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Thread: The Unicorn method
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31st July 2020, 04:25 AM #1
The Unicorn method
This is the inspiration of David Weaver (DW on the forum), 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
DerekVisit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.
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31st July 2020, 07:12 AM #2GOLD MEMBER
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Wow!!
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31st July 2020, 11:58 AM #3GOLD MEMBER
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I have been watching this with interest from day one, Warren doesn't seem to impressed! The whole thing sort of makes sense when thought about and it will be interesting to see what the reaction is from those who debate sharpening in fora such as this. I expect SMC to explode with all sorts of comment, the thread could go on for a year with civil war as the outcome.
CHRIS
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1st August 2020, 11:42 AM #4GOLD MEMBER
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Derek, judging from the responses or lack of the word has not spread yet. Someone needs to do some large scale drawings and not photos to show the idea so others can begin to understand what is being proposed. Everyone who has tried it is a fan so I guess that speaks for itself.
CHRIS
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1st August 2020, 05:06 PM #5
Yeah Chris, I expected that at least there would be questions and a discussion. Is no one interested? Confused? Both?
This is possibly one of the better sharpening aids we have seen in many years. It does not have to cost much - it can be done with a cordless drill and buffing wheel, or on a drill press, and perhaps even free hand ... it is all about creating a micro rounding of the bevel tip. We should be exploring this, and not just on chisels. I have used this successfully on some plane blades as well as lathe chisels.
Regards from Perth
DerekVisit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.
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1st August 2020, 08:19 PM #6
I’m interested
Will follow along.
Cheers Matt
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1st August 2020, 08:36 PM #7GOLD MEMBER
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As I said until it is explained with some illustrations there will be little interest outside the limited reach of Wood Central. I think it is the drawings that are needed more than the photos which have been used thus far but it has only been a few weeks since the discussion and experimentation has started. The idea of a shallow bevel of 20 Degrees and a bevel that is robust at that angle can only lead to good things. Perhaps our hardwoods might have a bit to say on that matter but perhaps the concept of using a rounded bevel at higher angles might be beneficial for our timbers. Until drawings and the concept are explained here there can be very little discussion and I am only an observer not having used the method as yet. BTW I hate the name!!
CHRIS
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2nd August 2020, 02:38 AM #8
Hi Derek,
Did you test chopping Jarrah end grain like you would do when chopping dovetail waste etc. Or just paring only at this stage?
Thanks,
Zac
Sent from my Nokia 4.2 using Tapatalk
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2nd August 2020, 12:25 PM #9
Zac, I have not specifically set out to do any testing. David and a couple of others have been taking photos of bevel edges following chopping, comparing standard sharpening methods with the unicorn buffed edge (I dislike the name but I know why David called it this - it’s a joking referral akin to finding a mythical creature). The edges of the Unicorned blades look as good at the end as they did at the start, while the standard edges are chipped or rounded over.
What is this all about? It is simply that one can add a (say) 45 degree micro (is there something smaller than micro?) tertiary bevel to an edge without affecting the entry characteristics. That is, a chisel with the Unicorn edge still enters the wood as easily as a bevel without this treatment.
While my initial foray into the Unicorn edge started with 20-degree Marples chisels, I am not keen to regrind all my chisels to 20 degrees. That is not the point of the exercise. For me, the point is the either/and/or produce a sharper/more durable edge, and to complete the process in a few extra seconds.
Last evening I finished up preparing a Japanese mortice chisel. It needed a lot of work flattening the back - lots of work on diamond plates and diamond paste. Eventually I could get to waterstones. I prefer to hone and use this chisel (as I do all my Japanese chisels) in the traditional manner, this being a straight bevel. I did drop the primary bevel from 35- to 30 degrees. A lot of work went into getting this blade as perfect as possible. It was honed to 13000 and then I attempted to pare Tassie Oak end grain. It did this reasonably but not as well as a bench chisel with the same 30 degree bevel. I went over to the buffer and firstly did a 2-second buff at the angle of the bevel, then raised the chisel about 10 degrees and buffed about 2 seconds more. Back at the Tassie Oak, the chisel now peeled off end grain shavings.
So, one question I am answering is that it is possible to get sharper edges using a power buffer (no surprise there), and that this process is very quick. I tried for years to do this on a Tormek hard leather wheel, without success. This soft wheel produces a better result and so much faster.
There are other questions to be answered, not simply longevity. Such as how buffing affects different hardness of steel, for example, softer O1 versus harder PM-V11. Will it enable A2 steel to avoid chipping? Can we lower bevel angles if we use this profile? And what is the profile - can it be reproduced by hand?
Regards from Perth
DerekVisit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.
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2nd August 2020, 02:34 PM #10
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2nd August 2020, 02:58 PM #11GOLD MEMBER
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Derek, for what it's worth, I'm very interested in this thread and the application thereof.
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2nd August 2020, 05:03 PM #12
This is an extraordinary thing.
When I first saw this (a little while back on YouTube) I was pretty amazed..... why has nobody done this previously?
Is this a case of the Old Methods overriding logic and/or simple observation?
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2nd August 2020, 05:12 PM #13
Chris, just to repeat a comment I made earlier, the 20 degree primary bevel is not sacred. For one thing, the Stanley chisel I posted earlier had a 25 degree bevel.
Here is a very short video from the discussion at WoodCentral made by Winston Chang. It illustrates what I showed, but with really basic tools ...
Sharpening a chisel with a buffing wheel on Vimeo
Regards from Perth
DerekVisit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.
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2nd August 2020, 05:38 PM #14
The video by David W could do with being a tad more....succinct!
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2nd August 2020, 05:42 PM #15
David is not known for being succinct!
Regards from Perth
DerekVisit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.
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