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Ionut's Small Knife Jig

Started by Herman Trivilino, March 10, 2013, 09:13:50 PM

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Herman Trivilino

I got your phone message, Elden.  Do you want me to call you back?
Origin: Big Bang

Herman Trivilino

Elden, what kind of pipe are you using?  I'm guessing black steel.
Origin: Big Bang

Ken S

Herman, your comment about the jig wearing down reminded me of a conversation I had with David Keller, inventor and seller of the excellent Keller jigs.  David knew his jigs occasionally ended up on the wrong side of a meeting with a router bit, and suggested a liquid welding type product for field repair.  I did that and it works fine.  (Your bondo experience, I suspect, is quite similar.)

Ken 

Herman Trivilino

Bondo has many applications, Ken.  It can fix just about any screw up where appearance doesn't matter or paint will be applied.
Origin: Big Bang

Elden

Herman, no your post answered my question.
Yes, it is an old piece of black pipe.
My son went to plug the welder in for me and pulled the plug off the electric cord of the welder. I had had him put a new one on it recently. He obviously hadn't tightened the lugs down well enough. So I'm stalled out for the moment as he left for his senior trip. :(
Elden

Herman Trivilino

#65
Just as well, Elden.  I thought of a modification.  In between the pipe and the plate you could weld a scrap piece of metal so there'd be a larger distance between the US and the plate.  That way knife handles won't hit the US.



Last night I was sharpening one of those "Swiss Army Knives", you know, the type with a corkscrew, scissors, frying pan, and just about anything else you can think of all folded into the handle.  The handle is so wide it hit the US when I was sharpening the blade tip.

I have to say, though, that this jig is marvelous.  The blade on this knife had obviously never been sharpened.  With a magnifier I could see the machining marks from the factory still on the surface of the bevel.  Also, the blade hadn't suffered any damage, no nicks at all.  It was just dull from regular use, plus there was no way it could have been razor sharp from the factory with those machining marks on there.

I used the angle master to measure the angle.  It was 35o so I set the jig at 17.5o.  Then I put the blade on the jig and measured the angle to the top surface of the blade, it was 22.5o so that means the blade is wedge-shaped with an edge angle of 5o.  I readjusted the jig to an angle that was smaller by half that much, or 15o

If you're having trouble following the math, that's 17.5o - 2.5o.

With the grindstone prepared fine I ground the edge.  It took only a couple of passes because I had reproduced the original edge angle so precisely.  I removed very little steel from the knife blade and restored it to a keen edge.

The precision of the Tormek is astounding!
Origin: Big Bang

Elden

Thanks Herman. I hadn't thought of getting into the USB as I thought the handle would be in front of it. I'll plan on a spacer.
Elden

Herman Trivilino

I made a wooden version of the small knife jig today.

Origin: Big Bang

Herman Trivilino

This is the same as the previous version, and attaches to the base of the scissors jig using the same two screw holes.  It has the advantage of being thicker so that the knife handles won't hit the universal tool support.

I've added another feature, which you can see in this view.  It's a small brass strip that can by used to index the position of the jig on the scissors base.  The intention is that in future versions it might be possible to use only one screw to attach the platform to the scissors jig.


Origin: Big Bang

Herman Trivilino

In this photo you get a better view of how the brass plate functions.  It hangs below the wooden platform so that it can placed up against the side of the scissors jig base.


Origin: Big Bang

Herman Trivilino

Quote from: kb0rvo on March 15, 2013, 08:26:48 PM
Thanks Herman. I hadn't thought of getting into the USB as I thought the handle would be in front of it. I'll plan on a spacer.

Elden, the handle hits the universal support when sharpening the knife tip, but only if the tip is curved too much, the knife handle is too wide, and the blade is just the right length.
Origin: Big Bang

Elden

Makes sense. Thanks for the suggestion of the spacer!
Elden

Herman Trivilino

You're welcome, Elden.  I'd like to see how it turns out.  I hope you can show us pictures.

And I'll be particularly interested in hearing about your sharpening experiences with it.

I've run out of dull knives to use on mine!  I've sharpened every paring knife and every pocket knife I can find.  Plus the only machete I own.  Next I plan to try it on a kitchen knife, a knife that you'd normally sharpen using the SVM-45.  You know, that "other" knife jig.  ;)
Origin: Big Bang

Ken S

Herman, I am curious to know your results sharpening regular kitchen knives with your new jig.  Do keep us posted.

Ken

Herman Trivilino

I sharpened a six inch kitchen knife yesterday.  It's large enough for the Tormek knife jig, but I used mine anyway.

It had been sharpened to 40o but I wanted to change it to 30o because I'd read somewhere that that was a better angle for kitchen knives, plus I wanted to see if I could get it as sharp as that Victorinox knife I bought a few weeks ago.

I started with the grindstone rough then finished it fine.  Polished the bevel on the leather wheel.  Success!  It cuts through paper as smoothly as the Victorinox.   :)

Now, if that Victorinox ever gets dull I'll have a chance to do a real comparison.
Origin: Big Bang