Measurement Jigs for Usb hight and Projection distance settings

[HaioPaio]

I would agree that it is desirable to meet the intended angle with not more than 0.5 deg deviation.
I have played a bit with the calcapp Knife Sharpening Angle Calculator to find out which deviations in Projection Distance or Distance to the grinding wheel would cause an 0.5 deg error.
For a single measurements, up to 0.7 mm deviation is allowed.
In case that both measurements are affected by an error, it is sufficient to measure both data with an error of not exeeding 0,4 deg.

An measurement error not exeeding 0.1 mm would only be needed if it is planned to meet the desired angle with an error of less than 0,1 deg.

While I agree that +/- 0.5 deg error can be achieved with the Tormek system, I strongly believe that an angle error of less than +/- 0.1 degree cannot be repeated on a Tormek system. Even when Projection Distance and distance to the grinding wheel would be measured without any error, the sum of all other errors and tolerances would cause that the resulting angle cannot be maintained repeatedly.

I therefore, do not see any benefit in measuring Projection Distance or Distance to the wheel with extreme high precision.

[Perra]

I have collected some pictures and user information about my latest project, WAT-prototype, in a pdf file. Attached below. Happy to receive thoughts and ideas about how a finished jig could look like! Or thoughts about function and precision. Have tested it on different wheels and with varying degree numbers and jig lengths and so far I am positively surprised by the result. The T-cube has already been presented before.

With this two tools you can set the grinding angle for knives on a grinding machine with rotating grinding wheels or honing wheels from Dia 200mm and up without using a calculator. There is no need to measure wheel size, usb height or projection length. It is possible to set degrees with an accuracy of 0.5 degrees.

There is already a small thought with me to produce a template for a 3d printer if it works well and if someone wants it. However, it is quite easy to make it yourself if you want.

[Dutchman]

A clever idea and beautifully executed!
However, the tolerance is greater than the stated 0.5°.
The variation in stone diameter (150-250 mm) already gives a tolerance of 1.27°. See attachments.
Other adjustment tolerances are added to that.
You cannot view this attachment. 

[Perra]

Hi Dutchman
I have the same result as you have. So that's good.
But I have calculated wheels from dia 200 to 250 and that gave me 2mm variation, then I moved up the center point of the scale 1mm to halve that error. Maybe it's not quite right to do that? but as you point out, there are more parameters to consider. It is also a bit difficult to hit the right spot with the ruler. Do you have any other solution to reduce the margins of error on?

[cbwx34]

The Jig/Tool that Jan, RickKrung, and others worked on came to mind, might want to take a look? 

https://forum.tormek.com/index.php/topic,2639.msg24567.html#msg24567

(It's a long thread, but I linked to where it seemed to pick up again when Rick worked on it.)

Edit:  Here it's described in Rich's site:  https://www.sharpeninghandbook.info/indexJigs.html#HanJig

Gotta say though, this is one instance where I'm thinking the KenJig might be the easiest route.  It's pretty tolerant of wheel size changes, (you don't have to measure that often, and can just use the scale on the machine), and is easy to use.

At some point, you gotta measure something... if your friend doesn't want to use a "calculator"... then maybe a spreadsheet would be just as easy.  (You're technically measuring the Projection in your setup, are you not?) 

[Dutchman]

...snip
... then maybe a spreadsheet would be just as easy.
... snip

And what is wrong with my tables?

[cbwx34]

...snip
... then maybe a spreadsheet would be just as easy.
... snip

And what is wrong with my tables?

Nothing... isn't that the same thing? 

[Perra]

Thanks a lot CBW I will definitely read through your suggested threads.
Yes, maybe Kenjig is a good solution for him too. Yes, I admit, I cheated a little. Technically, I measure projection distance but without noting any values. I just physically copy the length to the T-cube. Think it is technically impossible to try to solve this without having at least one fixed value to start from.
My goal is to avoid both calculators and measuring tools such as calipers etc.

And he knows the marker pen method. I told him the black one is 18 degrees and the blue one is 16... but he didn't believe me!

He has tried it a bit and is not satisfied with the handling. There are too many loose parts to handle at the same time as he has to read the scale and raise the usb support.
I am now looking at version 1.1, where the parts should fit together and make it easier to handle with one hand.

That's why I'm waiting with tables of measurements that still have to be measured somehow.
Hope that it is possible to find an acceptable level of the deviation in some way. The tests I do show that I hit very close to 0.5 degrees when I countermeasure with other methods.

Don't know what deviation Tormek's Anglemaster has.

What deviation do you think is acceptable on a tool like this to use it?

[Dutchman]

And what is wrong with my tables?

Nothing... isn't that the same thing? 

only if it is on paper instead of electronically 

[cbwx34]

And what is wrong with my tables?

Nothing... isn't that the same thing? 

only if it is on paper instead of electronically 

That's actually not correct. 

[cbwx34]

...
My goal is to avoid both calculators and measuring tools such as calipers etc.
...

I think part of the issue (maybe) is we took Dutchman's idea... "A Simple Adjustment of the Grinding Angle" and made it appear more complicated.  For me, a calculator is easier to use, I'm not constrained to a set Projection, Angle, etc.  But using a table and a simple ruler (I like a combo square), you can easily set the angle consistently and probably more than accurate enough.  Saying computers/calipers/etc. just makes it seem complicated (and I think a bit overkill for most).  My .02.

[Ken S]

For the record, my main goal in designing the kenjig was to avoid having to measure for every knife. My goal was NOT to avoid "calculators and measuring tools (including computers)". The purpose of the kenjig is to be able to preset both the Distance and Projection. Dutchman's tables allowed me to do this easily. More recently, CB's Calcapp works well, also. In rare cases, such as sharpening my Chinese cleaver, I need to make up a new kenjig. A simple cardboard kenjig suffices for situations like these.

Ken

[Perra]

A little update on what became of this project. Now the tool is ready and printed on my 3d printer. We are happy with the result and my friend uses it in his workshop.
The scale is now adjustable for different wheel diameters, 200 - 250 and also the length of the ruler's protrusion if you want to be even more precise. You can easily set the length of the jig with a knife directly on the tool. All the parts fit together and you can lock the setting with locking screws on the back, if you want, after making a setting. We find it easy and fast to work with and the accuracy meets the requirements we had, within approx. 0.5 degrees. End of this project.

[tcsharpen]

Very interesting. Will you be placing the final 3D files for download somewhere?

[Ken S]

"Don't know what deviation Tormek's Anglemaster has.

What deviation do you think is acceptable on a tool like this to use it?"

It is important to remember the function of any measuring tool and its practical deviation. Even a world class precision toolmaker like Starrett makes tools of different deviations for different requirements. Even Starrett's basic protractor type tools for measuring angles are reasonably accurate. The hash marks on its measuring tools are "engine cut" with sharp v shapes, rather than photo etched. Its more accurate protractors have more precise verniers and measure to five minutes or arc. (60 minutes of arc equal one degree) This level of accuracy is adequate for most tool and die work. An anglemaster of this accuracy might cost several hundred dollars.

For laboratory work, precision angle gage blocks are necessary. At this level, these gages are generally shipped to the National Bureau of Standards periodically for inspection and be priced accordingly.

The Anglemaster, like all measuring tools, is a balance between adequate precision and reasonable cost.

I have happily used Dutchman's tables since he first posted them in 2013. They are still my "go to" reference, although I sometimes use and like CB's Calcapp.

The real advances in knife sharpening are coming in honing, deburring. I don't see any real benefit in ultra precise bevel angle setting. I see real benefits in more thorough deburring.

Ken