Spoke Tension Meter Calibration

[foo_fighter]

I suspected my Park TM-1 was reading high so I built one of these for about $25 in parts.

Pretty much the same design as these in the videos, but with a wooden frame.
https://www.youtube.com/watch?v=xgsz7l1GWoI
https://www.youtube.com/watch?v=N_q_nxQl97s

The TM-1 was indeed reading high by about 3 ticks. I guess better high than low. I suspect that storing the meter with the spring under tension has relaxed it a bit.

[weisan]

Very cool!

I am intrigued and was thinking of building one for myself until I saw the first video where the gentleman said it seems like his wheelsmith tensiometer had retained its calibration after 9 years of extensive use. I have the exact same tensiometer so I guess I should be ok and would just save myself the trouble.

Thanks for sharing foo pal.

[ikecycke]

That's a pretty good setup! From what I've read, the TM-1's also tend to not be super-consistent across ranges of tension or different gauges of spokes. I seem to do all my builds with either Lasers or CX-rays, so I've thought about having separate gauges calibrated for each spoke...or just biting the bullet and buying a better gauge. Just hasn't been necessary since I only build about a dozen sets a year.

[BLD 25]

nice setup! Also, just of note, I sent mine back to Park, and their recalibration service is like $5. Not bad and pretty easy.

[Spaghetti Legs]

I’ve often wondered, for the Wheelsmith, like I have, how important calibration is, as long as you’re just gunning for the same reading between spokes.

[ergott]

When I went calibrate a Park I found the chart inaccurate. The spring rate must have been different so I made a new chart for the user. We just set the spoke at 10kg intervals and took new readings.

[Hindmost]

So a spoke tension meter can be calibrated with one gauge of spoke and be accurate for use with other gauges of spokes?

[weisan]

Originally Posted by Hindmost

So a spoke tension meter can be calibrated with one gauge of spoke and be accurate for use with other gauges of spokes?

That's the baseline, and then you use the chart for the different gauges.

[ergott]

Originally Posted by Hindmost

So a spoke tension meter can be calibrated with one gauge of spoke and be accurate for use with other gauges of spokes?

I charted 2 or 3 different spokes he commonly uses.

[Gsinill]

Great idea, was planning to weld something out of scrap but that is much easier.
Only concern I'd have is the bent plate of the U-bolt, doesn't it give in further when you engage the tension meter, impacting the read?

[cachagua]

I’ve often wondered how important calibration is, as long as you’re just gunning for the same reading between spokes...

Yes, you're right to wonder. Spoke tension of exactly X.xx kilograms of force is far less important, as a determinant of how a wheel will behave and how long it'll last, than consistent tension throughout the entire wheel (or one side if it's dished).

But insofar as they're a bike gadget, and we like to play with our gadgets, calibrating them is part of the ritual, I guess.

[foo_fighter]

The tension meter itself doesn't add too much more tension, but the first time I brought the device up to tension, I had to wait for it to settle and tighten the bolt a bit. It's been pretty stable since.

Originally Posted by Gsinill

Only concern I'd have is the bent plate of the U-bolt, doesn't it give in further when you engage the tension meter, impacting the read?

[Tall]

Cool project. Did you try and calibrate the scale at all? I'd be hesitant to trust the accuracy of a cheap-ish scale (sounds like that's what the guy who made the videos bought).

I recently saw someone post a calibration set-up where he used weightlifting equipment to create sufficient tension.

[foo_fighter]

The electronics are usually calibrated once at the factory and usually don't change much over time since it's electronic but I supposed you could weigh yourself from it to see if it matches a scale or weigh a known volume of water....next up a calibration device for the calibration device!

Originally Posted by Tall

Cool project. Did you try and calibrate the scale at all? I'd be hesitant to trust the accuracy of a cheap-ish scale (sounds like that's what the guy who made the videos bought).

I recently saw someone post a calibration set-up where he used weightlifting equipment to create sufficient tension.