Bandsaw blade breaking

[NT]

I fitted a nice new 6tpi bandsaw blade, it cut very happily, only used
it for 2 days, always been gentle with it, and the bugger broke today.
I noticed 2 things I wasnt expecting:

1 the blade is curved, it looks like the back has stretched, as if it
had been pushed hard, but I've been totally gentle with it.

2 the blade and 2 of the 3 saw wheels were covered with firmly adhered
clumps of sawdust.

I presume its down to the sawdust effectively enlarging the wheels and
extending the blade path. Add to this that the tension adjustment is
bolted tight and I presume thats what broke it. Are there any other
possibilities? I'd rather check things now than after more blades.

Thanks,


NT

 

[brass monkey]

I fitted a nice new 6tpi bandsaw blade, it cut very happily, only used
it for 2 days, always been gentle with it, and the bugger broke today.
I noticed 2 things I wasnt expecting:

1 the blade is curved, it looks like the back has stretched, as if it
had been pushed hard, but I've been totally gentle with it.

2 the blade and 2 of the 3 saw wheels were covered with firmly adhered
clumps of sawdust.

I presume its down to the sawdust effectively enlarging the wheels and
extending the blade path. Add to this that the tension adjustment is
bolted tight and I presume thats what broke it. Are there any other
possibilities? I'd rather check things now than after more blades.

Thanks,


NT

Did it break at the weld? Is there a 'cleaning brush' in the blade path?
Does the tensioner not have a spring? I spose having 3 wheels that they're
small so the blade has to flex more often around a smaller radius than
larger 2 wheel jobs.
Roddy will be along shortly with the correct answer.

 

[NT]

Did it break at the weld?

I'll find out.

Is there a 'cleaning brush' in the blade path?

no, I wasnt using dust extraction either. My bad.

Does the tensioner not have a spring?

Yes. Theres also a clamping nut that, if not done up, lets the wheel
wobble. I guess the solution is to do it up then back it off a tiny
bit.

I spose having 3 wheels that they're
small so the blade has to flex more often around a smaller radius than
larger 2 wheel jobs.

Yes, they're famed for premature breakage - but not after 2 days of
work.

Roddy will be along shortly with the correct answer.

heh


NT

 

[Tim Lamb]

In message

I fitted a nice new 6tpi bandsaw blade, it cut very happily, only used
it for 2 days, always been gentle with it, and the bugger broke today.
I noticed 2 things I wasnt expecting:

1 the blade is curved, it looks like the back has stretched, as if it
had been pushed hard, but I've been totally gentle with it.

2 the blade and 2 of the 3 saw wheels were covered with firmly adhered
clumps of sawdust.

I presume its down to the sawdust effectively enlarging the wheels and
extending the blade path. Add to this that the tension adjustment is
bolted tight and I presume thats what broke it. Are there any other
possibilities? I'd rather check things now than after more blades.

Inferior blade material with just the teeth induction hardened?

Could the guides be misaligned leading to heating and softening of the
blade back? I think you might hear or smell that.

Have you been sawing knotty pine and the resin tacking dust to the blade
and wheels?

regards

 

[Guest]

I fitted a nice new 6tpi bandsaw blade, it cut very happily, only used
it for 2 days, always been gentle with it, and the bugger broke today.
I noticed 2 things I wasnt expecting:

1 the blade is curved, it looks like the back has stretched, as if it
had been pushed hard, but I've been totally gentle with it.

2 the blade and 2 of the 3 saw wheels were covered with firmly adhered
clumps of sawdust.

I presume its down to the sawdust effectively enlarging the wheels and
extending the blade path. Add to this that the tension adjustment is
bolted tight and I presume thats what broke it. Are there any other
possibilities? I'd rather check things now than after more blades.

Thanks,


NT

Things that need setting: blade tracking, upper and lower blade guides,
and rear bearings. Where they all set correctly?
As BM said, a blade brush helps and is easy to add if you haven't got
one fitted.

 

[NT]

In message





Inferior blade material with just the teeth induction hardened?

I may be wrong but I very much suspect the machine rather than the
blade. It turned out to be in a grim condition.

Could the guides be misaligned leading to heating and softening of the
blade back? I think you might hear or smell that.

It was all set up

Have you been sawing knotty pine and the resin tacking dust to the blade
and wheels?

regards

Wickes fence posts, I dont know what theyre made of, but the sawdust
is stuck on pretty good, so I presume its resin. I'll use proper dust
extraction in future.


NT

 

[NT]

Things that need setting: blade tracking, upper and lower blade guides,
and rear bearings. Where they all set correctly?

yes. I did run the saw for a bit with the top guides removed today to
get that last little bit of height, but it broke later with the guides
back on

As BM said, a blade brush helps and is easy to add if you haven't got
one fitted.

Bit of steel bristled brush?


NT

 

[brass monkey]

Things that need setting: blade tracking, upper and lower blade guides,
and rear bearings. Where they all set correctly?

yes. I did run the saw for a bit with the top guides removed today to
get that last little bit of height, but it broke later with the guides
back on

As BM said, a blade brush helps and is easy to add if you haven't got
one fitted.

Bit of steel bristled brush?

I think mine is brass.

 

[brass monkey]

yes. I did run the saw for a bit with the top guides removed today to
get that last little bit of height, but it broke later with the guides
back on


Bit of steel bristled brush?

