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Thank you @Perra 👍

I published the model over at Printables --> https://www.printables.com/model/1193871-tormek-projection-length-jig

Enjoy!

Gents

After I recently adopted the calculator method to my workflow, I figured that I will need some tools in order to facilitate life. Something to facilitate measuring projection length in particular that is. I was inspired by Perra's T-Cube. I think it's a simple and efficient solution. So I thought why not base on this design as the actual measurement device and make up a jig to go with the T-cube.

Out came my KJ-45 projection jig. It's designed to work with the KJ-45 (go figure ... 😉) and knives with blade width up to about 8cm. The KJ-45 is locked into position to avoid the need of a third hand when setting the T-Cube and the ruler.

I think it came out pretty ok and it fits the job. I will upload it over on Printables for share. Before that, however, I request permission from Perra to also upload my model of the T-Cube. The jig alone is of limited use without the cube.
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Hi Werner

Danke für den Hinweis und die Ausführungen.
Den Klingenwinkel hatte ich schon auch auf dem Radar. Er erklärt aber einfach nur einen Teil der Abweichung von 3-4 Grad. Ich denke, beim WM-200 summieren sich einfach eine Reihe von systematischen und zufälligen Fehlern und daher ist es für Messer eher ein "Schätzmittel" und kein Messmitel 

@3D Anvil : That is a valuable piece of information as far as I am concerned. Thanks 👍

You have outlined an impressive workflow.

Naaah ... I'm just an engineer suffering from professional deformation 

I would not say that this workflow is impractical, only that it seems best suited to high quality, low volume sharpening. I would recommend you also formulate simpler, lower cost options. Reserve your procedure for your personal knives and for those people who really appreciate fine edges.

I sharpen for myself and very rarely for a good friend. No need to optimize economic efficiency.
I sharpen because I'm lost to the ZEN-effect of it.
You guys know what I mean ...

If that's of any help to you, the "Top-of-USB to wheel" distance depends on wheel size and projection distance only. It doesn't change with the position of the MB-102.

Good point - thanks!

Just to add my two cents, I have to say that I find the calculator method (Calcapp by Cbwx34)

https://connect.calcapp.net/?app=3fp8xu#/

extremely easy, reliable and repeatable.

Agree - but only as long as I stay on the Vertical USB.
I use the JS and the felt wheel edge trailing with HUSB/FUSB. And I don't keep my MB-102 fixed in its position. I play with its position depending on knife size for a comfortable handling and I remove it completely when I stow the the sharpening stuff away. Using the KS-123 to transfer the correct angle in that case is much more appealing than re-measuring and re-entering all distance values to the calculator.

Appreciate all feedback so far – cheers guys 👍

I think I settled on my way to skin my cat.

Status:
-   KS-123 is in the house
-   KS-123 differs from WM-200 in terms of angle readings
-   Absolute value readings questionable for both tools

Goals:
-   Want to ditch WM-200 and integrate KS-123 into my workflow

Consequence:
-   All my knives net to be set with new bevels

Principles & Assumptions:
-   Calculator method is the most precise method to set actual grinding angles. It's also the most reproducible at the cost of being somewhat cumbersome.
-   KS-123 is easy to handle and - with proper and careful handling -  sufficiently reproducible

Workflow:
-   Set the new bevel by means of the calculator method
-   Grind new bevel on grinding wheel
-   Use the KS-123 to "read out" the angle. That may differ from the calculated value.
     Note down "KS-123 angle" for each knife
-   Transfer to JS wheel and felt polishing wheel by use of KS-123. Quality control with microscope.
-   Future maintenance with KS-123

@Ken: Thanks for the kind welcome. Very much appreciated 👍
I hear you and I fully agree with you regarding the aspects of consistency and repeatability.
But Sir Amwell's objection is also valid and it is of relevance for my case. It's about the question if the indicated values of either tool are "true" values. And it is also about repeatability across tools that claim to output numeric measurements of physical values.

Why is this relevant for me? Well, I use my T-4 for knife sharpening only. And I own various kitchen knifes of European and Japanese make. Using my WM-200 so far, I did set the bevel of each knife according to knife and steel specs. This ranges from 14° for an ultra thin Nakiri up to 21° for my Wüsthof workhorse. And now I bought the KS-123 and I see that the two tools are not consistent in their readings of the sharpening angle.

The first issue now arises when I switch to using the new KS-123 as my standard. I cannot work with the values I've been using on the WM-200 to set the angle on the KS-123. This leaves me with two options. I can try and recalculate the correct value for the KS-123 with an offset based on the observed deviation. Bad idea in my opinion. I'm introducing an additional step in my workflow that is a source for errors – even more so as both of these manual tools do have limitations in their accuracy of measurement.
So I'm left with the option to properly re-set the bevel for each knife using the KS-123. But here it gets tricky because the observed difference of the tools made me aware that these tools do not show me the true value of the sharpening angle. At least one of them must be off. And because I do not own a goniometer I cannot verify the measurements and therefore I have to assume that both tools are not showing true values. And here it gets problematic. Especially with very narrow edges.

Let's take the Nakiri with a target angle of 14°. My observed difference between the WM-200 and the KS-123 is something like 3.5°. That is already an error of 25% with respect to the target value. And that is assuming that either one of the two tools is spot on the true value. But what if booth tools are off the true value in the same direction (i.e. both show a too large value)? In that case the error even increases. Not acceptable in order to put a suitable bevel to said Nakiri! So, right know I got two tools to measure my sharpening angle and I do not trust either one.

Apologies for the lengthy elaborations so far. I guess it boils down to two questions for me now.

1. Can my observed difference using the WM-200 and the KS-123 on (kitchen)knives be reproduced by other users as well? Or is the observer the problem due to his incompetence of tool handling? (BTW. I watched each and every instruction video and spent the whole afternoon yesterday trying to find the fault... but nobody is perfect)

2. Did anybody validate the correctness of the measurement with respect to true angle? I.e. by use of a goniometer.
Especially for the KS-123, as I want to use this from now on. But also the verification of the WM-200 would be interesting.
In other words, can I trust the values from the KS-123 or will I have to work with a correction offset to get my narrow knife angles correct?

Thanks for any feedback!

Runnig a T-4.
I just got my KS-123 together with a new DE-200 diamond wheel. Started playing with the KS-123 and also tried to compare the angle reading of KS-123 with my ol' WM-200. And I find a consistent offset of about 3-4 degrees. Retried again and again, also with different knives (blade width). The WM-200 always reads a higher angle. E.g. if I set the angle to 15° with the KS-123, the WM-200 will read between 18° and 19°. If I set the KS-123 to 20°, the WM-200 will read between 23° and 24°.
Completely clueless .. any help highly appreciated - thanks