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Jon Elson Jon Elson is offline
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Default Why do bandsaw blades break?

David Billington wrote:

On 14/12/2020 03:18, Jon Elson wrote:
John Doe wrote:

Seems my DeWalt portable bandsaw causes blades to break prematurely.

The shorter the blade, the more revolutions per minute it makes over the
wheels. That constant straightening/bending fatigues the metal. My
blades usually break at the weld, showing that my blade welding is not as
good as it should be.

Anyway, a giant 6 foot tall saw ought to have blades that last longer
than a
portable one. That's just expected.

Jon


Without having done the bending calculations I'm inclined to think the
stress in the blade will be well below the fatigue limit for the
material so should go around indefinitely without breaking. All the
blade breakages I've had had a root cause such as tooth damage which
results in the blade getting hammered in that area till it breaks. I
normally use Lenox bimetal blades and they seem to last well.

I have one of those horizontal-vertcal bandsaws, so the blades not only go
around the wheels, they get twised about 45 degrees in the cutting region to
cut straight. I think that puts a lot more stress on the blade than on a
big wheel vertical-only saw. Also, the smaller the saw, the smaller
diameter the wheels are. That increases the bending.

Jon