tall tales of sharpening.

Cliff Stamp · Dec 16, 2006

Tai Goo said:
I'm not sure what the "push cutting toilet paper" is, slicing a sheet, or pushing the blade through a whole roll against a cutting board.

Push cutting toilet paper is the same as push cutting newsprint. A single piece of the paper is held with one hand and the knife brought down perpendicular with the other hand and pressed through the paper with no draw. Slicing the paper demonstrates a much lower sharpness, pushing through stacks is more a demonstration of geometry than sharpness.

-Cliff

Vorpal Blade · Dec 16, 2006

Cliff Stamp said:
Push cutting toilet paper is the same as push cutting newsprint. A single piece of the paper is held with one hand and the knife brought down perpendicular with the other hand and pressed through the paper with no draw. Slicing the paper demonstrates a much lower sharpness, pushing through stacks is more a demonstration of geometry than sharpness.

Live and learn! That makes alot more sense than the what I pictured:-- pushing the blade edge against the edge of a short, free hanging strip of toilet paper. Thanks for the explanation.

gunmike1 · Dec 16, 2006

GibsonFan said:
Well, these things happen...

Personally, I sharpen till it shaves hair off my arm or leg and leave it alone. But that's because I use my blades for things other than toilet paper, and don't really see the point of making the edge that thin. My knives cut paper, cardboard, meat, tomatoes and wood just fine, and I don't baby them.

It's interesting stuff to read though, mostly to see how fine of a finish different steels will take. But I regard it much the same as I do arguments of sub-minute-of-angle rifles; don't need it, don't care.

That thinly ground Fallkniven U2 Cliff lent me does all of the things you mention with no problems (except the wood, I haven't and probably won't try that), even with an edge under .005". The key is not to twist the cut, just keep it controlled and straight (which is easy considering the sharpness and how thin the stock is). If you do twist it out of a tough cut you would probably end up with a new serration on the blade. It is interesting to note that even at the spyderco medium finish this knife can shave above the arm, and that you can get pushcutting edges at coarse finishes if you form them right and remove the burr. Since that knife has such a thin angle a given finish will seem much more coarse than on a standard angle, so I bring it up to the Spyderco ultrafines and strop it. It is good to remember though, that the better your knife pushcuts AT A GIVEN FINISH, the better your edge retention will be. Since your knives can shave they are obviously pretty sharp.

As for the sub MOA rifles, I know a thing or two about them also. My customized Remington PSS will shoot well under 1/2" at 100 yards from the bench (off a bipod, no other rests or supports) with my handloads, but in the field a cheap Savage or lower end rifle with cheap ammunition will kill a critter just as dead. I bought that rifle mainly to challlenge myself to shoot tiny groups, but I do carry it to the field and have extreme confidence in it if I need to take a long shot. However, in 99% of the hunting situations I've seen in my area a good old lever action .30-30 would have worked just fine on the tiny things we call deer here in northern California.

Tai Goo · Dec 16, 2006

Cliff Stamp said:
Push cutting toilet paper is the same as push cutting newsprint. A single piece of the paper is held with one hand and the knife brought down perpendicular with the other hand and pressed through the paper with no draw. Slicing the paper demonstrates a much lower sharpness, pushing through stacks is more a demonstration of geometry than sharpness.

-Cliff

O.K. Thanks. I wasn't sure. I've done it with the newsprint and even a cigarette rolling paper, but not the sheet of T.P... something to shoot for I guess.

Tai Goo · Dec 16, 2006

I don't have a DVD yet but here's some pics of a few cuts that I have been able to make without too much trouble,... just some hand stones and a cork/paper composite strop.

The standing hair.

Freestanding rolling paper tube with a "swipe" cut.

Five rolled tubes of phone book paper with a "swipe" cut.

hardheart · Dec 16, 2006

smegs · Dec 16, 2006

My test for sharpness involves a strip of toilet paper about a foot or so long. I pinch the top, let it hang and pierce the sheet near top center. If I can slice down the sheet with no tearing or bunching under the blade, I'm good to go. I like this test because blade geometry doesn't factor in that much. Sometimes edges that I thought were optimal and were hair popping would fail this test.

Tai Goo · Dec 16, 2006

smegs said:
My test for sharpness involves a strip of toilet paper about a foot or so long. I pinch the top, let it hang and pierce the sheet near top center. If I can slice down the sheet with no tearing or bunching under the blade, I'm good to go. I like this test because blade geometry doesn't factor in that much. Sometimes edges that I thought were optimal and were hair popping would fail this test.

Cool!

What's your honing method and toilet paper brand? I've always used quilted double ply Charmin as the standard. :jerkit:

I like a nice soft T.P. for my ass wipe!
http://www.charmin.com/chm_gateway.htm

Broos · Dec 16, 2006

That's some nice cuts, Sir. The cigarette paper cut is neat.

Cliff Stamp said:
pushing through stacks is more a demonstration of geometry than sharpness.-Cliff

Geometry is important, but when I've tried it the edge had to be sharp for a good cut, as well.

