One Bevel, Two Bevels, Three Bevels, More?

[Jacob]

I suppose most everybody here knows (and went through...) Brent Breach's Pages?

http://www3.telus.net/BrentBeach/Sharpen/index.html

More than one could ask for (certainly much more than I ask for...), but he has some interesting reasonings for the use of multiple bevels.

Knows of; yes. Went through; no. Pseudo science. Nonsense.

 

[bugbear]

I suppose most everybody here knows (and went through...) Brent Breach's Pages?

http://www3.telus.net/BrentBeach/Sharpen/index.html

More than one could ask for (certainly much more than I ask for...), but he has some interesting reasonings for the use of multiple bevels.

Knows of; yes. Went through; no. Pseudo science. Nonsense.

You haven't read it but you're sure he's wrong.

Typical.

:lol: :lol: :lol:

I've found Brent's work to be careful, thoughtful and helpful. And like all research, incomplete.

Recommended reading, along with Steve Elliott, for those who don't think they know it all already.

BugBear

 

[Phil Pascoe]

...heeeeeeeeere comes annnnnnother one...

 

[Corneel]

One of the conclusions of mr. Beech is the necessity to use a backbevel to get a truely sharp edge. Now, back bevels are nothing new, but the vast majority of the woodworkers from previous generations didn't bother with backbevels. They even didn't pay much attention to flattening the back. It is rare to see an old plane iron with a polished back, and I don't think I have ever read an old woodworking text where back flattening was teached. So they just sharpened the bevel, turned the iron over on the stone and smeared it around a bit to remove the wire edge. That was presumably good enough for them to do their work.

Because I like to use old tools, I have to do the dreaded back flattening procedure more often then I like, because of pitting of the steel. Pitting seriously disturbs a sharp edge. But that's a typical problem of old tools, not so much when they were new.

 

[David C]

Brent Beach is a much recommended read.

Good stuff.

David

 

[GLFaria]

"One of the conclusions of mr. Beech is the necessity to use a backbevel to get a truely sharp edge..."

I dont't see it so. What I believe Mr. Beach means is that a back bevel is needed for a sharp edge to stay sharp for as long as possible, which is quite different. A question of efficiency.

Given his resoning, I believe he is probably right (although I am probably not going to start putting back-bevels on my irons - I'm not good enough with a plane, nor do I work with such hard woods, to possibly feel that much of a difference)

 

[Jacob]

When you sharpen a plane or a chisel you effectively put a "back bevel" on every time, unless you flatten the face every time, which would be totally impractical. The back bevel will be barely noticeable unless you are having to do a steeper one to take out pits etc.
BBeach says:
Everyone uses a jig. Some prefer to use the jig that is the human body. They have devised ways of locking their wrists and hands, rocking from heel to toe, etc.
This is nonsense and shows that he doesn't know the first thing about sharpening, quite literally; the first thing being how to sharpen without a gadget, in the traditional way, as done by millions past and present.

He shares our own BB's belief that traditional sharpening is impossible - "Unless you happen to have an uncanny ability to judge and hold a desired angle freehand, some kind of assistance is definitely called for. BugBear" and everything he says is based on this one mistake.

 

[Mr T]

As others have said the second bevel means less time honing, you should be able to re-hone the edge in less than 30 seconds. As well as saving time it also means you are likely to resharpen more often. There can be a tendency to struggle on with a blunt tool if re-honing is a chore.

Chris

 

[Jacob]

As others have said the second bevel means less time honing, you should be able to re-hone the edge in less than 30 seconds. As well as saving time it also means you are likely to resharpen more often. There can be a tendency to struggle on with a blunt tool if re-honing is a chore.

Chris

Yes but honing gets progressively more difficult and eventually you have to sharpen the secondary bevel, so it doesn't save time in the longer term.
Honing and all the bevel is taken care of in one operation if you do it the Paul Sellers (and my) way.

 

[Corneel]

"One of the conclusions of mr. Beech is the necessity to use a backbevel to get a truely sharp edge..."

I dont't see it so. What I believe Mr. Beach means is that a back bevel is needed for a sharp edge to stay sharp for as long as possible, which is quite different. A question of efficiency.

