bandsaw tension gauge-crazy idea?

[nic obie]

Kurt,

Brillant Idea. I wish you would have posted it before I spent the $150 for one of Iturra's gauges. When I get a chance I'll compare the two.

I agree with Lars, send the idea off to FWW or another of the mags before somebody else does.

[Allen Bookout]

I tried the flutter test as that seemed to be the proper way to test according to what I have read. Then I used the dial caliper idea posted here. I did not have time to verify the results exactly but from what I saw the tension seemed to be hugely more using the caliper than using the flutter test setting. Seems like a lot of tension to me but I am surely not a bandsaw expert. I do not know if I was being careful enough but will try it again later when I have the time. Has anyone else compaired the two?

One other thing that I found was that Michael Perata in a post showing simular threads below (Blade Tension Guage) briefly mentioned using a dial caliper instead of a tension guage. He did not expound but there must be at least on other person using this method.

[Dale Thompson]

If Dale blesses it, it's gotta be good!

Hey San Josey,
You are a TERRIFIC judge of character and celestial influence! Contrary to popular opinion, salt water DOES NOT build brain cells, even if it is well iced! Anyway, thanks for the compliment - I think??

Dale T.

[Dale Thompson]

As I cranked it up, I got .001, .002 AND .003 on the caliper synchronizing with the 10, 20 and 30 on my machine gauge!

Hey Spring,
Remember that the same in/in strain(stretch) occurs on BOTH sides of the blade and the "stretch" on the blade is actually double your reading. OK. You already knew that! As a good friend, I just wanted to set the record straight. By the way, BS (Badger Stadium) is an ancient acronym. We now call it Camp Randall Stadium.

Dale T.

[Dale Thompson]

4. I usually tension my blades using the "flutter" method rather than the stretch method. It turns out that when I did this test that my ideal blade tension seemed to be about half of what the stretch school of thought predicted.
5. Are there any other creekers that use the flutter method for tensioning their blades?

lou

Lou,
Timberwolf recommends the "flutter" method. I've tried it and have no complaints with the results.

Lou, we all have skeletons in our closets. One of mine is that I SELDOM detension my Band Saw blades. That negates the purpose of the whole post for idiots like me. If there are any "sharks" in the Creek, I am fair game!

Dale T.

[Alan Tolchinsky]

Hi Lou, I use the "flutter method" for tensioning. But isn't that just for low tension blades? Now I just crank it up and check performance.

[Richard Butler]

good post and topic all

I had been planning on posting a similar topic. good use of the caliper. Thanks dale for the info. Here are a couple of thoughts
1. youngs modulus is independent of size and shape of that material. it is defined as the ratio of the stress /strain of the particual material. as dale has said it is about 29x 10^6 psi
2. the 15000psi results in about .05% elongaton of the blade. I guess this must be a reasoanble preload for the steel blade.
3. Although the blade size will have an effect on the amount of spring tension you need, it will not change the .003"/5" that you need to stretch the blade.
4. I usually tension my blades using the "flutter" method rather than the stretch method. It turns out that when I did this test that my ideal blade tension seemed to be about half of what the stretch school of thought predicted.
5. Are there any other creekers that use the flutter method for tensioning their blades?

lou

I have tried the "flutter" method and found it to be the most inaccurate way to test tension. My results yielded tension so low as to be dangerous.

[Richard Butler]

Hi Lou, I use the "flutter method" for tensioning. But isn't that just for low tension blades? Now I just crank it up and check performance.

As far as I am concerned there are no "low tension" blades. Steel is steel and the only reason that I can see for advising low tension is to hide weak welds.

[Mike Weaver]

...The article states that for every 6000 psi applied to 5" of blade, the steel stretches .001. Instead of making the gauge in FWW, I decided to clamp my inexpensive Harbor Freight dial caliper to the blade. I opened the caliper to 5", c-clamped the jaws to the blade and zeroed the dial. I tensioned the blade until the caliper read just shy of .003 attempting to approximate 15,000 psi, the minimum recommended tension of most blade manufacturers....

Kurt,
THANK YOU!
You just saved me a bunch of $$ for a tension gauge. (And, made SWMBO happier to boot).

GREAT Idea and it's so easy, a Caveman could do it.
-Mike

[Basil Rathbone]

This sounds like a great way to set up the blade in my new Rikon 10-325 that arrived today, but I am wondering at what tension do you start your measuring at and how do you know what that is?

Thanks. I agree with the other posters, if this works, you should get a prize.

[Richard Butler]

I had planned to make the shopmade bandsaw tension gauge that was in the February 2001 Fine Woodworking magazine, but I decided to try something different. The article states that for every 6000 psi applied to 5" of blade, the steel stretches .001. Instead of making the gauge in FWW, I decided to clamp my inexpensive Harbor Freight dial caliper to the blade. I opened the caliper to 5", c-clamped the jaws to the blade and zeroed the dial. I tensioned the blade until the caliper read just shy of .003 attempting to approximate 15,000 psi, the minimum recommended tension of most blade manufacturers. As I suspected, the saw's tension gauge was not accurate. As far as I can tell, the tension seemed appropriate and I got good results in some resaw tests which was the point of checking the tension in the first place. Do you think this method is half way accurate to determine blade tension?

Kurt

Sure it is accurate. It would be more accurate if you had a larger span to measure.

[John Schreiber]

I don't want to rain on the praise parade here, but doesn't this assume zero tension at the beginning measurement? How do you get it to be at zero, but still have the blade straight, so that any further elongation is due to tension?

[Chris Barton]

This is a vintage post and, Kurt did win a prize from FWW and his tip was in the magazine, about 2 years ago...

[Cliff Rohrabacher]

Accurate? I have no idea.

Different steels at different hardnesses will perform differently under stress. So too will the performance change with the width and thickness of the blade as well as little things like tooth and gullet grind.

Over my years in machine shops with band saws I never once pulled out a tension gauge (never saw or heard of one). I just tightened the blade to just the right "feel." However, it is absolutely true that a DO-All or a Grob (common machine shop saws) are stratospherically better (heavier) machines than what a few lousy grand will purchase in the consumer retail market.

Kids new in the trade would over-do the tension such that they'd snap the blades over and over and the machines would be no worse for it.

I rather suspect that that sort of treatment would destroy most made-for-the-consumer band saws. But then you aren't paying 20 grand for them either.

[Eddie Darby]

I've used the TimberWolf flutter test, and am happy with it most of the time, but when I am pushing my saw and thus blade more than usual, I will give it a few more cranks higher. I usually find another flutter free zone, higher up in tension, that I use for the hard cases.

I haven't tried this yet, but I do have the article. Same idea though.

https://www.taunton.com/finewoodwork...F.aspx?id=2702