Sharpening angle for showing off

[Rhino]

I want to sharpen a small knife as sharp as can be for showing off.  Just for fun.  It will be for show only.  I guess it would be for cutting paper, tomatoes and other demonstrations.  I won't use it on meat, bone and I won't let it cut an orange seed or an apple seed.

So just for the purpose of showing off, what angle should I use?  I suppose I can use a single bevel blade - like a Japanese knife and maybe 15 degree bevel on the bevel side.  So that would be a total of 15 degree angle at the cutting edge.

If anyone have a good suggestion for demonstrating sharpness - for showmanship, not for practical purposes like cutting wood or even food - please let me know.

Just having fun this summer.

[Herman Trivilino]

It depends on the steel, Rhino.  Go with the smallest angle that will produce satisfactory results.  There are two issues here.  One, the steel has to be able to tolerate being ground at such a small angle.  Some steel will break along the edge due just to the forces applied during the sharpening process.  Obviously, these knives will have to be ground at a more blunt angle to produce a sharp edge.

The other issue is the steel's ability to hold an edge when it's very thin like that.  You may find that the knife is sharp when you do your first demonstration, but will quickly dull and future demonstrations will not go so well.

You'll just have to experiment.

If you plan on grinding the bevel on just one side you will of course have to make sure the other side of the blade is flat and polished.  Just like you would a chisel, but I'm sure you know that.

[Rob]

copying the thinking behind my global knives which are amazingly sharp....I would try 7%.  If that doesn't work, go up in 5 degree increments till it holds an edge but is still stupidly sharp.

[Rhino]

Thank you so much.  I'll give both your advice a try.  I think it will be a fun project to make something crazy sharp for paper.

[Jeff Farris]

Depends on what you're showing off and how you do it. Steering control says more to me about how an edge works than just about anything else. I used to cut 3/4" circles out of paper with a 13" chef's knife. That kind of steering type of cut is going to be easier with a bevel on both sides of the blade. Japanese single bevel knives excel at taking incredibly thin slices off things, but balk a little if you try to steer the cut.

You need a knife that has good steel, a bevel designed to your style, and a thiiinnnn blade. You can put that paper cutting edge on a  heavy knife, but it's technically more difficult and not very practical.

[Rob]

There's a few years in the game behind that post 

Nice one Jeff.

[Rhino]

Jeff,

Thanks.  I haven't thought of that.  I'll especially like the idea of cutting small circle in paper.  I'll let you all know how it turns out.

Eric

[Herman Trivilino]

Japanese single bevel knives excel at taking incredibly thin slices off things, but balk a little if you try to steer the cut.

I'm watching the movie Goodfellas and I'm at the scene where the wise guy is slicing the garlic so thin it dissolves in the frying pan with a little oil.  I'm gonna have to get one of those Japanese knives and give that a try!

[Rob]

bada bing......bada boom :-)

[grepper]

I've found if you want to do the paper show off thing, you want a perfectly clean, highly polished edge.  Any imperfection such as a burr fragment can cause the knife to hang and wreck the show.

Get the grinding wheel as smooth as possible for the final sharpening.  Any small grit pieces on the wheel can cause micro scratching on the cutting edge.

Put a fresh coat of the wonderful magic Tormek honing compound on, and then strop until you get a mirror finish.  Use the jig to insure against rotating the blade over the edge and dulling the edge.

Looking at edges at 200X magnification shows that even after stropping there can be tiny fragments of burr left along the edge.  Sometimes they have folded over and are flattened against the edge.

Very gently dragging the edge over the corner of a piece of soft wood, with the grain, seems to remove these burr remnants.  Under a bright light or sunlight, rock the knife slowly back and forth with the edge up so that the light reflects off of the edge.  If you see any little shiny sparkles, there are still burr fragments there.

Very gently drag the knife through the paper pulling from heel to tip.  Notice any grabbing?  If so, recheck the edge there as there very well may be some imperfection there.

Try different types of paper.  Some paper is very difficult to cut cross fiber.  Some paper types have uneven fibers that could cause a problem for the show.   I like to use the very thin shiny paper from some catalogs.  While blades glide through 3 sides of it, It is very difficult to cut along one side.  The difficult side is the side I use for testing.