Messages

Rick, CB, I like your solutions!

Sometimes I use my knife setter inspired by the Tormek jig TTS-100. It is designed for projection distance 139 mm and different grinding angles. The shown jig is made of two Al plates and four small ball bearings.

It works for all wheel diameters and both grinding directions. All that is needed is to generalize this concept to variable projection distance.

Jan

Five years ago I have modified the Starrett combination square for easy setting of the USB. I use it mainly for setting the top USB – stone distance, but it can be used also for setting the USB height above the Tormek housing.

The 12 mm Al sleeve is attached to the body of the combination square. The sleeve offsets the position of the universal support with respect to the zero on the ruler. This offset is compensated by the contact block made of two Al plates of trapezoidal shape attached to the square head.

I use it every day.

Jan

CB, you are correct, I agree with you.

The updated KG software uses the old, approximative Dutchman formula. For input parameters 250 mm, 139 mm and 12⁰ the top USB – stone distance is biased by 1 mm which means that the grinding angle is biased by 0.7⁰ per site.

If we add the strange jumps depending on the thickness behind the edge the bias of the grinding angle increases to some 1⁰. It is definitively not sufficient accuracy for setup of multiple Tormeks for advanced deburring.

Nevertheless when all your wheels have the same diameter you will get consistent results and small BESS score.

Jan

Jan,
The 1° error you mention, is it consistent? As an example, if what reads as 15° is actually 16° (or 14°), If the error is constant, we can either live with it or compensate for it. If that is the case, it doesn't seem any more of a problem than a mariner correcting his magnetic compass.
Ken

Ken, John,

all programs discussed on this forum are okay except those that use the old, approximate Dutchman formula.

I think they are only one or two calculators that use the old Dutchman formula, which can cause an error in the Kenjig length up to 1 ¼ mm. This error is not constant but depends mainly on grinding angle and stone diameter.  One calculator which requires blade thickness behind the edge produces unacceptable jumps in the set up parameters.

If you are in doubts do not hesitate to contact me, jvh or cbwx for comparative calculation. The major calculators are mature now and use only Euclidian geometry to calculate the set up parameters.

Jan

John,
full answer to your question would open the Pandora's box. Sometimes it is better not to open it because you can't close it again. 

Some calculators may cause an error of 1⁰ per side. When you are grinding a 15⁰ per side angle it will not strongly influence your results. When the error occurs also at the honing wheel set up it can influence the quality of some advanced deburring methods and increase the BESS score.

When a knife maker grinds a 1⁰ or 2⁰ per side primary bevel angle than an error of 1⁰ degree per side is fatal.

Jan

BeSharp,

I agree with Dutchman. As far as you are able to set up grinding/honing angle with an accuracy 0.5⁰ or better, you will get similar BESS score also if three Tormeks are used.

Jan

Tomas,

the attached picture shows how I would mount the knife in the knife jig.

For such a big knife as the G-16 the projection distance 139 mm is too small.

Tip sharpening is a trade-off between pivoting and handle lifting. If the shape of the blade corresponds well with my template, than pivoting is the dominant movement to get equal bevel on the tip.

Jan

OK, you are correct, the long blades have to be mounted in this disproportional way, which is not very suitable for sharpening the heel of the blade.

Jan

Tomas, use the knife jig SVM-45 and place the centre of the knife jig approximately 3 1/4" (8.25 cm) from the point of the knife. Test this setup with sharpie. I hope it will work fine.

Jan

CB,

thank you very much indeed! 

Jan

CB,

If I may put my 0.02$ in, the displayed USB Top to Wheel Distance is by 0.02 mm smaller than the exact value. 

It is of course fully negligible. The reason for it may be some rounding or number representation.

Jan

CB,

I suggest you publish it as a book. The title of the folding concertina book may be KenJig Calculator in Images by C.B. It would make me happy if you add a disclaimer that the maximum absolute error is 1 mm because the original formula was used. 

Even better idea may be to join forces with Ken and prepare concertina booklet "How to Build  a KenJig". KenJigs for different set up parameters could be printed as jigsaw puzzles.

Jan

John, it is definitively good to have two Tormek machines! In your situation I would use the T8 for sharpening and the T4 for honing. Standard honing is done on the leather wheel however some people use the SJ wheel for almost the same purpose. Strictly speaking SJ wheel is still grinding wheel.

Modern setup calculators, e.g. TormekCalc2, overcome the difference in wheel radiuses without any difficulties.

I recommend the Kenjig concept to your attention. Suitable Kenjig can solve most of your setup problems with kitchen knives sharpening for quite a long time. 

Jan

Ivar, if you like simple zero cost solutions you can use a wooden block with two holes for USB legs and two threaded inserts for the USB locking screws.

Jan

Yes Rick, you are correct. The apex width of 100 BESS score should be about 0.2 micron (200 nanometers).

The reference material is here: https://www.edgeonup.com/Support_Document.pdf

Jan