Thursday, 26 April 2018

Spoke tension meter calibration device

If you're watching this blog you realized (I hope) that in all my work I constantly seek for improvement and perfection.

While the custom wheel building business is really well developed there are few tools which you are not easy to get or the prices are so high that it doesn't justify the investment. Due to that usually people either don't have those tools or use some home-made workarounds. However, if we are talking about high-end custom wheels is there a place for workarounds? Of course the answer is "NO" and therefore in order to close this gap I decided to develop few own branded tools which should be in every good wheel-building workshop. 

The first one in the queue is the "Spoke tensiometer calibration device" 



Designing and producing a tool from the scratch is not a peace of cake. Those who tried know what I mean. 
I can build a pair of good wheels, drive the project as Project Manager but I can't create a tool. As with everything else you should always use right tools for right job so therefore I made the partnership with the fetish.bike
Tomasz is good, I mean really good. He can design, create a professional project and turn the idea into reality. He has a great knowledge about engineering, bikes, steel frames, welding, CNC, painting any many many more. Moreover he has a workshop which many of us can only dream about.

Two guys talking the same language, in our case "bikes" help a lot. Only few email exchanges were required to draft the vision of the tool. 

The project requirements were the following:
- robust and high quality tool
- tool which will allow to measure the spoke tension up to 250kgf +
- spoke lenght from 150-320mm
- any spoke type (round, bladed, straight pull, j-bend)
- any nipple type
- right/left handed
- with possibility to use different type of weight scales
- with the possibility to mount into the workbench

Few weeks later I've got the prototype with all the tiny details. I was speechless!



Visualization like that really helps. You can imagine the tool and make corrections so you avoid the rework, time and precious material. 
After couple of changes Tomasz did the first prototype. 
Using the opportunity that I was near by when Tomasz was working on my tool I made him a visit and documented the first tool assembly.




..and while Tomasz was focusing to assemble the initial Spoke tension meter calibrator I did the small tour on his magical workshop...

Frame building jig:



 Lathe:




Drilling station:




Welding - my favorite!





And few other handy tools:




At the time when I was finishing the tour, Tomasz finished the job so it was time to test it :)

The tool works very, very well. It's made from high quality parts like "kipp", "igus", mainly supplied from Germany.
Big, heavy, solid, bullet proof. When you use it for the first time you quickly realize that's not a toy which will brake after couple of usages. You really need to be careful when stretching up the spoke as you don't feel any resistance. Half of the turn and you have 100kgf on the scale. 

What I like with the tool is that you don't loose any tension. In my previous home made tool based on the wooden frame I could see a slow tension drop and I assume that was due to whole stiffness of the construction. Here we used 4-8mm steel and large industrial screw which obviously has zero flex and the whole construction is much more stronger than spoke & the tension. Once you apply the tension it stays and doesn't go down. 

As per initial requirements you have a freedom to put any spoke of any length. If required you can use your own digital scale. There is enough space and configuration possibility to install any device you need. We will be offering the version with and without Crane digital scale.

The production devices will be painted in black. The prototype we did is raw in order to show you the quality of mounts and welding.

Couple of pictures showing the details and high-end finish of the tool:











Now, reading that you may ask yourself the fundamental question - "What is this for?" Since with every tension meter you get the chart with tensions and values.

My answer is: default charts are good for start with the wheel building but if you want to achieve highest perfection and properly tensioned wheel, you should not rely on generic chart and measurements somebody else did - You have to make your measurements by yourself.

Couple of key facts:
  1. Tension meters with time get used, especially the spring. With time the readings will be different and you should be aware of that. 
  2. The charts you get with spoke tension meter devices do not consider the spoke manufacturer. Different brands, different steel, different spoke stretch, different readings. Sapim CX-Ray will not have the same reading as DT Aerolite
  3. The charts you get do not consider the spoke color. Sounds unbelievable? Check CN spoke black vs white. The readings will be completely different due to thick coat on the white spoke
In order to demonstrate all above see the below videos

Tool introduction:

Tool build and construction:

Tool usage and benefits:

As shown in the videos, when building a high end wheel (or actually any wheel) you want to make sure that the tension you apply is not too high and not too low. Well tensioned wheel after stress removal will be consistent and no re-tension will be required. You will have satisfaction and confidence that neither the spoke nor rim will break.

The measurement takes less then 5min. What I do personally, before the wheel build I put the spoke which I'll be using and run the measurements of 100, 105, 120, 125kgf. 
I do that especially if I get the spokes from different distributor (Asia vs EUR), spoke type which I haven't used before or colored spokes.
Quick check and I'm confident that I will have properly build wheel.

Obviously you also want to use the tool to calibrate your tension meter from time to time.

Last but not least question - the pricing and ordering

Prices:
Tool without the digital Crane scale: 549 CHF
Tool with digital Crane scale: 649 CHF
World wide shipment, shipment prices will be calculated individually based on the qty and the destination country.

Ordering:
As of now I'll be collecting the pre-orders for the first production batch. If you're interested or have questions drop me an email on: [email protected]
You can also place the direct order on the online store (preferred way)

I aim to close the orders for the first batch by end of June 2018 and deliver the first units by end of August 2018.

...and that's all for now, hope you enjoyed that post. 
Feel free to comment and open the discussion. Your feedback will be much appreciated!

Cheers
Tomasz
blog-wheelbuilding

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