Prototype of a self-centering knife jig

[Jan]

My prototype of a self-centering knife jig for Tormek was inspired by the knife clamp for Lansky controlled-angle system. See the thread Clamp of the week at https://forum.tormek.com/index.php?topic=3792.0
The original Lansky knife clamp is not fully suitable for the use on Tormek USB, because it is of subtle construction and clamp width is 1" only.

I used similar design, but made the clamp from robust steel brackets of 4 mm = 0.16" thickness and 40 mm = 1.6" width. My jig, similarly to Tormek knife jig, has an adjusting screw (M6) and a tightening knob, also M6. The edges of the jaws are tapered at an angle of 15⁰. Between the jaws they are two pairs of guiding pins. The length of the clamp is circa 120 mm ≈ 4.8".

My jig has no adjustable stop, the edge angle is set with the Microadjust on the Universal support.

The major advantage, compared with the Tormek knife jig, is its self-centering property. The jig is able to accommodate quite thick blades and even cleavers.  You can also symmetrically mount blades which are tapering from spine to the edge.

For the time being I am collecting experience how the jig behaves during sharpening of the tip, using lifting and pivoting. Based on my first tests, the jig behavior is not so different from the standard Tormek knife jig as I was expecting.

Jan

P.S.: Some holes in the clamp were inherited from its bracket past and have no function now. 

[cbwx34]

Very cool! 😎 👍🏼👍🏼

Just want to add... it goes with what I've said before... this doesn't have to be an expensive, complicated endeavor.  What's the old saying... sometimes the best solution is the simplest!   

[Ken S]

Well done, Jan!

Ken

[Jan]

Thank you CB and Ken! CB you are correct, this jig can serve as an example that simplest solution may be the best solution. 

There is of course enough space for different improvements, esp. in forming the part of the clamp which is in contact with the USB and determines jig response to lifting and pivoting. Also notching the jaws may be considered.

Jan

[Jan]

I was waiting for years, like Simeon in the temple, for a simple self-centring knife jig that I could make myself in a modestly equipped workshop. This jig is really so simple, that everybody who has a drill press, file and screw tap, can make it. (To be fair, for tapering the edges of the clamp I used bench belt sander.)

When you make the clamp from a flat steel stripe of 5 mm = 0.2" thickness, slightly longer than my 120 mm, than you will be able to use almost the same USB setting as the kenjig.

Jan

[cbwx34]

The only thing I noticed, looking at your measurements, is now we're back to a pivot point, about as wide as the original Tormek Stop Collar? 

Still, I suspect for many, "self-centering" might be the more important feature between the two options.

[Jan]

CB, your observation is correct. The equivalent width of my jig is comparable with the size of the Tormek collar.

For me, who is sharpening mainly longer restaurant and kitchen knives it is not a problem, but for shorter knives with significant curvature in the belly to tip area it may be a problem.

There is an open room for improvements here. Eg. the end part of the clamp, which is in contact with the USB, could be narrowed in a suitable way without compromising the self-centring property of the jig. 

Jan