Knife Jigs Solution

[wootz]

Hi Jan,
The pictured is 1mm off, and it is not the latest slim knife jig.
I can't say if it would be possible to grind 1mm off the thinner jaw in the new version of the jig.
We haven't got them here in Australia yet.

[Ken S]

Wootz,

Do not despair. The longboat left Sweden two weeks ago. With favorable winds, you should have one soon. 

Ken

[wootz]

Ken, how is it possible that you can be so hilarious and helpful at the same time?

[Ken S]

A little levity helps lubricate the serious work to be done. 

Ken

[RickKrung]

Tormek Knife Jig SVM-45 has 1.25mm spacing from the centreline of the handle to the bottom of the knife

Cross posting some discoveries I made today about the offset from centerline of my SVM-45 and 140

https://forum.tormek.com/index.php?topic=3445.msg21498#msg21498

Rick

[wootz]

I take occasion to wholeheartedly thank Rick for his measurements of the new SVM-45 knife jig.

The old Tormek Knife Jig SVM-45 has 1.25mm spacing from the centreline of the handle to the bottom of the knife clamp.
The new thinner Tormek Knife Jig SVM-45 has 1.054mm spacing from the centreline of the handle to the bottom of the knife clamp.

The old SVM-45 knife jig gives ideally symmetric bevels on the blades 2.5mm thick at the spine;
while the new SVM-45 knife jig gives ideally symmetric bevels on the blades 2.2mm thick at the spine.

Simpler than shims method is putting on the spine at the clamping site layers of cloth tape to match the ideal thickness. After a few trials, I found that the Norton Bear 50mm cloth tape is best for that (and also protects the blade from scratches left by the jig jaws).

[RickKrung]

You know what grinding marks look like...  Those are end mill cutter marks.  That is how I would have machined your jig, if I were the one you brought it to. 

Rick

[wootz]

The lesson learned today is measure your own jigs offset using Rick's clever method
https://forum.tormek.com/index.php?topic=3445.msg21498#msg21498

[wootz]

@RickKrung
Rick, you are a bloody genius.
I've remeasured all the jigs I have using your method and had to correct offset for each.
My bevels should be perfectly symmetric from now on.

[Jan]

I have to add my 0.02.

Based on my measurements the newer (zinc) knife jig the offset is 1.0 +/- 0.2 mm. https://forum.tormek.com/index.php?topic=2577.30

The large uncertainty in the offset estimation lead me to estimate the value by a deductive way.

I have assumed that the Small Knife Holder works symmetrically with respect to flip. Because the steel guide bar (1) of the Small Knife Holder has a thickness of 2.5 mm, I have deduced that the jig offset is 1.25 mm.
https://forum.tormek.com/index.php?topic=2577.msg15232#msg15232

Correctness of my value 1.25 mm was not confirmed by Tormek.

Jan

[wootz]

I can only rebuke myself for forgetting that assumptions is the mother of all f*ckups.
Rick's method to measure knife jig offset has eliminated guesswork completely.

[cbwx34]

Thanks for all the work and update.

But this thread really shows the need for a self centering clamp. 

Hopefully Tormek is paying attention... and will come out with one, like many of the other clamped sharpening system have.... 

(... and fix that crazy wide jig stop too). 

[Jan]

Rick, attached there is an image of the static knife jig clamp. The surface is not planar. One feature is the threshold denoted C. Other features are the two very slightly raised strips denoted as A and B. The area D between those stripes is below the level of the point E! (I am describing a new zinc jig.)

What we really need is to measure the spacing between the centreline of the jig shaft (at a place where there is the jig stop, not at a point E) and the slightly raised strip A or B near the bottom of the knife clamp.

To make such measurements reliably and repeatedly was beyond my limited possibilities and that was the reason for my adoption of the spacing 1.25 mm.

Jan

[RickKrung]

Rick, attached there is an image of the static knife jig clamp. The surface is not planar. One feature is the threshold denoted C. Other features are the two very slightly raised strips denoted as A and B. The area D between those stripes is below the level of the point E! (I am describing a new zinc jig.)

What we really need is to measure the spacing between the centreline of the jig shaft (at a place where there is the jig stop, not at a point E) and the slightly raised strip A or B near the bottom of the knife clamp.

To make such measurements reliably and repeatedly was beyond my limited possibilities and that was the reason for my adoption of the spacing 1.25 mm.

Jan

Jan,

I agree, mostly.  Using a straight-edge, it appears to me that points A and B are on the same plane as the whole surface between C and E.  It appears to me that the area between A, B and C is recessed, making A and B appear to be raised.  I will use my surface plate and height gauge to confirm or refute this later today.  Using my micrometer, I have already confirmed the area between C and E is the same thickness, 0.353", at least within +-0.001".  I will have to rest the jig on parallels as there is a raised "Tormek" logo on the back of my jig.

To be continued...

Rick

[kwakster]

Thanks for all the work and update.

But this thread really shows the need for a self centering clamp. 

Hopefully Tormek is paying attention... and will come out with one, like many of the other clamped sharpening system have.... 

(... and fix that crazy wide jig stop too). 

Exactly what i've been thinking for years now.
Sometimes i think i have to buy a KME knife clamp and modify that for use on the Tormek.