I think mine is brass.

Or maybe nylon, can't remember.

 

[harry]

I fitted a nice new 6tpi bandsaw blade, it cut very happily, only used
it for 2 days, always been gentle with it, and the bugger broke today.
I noticed 2 things I wasnt expecting:

1 the blade is curved, it looks like the back has stretched, as if it
had been pushed hard, but I've been totally gentle with it.

2 the blade and 2 of the 3 saw wheels were covered with firmly adhered
clumps of sawdust.

I presume its down to the sawdust effectively enlarging the wheels and
extending the blade path. Add to this that the tension adjustment is
bolted tight and I presume thats what broke it. Are there any other
possibilities? I'd rather check things now than after more blades.

Thanks,

NT

The likely cause is insufficient tension. (Allows the blade to flex
too much)

 

[NT]

The likely cause is insufficient tension.   (Allows the blade to flex
too much)

good question: how do I know when tension is correct?


NT

 

[Tim Lamb]

In message

good question: how do I know when tension is correct?

Mine has a sprung marker. However, I never release the tension or bother
checking

regards

 

[Guest]

yes. I did run the saw for a bit with the top guides removed today to
get that last little bit of height, but it broke later with the guides
back on


Bit of steel bristled brush?


NT

Try a paint brush head - mine has lasted many years

 

[NT]

Try a paint brush head - mine has lasted many years

That wouldnt have a hope in hell of removing what's stuck on there.
Brass should be able to pull a little bit off at each pass, I'll look
for a brass brush of some sort later.

cheers


NT

 

[Dave Liquorice]

That wouldnt have a hope in hell of removing what's stuck on there.

I don't know but wouldn't the brush remove the dust before it gets
compressed onto the blade by the rollers? What you are cutting will
make a difference, a resiny bit of softwood will bung up any saw
blade...

Brass should be able to pull a little bit off at each pass, I'll look
for a brass brush of some sort later.

I'd have thought stuff that is already stuck on needs to be removed
manually rather than hopefully brushed off.

 

[NT]

I don't know but wouldn't the brush remove the dust before it gets
compressed onto the blade by the rollers? What you are cutting will
make a difference, a resiny bit of softwood will bung up any saw
blade...

I'd have thought stuff that is already stuck on needs to be removed
manually rather than hopefully brushed off.

I get the feeling people are underestimating how sticky this is. It
seems I've got a problematic piece of wood, won't use it in future. To
finish this project I'll use dust extraction and clean the saw out
after each cut. Yes, it will need it, it only took one cut of a foot
or so to clog the blade so much it broke.


NT

 

[Guest]

I get the feeling people are underestimating how sticky this is. It
seems I've got a problematic piece of wood, won't use it in future. To
finish this project I'll use dust extraction and clean the saw out
after each cut. Yes, it will need it, it only took one cut of a foot
or so to clog the blade so much it broke.


NT

The brush is to prevent build-up, not to remove it.

If you're not using one already, switch to a skip-tooth blade.

If it's a 3-wheel bandsaw the wheels may be smallish so make sure you
choose a sensible blade thickness for the wheel diameter - loads of info
on-line but have a look here for a starter:
http://www.toolcenter.com/BLADE_SELECTION.html

(I assume that you fixed the tyre problem you mentioned earlier, and
that the blade was tracked correctly)

 

[Dave Liquorice]

I get the feeling people are underestimating how sticky this is.

Softwood resin is very sticky stuff even worse when it gets warm or
hot. That's why I suggest manually removal of anything already there,
brushes will help prevent the build up. Note, "help prevent" not
"stop"...

Yes, it will need it, it only took one cut of a foot or so to clog the
blade so much it broke.

A rip rather than crosscut cut then? Rip saws have a different tooth
profile and cutting action compared to crosscut ones, certainly for
hand saws. I can't see that a band saw should be any different.

IIRC a rip saw is like a lot of inline chisels. A crosscut two lines
of inline knives.

http://www.vintagesaws.com/library/primer/sharp.html

Nice illustrations and explanations about 1/4 way down.

 

[NT]

The brush is to prevent build-up, not to remove it.

I fitted a brush under the table today, it does seem to help.

If you're not using one already, switch to a skip-tooth blade.
Done.

If it's a 3-wheel bandsaw the wheels may be smallish so make sure you
choose a sensible blade thickness for the wheel diameter - loads of info
on-line but have a look here for a starter:http://www.toolcenter.com/BLADE_SELECTION.html

Yes, using 0.014" blades suited to 6" wheels.

(I assume that you fixed the tyre problem you mentioned earlier, and
that the blade was tracked correctly)

I recrowned the wheels, didn't fit tyres, and shimmed the mounting to
sort out the tracking.The 6tpi blade worked nicely, until it snapped.
I think the problem there was either muck buildup plus the tension
spring being clamped, or perhaps a blade fault, it split on the weld.

Today I used a new unbranded 10tpi that came with the saw, and its
cutting askew and leading. I'll get more of the 6 skip tooths.

I'm hoping it'll now work ok, as its set up right. I'll just have to
see how it goes. Thanks to everyone for the suggestions.


NT

 

[NT]

In message
<5d798e6d-[email protected]>, NT





Mine has a sprung marker. However, I never release the tension or bother
checking

regards

This is the one thing I must still figure out.


NT