Bandsaw blade tension gauge

[Steven Cok]

Here’s my quick cobbled up version of an 18” gauge. I wasn’t happy with the way I set up the clamping, at least on the short floating arm. Any tweaking around near it, like trying to set zero on the indicator, and the arm would move slightly. When I left it alone it would stay in place and I could get repeatable results, so I’m not going to bother trying to improve it at this point.

I just replaced the stock spring with a Carter replacement, and I’ve been running a 1/2” blade. With the new spring I liked how it was running if I put the saw’s “tension” indicator at or just above the 1/2” mark. When I hooked up the dial indicator tension gauge and set the spring to the 1/2” setting I was getting a pretty consistent 0.009” of movement over the 18” gauge. That works out to 15,000 psi. When I cranked it up to the 3/4” setting I was getting around 0.012”, or about 20,000 psi. (I wasn’t comfortable with the way the saw felt at that tension, so I didn’t try running it there.)

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[John TenEyck]

Good stuff, Steve. If your saw is cast iron 15 ksi is probably as high as you should run it. As long as the upper blade guides aren't moving so far to the right that the one on the left side starts rubbing on the side of the blade it should be OK.

Glad the gage worked out for you. In the second photo it looks like the short arm is not 90 degrees to the long piece. If it stays that way and the dowel can travel freely in its mating hole in the end of the long piece then it will work as it should, but you might still want to set it square the next time.

And now you know what tension you have at the 1/2" mark with a 1/2" blade. You can do the same test when you install a 1/4" or 3/8" blade, too, and adjust the tension if needed to whatever value you want, and then you'll know where to set it for any of those blades in the future.

John