Replace tensioning spring?

[David Utterback]

What signs in band saw cuts or other performance measures would mean that it is time to replace the tensioning spring? I admit to leaving tension on the blade for extended periods. The 18" Laguna is over 20 years old and I doubt that the tension spring has ever been replaced. Should it be replaced simply because it is old and likely abused by keeping it stressed?

Thanks,
David

[Mike Cutler]

What signs in band saw cuts or other performance measures would mean that it is time to replace the tensioning spring? I admit to leaving tension on the blade for extended periods. The 18" Laguna is over 20 years old and I doubt that the tension spring has ever been replaced. Should it be replaced simply because it is old and likely abused by keeping it stressed?

Thanks,
David

No, you don't need to replace springs as a general rule. Keeping a spring under a static load would probably never exceed a spring's properties.
Cyclic stresses would be more apt to fatigue a spring. Again though, were talking millions of cycles. Cyclic rate would factor in, but,,,,,

The best way to know if your spring has fatigued would be your inability to properly tension a blade without the spring going solid. If the blade is tensioned properly, and the cut is acceptable, as long as there are gaps between the coils, the spring is doing it's job. The spring on a bandsaw should never be solid.

[John TenEyck]

What Mike said. I'll add that you can get a pretty close idea of what the actual tension in your blade is by clamping a vernier caliper to it with two little C-clamps and measuring the strain as you increase spring tension. It's really not hard and I can provide more details if you are interested. The results of that test will tell you whether or not your spring is providing adequate tension. If the spring that was supplied with the saw was capable of providing adequate tension it shouldn't matter how old it is as long as it hasn't been abused or corroded. Leaving constant tension on the spring is not abuse, despite what those selling spring tension relievers might advertise. If your cut quality is not what you'd like I'd focus my attention on other things first, primarily the blade, tracking, and feed rate.

John

[Lee Schierer]

Compressing most springs to solid height will change their spring rate and overall length.