bandsaw tension gauge-crazy idea?

[Ray Scheller]

Be careful claiming this as your idea as I think I read this in a Popular Mechanics article a year or two ago . Just my $.02 worth.

[Chris Barton]

I dodn't think Kurt was trying to steal anyone's idea. And, his was published in FWW at about the same time, 2 years ago (when this post first started)!

[Kurt Loup]

Be careful claiming this as your idea as I think I read this in a Popular Mechanics article a year or two ago . Just my $.02 worth.

Ray,

I assure you that I did not come across this idea from another source prior to my post. Note that this post was started over 2 years ago. On the recommendation of others, I submitted the idea to FWW and it was accepted and published in the tips section a year or two ago. Maybe you saw it there?

Anyway, check out Mark Duginske's post about bandsaw tensioning. He doesn't think this is a good idea for various reasons. I have no reason to disagree. He and others certainly know more about this than I do.

Kurt

[Mark Duginske]

Do you think this method is half way accurate to determine blade tension?

Kurt

Sorry to rain on the caliper for tension party but I see it differently.
This whole idea is based on a number of questionable assumptions.
If you read the other band saw thread that is going on that I started on damage from over tensioning you will pick up information on springs, aftermarket tension (strain) gauges and how they compare and how useful they are.

First, the original FWW article is based on the assumption
that spring weakens and the gauge is thus not accurate. Neither of these is correct. The band saw spring does not weaken or lose its strength over time. Also the gauge is relatively accurate just like the gas gauge in you vehicle.

To test the usefulness of the blade stretch test theory for woodworking I bough all of tension gauges (over $1000) that measure 4 or 5 inches of blade for stretch to determine their usefulness. I first tested them with Aaron Gesicki who has an undergrad and masters degree in metallurgical engineering.

Then I sent them to Mike Cutler, who is a frequent SMC contributor and he did another evaluation which is summarized in the other thread. In short, gauges that measure 4 or 5 inches of blade stretch are not applicable to woodworking machines and are not applicable to blades under 1” wide.

The third wrong assumption is that the clamp on strain gauges are of value for the woodworking band saw tension range. Read Mike Cutler's testing report in the other thread on these gauges. These gauges are designed for very large metal cutting band saws using by woodworking standards tremendous tension. They are like using a gallon jug to measure a spoon of fluid. It is simply not the appropriate scale.

The FWW article was about doing something on the cheap that in reality is not worth doing. I think that the article fulfills the fantasy of doing something, that is the duplication of what a $300 tool does for a couple of bucks. And that is what it is, a fantasy. Even more of a fantasy is that the $300 strain gauge tool is the answer
for woodworking band saw tension.

Wrong assumption #4 is that it is simply a mater of clamping something to the blade and tensioning it. As Mike described it, the 1/2" blade is too flexible to get a good reading. I tried the feeler gauge idea and the caliper idea several times (clamping and unclamping) on a saw with a Carter ETG electronic gauge and was amazed at the differences I got on ten different test.

Sure the blade does stretch and you could measure but there are so many variables that it is beyond the scope of a back yard mechanic. You would need a room full of expensive equipment to measure it accurately. Another problem with blade stretch measuring (blade load) is that it is not as accurate as the saw gauge or the Carter ETG (or the standard saw gauge) which is measuring wheel load.

The number may or not work but it will give you a plecebo effect. It is about as accurate as holding your hand out the widow to measure the speed of your vehicle. Why not use the speedometer?

No field of woodworking has more misinformation than the band saw as it relates to tension and the standard tension mechanism.
Although the feeler gauge and caliper method of measuring tension is theoretically valid the actual usefulness of this technique is doubtful. How many of you measure tire pressure to know how much fuel is in your tank? Theoretically you could measure either your car weight or the tire pressure to determine the amount of gas in the tank. Why not use the gas gauge?

90 percent of the time you can use the gauge on your saw with good results. For cutting thick material or if the blade is dulling
go to the next higher setting. Just like the gas gauge in your car
it is a “good enough” device.

[Kermit Hodges]

Great idea, but afraid it's not a new idea. But it is as accurate as your dial caliper and how well you set it up. (how much tension or slack was in the blade when you started).