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So why did the blade break?

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HF bandsaw. The one that can be operated vertically or horizontally. Blade was factory installed, I didn't change the tension.
I made about 15 cuts and then it broke.

Any idea what the problem was - too tight? too loose? too much down pressure? too little? speed wrong?

I was cutting 1/8" mild steel angle iron at 45 degree angles at the slowest speed setting (80fpm) if it makes a difference.

I'm asking because a replacement is $15 so that's $1 a cut if it keeps up!

I tried welding it back but I must be getting too much heat into the blade - it's becoming super brittle and breaking right next to the new weld.
 
Hi Alan,
My first guess would be the Harbor Freight blade itself. Maybe find a higher quality one of the same dimension. If this is the saw that swings down onto the metal, the spring tension is probably too loose, making the blade cut into the metal too fast. Try more tension on the spring. You should be able to let go of the saw and let it cut by itself. Start with too much tension and back it off until you achieve the right setting.
 
The other thing is the 45-degree angle you were trying to cut - move just a little & you put the band in a bind
 
I hear the words "break" and "Harbor Freight" in the same sentence very, very often. It's low quality Chinese tools that are usually the problem.
 
I'm surprised the teeth lasted 15 cuts. I would find a decent bimetal blade. It is going tho set you back a little more, but should last longer. Many bimetals are more flexible and will hold up better to the stresses of cutting.
 
Never assume that HF assembled anything correctly ! Actually, I don't believe the factory assembled it at all ... more likely the store or warehouse did it as a "demo". When you replace the blade, pay careful attention to all the alignment points, especially the blade guides. Anything that forces the blade through a sharp corner will cause it to break eventually.

Another thing to look at is the number of teeth on the blade, vs the minimum thickness you are cutting. If the walls of the angle iron were fairly thin, you need a very fine tooth blade to cut it; should have 3 teeth in contact with each cutting area all the time.

Haven't tried out my HF metal-cutting bandsaw yet; but I broke the first blade on the wood-cutting bandsaw pretty quickly. Next one lasted a lot longer, the third set (I now have 3 of them according to application) has lasted many years. All the same quality HF blades, I just learned more about how to adjust, and how to use the saw.
 
Two things that are common to the cause of blade breakage besides a worn out blade are.
1. too much downward force, adjust the counter weight so that the downward force isn`t as agressive.
2. Use a lubricant while cutting, beeswax works well. {of course you will have to clean the lubricant off of the cuts before attempting welding them.}

When welding these blades you need to anneal the weld area after welding. Heat the weld area up 1/2 inch on either side of the weld to dull red then let cool. DO NOT QUENCH the weld. It needs to cool down slowly. You also need to grind the welded area down to the surface of the blade so that it will go through the guides without binding. {do this before the annealing process}

A good investment with a high use bandsaw is an induction bandsaw blade welder. Bandsaw blade stock can be purchased in bulk rolls in any T.P.I. {Teeth Per Inch} you need or desire
with bulk rolls and a blade welder you can make spares and repairs to broken blades easily.

Here is a bandsaw balde welder from H.F. for $120.00
Bandsaw Blade Welder
 
If you intend to do a lot of angle cuts, buy a cheap miter saw (sliding or fixed) and mount an abrasive wheel in it. You will burn up more material because the kerf is wider, but there is very little chance that you will break a blade. Down side is lots of sparks and stink but they are very effective.
 
I had bad luck using a miter saw with an abrasive wheel. No matter how tight the blade was mounted, it wobbled badly and would have made a cut ½” wide. I went and bought a metal chop saw instead.
 
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