I am surprised

[cputnam]

I am surprised by the lack of discussion here about the so-called Unicorn method which has been well researched by David Weaver and posted on WoodCentral. His results have been confirmed by other leading lights - including Derek Cohen.

In short, the method as described (if I have it correctly) is:

* - set primary bevel to around 20°
* - hone a few strokes worth of secondary bevel a few degrees steeper.
* - power buff with a cotton wheel loaded with compound

When applied to el cheapo chisels one gets and edge as good and as durable as premium chisels in a matter of seconds.

I strongly suggest it is worth your while to read all the posts on the subject.

[C. in Indy]

Most interesting!

I think the magic must be the electrostatics of the cotton 


Seriously, though, while using hand tools a lot, I couldn't go without a power bandsaw and -- in recent years -- a power buffing + stropping setup.

Chris

[Derek Cohen]

Note that this is not the power buffing of carvers, using hard leather on wheels. This is also not the buffing of the edge to increase the sharpness (a by-product of the method also leads to sharp edges). What it involves is a nano rounded bevel at the edge of the blade. This strengthens the edge as the very tip may now be about 45 degrees. However, since the chisel bevel remains at a low angle, it remains capable of penetrating the wood as if the edge was the same low cutting angle.

The primary bevel does not need to be ground back to 20 degrees. I have been doing the unicorn edge on 25- and 30-degree bevels as well.[

Why "unicorn"? That was David's little joke about the elusive and fictional search to the pipe dream of the ultimate edge.

To get the ball rolling, here is an early post I made on WoodCentral ...

This is the inspiration of David Weaver, who is really a sharpologist extraordinaire. David was the drive behind the re-emergance of the double iron, that is, the use of the chipbreaker for controlling tearout.

More recently, he came up with the Unicorn bevel. This is, in its simplest explanation, the buffing of the bevel of a chisel in a particular way, which promotes a longer lasting edge. Not only does it do this, as I discovered, but it also leaves a very sharp edge. And the good part is that it can turn a crappy, cheap chisel into a performing demon!

The understand this, watch his video ...

https://m.youtube.com/watch?v=Do7FdOh6S9s

To quote David, “It's simply this:
* grind a primary bevel at 20 degrees
* hone (with a medium stone) a secondary bevel around 3 degrees higher (not precise, just a little higher). No wasting time with wire edges or anything ,just leave the wire edge in place
* buff the chisel briskly in a cotton buff (charged with any reasonable buffing bar) on a buffer for about 5 seconds held about 45 degrees to the buffer wheel and moved about just a little. A light touch of the back of the chisel on the very fluffy outside corner of the wheel will remove any swarf or wax stuck around the back side”.

The following is a post I wrote at WoodCentral ...

There has been a great deal of interesting photography of buffed edges to date. I don't have the microscope to add to this, and so I will just take what has already been presented that provides evidence of enduring edges. Edges which last longer are lovely, but ...


... I want the edges also to be sharp and take the type of shavings that are evidence of a working tool, not just a long-lasting, but dull-ish edge. Rounded edges increase the cutting angles from 20/25 degrees to 40-ish degrees? I mean, chisels are not expected to act like BU planes, are they? Or the scraping chisel of Bill Carter?


Then I sharpened a chisel. Not just any chisel, but a Marples Boxwood with a 20 degree bevel. Actually, 5 of them. I wasn't in my right mind when I hollow ground them to 20 degrees - thinking that I could do with a few chisels with low cutting angles for dovetails - especially when they struggled to hold an edge at 25 degrees!


And the new buffed edge? Well, it took amazing shavings. Amazing! And it did not stop taking these amazing shavings .... which is a miracle, since the blades of these chisels are made of cheese.


They looked like this .. unfortunately not the Marples, but a Stanley #60 chisel (we all have a few of these for opening paint cans). The wood is Tasmanian Oak (similar to White Oak) ...




Sharpening system? Nothing much. I had a much used 6" stitched mop soaked in Lee Valley green compound. This was chucked into my lathe ...





