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Measurement Jigs for Usb hight and Projection distance settings

Started by Perra, November 26, 2022, 02:28:38 PM

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Perra

I've been busy trying to see how accurately and repeatably you can grind with a Tormek. I know it's a little geeky and maybe not always necessary with exact angles to sharpen some knives for the wife!
There are several fine and precise calculation programs now that give us all the measurements we need, but I have had difficulty measuring these measurements with insufficiently high accuracy.  I think measurements within 0.1 mm are needed! Therefore I use calipers to measure with in my jigs.
Mainly talking about usb height and projection distance.  How to easily find the center line on different sizes of wheels and the height of the usb support? How easy and accurate to find projection distance on knives even if you angle them differently in the jig?
I have made two new measuring jigs for this purpose. They help me work faster and more precisely when I work with knife grinding. I can also rehearse my angles and measurements more accurately with these jigs.
Perhaps it may be of interest to some of you to take part of what I have worked with. Or maybe i can inspire someone. Or do you also have ideas on the same theme to share?
More pictures and information can be found in the excel file "Angle Calculator Lite V1.4" which is updated in this link. https://forum.tormek.com/index.php/topic,4885.msg37303.html#msg37303

TireguyfromMA

Perra, both jigs are pretty sharp, cheap pun, but I really like the jig you came up with to measure from the top of the USB to the wheel.  Making those slots helps locate it on the radius of the wheel. I wonder how much of the radius of the wheel will protrude into that slot opening though?  You might be losing that 0.1mm accuracy your looking for?  Have you tried making comparison measurements using the protruding end of a caliper from the top of the USB to the wheel?  Again, I do like the concept and really admire the creativity.

Perra

Hi
Glad you liked them.
You can compensate for  a small measurement errors due to the height of the grinding wheel between the legs. Measurement error for wheel diameter 250 is 0.144mm and for wheel dia 214 it is 0.168mm.
Recommends adjusting the position of the caliper by 0.156mm.
You can read more about it and se more pictures in you follow the link and download Angle Calculator Lite V1.4

cbwx34

Quote from: Perra on November 26, 2022, 02:28:38 PMI've been busy trying to see how accurately and repeatably you can grind with a Tormek. I know it's a little geeky and maybe not always necessary with exact angles to sharpen some knives for the wife!
There are several fine and precise calculation programs now that give us all the measurements we need, but I have had difficulty measuring these measurements with insufficiently high accuracy.  I think measurements within 0.1 mm are needed! Therefore I use calipers to measure with in my jigs.
Mainly talking about usb height and projection distance.  How to easily find the center line on different sizes of wheels and the height of the usb support? How easy and accurate to find projection distance on knives even if you angle them differently in the jig?
I have made two new measuring jigs for this purpose. They help me work faster and more precisely when I work with knife grinding. I can also rehearse my angles and measurements more accurately with these jigs.
Perhaps it may be of interest to some of you to take part of what I have worked with. Or maybe i can inspire someone. Or do you also have ideas on the same theme to share?
More pictures and information can be found in the excel file "Angle Calculator Lite V1.4" which is updated in this link. https://forum.tormek.com/index.php/topic,4885.msg37303.html#msg37303


I really think that "measurements within 0.1mm are needed"... should come with a bit more of an explanation, since, for the most part, it's really not needed.

So.... why?  :)

Nice job on the jigs though...  A+ for accuracy and consistency.  I just think that trying to compensate for fractions of a mm, (can you have fractions of a mm?)  ;D  isn't really necessary.

Quote from: Perra on November 30, 2022, 10:35:33 AMHi
Glad you liked them.
You can compensate for  a small measurement errors due to the height of the grinding wheel between the legs. Measurement error for wheel diameter 250 is 0.144mm and for wheel dia 214 it is 0.168mm.
Recommends adjusting the position of the caliper by 0.156mm.
You can read more about it and se more pictures in you follow the link and download Angle Calculator Lite V1.4
Again (although this is a little different than trying to achieve the .1mm accuracy)... wouldn't you get the same result if you didn't adjust for this error?  If you're always adjusting the caliper by "0.156mm" (since it reads that you are, regardless of wheel size), would it be any different than if you didn't?  (Hope that makes sense.)
Knife Sharpening Angle Calculators:
Calcapp Calculator-works on any platform (Just point your phone at the QR code)
or, a list of available Calculators

tgbto

Quote from: cbwx34 on November 30, 2022, 04:53:53 PMAgain (although this is a little different than trying to achieve the .1mm accuracy)... wouldn't you get the same result if you didn't adjust for this error?  If you're always adjusting the caliper by "0.156mm" (since it reads that you are, regardless of wheel size), would it be any different than if you didn't?  (Hope that makes sense.)

