Band Saw Vibration

[mickey cassiba]

It's me again, with a question about band saw tune up. The tool in question is a Delta 28-206, heavily modified, with Carter guides, and step pulleys from a -475X. Got it unpacked and assembled after about five years in storage. Trued everything up, indicated the wheels(aluminum, I'm afraid) and installed the new tires I purchased when I originally built the saw(never folded). installed a new 1/2" blade and turned it on and the darned thing nearly jumped out of the MB. Checked the pulleys for run-out, nothing significant found(.010 on the motor, .003 on the saw). I even stoned the back edge of the blade. No change.Could the culprit be the v-belt? I have re-built many of these saws and never seen the like. I have read many posts touting the advantages of twist link belts, but did not considered them as the motor is quite firmliy mounted.
I defer to the experts

[Harold Shay]

first take the blade off and then see if the vibration still exist if so it is probable the belt. The do have a tendency to get stiff over time of non-use. I have only had one experience with link belt on my old contractor saw and it took the vibration out of it.
Harold

[glenn bradley]

+1 on belt suspect. Run without belt to test.

[Cary Falk]

I had that same saw and it had vibration also. I put a link belt on it and didn't completely solve the problem. I sold it because it drove me crazy.

[Chris Tsutsui]

Sort of a minor tune, but if it's not the belt then is it possible that the wheel with new tire is out of balance?

I would twist a wire around a wheel spoke and then turn it on and see how the vibration is.

Then move that wire to the other side of the wheel and see if it helps or worsens the vibration.

Through trial and error you can balance a wheel this way by systematically moving the wire around the wheel. Then once you found the best spot for it, you can add or remove weight from the wire to finish balancing.

Also, my carter guides on my delta made a vibration every time the saw blade's "weld joint" hit the bearing guide. If a band saw blade has a weld joint that isn't perfectly flush with the rest of the blade then this can cause it to vibrate.

[Chip Lindley]

Most vibration from these 14" BS's come from unbalanced wheels or the drive belt.

But, .010" IS significant runnout on your motor pulley. Significant enough to induce vibration.

A PowerTwist belt cured most of my vibration problems. As Chris suggests, taking time to finely balance the wheels will give better results fast! These aluminum wheels are balanced *iffily* at the factory.

[mickey cassiba]

I balanced the wheels when I built it(ala cone type wheel balancer). Anyone know of a source for machined step pulleys? Grainger doesn't carry them. Motor shaft indicates .000, and I turned the pulley bushing myself, on a engine lathe of known accuracy. If it isn't the belt, it's gotta be the lower pulley. Re: the "Nickel Test": I assume you stand a nickel on end...?

[Paul Atkins]

What does "heavily modified" mean?

[mickey cassiba]

Mods include the Carters, 3HP motor, 5 speed step pulleys, high tension spring, dynamically balanced wheels, new tires. about the only thing I didn't change is no riser block. Don't intend to re=saw, and I didn't want to lose the vertical alignment(something we saw a lot of in the recon shop at Delta). Considered CI wheels, but none were available when I built the saw. It was built out of several scrapped warranty return units,

[mickey cassiba]

Took the little band saw to work this morning to do some serious investigation, as all of my hi-class tools and indicators are in the plant maint. shop. As I was sizing the v-belt to order replacement I noticed little bumps on it. It seems that the two-part expanding foam that I packed the machine in to move down here had leaked through the poly liner and adhered to the belt. Installed an old worn out belt of similar size and flipped it on and the little booger just sat there and purred. Nary a shake or shimmy. Thanks for the feedback though, goes to show: when you think you've covered all the bases, take another look.
Gotta update my porch lighting though...