Another, non My Time Media, UK, M E magazine had an article on making a tension meter, a few months back.

It used a DTI to measure the blade extension as it was tensioned. Other than the DTI and the Silver Steel pivot and a few small capscrews, it all came from a bit of square bar (15mm from memory)

I made one and used it to set blade tension on my elderly 4.5" bandsaw. Since then no broken blades, and seemingly improved accuracy. The first trial cut off a bit of 38mm round bar, suggested a variation on thickness of about 0,025mm on a 1.5mm thickness. But I don't expect that degree of accuracy!, purely a one off!

So, in my book it is a very useful, but rarely used, device.

Have you checked that all the guide rollers are correctly set and aligned?

The shorter the blade, the more sharply the blade twists as it enters or leaves the wheels. Before the 4.5" I had a little one, and was lucky to cut one piece of 38mm angle iron before the blade broke, despite being carefully set up. Needless to say that went back!

Howard

Which way round are you fitting the blade? is the drive pulley pushing or pulling the blade?

I was told tighten till it will twang like a banjo – works for me

The only way to be certain is to set a suitable tension but as you can't directly measure the tension and the hand wheel stiffness will vary with lubrication, contamination etc, plucking the blade as Fizzy suggests is a good way to measure it indirectly. I set mine to give a tone that is probably not far off Middle C although I haven't checked precisely. Certainly, it's close to the limit of what can be achieved with bare hands on my Chinese 4×6 bandsaw using the small handwheel.

Murray

Ps – look up "Bandsaw blades" on this site.
BobH