While commuting in the train I quickly scanned through his website (which is very chaotic BTW!). I don't see Brent testing the longevity of differently sharpened edges anywhere. I do see this quote from the home page of his website:

Sharpening using a jig like mine will quickly return the tool to the sharp state. Other methods probably won't. For example, any freehand method will instead take you somewhere between sharp and dull (closer to dull). Any jig that does not do back bevels will get you somewhere between sharp and dull.

That's complete nonsence of course. Generations before us have created a complete living environment out of wood, often to astonishingly high quality levels. They used handplanes, they didn't use jigs or backbevels. Since we handplane users are only hobbyists, fumbling around a bit in our tinshed in the backgarden, we shouldn't ever forget this heritage. Any research (which is fascinating subject!) should start from that tradition. They are our reference.

Brent focuses a lot on the wear bevel on the upper side of the edge, where the shaving is rubbing over the steel. His idea is that to get a truely sharp edge you need to remove the wear bevels on both sides of the edge and the roundness of the edge itself. He drew all his conclusions from looking at the length of these wearbevels through a microscope. While this is an interesting detail, it doesn't tell us much about the actual shape of these wearbevels. All about his ideas you can find on this webpage: http://www3.telus.net/BrentBeach/Sharpen/bevels.html#lowerwear

Another hobby researcher, Steve Eliott, looked at the side of the edge from a rebatting plane with a much better microscope. This gives us a better idea of the actual shape of the worn edge. The Japanese research from Kato has similar images.
http://bladetest.infillplane.com/html/wear_profiles.html
He concluded that the wear bevel on the clearance side of the edge forms a bulge which is lifting the edge out of the cut. This is bad for the performance of the plane, this is what makes us wanting to sharpen the edge after a while. It needs to be removed through honing the bevel of the blade. Another feature of the worn edge is the round nose of the edge. Roundness is not as nice as sharp of course. And finally the wear bevel on the upper side of the edge. This is officially called the rake side, thus we can call this the rake wear bevel. Something peculiar is happening with this rake wear bevel. First, because of its shape it reduces the roundness of the edge. It removes material from the upper side of this roundness, thus decreasing the radius. The Japanese call this the self sharpening effect.

Another peculiar thing about the rake wear bevel is that it is actually highly polished. We can even see this with our naked eyes. We can see a gleaming line along the edge on the rake side of a dull blade. That is the the rake wear bevel. It is as if the wood strops this side of the blade. When I look at it with a microscope I can see that it has a better finish then my Naniwa SS 8000 stone!

So, looking at all these images I come to a carefull conclusion (bearing in mind that there is still loads we don't know). Polishing the rake side of the blade isn't necessary. The wood allready polished it. Of course we need to remove the burr from sharpening the bevel. This is something that still intrueges me. But we surely don't need to remove all of the rake side wear bevel.

All this is about bevel down planes. I know nothing about bevel up planes.

 

[bugbear]

"One of the conclusions of mr. Beech is the necessity to use a backbevel to get a truely sharp edge..."

I dont't see it so. What I believe Mr. Beach means is that a back bevel is needed for a sharp edge to stay sharp for as long as possible, which is quite different. A question of efficiency.

Given his resoning, I believe he is probably right (although I am probably not going to start putting back-bevels on my irons - I'm not good enough with a plane, nor do I work with such hard woods, to possibly feel that much of a difference)

Brent's experiments and results are more trustworthy than his extrapolations and conclusions.

Nobody's perfect

BugBear

 

[Cheshirechappie]

The 'quickest' overall sharpening method is probably the one that removes metal fastest. That'll be grinding on an offhand grinder or coarse belt linisher, leaving as little work as possible to refine a working edge by honing on oilstones, diamond plates, lapping films, doorsteps or whatever. When it starts to take too long to restore the working edge on the said oilstones, diamond plates etc., zap a bit more off with the grinder, leaving a sliver of edge to refine on the stones.

Grinding bulk metal off on stones, however coarse, by hand is bound to be slower than zapping bulk waste off with a grinder. 'Bulk waste' is any metal behind the immediate cutting edge - it has to come off to preserve the tool's cutting geometry.

