Author Topic: kenjig modification for paring knives  (Read 3202 times)

Offline Ken S

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kenjig modification for paring knives
« on: July 09, 2017, 05:14:25 am »
I am making up a set of kenjigs to give to a friend. The original plan was to keep both the Projection of the knife blade in the jig (139mm) and the Distance between the support bar and the grinding wheel constant for most kitchen knives. I set my 140mm knife jig for my chef's knife; my out of production 100 mm knife jig for my slicing knife; and the regular 45mm jig for my paring knives. In order to keep the Distance constant, I had to place the paring knife and small blade tool in the regular 45mm knife jig. This works, however, I feel the small blade tool is optimized for carving knives with small blades and substantial wooden handles.

For a long time, I have thought of making a second kenjig using a Projection of 125 mm, the approximate Projection of my paring knife in the 45mm jig adjusted mid range. That thought has now become a second jig. My friend is an old hand with the Tormek, although he does not work at the hectic pace of a farmers market sharpener. He will have no trouble going back and forth between two fixed Distances.

Using Dutchman's chart for a 250mm diameter grinding wheel, and a Projection of 125mm, the Distance would be 68mm for a fifteen degree bevel angle and 75mm for a twenty degree bevel angle. I will make up one of each for him, as well as both bevel angles for the wider knives with the standard 139mm Projection.

Dutchman's well done booklet, the source of my calculations, can be located on the forum. Either do a member search for Dutchman or our forum research expert, Elden. Check their posts. Elden's post with the links is quite recent. Do not be intimated by the charts. With just a little effort, they are easy to use and a valuable reference. I have them in ibooks on my ipad and printed out.

Ken

Offline Elden

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Elden

Offline Ken S

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Re: kenjig modification for paring knives
« Reply #2 on: July 09, 2017, 01:15:34 pm »
Thanks, Elden. Your lightning fast, accurate research skills are always appreciated.

Ken

Offline bisonbladesharpening

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Re: kenjig modification for paring knives
« Reply #3 on: July 10, 2017, 10:38:22 pm »
My head just exploded.  Need pictures
Best Wishes
Tim

Offline Ken S

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Re: kenjig modification for paring knives
« Reply #4 on: July 11, 2017, 01:23:33 am »
Tim,

Look in the Tormek General subforum in page one of the Angle forty degree topic. Elden and Jan have posted links to my article with photos.

Ken

Offline cbwx34

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Re: kenjig modification for paring knives
« Reply #5 on: July 11, 2017, 02:35:03 pm »
I have a question I'll ask here, (since both parts are in this thread)...

In the "Grinding Angle Adjustment" booklet, referenced above... there's a diagram that shows "S" as a measurement from the center of the Universal Support to the stone (here's the diagram from the booklet)...



... but in the Kenjig measurements and document, as well as the charts later in the "Grinding Angle Adjustment" booklet, the measurement seems to be taken from the top of the Universal Support, (by that I mean the outer circumference... farthest point from the wheel), not the center.

What am I missing/misunderstanding here?
« Last Edit: July 11, 2017, 05:25:16 pm by cbwx34 »
Knife Sharpening Angle Calculators:
Calcapp Calculator-works on any platform
or, a couple of iOS Calculators

Offline Dutchman

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Re: kenjig modification for paring knives
« Reply #6 on: July 11, 2017, 05:32:50 pm »
The distance is measured NOT to the top NOR the center of the support. It is part of the triangle through the knife in the jig. So it should be measured to the heart of the jig just above the center of the support. Measuring the distance to the top of the support however will give a negligible error.
Please keep in mind that this subject is not an academic item, but a proposal to simplify the jig-setting  ;) Thank you :)
« Last Edit: April 13, 2018, 03:14:33 pm by Dutchman »

Offline cbwx34

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Re: kenjig modification for paring knives
« Reply #7 on: July 11, 2017, 05:55:08 pm »
Ah, thanks, that clarifies it.  I misinterpreted the drawing... and it was throwing off me trying to duplicate it, (so I could validate something I'm working on).  Figured it had to be something I was missing.

Thanks for the excellent work on the booklet BTW.
Knife Sharpening Angle Calculators:
Calcapp Calculator-works on any platform
or, a couple of iOS Calculators

Offline Jan

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Re: kenjig modification for paring knives
« Reply #8 on: July 11, 2017, 09:12:02 pm »
I have modified the Ken concept and suggested a double ended kenjig which enables to set the position of the universal support for both, the grindstone and the honing wheel.

My drawing answers your question concerning "S".

My excel spreadsheet entitled "KENJIG_wheel_support_distance_1" enables to calculate the wheel-support distance for given wheel radius, projection length and bevel angle. https://www.dropbox.com/s/ypbtaxgycgoyls0/KENJIG_wheel_support_distance_1.xlsb?dl=1

Jan
« Last Edit: July 11, 2017, 09:23:27 pm by Jan »

Offline cbwx34

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Re: kenjig modification for paring knives
« Reply #9 on: July 11, 2017, 09:55:25 pm »
Thanks for the additional info.

My mistake earlier of misreading the booklet... then trying to compensate by deducting half the support width, and going the wrong way, which made it worse... really threw things off.

It's all coming together now. :)
Knife Sharpening Angle Calculators:
Calcapp Calculator-works on any platform
or, a couple of iOS Calculators

Offline bisonbladesharpening

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Re: kenjig modification for paring knives
« Reply #10 on: July 12, 2017, 12:22:46 am »
Thank you Ken, I understand the kenjig now.
I do a lot of adjusting the jig rather than the support
arm to suit the knife.  Mainly by eyeball and feel.  I keep the 145 way further out
to accommodate thinner blades and the 45 in closer for chef knives to try and minimize adjusting the support.
Where do we get a 100mm?

Best Wishes
Tim

Offline Ken S

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Re: kenjig modification for paring knives
« Reply #11 on: July 12, 2017, 04:20:27 am »
Tim,

My three (now four) knife jig technique was part of researching the kenjig for farmers market sharpeners. The purpose was to be able to set the Distance once (while setting up for the day). The jigs would all be left approximately preset. Only occasional, minor tweaking of the jigs should be necessary. In fact, most adjustment can be made in securing the knife in the jig.

For home sharpeners, or low volume sharpening businesses, the extra jigs are unnecessary. Slicers, and chef's knives are easily handled in the regular jig. Only long and thin knives need the wider jig.

I picked up my 100mm jig on ebay. They were replaced by the 140mm jigs years ago. I chose it because I wanted a very distinctly different jig from the 140mm I use for chef's knives. I could have done the same thing with a band of colored tape.

I am glad both Dutchman and Jan replied. You have good replies from two of the forum's math heavy hitters. I say with no false modesty that my math skills have diminished in forty nine years out of high school. I am very appreciative that we have members like Dutchman and Jan.

Jan's double ended jig is one of a number advances suggested by forum members. There is great power in sharing ideas!

Keep posting.

Ken