IPassGas

I built a jig to calibrate my park tension gauge. The spoke in the calibration jig is vertical. I consistently find that the calibration is different by 1 park gauge unit (about 10-12 kgf) when I flip the gauge upside down to measure (handle moving upward or downward during calibration). So during use, I always rotate the wheel and use the same orientation of the gauge as in the calibration setup. I wonder if others have noticed this quirk?

Bill Kapaun

I've always rotated each spoke to the same position as a simple matter of ergonomics. You have to hold the tension meter the same way if you want to measure the same way.
Any reading that didn't "feel right" is simply repeated.
Consistency is the key.

Retro Grouch 

I've got to compliment you on calibrating your tensiometer. I have a Wheelsmith that's 20 years old and has never been re-calibrated.

Frankly, I'm more concerned with spoke-to-spoke consistency than I am the actual tension number. As long as the spokes all measure close to the same, I'm happy. I do hold my tensiometer and the wheel the same way as I check the spokes but I had no idea the variance would be that much.

reburns

My new Park TM-1 was so far off, more than 30 kgf, that the adjuster couldn’t compensate due to lack of range. I didn’t realize this until I finally did the work to rig up a jig to calibrate it, which I only did after causing cracks around spoke holes in the rim. I sent the tool back to Park for recalibration and it came back with a new spring, but still about 10+ kgf off. At least that was close enough to adjust out.

Regarding variation due to orientation, I may see some, but even using the same orientation there is variation just from how slowly it engages the spoke and possibly other effects.

UniChris

But isn't that the part you can do by plucking them?

Seems like what a meter would offer is the absolute reference. Though so could a spoke in a scale jig with a "fret" at the position of the cross.

Bill Kapaun

I have pretty much a zilch sense of tone. I'd need some kind of tone generator beeping in the background with the correct pitch for the tension of the spoke I was plucking.
Comparing 2 spokes? It's like I can't really remember what the other one was like.
I have Asperger's and at least 1 attention disorder, so that might have something to do with it?

Russ Roth

There's not much to go wrong with a wheelsmith. If you do a lot of wheels you can send it in to wheel fanatyk and they'll put a new spring in and send you a new chart to match the new spring. That's really what's best about them, each isn't exactly the same but the chart was matched to the meter to make things accurate rather then a generic measurement that the meter might not meet.

Dan Burkhart 

And that's the issue with the Park meter. They all come with the same calibration chart which is theoretical, not actual.
I have a Park, a Wheelsmith, and a Wheel Fanatyk meter and have calibrated them all on my calibration jig. The Park meter is off by quite a bit. The Wheelsmith that I've had for over 15 years is still close.

IPassGas

Incidentally, a calibration jig costs <$40 to build including a gauge like this.