You can generally get several honings - maybe ten or so - before the secondary bevel becomes large enough to take too long to rehone on the stones. You can either regrind 'little and often' (every five honings, say) or hone on and have a heavy session on the grinder now and again. Individual circumstances will probably dictate which approach is more appropriate.

 

[Jacob]

One of the most hilariously daft things which BB says is ".....any freehand method will instead take you somewhere between sharp and dull (closer to dull)...."
Does he really think that no craftsmen, from the stone age onwards, could sharpen tools, until the advent of BBeach? :lol: :lol:

 

[Jacob]

......You can either regrind 'little and often' (every five honings, say) or hone on and have a heavy session on the grinder now and again. .....

Or you do it the trad way and "regrind" with every sharpening and never go near a grind wheel except for repair/reshape etc.
I prefer this method because every sharpening is done the same way, with no slow-down fine-honing a progressively extending primary bevel, and then having to start again with a regrind.

 

[bugbear]

......You can either regrind 'little and often' (every five honings, say) or hone on and have a heavy session on the grinder now and again. .....

Or you do it the trad way and "regrind" with every sharpening and never go near a grind wheel except for repair/reshape etc.
I prefer this method because every sharpening is done the same way, with no slow-down fine-honing a progressively extending primary bevel, and then having to start again with a regrind.

Many adjectives can be justifiably applied to your round bevel made on a fairly coarse india stone technique, but "trad" isn't one of them.

In the good old days of Charnley Forrest stones, double bevel was the practical way to get things done.

Still, it's always interesting to hear about your particular technique. :roll:

BugBear

 

[AndyT]

As an interruption to the theorising maybe I could just offer an example of an approach to grinding and sharpening which clearly suited one experienced professional woodworker...

I know I've mentioned it more than once, but the 1983 Swiss TV film of the last hand tool makers in Geneva is worth watching more than once. If you are in a hurry, just skip to 10 minutes 35 seconds in, and watch for the next 60 seconds or so, to watch Eric Raggenbass take an old laminated iron, grind it to fit the plane it is to be used in and hone it on an oilstone, ready for use. He does have to slow down a bit, to explain what he is doing, but he is clearly doing something that he has done so many times that his actions flow naturally and economically; no motion is wasted.

If you skip to 19:06 you can see one of his planes in use, showing that he got the results required.


http://www.rts.ch/archives/tv/culture/suisse-au-fil-du-temps/3464421-les-outils-de-bois.html

 

[Corneel]

Such a pitty I don't understand French.

 

[GLFaria]

One of the most hilariously daft things which BB says is ".....any freehand method will instead take you somewhere between sharp and dull (closer to dull)...."
Does he really think that no craftsmen, from the stone age onwards, could sharpen tools, until the advent of BBeach? :lol: :lol:

I hope purists will not blast me (too much... :wink: ).
Coming from a precision mechanical production environment as I do, where the refence measurement unit was the micron, or at worst the hundredth of a millimeter, whenever I see this kind of argument I wonder where our industry would be if traditional methods of production were still in use nowadays. Speaking not only of precision, accuracy and reliability, but also the cost of tools and implements. For example, I can sharpen a drill by hand, by I know for sure that I will make it much better and accurately - and make a more perfect hole to boot - if I do it using a mechanical implement. Sharpening freehand is an expedient and convenient method, but repeatability, not to speak of precision, is never assured.

By all means go the traditional way if that is what you like, and if you are good enough to get the results you want, but no one will ever convince me that freehand will consistently get the same results as a honing guide - even though I know some very good woodworkers who say they never, ever used a honing guide in their professional life.

But, of course, to each one his own.

 

[AndyT]

Such a pitty I don't understand French.

... plenty of double Dutch on this forum! :wink:

 

[Jacob]

...., but no one will ever convince me that freehand will consistently get the same results as a honing guide ......

You are right of course, but we are talking (well I am!) about practical sharpening regimes for working woodworkers, not precision engineering. Consistently getting good enough results - optimising your efforts rather than going for ever higher degrees of sharpness. Very sharp edges become less sharp very quickly in use. There has to be a compromise somewhere between sharpness, sharpening time, edge retention.
Plus it's not easy to get a camber with a jig- it's unavoidable freehand. And you don't have to waste time (and stone) by flattening stones