It makes a significant difference : You will be 0.024mm closer to the honing wheel. So probably honing at a 0.018° lower angle than you're trying to !!! Instead of just 0.009°. But then you'd be sharpening at a 0.009° higher angle. So more precise, but not more accurate. Or the other way around ?

Perra

I can agree with you cbwx34 that it may not always be necessary in practice with such accuracy, within 0.1mm. But that's not my point here.
I think it's up to everyone to decide how exactly they want to try to get their angles. But the more you know, the more precisely you can grind. Learning how what you do and how it works, both in theory and in practice, is education. And my ambition is to learn as much as possible to understand what I am doing. Therefore, I am thinking, measuring and producing jigs that can match the factually correct values of the calculation programs. And try to get as close as I can. In that case I think "measurements within 0.1 mm are needed!"  I hope I managed to answer your question
I believe that the more I understand the more I become a better sharpener And it has also given me tools so I can measure and tune my Tormek both faster and better when am working. I also share it with you all and it is up to each of you to decide if or how you want to use them or not and how accurate you wont to measuring. Don't get me wrong, I'd love for you to come up with suggestions for improvements or correct me if I'm on the wrong track. With an adjustment of 0.156mm on the caliper you are less than 0.024 error from all wheel sizes within 250 to 214 but again it is up to each individual to set the tolerances.

Sir Amwell

I think we are entering the accurate vs consistent debate again here. I'll tell you a bit about my journey. I obsessed with accuracy for a long time, trying to replicate Wootz protocols with similar Bess scores. Then with research I went for consistency across all formats so to speak- setting edges on Tormek wheels, honing on Tormek leather wheels, refining on paper wheels etc.it is easy to disappear down rabbit holes with both and tie yourself in knots.
CB helped me to realise that a compromise between the two works.
3D Anvil taught me to experiment and find my own way.
Depending on what you are hoping to achieve find a way to get the results you are looking for. It will take time and learning but you will get there.
Anything under 100 Bess is good enough for me and my customers.
The sub 50 Bess we all want to get for all knives under any conditions is a rabbit hole not worth exploring in the real world I have concluded.
Having said all that, personal correspondence with Wootz just before he died, recommended getting ALL measurements within 0.1mm. Those were the tolerances he was recommending.
So...... the debate will continue.

3D Anvil

You can't argue with Wootz's results, but I think 0.1mm tolerances are simply not attainable with the tools in question.  Even if you measure to that accuracy, the USB moves slightly when it's screwed down.  Then, even if you stay with wheels the whole way, you're going to be using wheels of different diameter (paper wheels and/or leather wheel), so you're not hitting precisely the same spot on the bevel from one stage to the next.  And of course the Tormek jig isn't locked down, so there's always some variation as you move the knife across the wheel. 

I haven't been using the Tormek system nearly as long as many others here, but my feeling is that, while it helps to be reasonably precise, attaining sub-50 BESS scores requires technique and lots of practice.

Perra

I think we are talking about two different things here. Knowing which angle you grind with and being able to repeat it in the future is one thing. Getting the ability and skill to reach below 100 bess is another matter. You can probably reach about 80 bess with 14, 15, or 16 degrees or without knowing which degrees you grind with. It also depends on which stone you use, how you hone, if you polish with a paper wheel or rock hard felt wheel, diamond spray etc. I find that my customers are most satisfied if the knife works as they expect and I believe that the right angle for the right knife and field of use is more important than 80 bess. (which most people don't even know what it is)
A working knife must also last as long as possible and then perhaps a higher angle is better for that particular knife. With perhaps a higher Bess number! But I want to be able to repeat that result and that angle again.
What do you think?
Or am I thinking wrong?

Sir Amwell

No I don't think you are "thinking wrong" at all.
There are three things of issue here:
Accuracy ( your desire or Vadim's desire for accuracy down to 0.1mm)
Consistency.
Repeatability.
I would argue that the second two of these are interdependent.
The first is also very important for the 2nd and 3rd to be achievable.
But I think if you put all the emphasis on accuracy then you may be putting less emphasis on the consistency and repeatability.
In real world sharpness, as you say, 80-100 Bess is more than adequate for a customer who can't tell the difference. If you can achieve these results ( I always try to for my sense of pride and job satisfaction) then that's great. If you can consistently repeat the process without looking at software and calculators and trying to raise the Usb by 0.1 of a mm, then that's even better.
Sharpening for customers becomes uneconomical if your main objective is accuracy, the repeatability and consistency are more important as speed of process becomes an important factor.
I am not advocating prioritising speed over accuracy. If you wanted to do that then get a belt grinder and learn how to sharpen super fast and not necessarily super accurate or even super repeatable or consistent.
Tormek use is never any good done at fast pace. It is a great tool to use PRECISELY because it can be used consistently and repeatably to a good level of accuracy.

