How sharp should chisels really be?

[adamcherubini]

I can see some chisels being really sharp that need to take off .005 of a shaving but does it really matter if you are just taking out hunks of wood or chopping out DTs or joints?

Arlin, You want all your hand tools razor sharp, especially chisels. You are right that some operations/techniques dull chisels quickly.  Ditto, some woods are harder on edges than others.  If they start razor sharp and highly polished (like a mirror), they will stay sharp longer- not because they started super sharp and end up kinda sharp, but because polished steel is stronger than scratched steel or steel with a ragged edge. When they test the strength of steel they polish it like a mirror.  Any scratch will weaken it.

[Timberwolf]

Arlin, You want all your hand tools razor sharp, especially chisels. You are right that some operations/techniques dull chisels quickly.  Ditto, some woods are harder on edges than others.  If they start razor sharp and highly polished (like a mirror), they will stay sharp longer- not because they started super sharp and end up kinda sharp, but because polished steel is stronger than scratched steel or steel with a ragged edge. When they test the strength of steel they polish it like a mirror.  Any scratch will weaken it.

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Arlin, You want all your hand tools razor sharp,

Right !!!! Why would anybody want to expend any more effort than necessary by using blunt tools ????? I have said many times, I want my tools as sharp as they CAN be for the task at hand, whether it be a mortice chisel, axe or straight razor...The material being cut determines how acute the bevel angle has to be...wood OR metal.
To me, an edge that leaves a polished, shiny surface on wood is where I want my knives to be..when they don't do that, they are too dull to be enjoyable...and the same goes for all edge tools, and I polish the edges to a mirror shine....Shaving hair on your arm isn't a good test,,,try cutting a paper towel. It takes a very sharp edge to do that without tearing...this is where the polishing pays off

[adamcherubini]

So who does a bevel angle and which ones and what degree between the very front and the back part?

I know it was a big discussion a years ago but do not remember any of it?

Cutting tool angles is complicated science. The perfect bevel angle depends on the properties of the steel, how well its honed, how its used, and in what materials it cuts.

For most woodworkers and most steels, 30 degrees is as good a starting point as any.  I typically grind 20-25 degrees, then hone and polish the cutting edge just a tiny bit higher than that. I don't like hollow grinds for a couple reasons I won't go into.

[Handplanesandmore]

Sharp enough to get the job done, but no sharper...

This is a piece of useless advice.

A blunt edge is sharper than a very blunt edge. To get the job done, one could use a screw driver, but that is the kind of advice people look for on chisels?

Simon

[adamcherubini]

I think I’d pick a nit there. When I use a chisel, it gets dull pretty quick and it continues to function acceptably. For many years I sharpened using no better than 600grit wet and dry sandpaper. I did fine. Everyone knows the difference between a tool cutting okay and a blunt object. So it’s ok to have a tool that’s only sharpened good enough. IMHO, that’s a valid viewpoint.

What experience taught me is that 10 minutes into using a tool that was sharpened good enough, performance really dropped off and I realized I needed 5 or 10 minutes of sharpening instead of 1 minute. So it’s okay to make it just good enough. It’s really fine. It’s just inefficient. And if you have bevel edged chisels and you dry grind, you really risk over heating if you aren’t careful. That’s why my answer is make them super sharp. Nicer to use and easier to maintain. But no wrong answer. I’ve sharpened tools with stones I found, I sharpen my chef’s knife on the ceramic bottom of my coffee cup!

[Handplanesandmore]

I remember a story told in a conference on employee motivation and communication:

A boy, aspiring to become a writer when he grows up, is disappointed that his stories are never given an A by his teacher. So he goes to his teacher one day and asks how he can ace in his next story. His teacher says in a-matter-of-fact tone, "When you write well enough to get an A."

Simon

[bandit571]

Note:   You can polish both the bevel and the back mirror bright and flawless.....and it still would have trouble cutting warm butter.....it is all about the meeting of the two surfaces....both can be dull as a Model T Ford in colour, and shiny, yet still be sharper than a razor on the edge....


DAMHIKT..

   
Never felt a thing...until I saw the red spots on the wood...

[Timberwolf]

Note:   You can polish both the bevel and the back mirror bright and flawless.....and it still would have trouble cutting warm butter.....it is all about the meeting of the two surfaces....both can be dull as a Model T Ford in colour, and shiny, yet still be sharper than a razor on the edge....


DAMHIKT..

Never felt a thing...until I saw the red spots on the wood...

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The bevel angle has to be at zero degrees to be as "sharp" as possible, and even if that was possible, when the edge met the wood, the angle would change instantly......no matter how hard the steel or how soft the material...so we "aim high and settle"......

[Stwood_]

This is a piece of useless advice.



Simon

That's real blunt.

[Arlin Eastman]

,,,,,,,,,,,,,,,,,,
The bevel angle has to be at zero degrees to be as "sharp" as possible, and even if that was possible, when the edge met the wood, the angle would change instantly......no matter how hard the steel or how soft the material...so we "aim high and settle"......
 

Jack

Do you mean the back has to be flat?