Dean51 

An early snowfall in the Pacific Northwest has taken me off the road and into my workshop to get after a slew of winter projects. First up was the rebuild of a spoke tensiometer that I built a few years ago. This is my take on the Jobst Brandt / FSA / Wheel Fanatyk device. Like other tensiometers, it measures spoke deflection between two points under a fixed load. I built this for $0 with materials I had on hand. Looking closely at the photos of my tensiometer, you will see that the spokes are are "nested" between two ball bearings separated by a thin spacer. I think this makes it easier to use than the FSA / Wheel Fanatyk tensiometer.

My first version used much larger ball bearings (32mm OD)....'cuz that is what I had on hand. This resulted in an overall width that was awkward to place in some wheel/spoke configurations. Yesterday's rebuild involved replacing the large bearings with 13mm OD bearings. The device is now ~1" narrower and much easier to use. This prompted me to make new calibration charts for 2.0, 1.8, and 1.7mm spokes.

Soooo....here is the rebuilt tensionmeter in use.



A view of my calibration fixture.



And a close up of the tensiometer while in the calibration fixture.

trailangel

https://itunes.apple.com/us/app/spok...518870820?mt=8

sweeks

Beautiful! Nicely thought out and made. I'm getting by with the Park Tools gauge, but I couldn't build one myself.

Tuning by pitch is complicated by contact with other spokes, which can damp the vibrations. Still, $5 ain't bad!
I'll keep my gauge, thanks.
Steve

kevindsingleton 

I'd steal that design, if there was a picture of the back??

Reynolds 

Great job! I thought about making one myself, but doubt it would turn up as neat as yours.

leob1

Since I don't use one, and probably never will, because I have no interest in building wheels, does the calibration of the tool matter? Are you measuring specific spoke tension, using what scale? Or do you just need to verify the tension difference between the spokes?
BTW, Nice polish job on the frame.

HillRider

Interesting calibration technique, using a stress gauge to measure the spoke tension and then calibrating the deflection caused by an an "unknown" force (the spring) as a function of the known spoke load. I don't think many of us have access to a load measuring device like yours but I suppose known weights could be hung from a spoke and accomplish the same thing.

Dean51 

Kevin.... I will take some side view and back view pics later today that will show you more detail.

dsbrantjr

I would be very interested to see how the calibration curves look. One should be able to get pretty good resolution using that force gauge.

Dean51 

Hillrider.... You are spot on. The loading force is unknown. I experimented with different springs to produce a range of deflection that I could observe on the dial indicator. For each spoke gauge, I measured and recorded deflection in 5 kg increments from 50 kg to 140 kg. As an example, a 2 mm spoke deflects 0.0285" at 95 kg tension and 0.0275" at 100 kg. My "load measuring device" is an inexpensive digital scale I purchased on eBay for another project. Not shown on my earlier pics....the top side of the scale is attached to an eyebolt with fine thread. To increase the load, I turned a nut on the eyebolt. Simple, and very repeatable.

Dan Burkhart 

Nice work on the tension meter. Your calibration fixture is quite similar to the one I made.

Soil_Sampler

Dean51
Nice stuff!

Dean51 

For Kevin and any others interested in more details....

Side view:



Back view - assembled:


Slide details:



The slide rails were 5/16" key stock. There are two guides. Each has a fender washer on each side of the key stock, with the convex side of the washer facing the slide, and a small bronze bushing that separates the washers such that there is clearance for the slide to slip through them.

Andrew R Stewart 

Besides the cool factor in making one's own tools what I am drawn to is the hand finishing that this tool has had. I am glad to see some still use their hands and make their own ****. Andy

HillRider

Very clever. It looked far more sophisticated (and expensive) in the picture until you explained what it was. I'll bet you could do a nice business calibrating other wheelbuilder's commercial spoke tension gauges sort of the way other companies get paid to calibrate torque wrenches.

Dean51 

For what it's worth, my LBS....where I do some volunteer wrenching on donation bikes..... has a Wheelsmith Tensiometer that has no calibration chart. I'll be making one for him tomorrow. This is fun/rewarding stuff for me!

Dean

kevindsingleton 

Very cool! Thanks! I thought it was made from aluminum, but you went old school with steel. Very "Pittsburgh" of you! I like that. This will be one of my winter projects, and I'll post my version, when it's done.


Thanks, again, for sharing.

MePoocho

Now that is what I'd call 'Art'. You have quite a mind for design and skill in fabrication. Wonderful to see such a fine piece.

I have a band saw band (blade) tensiometer dial indicator that works on the same principle. If I had your talent I'd adapt it to spokes.

Dan Burkhart 

If you want to add a bit of decorative flair to your home built tools, you can give it a jewelled finish with a wooden dowel in a drill press.

wschruba

Great looking tool, all around. I'm always on the lookout for dial gauges at flea markets, so this could be a cool project, for sure.

Dan, I always wondered how they made the jewel effect on (softer) metals, looks neat. That's almost sacrilege to do that to a pair of Uticas, though...of the 7-8 different brands floating around my box, from Mac, Snap-on, Wera, etc, the Utica pliers have the best finish, with the deepest luster, even with the complicated shapes.

Good candidate for jeweling, though

Dan Burkhart 

I learned the jewelling technique fifty years ago in high school machine shop. It's actually quite easy, like I said, a wooden dowel in a drill press, and overlap the swirl just enough to get the desired effect. It works on mild steel, but probably have to use an abrasive for harder stuff.
Oh, and that wasn't my work in the photo. I grabbed that off the net.

HillRider

Yeah, gunsmiths often "jewel" the bolts of custom rifles that way but they do have to use an abrasive compound on the hardened steel.

A company named Cratex sells abrasive rods in various diameters just for this use and other companies make holding fixtures to assure even rows of the swirls.

Dan Burkhart 

Good to know, thanks. Looks like a good resource.
https://www.cratex.com/Products/Rubb...ives/Jewelling

bluehills3149

I wonder if you could use a digital tire gauge instead of a dial guage. These things are almost free on ebay.