Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old December 16th 20, 07:53 PM posted to rec.crafts.metalworking
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Default Why do bandsaw blades break?


On 12/13/2020 12:03 PM, John Doe wrote:
Seems my DeWalt portable bandsaw causes blades to break prematurely.

They just crack with a telltale clacking/clicking sound, meaning it

must be
stopped and the broken blade changed, or risk the bandsaw coming to a

jolting
halt when the broken blade catches on something.

I hardly use the thing, unlikely it's from normal wear. It has gone

through
three or four blades, about one per session of light use.

I usually cut small pieces of 1/8-1/4 inch thick aluminum (6061).

I bought the larger version, so this problem will (hopefully) be moot

soon.
But I would like to know. Maybe using the larger version will provide

evidence
on whether it's the saw's fault. But the large one needs a stand,

waiting on
the metal plate for that.

Thanks.




I break some blades, but usually I dull them when I need to cut anything
harder than mild steel for very long. Long before most will break. On
my upright wood bandsaw all breakages are from getting in a hurry and
binding the blade. I have not broken one on my upright metal cutting
bandsaw (yet), but I have dulled a fair number of blades. On the
horizontals I think they break from fatigue due to excessive cutting
pressure because I feel time is more valuable than bandsaw blades.

Generally I buy Lennox or Starret bimetal blades for metal and
WoodSlicer blades for wood. (Except for my little 4x6 bandsaw. The
slightly more expensive Harbor Freight SuperCut bimetal blades are quite
good on it. I just use that saw for backup nowadays though.)

P.S. I was amazed the first time I did some resawing with the Wood
Slicer blades.


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Old December 20th 20, 01:55 PM posted to rec.crafts.metalworking
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Default Why do bandsaw blades break?

"DoN. Nichols" wrote in message
...
.....
As for the 4x6 horizontal/vertical bandsaw, (lots of brands, all
pretty much identical) -- it is very difficult to get the tension
appropriately high. The knob on the tension screw is too small a
diameter to allow applying enough torque. Essentially, tighten it as
tight as you can manage, and it is likely not *too* far below the proper
tension. Hmmm ... perhaps a low profile thrust ball bearing under the
knob might help.

Good Luck,
DoN.

-------------------------
I wonder if the frame / wheels / bearings are as inadequately sized as the
tension knob. Maybe they knew the machine can't handle the proper tension
and intentionally undersized the knob rather than redesign it.

https://pat7.com/js/4x6bsFAQ.html

I drilled two more mounting holes in the fixed vise jaw so I can place it
very close to the blade to hold short pieces, or move it back to the
original position to cut angles.

When I cut long stock out in the driveway I have to find a spot where both
sides of the base contact the asphalt simultaneously when lowered or else it
won't cut square vertically. The base casting isn't neatly stiff enough to
resist twisting.

To support long stock I balance it on the saw and raise a jack to touch the
outer end(s). Then the jack will be near the balance point when I move the
stock to cut off an end. I've cut a smooth square end on 6x6 landscaping
timbers this way.

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Old December 20th 20, 05:35 PM posted to rec.crafts.metalworking
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Default Why do bandsaw blades break?

On 12/19/2020 10:00 PM, DoN. Nichols wrote:
I would hope that it is adjustable for tension, ...


The OP has a portable bandsaw, e.g., a "Portaband". I have the
Milwaukee version and its tension is preset with a spring. (There's a
lever to unload the tension for blade changes.)
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Old December 20th 20, 05:37 PM posted to rec.crafts.metalworking
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Default Why do bandsaw blades break?

One of the blades (33", for the small saw) looks like it has up to 40 cracks
in it.

I will get around to testing the twisting theory, hopefully before moving on
to the larger cordless saw.

Seems to me blade tension would be not so difficult to get right, using a
lever (as they do) to release the tension. They probably can provide uniform
tension for a certain small distance of wheel movement when the lever is
restored to operating position. People familiar with spring tension should
know that better than I do.


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Old December 20th 20, 11:12 PM posted to rec.crafts.metalworking
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Default Why do bandsaw blades break?

"Bob Engelhardt" wrote in message ...

On 12/19/2020 10:00 PM, DoN. Nichols wrote:
I would hope that it is adjustable for tension, ...


The OP has a portable bandsaw, e.g., a "Portaband". I have the
Milwaukee version and its tension is preset with a spring. (There's a
lever to unload the tension for blade changes.)

-----------------------------------

Do your blades break?

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Old December 21st 20, 12:23 AM posted to rec.crafts.metalworking
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Default Why do bandsaw blades break?

"DoN. Nichols" wrote in message
...
....
Hmmm ... perhaps a low profile thrust ball bearing under the
knob might help.
=============

Somewhere I read that a stack of greased alternating steel and brass washers
makes a decent DIY thrust bearing. I tried it when I rebuilt my sawmill's
blade tensioner to include the hydraulic force gauge.

The wrench handle effort for 1000 lbs is fairly low though too variable to
use a torque wrench. The previous tensioner was the shaft and knob from a
disk brake pad pusher and was difficult to tighten to 500 lbs.

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Old December 22nd 20, 05:18 PM posted to rec.crafts.metalworking
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Default Why do bandsaw blades break?

replying to John Doe, Factorial wrote:
From what I can tell on wiki https://en.wikipedia.org/wiki/6061_aluminium_alloy
The aluminum alloy you use is pretty sturdy and that could also be a potential
problem on top of what everyone else stated here..

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