Second hypothesis

[bridger berdel]

I guess I'm trying to lay out some basic principles here rather than discuss technique or equipment.

So.

For any given combination of steel/wood/process there will be an optimum sharpening angle. Deviating from that angle will result in a reduced edge life. If you average out a large variety of woodworking tool edges you will arrive at something very close to 30°.


This information is useful for beginners; start sharpening at 30°.

There are other factors that come into play with edge longevity. Most will devolve into tool abuse at even moderate elongation.

Thanks
Bridger

[ken hatch]

Bridger,

Working on your syllabus?:)

ken

PS. Good plan, much better to know why along with how.

[Pat Barry]

There are other factors that come into play with edge longevity. Most will devolve into tool abuse at even moderate elongation.
What do you mean by "even moderate elongation"?

[Stewie Simpson]

What ya smoking Bridger.

[Warren Mickley]

For any given combination of steel/wood/process there will be an optimum sharpening angle. Deviating from that angle will result in a reduced edge life. If you average out a large variety of woodworking tool edges you will arrive at something very close to 30°.


This information is useful for beginners; start sharpening at 30°.

There are other factors that come into play with edge longevity. Most will devolve into tool abuse at even moderate elongation.

Thanks
Bridger

The hypothesis is ridiculous because an optimum sharpening angle might not be the one with longest edge life. Deviating from the optimum angle might increase edge life but be otherwise not desirable. Hypothesis lacks integrity.

I use 30 degrees for lots of tools. However many guys who have made videos and profess expertise are sharpening in the 35 to 40 degree range.

[bridger berdel]

The hypothesis is ridiculous because an optimum sharpening angle might not be the one with longest edge life. Deviating from the optimum angle might increase edge life but be otherwise not desirable. Hypothesis lacks integrity.

I use 30 degrees for lots of tools. However many guys who have made videos and profess expertise are sharpening in the 35 to 40 degree range.

Hmm... I may be off here. A higher than necessary angle may yield long edge life, but it will have other costs- more effort required, poor surface finish.

Part of the question would have to be what are we optimizing for. A reasonable answer would be efficient tool use.

Thanks.

[bridger berdel]

What do you mean by "even moderate elongation"?



"Take it a little further". For instance, you can extend the time between sharpenings by increasing the pressure on the tool as it gets dull. If you take that very far you will likely damage the tool.

[bridger berdel]

What ya smoking Bridger.

Wood shavings, seasoned with honing oil. Delicious....

[bridger berdel]

Bridger,

Working on your syllabus?:)

ken

PS. Good plan, much better to know why along with how.

Pretty much. Although most of the students who take that class are pretty focused on the how....

[Dave Anderson NH]

Not to be a stick in the mud, but personally I find that hard and fast rules rarely work. I understand your idea of offering some guidance for the beginner, but when people are given rules by those whose opinions they respect they will often continue to adhere to those rules in situations where they don't work. This can lead to a lot of frustration and questioning of what they did wrong when it was actually a situation where the rule just wasn't applicable. I prefer "general principles" where it is clearly stated that there are many exceptions.

[Prashun Patel]

If your motivation is to give beginners guidance, then IMHO, it's best to leave controversial words like 'optimal' out of it.

Beginners "should" maybe start at 30 degrees for KISS reasons; 30 degrees performs respectably and respectably long enough with a wide variety of steels, tools, and woods.

If your goal is to foster debate among experienced users, then your statement is well crafted.

[James Waldron]

If your goal is to foster debate among experienced users, then your statement is well crafted.

Now that's droll!

[Phil Mueller]

The whole hypothesis is moot without a way to prove it. Edge angle is the only real constant. How would you ever quantify the actual amount of time it stays sharp and quantify the quality of shaving that represents sharp?

it's just a feel that comes from experience. Sometimes it seems to stay sharp for a long time, other times it goes dull quickly. Type of wood, end grain vs long grain, chopping vs paring, etc.

[bridger berdel]

Not to be a stick in the mud, but personally I find that hard and fast rules rarely work. I understand your idea of offering some guidance for the beginner, but when people are given rules by those whose opinions they respect they will often continue to adhere to those rules in situations where they don't work. This can lead to a lot of frustration and questioning of what they did wrong when it was actually a situation where the rule just wasn't applicable. I prefer "general principles" where it is clearly stated that there are many exceptions.

basic principles are what I'm after here. I'm not after a set of "rules" which if adhered to will yield a sharp edge, I'm after an understanding of the underlying "what's happening" at the steel/stone/wood point of action.

a "general principle" with many exceptions isn't very general, is it?





If your motivation is to give beginners guidance, then IMHO, it's best to leave controversial words like 'optimal' out of it.

Beginners "should" maybe start at 30 degrees for KISS reasons; 30 degrees performs respectably and respectably long enough with a wide variety of steels, tools, and woods.

If your goal is to foster debate among experienced users, then your statement is well crafted.



while most of my students are beginners, this isn't for them. it's for us. some of us are beginners. most of us aren't.

debate is fine, but careful observation is better here. if I want to go trolling, I'll pick a more fun bridge to lurk under.


thanks
Bridger

[bridger berdel]

The whole hypothesis is moot without a way to prove it. Edge angle is the only real constant. How would you ever quantify the actual amount of time it stays sharp and quantify the quality of shaving that represents sharp?

it's just a feel that comes from experience. Sometimes it seems to stay sharp for a long time, other times it goes dull quickly. Type of wood, end grain vs long grain, chopping vs paring, etc.


edge smoothness is a factor. an edge straight off of the grinder will fail sooner than one that has been honed, even at the same angle doing the same thing in the same wood.


there is no proof. since few woodworkers maintain testing laboratories in their shops, feel and experience is what we have to work with. that information won't ever become complete in a single woodworker's lifetime, though an accomplished woodworker must be able to achieve sharp tools efficiently. in aggregate however, we can create a very broad yet precise body of knowledge in the subject.

for example, George and Warren, two very accomplished woodworkers here both have (IIRC) fairly simple sharpening setups that they haven't varied much from in decades. George has lots of experience with spyderco stones, but maybe has never used lapping films. he hasn't needed to, and going down the sharpening rabbit hole isn't his interest.

[bridger berdel]

perhaps this is better....



For any given combination of steel/wood/process there will be an optimum sharpening angle. Deviating from that angle will result in a reduced edge performance.



of course this leaves us needing a complex definition of performance.

thanks
Bridger

[Phil Mueller]

I guess my point was how do you define "fail"

I can take a chisel off the grinder and slam out a pretty good mortise, but it certainly wouldn't shave pine end grain.

[bridger berdel]

I guess my point was how do you define "fail"

I can take a chisel off the grinder and slam out a pretty good mortise, but it certainly wouldn't shave pine end grain.


a definition of edge failure could get complicated, if failure modes are included. most simply I suppose edge failure involves not cutting properly. a honed mortise chisel will outlast a ground, unhoned one, no?


thanks
Bridger

[Patrick Chase]

For any given combination of steel/wood/process there will be an optimum sharpening angle. Deviating from that angle will result in a reduced edge life. If you average out a large variety of woodworking tool edges you will arrive at something very close to 30°.

This has been beaten into the ground in other threads, but there is a lot of variation in peoples' "ideal" sharpening angles even after the variables you call out are controlled. I think that you also have to factor in:

Depth of cut
Technique
User preference (esp in re: things like resistance and downforce)
Etc etc.