Testing blade sharpness with paper?

[ken hatch]

Testing just starts the dulling early.

ken

[James Pallas]

The instant you put it to work you will know. It's a good feeling when you sharpen and go to work with confidence. Every once in a while it doesn't work. You either missed a step, tried to shortcut, or something is awry.
Jim

[Bill Houghton]

Test it on the wood.

Well, yes, that'll be the final test. But I find it handy to have a test before the iron goes into the plane. I generally test the edge by "ticking" it against my thumbnail. I've tried the paper test in the past, and maybe I should think about it again; but my thumbnail's always conveniently there - no need to look for it.

[Doug Hepler]

John Jordan,

Yes, that's what I was referring to as a maximum force gauge. You are of course guided by your own interests and needs. I think a simpler thread test is easier. Make a loop 40 weight rayon thread and attach it to a weight (say 60-100 grams). Twenty U.S. nickel coins or 40 pennies weigh 100 grams. An edge that cuts the thread (without slicing) at 65 grams is super sharp, sharp enough for easy woodcarving. 85 g. is sharp enough for almost any woodworking task.

Brian,

I understand your point. I see that opinion expressed a lot. Basically I agree that cutting wood is the point of sharpening. However, it's all too easy (and a bit condescending) for an experienced hand tool woodworker to say that. Lacking your level of experience, one has to have a starting place to know what sharp enough feels like.

Doug

[John K Jordan]

The Sharp Check guy said they found single-edge razor blades to be consistently close to 50 grams. I saw that too when I tested my little tester when I first got it. Maybe I'll compare their calibrated monofilament thread with the 40 weight rayon thread you mentioned.

I like having the numbers to compare. Better than "shavin' sharp", not quite traceable to the bureau of standards.

Yes, that's what I was referring to as a maximum force gauge. You are of course guided by your own interests and needs. I think a simpler thread test is easier. Make a loop 40 weight rayon thread ...

[Jim Koepke]

What a way to spend time in the shop today, taking pictures of sharpness tests.

Here is one of my favorite paring chisels, a 1" Buck Brothers:

First Trim EG.jpg

This is right out of the drawer. It was a little chattery. The results tell a bit more:

First Trim EG Results.jpg

You can see whitish lines were the blade trimmed the end grain. This is caused by little nicks or rounded parts on the edge.

Here is the blade after being sharpened:

After Sharpening.jpg

The difference in the surface at the top compared to at the bottom is very noticeable.

For the record this blade is honed at 15º.

This blade will also slice paper:

Slicing Paper.jpg

This paper is about the same as copy paper.

This edge would cut arm hair with a little resistance, pulling. My stones would likely need a session of flattening to get the edge any better.

My main use for thin shavings is to set the lateral on a plane:

Unequal Shavings.jpg

It is much easier to compare thin shavings than thick. Also with thin shavings it is more likely one side will cut and the other will not.

The other use of course is in the prevention of tear out. Super fine shavings do not pull out big divots from a surface.

jtk

[Tom M King]

The reason I like stones with "feel" is so I don't have to bother to test. I used oil stones for probably 30 years before going to water stones most of the time. The oil stones still give me the best feel, but having learned that feel on them, I can transfer it to water stones that I like. For this reason, I have no liking for diamond stones, or hard stones.

When the edge feels like you're slicing down into the surface of the stone, it's done what it's going to do. This is easiest of straight edged tools, like chisels, but does carry over to cambered irons if you have watched the swarf being taken all equally all across. This feel tells you when you can go from one stone to a finer stone too.

I don't even feel for a wire edge.

[Frederick Skelly]

You guys are great! So many good thoughts here. Thank you all, again!
Fred

[Rob Luter]

The reason I like stones with "feel" is so I don't have to bother to test. I used oil stones for probably 30 years before going to water stones most of the time. The oil stones still give me the best feel, but having learned that feel on them, I can transfer it to water stones that I like. For this reason, I have no liking for diamond stones, or hard stones.

When the edge feels like you're slicing down into the surface of the stone, it's done what it's going to do. This is easiest of straight edged tools, like chisels, but does carry over to cambered irons if you have watched the swarf being taken all equally all across. This feel tells you when you can go from one stone to a finer stone too.

I don't even feel for a wire edge.

I find the tactile response element missing with the abrasive films I use. I feel myself getting closer to the water stone rabbit hole.

[Tom M King]

I agree. No feel from films. They are handy to have for many uses though, even for things like polishing hydraulic cylinder rams to get rid of specs of rust before lubing, and shafts or bushings that seals go on.

[John K Jordan]

I find the tactile response element missing with the abrasive films I use. I feel myself getting closer to the water stone rabbit hole.

For chip carving knives I use fine abrasive strips. Works extremely well (at least for chip-carving knives!) The method substitutes procedure for feel, basically by counting strokes. The finest strip is 3 micron. BTW, these strips are the best I've seen - the adhesive backing "paper" is a strip of tough plastic or some kind, thick enough to insure a flat surface.

I like their method of mounting four strips on the edges of a square.
https://www.youtube.com/watch?v=mmUn2EXLocs

I bought extra strips from them. I want to get some full sheets to use in the in my little machine shop. https://mychipcarving.com/product/abrasive-strips/

JKJ

[ken hatch]

I find the tactile response element missing with the abrasive films I use. I feel myself getting closer to the water stone rabbit hole.

Rob,

Come on in the water is fine. Truth is good usable JNats are not much more expensive than some of the man made waterstones if you stay away from collectable stones.

ken

[Brian Holcombe]

Brian,

I understand your point. I see that opinion expressed a lot. Basically I agree that cutting wood is the point of sharpening. However, it's all too easy (and a bit condescending) for an experienced hand tool woodworker to say that. Lacking your level of experience, one has to have a starting place to know what sharp enough feels like.

Doug

I disagree. The purpose of going straight to the wood is to cutout the confusion associated with testing. The wood tells you everything you need to know immediately and a beginner is better off taking the blade in and out as many times as necessary to get it right. It will improve their ability to reset their plane.

Familiarity with process is just as important, if not more important than ultimate sharpness.

Furthermore cutting a piece of paper doesn't tell you if you're raising the bevel too highly, but putting the iron back in the plane and attempting to cut wood certainly does.

It seems to me, no different than sharpening a saw. You wouldn't likely test a saw on a piece of paper since it makes sense to cut a board with it.

[michael langman]

I can look at the edge with a loop in light and examine the edge for sharpness. And feeling the edge with my fingertips . Mostly I will just use the tool after going through the steps of sharpening and the tool is sharp enough for most work.
I have cut paper once or twice for the heck of it, but not to check sharpness anymore.

[ken hatch]

I disagree. The purpose of going straight to the wood is to cutout the confusion associated with testing. The wood tells you everything you need to know immediately and a beginner is better off taking the blade in and out as many times as necessary to get it right. It will improve their ability to reset their plane.

Familiarity with process is just as important, if not more important than ultimate sharpness.

Furthermore cutting a piece of paper doesn't tell you if you're raising the bevel too highly, but putting the iron back in the plane and attempting to cut wood certainly does.

It seems to me, no different than sharpening a saw. You wouldn't likely test a saw on a piece of paper since it makes sense to cut a board with it.

Brian or maybe it should be for Doug,

For those reasons along with the need to learn to see and feel sharp plus testing can degrade the edge. Bottom line it's counterproductive unless sharpening and testing is what blows your skirt.

ken