the blade or the weld, or during the welding.

This is also the very first Woodmaster CT which ever broke, and I am using the same tension on all of them. Tomorrow I will contact the company where I bought these baldes, I hope they will cooperate and send me a new blade.

Please have a look at the pictures in the link below, how do you judge the situation?

https://picasaweb.google.com/1157931...iBladeBreakage

Cheers, Alex

[joe maday]

because it is so close to the weld...could the heat from the welding when the blade was made....harden that area??...then over time bending around the diameter of the tires, cause it to fail?

[Erik Loza]

Was the wood green or was it dry?

Erik Loza
Minimax USA

[Joe Kaufman]

I was trimming acrylic pen blanks to length when a 1/8 inch thick cutoff ended up between the blade and tire. Looking back, it is surprising how long you can get away with some thing before the expensive reminder. I don't trim pen blanks with the band saw anymore. Any chance a small piece of scrap got caught in your case.

If what appears to be a brown discoloration is actually on the surface of the fracture, it could be indicative of a preexisting fracture. Good idea to contact the mfg.

[Al Launier]

In the 4th & 5th pictures there appears to be something unusual in the cross-section of the blade. When looking at it, it appears to be an "inclusion" in the metal. If so, then I would guess it failed from fatigue in this area. Can you look more closely through a magnifying glass? Doe it look like there may have been some missing material, or perhaps foreign material within the blade when it was molten, before making it into metal bands?

[Shawn Pixley]

I am with Al here it looks like there is a slag inclusion or porosity at the break. You obviously ran a lot of stock through the saw. If BRW is Brazilian Rosewood in your post, then the blade has done its duty. I am not convinced they owe you a new blade. If I interpret your comment to mean you cut fifty sets of five inch by four foot sides for a guitar, then the carbide had likely dulled enough that you compensated by pushing harder. The steel band is not going to hold up indefinately.

[Herr Dalbergia]

@Mr. Loza: the wood was dry, abot 60 years old.

@Mr.Launier and Mr.Pixley:

Yes, I also think so, you have very good eyes btw . For me it looks also like there is something IN the blade, actuallly it looks like there is rust IN the blade.
Later the day I will call the manufacturer, lets see what his opinion is.
BTW, Yes, BRW is Brazilian Rosewood and I am cutting guitar sets, BUT for a Woodmaster CT 50 side sets is nothing, I am using the Woodmaster CT since about 2 years, and all the others have done way more wood before they got dull. Also this blade was still cutting like butter, like new, and my feedpressure was still very low.

Thank you for your comments, Alex

[Jim Matthews]

What does a blade like this cost?

[Herr Dalbergia]

I payed 650 Euro for 5 blades.

[Tai Fu]

Sometimes it's down to the welder too, if they're having a bad day or whatever. Maybe you can tell them about it and see what they think. If it's their fault I am sure they will replace it.

I quit using Woodmaster CT because I find I don't really move that much wood (I doubt my bandsaw could handle that kind of volume, I'd like to have a 26" if I am moving that kind of volume) so I switched to steel blade of the same pitch as the Woodmaster CT. It has a slightly thinner backing (.032 rather than .035) so less worry about breakage but it can be resharpened cheaply when dull. So far I have not needed to resharpen them.

Someone said that the problem with carbide blade is that you can't really tell the blade is dull (I think the feed pressure just increases) so people would force it in anyways causing the blade to break, but that's usually not at the weld. In fact I was initially going to get carbide blade from him but he recommended against it because he showed me one that was broken and rewelded in several places... obviously if it did that no amount of rewelding is going to fix it. He said that the carbide blade might last twice as long before dulling rather than 10x like manufacturers claimed.

[Erik Loza]

Just observations I have made about carbide blades over the years (and I probably have as much personal experience and owner feedback as anyone...).

1.) Carbides are very sensitive to feed rate and pressure, due to their flat kerf. They don't clear stock as quickly as a skip-tooth blade, so as the user, you need to be aware of this. Sometimes, I hear, "Oh, it's carbide. I can just power through the cut", and that often fatigues the teeth prematurely.

2.) Because the backing material is so rigid, they may snap under conditions where a more ductile steel blade could stetch and accomodate higher feed pressure.

3.) Green wood will dull them very quickly. I suspect what happens is that there is a lot of heat buildup in the gullets, where the wet sawdust accumulates, and that actually heat-fatigues the blade.

4.) You can get a blade with bad welds from anyone. ANYONE. Have forgotten the number of times an owner will call me and swear up and down that their machine is at fault and sure enough, it's the blade or blades.

Just my 2-cents as always,

Erik Loza
Minimax USA

[Gus Dundon]

Band saw blades don't last long. Though carbide blades last 10x longer than any other blade ,it won't staysharp forever. If you used a dull blade for cutting, I could conclude that its dullness caused the breakage.As what have said, it's hard to tell if carbide blade is dull. However you said that it still cuts like a butter, so, the other two reasons I could think of are bad band stock and feed rate.

[Steve Menendez]

The proximity of that break to the weld seam strongly suggests a problem with the welding process. Often, if the alignment at the weld seam isn't correct (negative camber for example), a fracture like this will be the result. Sometimes a blade with improper alignment across the weld seam will make a rhythmic noise as the weld seam passes through the saw's guides.It's also possible that there was a stress riser left over from the jaws installed in the welder at the time your blade was welded. Typical band saw blade welders can operate with thousands of pounds of clamping force. If there is a bit of grit, slag, or whatever stuck between the welder jaws and the blade, an indention will be made in the blade which will serve as a stress riser and a source for future failure.Often, if there is anything stuck on a welder's jaws, it will show up as "snake eyes" on the finished band. That is, there will be a second indentation located between 1/8" to 1/4" away from the first indention. This is due to the way welder jaws are re-positioned for welding and tempering of the weld seam and heat affected zone.If that were my blade, I would definitely submit a claim to the people who welded the blade, asking for a replacement or credit.Steve.

[Willem Martins]

What is the blade width and the blade thickness?

What is the diameter of your bandsaw wheels?

The reason I am asking is that blade would fail pretty fast in fatigue on my 17" Grizzly as the wheels are too small in diameter and that blade is too wide and thick.

[Erik Loza]

FYI that I have sent out probably hundreds or Tri-masters and Woodmaster CT's for 16" saws over the years and never had a failure occur due to the diameter of the flywheel. Whether or not this or that 16" or 17" machine can tension either of those blades enough to get it to cut straight is often a different story.

Erik Loza
Minimax USA