Here's a few very poor quality pics, 1st two are a horizontal cut into regular paper - tough to tell but it cut cleanly. Couldn't do the same with phone book paper last night, though. Last one is an attempt to keep the paper standing. Didn't make it but a cool shot. The knife is thanks to Mr. Phil Wilson.

None of mine will push cut charmin extra.

Tai Goo · Dec 16, 2006

Geometry effects "EVERYTHING"!

smegs · Dec 17, 2006

Tai Goo said:
Cool!

What's your honing method and toilet paper brand? I've always used quilted double ply Charmin as the standard. :jerkit:

I like a nice soft T.P. for my ass wipe!
http://www.charmin.com/chm_gateway.htm

EdgePro mostly. Touch ups on the Sharpmaker. After about 4 or 5 touch ups it's back to the EdgePro. Since I start the cut by piercing the tp first, it's nowhere near the test of those paper rolls but the edge seems to hold up longer when that level is reached. I guess what it really shows is a well formed crisp edge. Oh yeah, the tp is Scott two ply or industrial stuff at work. Ouch. Haven't tried Charim yet.

Dog of War · Dec 17, 2006

Who'd have thought a bunch of manly knifeknuts would insist on the gentle softness of Charmin Ultra?

Cliff Stamp · Dec 17, 2006

Tai Goo said:
... not the sheet of T.P.

I have not seen it either personally, but I don't in general focus a lot on high polishes. I am getting some knives made shortly which are specifically intended to optomize that type of performance so I'll try a shapton or high finish paper on them and see what happens.

[book cutting]

Broos said:
Geometry is important, but when I've tried it the edge had to be sharp for a good cut, as well.

Yeah, the edge has to be sharp, but as soon as the blade actually moves past the first sheet you are no longer testing sharpness but just the cutting ability as influenced by geometry.

-Cliff

hardheart · Dec 17, 2006

could someone math savvy estimate what edge width you need to push cut TP? I wouldn't know where to start, but there has to be a way to give an estimate. the more i think about it, the more I want that little piece of black glass, just to see how it does against 2-ply... it's official, I'm weird.

Cliff Stamp · Dec 17, 2006

The better sharpened knives I have seen were at the point where it looked like it would be possible and they were not on ideal steels. The sharpest measured knife edges I have seen recorded are 0.1 micron and most consider anything up to 1 micron to actually be sharp. Ideally you would want something like 13C26, 1095, etc., at 64-66 HRC and finish with sub micron boron carbide or diamond.

-Cliff

Tai Goo · Dec 17, 2006

There’s really no mystery to sharpening. The way I see it, there’s only three key variables, or points of reference,… the angle, the grit and the burr. After that it’s just a matter of what materials you are trying to cut and the techniques you are using.

I like natural oil stones and free hand sharpening. I use a Norton combination bench stone, soft, hard and black hard Arkansas whetstones. The best thing I’ve come up with for stropping is a wood paddle with 1/8 inch cork and watercolor paper laminated to the surfaces. One side is charged with a course stropping compound and the other fine side with Simi Chrome or MAAS crème. I like the paper stropping surface better than leather, but it's not quite as durable. It goes about a year before it wears out.

Cliff Stamp · Dec 17, 2006

Tai what steels do you generally work with and have you noticed any difference in them in terms of ultimate sharpness.

-Cliff

thombrogan · Dec 17, 2006

I'm not Tai, but most of his knives seen over at Don Fogg's place were 1065 with a few 5160.

matt321 · Dec 17, 2006

There’s really no mystery to sharpening. The way I see it, there’s only three key variables, or points of reference,… the angle, the grit and the burr. After that it’s just a matter of what materials you are trying to cut and the techniques you are using.

Tai,
I'm thinking that the angularity or sharpness of the abrasive grit and the type and heat treat of the blade steel are important too. I've been working 420HC with sharpmaker ceramics and I am starting to think that the ceramic stones tend to push the steel around without cutting clean.

Tai Goo · Dec 18, 2006

Cliff Stamp said:
Tai what steels do you generally work with and have you noticed any difference in them in terms of ultimate sharpness.

-Cliff

I've worked with a wide variety over the years, (29 years professional), air, oil and water hardening steels of high, medium, and low carbon. About 6 years ago I moved to a more basic open air blacksmith type shop, and started working more with spring steels and simple steels again.

The knives in the pics are 1095. It's a little bit harder to get that type of edge on 1065 or 5160.

I do think that some steel alloys are easier to sharpen and maintain the edge on. This may give the illusion that they will obtain a higher degree of sharpness.

I think the heat treating is also a definite factor. If there is abnormal grain, the steel is too soft or too hard, it can make it difficult if not impossible to get a really keen edge on.

However,... I don't consider "steel selection" and "heat treating" as parts of the sharpening process.

What I look for is a blade that's easy to sharpen,... AND holds an edge well. It's the ratio between edge holding and ease of sharpening that's important to me.

In a very real sense, sharpening is a test. You can tell a lot by the way the burr and edge behave.