Easily Dial in the Right Tension
One of the more popular courses I teach is on bandsaw tune-up and use. While there are various questions from students, the one question that everyone seems to ask is how to properly set blade tension. While some machines don’t, most modern bandsaws will come with a factory-set tension gauge. Using a wheel, knob or similar, you adjust the tension according to the width of blade in use.
I’ve wondered about their accuracy; however, I wasn’t willing to shell out $500 or more for a gauge made specifically for such measurements. Instead, I put my faith in the machine’s gauge. More importantly, though, is how to describe the proper tension to students, especially if their model doesn’t include a gauge. When I was in school, one of my teachers would pluck at the blade, listening for a certain note. I always felt like he was just pulling our legs. Besides, I played the drums not the bass. Another method involves pushing the blade from the side to a certain deflection. What if you ate an extra bowl of Wheaties that morning and pushed harder today than the last time you put on a new blade?
While falling down an internet rabbit hole one day, I came across the EZTension bandsaw tension gauge. The gauge is the brainchild of Mark Juliana, who works at the Centre for Furniture Craftsmanship. Part of Juliana’s job includes tuning up the school’s multiple bandsaws. The device is quite simple both in design and use. It has a slim body, a small screw between two rare-earth magnets, a pair of setting guides and a hex wrench. The guides and hex wrench store onboard the body, which in turn conveniently attaches to the band saw when not in use. To set the gauge, attach it to the side of your table. Pull out the setting guide with the notch that matches your blade’s width. Next, use the hex wrench to adjust the screw to the proper projection and place it on your blade with the arrow pointing up. Increase the tension of your blade until one of the magnets detaches from the blade. Alternatively, if both magnets are not attached to the blade, back off the tension until they do, then increase as before.
I checked my machine’s indicator after using the EZTension gauge. The factory setting called for much more tension. Contrary to what may seem to make sense, over-tensioning a band saw blade does not lead to straighter cuts or fix tracking issues. In fact, too much tension leads to premature wear of both the tires and tensioning spring. It’s also harder on your bearings and can cause blades to break. Under-tensioning isn’t good, either, and leads to poor cuts. While proper tension is good you don’t want it on all the time. Proper maintenance of a band saw calls for the release of blade tension at the end of the day or for storage. A bonus feature of the EZTension gauge is that you can place the gauge on the blade, release tension and the next time you need the bandsaw you’ll have a visual reminder to re-tension the blade.
There are two versions of the gauge and each costs $39.95 plus $10 shipping (US dollars). The original will fit on bandsaws with at least a 6″ depth of cut and blade widths from 1/4″ to 3/4″. The mini version will fit bandsaws that have a 4″ depth of cut and blade widths from 1/8″ to 3/8″. One note of importance is that the gauge only works on carbon steel blades and not bi-metal blades due to their magnetic properties.
I’m happy that my surfing brought me to the EZTension website. It’s now very easy to show students what proper tension is, whether they’re musicians or not, and at an affordable cost.