When I run my 4x6 bandsaw there is a distinct moment on each rotation
of the blade where there's a "whump" sound and the saw bounces slightly.
On the face of a thin cut (where the saw is moving through the stock
fast enough) you can see these points as gashes in the face of the metal.

The blade doesn't look any different as it passes over the stock at that
point (there's no weld, and it's not missing teeth). The only difference
I see is that if I watch the blade before it enters the guides I see a
slight inward twist that seems to correspond to the whump. The twist
seems to be removed by the guides. I have the tension as tight as I can
get it by hand.

Was this caused by leaving the bandsaw tensioned between uses? Can I
fix that kink? Should I just toss the blade (hate to, since it's
relatively unused).

--
Ben Jackson

http://www.ben.com/

"Ben Jackson" wrote (clip) Was this caused by leaving the bandsaw tensioned
between uses?
^^^^^^^^^^^^
Probably not.
^^^^^^^^^^^^
Can I fix that kink?(clip)
^^^^^^^^^^^^
This trick works on carpenter's saws--it's possible you could make it work
here. Hold the blade on a flat metal surface (like an anvil), with the
curve pointing up. Holding the blade as flat as you can, gently tap the
metal with a light hammer. Each hammer blow will raise the stress locally
above the yield point, so the metal gets flatter. Of course, be careful not
to hit the teeth, or you will screw up the set.

"Ben Jackson" wrote in message
...
When I run my 4x6 bandsaw there is a distinct moment on each rotation
of the blade where there's a "whump" sound and the saw bounces slightly.
On the face of a thin cut (where the saw is moving through the stock
fast enough) you can see these points as gashes in the face of the metal.

Common

The blade doesn't look any different as it passes over the stock at that
point (there's no weld, and it's not missing teeth).

Sure there's a weld. It may have been well-blended, and perhaps even
re-blued after grinding -- but there's a weld. And because of that, there's
a slight change of geometry there. Maybe it's thicker or thinner than the
rest. Maybe the teeth skip a stagger at that point.

Was this caused by leaving the bandsaw tensioned between uses? Can I
fix that kink? Should I just toss the blade (hate to, since it's
relatively unused).

If you're sure you can spot the 'twist', you can probably fix it with
judicious use of a hammer on an anvil (with the blade off the saw). But you
should have numerous blades "in stock". It's a bitch to break your last one
during a job.

LLoyd

Ben Jackson wrote:
When I run my 4x6 bandsaw there is a distinct moment on each rotation
of the blade where there's a "whump" sound and the saw bounces slightly.
On the face of a thin cut (where the saw is moving through the stock
fast enough) you can see these points as gashes in the face of the metal.

The blade doesn't look any different as it passes over the stock at that
point (there's no weld, and it's not missing teeth). The only difference
I see is that if I watch the blade before it enters the guides I see a
slight inward twist that seems to correspond to the whump. The twist
seems to be removed by the guides. I have the tension as tight as I can
get it by hand.

Was this caused by leaving the bandsaw tensioned between uses? Can I
fix that kink? Should I just toss the blade (hate to, since it's
relatively unused).

I've had the same problem. I straightened the kink on an anvil and then
continued to use it until the blade finally broke. It will probably
break at an inopportune time, so have a spare handy.

--
Gary Brady
Austin, TX
www.powdercoatoven.4t.com

On 2005-01-31, Lloyd E. Sponenburgh wrote:
"Ben Jackson" wrote in message
...

The blade doesn't look any different as it passes over the stock at that
point (there's no weld, and it's not missing teeth).

Sure there's a weld. It may have been well-blended, and perhaps even
re-blued after grinding -- but there's a weld.

What I meant was that the spot doesn't correspond to the weld in the
blade, which is visible.

Thanks all for the pointers.

--
Ben Jackson

http://www.ben.com/

could it be when the weld passes around one of the wheels is when the
'bump' happens ?

When I run my 4x6 bandsaw there is a distinct moment on each rotation
of the blade where there's a "whump" sound and the saw bounces
slightly.

I have a Horror Fright 4x6 bandsaw that does the same thing. On mine,
both pulleys have significant runout. Switching to a Starrett blade
helped, but I suspect that correcting the runout is the real solution.