Ken S

I feel like I have one foot on each side of this debate. I want to state up front that I do not intend to be critical of either side. Nor do I feel that the two sides are mutually exclusive.

I have a hobby interest in precision machine shop measurement which predates my starting with my T7 by many years. My interest in automating accurate jig setting with my Tormek actually predated the kenjig. It began with chisels and was designed to eliminate the need for measuring each tool. The kenjig uses the concept of gage blocks. The highest quality gage blocks are capable of accurate measurement within a very few millionths of an inch. Naturally baltic birch plywood kenjigs are nowhere near that accurate, although I am certain that they can give digital calipers a good run for the money. I understand the desire for maximum precision.

On the other hand, I also appreciate the desire for practical sharpness as expressed by Stig in his online class.  I feel that knives sharp enough for the Swedish Culinary Team meet or are beyond my needs. I was an early convert to BESS, although my goal is sharpness adequate for my needs instead of meeting a number. I make no claim to being very scientific, nor do I criticize those who are.

We have different sharpness expectations. I support this diversity. A "farmers market" sharpener sharpening many knives at $5 each fulfills a valuable service. So does the sharpener who strives for optimal excellence typical of Wootz. We must not forget the home sharpener who sharpens knives for himself and his spouse. I want our forum to serve all of our needs.

Ken

Perra

I agree with you Ken. Different ways to reach a sufficiently good result must be good. I think Sir A has several good and wise points as well. And sometimes I think it's good to fall down a rabbit hole to learn. Sometimes I joke and call it a mess tester when people want to compete in "Bess" it looks like a deep rabbit hole at the end. Sorry for the bad English but it's a joke!

Cbwx has a good point of view with "wouldn't you get the same result if you didn't adjust for this error?" If you always measure with a small error, the result will always also have the same small error. This can become perfectly acceptable if you continue to "measure wrong" over time and accept the small error.

I think Ken agrees with this. -If you want useful results from measurements, you have to measure with the same technique every time, it is the difference between the measurement results that is most important. do not change the measurement method, you will soon not know what the results mean.

I very much appreciate your answers and that you challenge and develop issues with your experiences. Thanks

My problem is probably that I like rabbit holes! Maybe I'm a little crazy. Or much!
As an old retired engineer with long experience from manufacturing tools, jigs and prototypes, I have a built-in interest in solving problems and taking on every challenge. Sharpening knives, drills and similar tools is now my hobby but I enjoy just as much solving any problem I come across and trying to make a tool or jig for it.

And now I may have fallen down a new rabbit hole. An old friend of mine, very good knife sharpener, came to me and asked if I could build him a simple jig to set his knife angles but without having to use calculators or measure wheel sizes, usb height or other measurements. He doesn't use computers or smartphones that much and is quite analog. But he has discovered a need to be able to know what angle he is grinding with and to be able to set a specific angle. And he is not comfortable with Tormek's anglemaster on knives.
Has anyone of you worked with the same "rabbit hole" sorry! and maybe have ideas about solutions.
I have come a little way and am in the process of testing a prototype that can handle an accuracy of approx. 0.5 degrees right now.

Ken S

Good post, Perra.

Similar to your helping your friend, my interest in automating jig set up with the Tormek began in 2009 by wanting to help a forum friend. He was a good fellow up in years with a keen mind and visual limitations. Fortunately, the Tormek is quite adaptable with innovative users.

I look forward to your innovations.

Ken

Dutchman

Quote from: Perra on December 19, 2022, 01:19:46 PM... snip
... a prototype that can handle an accuracy of approx. 0.5 degrees right now.
I'm curious, show it. An accuracy of 0.5 is certainly good enough.
The black marker method can be used for re-sharpening.

Ken S

In industry, tolerance ranges are well established. Different grades of threads have well defined tolerance ranges. (See the link for a description of this:
https://www.boltscience.com/pages/screw8.htm) Fits have different tolerance ranges depending on whether the two parts must slide of remain in place.

Bevel edges on knives or woodworking tools do not have to mate with another part. We want our edges to be sharp. We want our bevel angles to be in an appropriate range for the intended tasks, and we want double bevels to be visually "matching" to the naked eye.

Ken

PS. I believe in the old maxim that a rising tide raises all boats. Regardless of our individual sharpening expectations, we are all indebted to the intrepid forum precision pioneers who continue to push back the frontiers of sharpening.