The wheel was spun at 1450 rpm, which is the speed of a half-speed bench grinder in Australia. I use an 8" half speed bench grinder to hollow grind blades, so it made sense to use the same speed.


The bevel was presented to the spinning mop and angled about 10 degrees (please note, if you are reading about this method for the first time, that the mop is spinning away from the edge).





This resulted in a fine wire, and rather than buffing this off on the mop as David has done, I wiped the back of the blade on a section of hardwood with green compound.


Having satisfied my self several times over that this method worked, and that it looked a Good Thing, I decided to purchase another grinder rather rely on the lathe .








I got to thinking about trying this out on plane blades. In fact, I did so, and realised that it may not be a good idea. All the bench plane blades I have are cambered. Planing with a buffed cambered blade created shavings that were stringy, indicating an uneven edge. You can get away with this in a chisel, but not a plane blade. I shall try again, but that is my initial observation.


I also tried this with block plane blades. Now this was different: 25 degree straight bevel, just like a chisel. But would it cut differently, especially on end grain where low cutting angles are expected to rule?


A LN blade was hollow ground at 25 degrees, and then went through a typical process of extra fine diamond stone/Medium and Ultra Fine Spyderco ceramic stones, and a final polish on green compound-on-hard wood. At least the green compound would be the unifying medium.




The surface/shaving on Jacaranda (the softest wood to hand) looked like this ...




The buffed edge looked like this ...




The buffed edge felt sharper and left a cleaner surface.


This was repeated on Jarrah end grain. First the honed blade ...



.. and the buffed edge ...



Nothing in the two? If so, that is a win.


Regards from Perth


Derek.

[Handplanesandmore]

Sure someone will benefit from the new (another) sharpening idea.

But not for me, if it aint broke kinda thing....... at least I'm very happy with the tried and true method used for over two decades in my shop. Or perhaps this old dog is too old.

Simon

[stav]

I just found Rob Cosman's sharpening technique (I'm a sharpening noob so to speak).  Now there is this one to master as well...

[Arlin Eastman]

Cripes

I guess I have been doing that now for 7 years without even knowing it.  The only thing is I use tripplee and white diamond after.  Who knew..

I have been trying it lately with some hard felt and the board that is made from wood powder I forget what it is called.  Both make to 8" wheels that are 2" to 2.5" wide and then power strop them on my leather wheel at 600rpm.  I just touched my palm and it drew blood just touching it and not pressing against it.

[cputnam]

Keep a diamond plate on the bench where the grinder is. Spend 10 - 20 seconds honing off the last edge and another 10 - 20 seconds on the buffer and you are back t work with a durable and sharp chisel edge. Fast and closing in on foolproof.

David has now extended the method to plane irons. It is slightly different - you need to read about it and watch the upcoming video.

There will always be those who denigrate the method because it goes against the grain of what we have learned up to this point. There will be (and already are) people claiming to have done this for decades. There will be others who ignore this due to a lack of interest. Maybe Derek will re-post about the "Backfire Effect" here. Otherwise, read about it on WoodCentral.

[AHill]

There are similar methods out there. Paul Sellars' method intentionally creates a curved or rounded bevel. He does it while stropping very aggressively. Timberwolf, myself, and others utilize a charged leather wheel on a grinder to power strop. Literally a couple of seconds on any edge and boom, it's sharp as all get-out. You can easily powerstrop to create a rounded bevel like the Unicorn method.

[Derek Cohen]

Allan, Seller’s method is not the same thing. The aspect that makes it appear similar is that his bevel face is rounded. However the leading edge of the bevel is not. And that is the important feature of the unicorn profile.

Similarly, if you buff edges on leather or felt wheels, unless you are deliberately lifting the chisel to raise the buffing angle to around 45 degrees, then what you are doing is just buffing at the angle of the face or the bevel. That is also not going to create a unicorn edge .... sharp certainly, but not unicorn.

Regards from Perth

Derek

[Derek Cohen]

Link to the Backfire Effect ...

http://www.woodcentral.com/woodworking/f...re-effect/

Regards from Perth

Derek