How do bandsaw blades wear out?

[evfreek]

I went to going out of business sale at a fabrication company. They had some dumpsters filled with different metals and sold stuff out of them for low prices before they were hauled away as scrap. I fished out several pieces (about 3-4 ft long) of 1" bandsaw blade. It felt pretty sharp, and all the teeth were there, so I decided to try out BP0142. Free hacksaw blades. Well, not really free, but close. I have a lot of trouble drilling holes in the ends so I tried a new trick. DCEN on a battery carbon . Zkpped right through, and pretty accurate too. Pretty small HAZ, and nobody uses that part of the blade anyway .

The blade was noticably dull. It had a difficult time biting. Not enaough pressure, or maybe it was just plain dull? From the Blueprint, it looked like bandsaw blades wore out by getting teeth stripped off them, and you just had to go to the good sections and they are usable as hacksaw blades. Or, do they wear out uniformly? As for hacksaw blades, I usually break mine before they get dull. But they cut a L O T of steel, including annealed tool steel, before they get retired.

[easilyconfused]

They don't necessarily have to have the teeth stripped off. The teeth points can dull on steel that's more hard than them, or bend over, particularily with too much pressure on the back cut.

[jayco]

Sometimes bandsaw blades are discarded because of tiny 'hairline' fractures in the blade.
These fractures are just the result of the band being rotated thousands of times.

A pallet mill near my home throws away lots of blades........some have wornout teeth........many have stress cracks which make them unsafe.

[evfreek]

Hi easilyconfused and jayco. Thanks for your replies. They are very informative. This blade does cut, but slowly. Good Starrett bimetal blades are so inexpensive, for the amount of cutting that they do, at the hardware store and decent old garage sale "tungsten steel" blades are even more so that it does not pay to economize here. The teeth don't seem to be bent or deformed. It looks like the blade was sheared into several pieces, probably because it was becoming troublesome.

Oh well, it was at least worth a try. The scrap cost was minimal, and I did get to try my new "hole drilling" method . There are maybe two or three more things I can do with these blades:

1) knife stock
2) spark test (I tried, and cannot see any nickel, but I am not an expert). Try acid etch too.
3) mini steel rule (just "lost" my 3rd vintage one), bet I won't lose one made from a bandsaw blade.

[Ice Czar]

4) grind flat and they make great shims

do quite a bit of bandsaw cutting at work
near immediate death would be hitting a weld (far harder steel)
generally will slowly wear down, but accelerates with increased heat (friction from longer cuts)
can definitely kill them quickly cutting steel that is itself hot
generally the root cause for loosing a tooth is lateral binding
once one tooth is gone they will start to strip

lateral binding is also the leading cause for the band snapping

[Phil Patrick]

I had one our newbie mechanics find me at work the other day and ask me where we keep new bandsaw blades. I hooked him up. I then found out he was trying to cut hardered HPS tool steel with it.
So, that is another way you can wear out a blade.

[irnsrgn]

band saw blades usually get hair line cracks because of too much tension or imporper heat treat of body, tooth loss = trying to cut too thin of material with too large of tooth blade. or when one tooth breaks off in a cut it is hard and will take a whole bunch off or apreciably dull all the teeth that ride over it. Worst thing is cutting close to a torch cut or a weld, not only dulls the teeth from the heat affected zone, but usually dulls the side nearest the weld or cut so that the blade will not cut straight anymore. Band saw blades are easy to drill with any good bit, you can also use an old butchers punch to punch holes in the blade or a hand held whitney punch. Most good bandsaw blades nowadays are bimetal, soft back and hardened teeth welded on. The Neotype are the soft all one steel blades and don't hold up well for production or shop work well, but they are much cheaper, and you get what you pay for.

[ThomasPowers]

one trick for cutting bandsaw blade is to just cut the soft back and snap the hardened edge.

[wolfy9005]

They heat up when they cut metal, and as any blacksmith/metalworker will know, metal that cools down slowly forms large crystals which weaken the metals structure. It's reasonably thin so it takes a while to completely wear out, but eventually it will. Also, as said above, if the metal is harder then the blade it will also blunt it much faster then usual.

[ThomasPowers]

Of course you have to heat them to near glowing for crystal growth to occur.