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Thread: The Unicorn method
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17th October 2021, 01:19 PM #136
Well after sitting on the fence for some time while keeping in touch with this thread I decided to give it a go since I've been continually frustrated with my inability to get a good initial edge on my chisels, never mind one that lasts. Full disclosure, I'm a fairly new woodworker but early on when I bought my bench chisels I decided to buy once, cry once, and purchased the Veritas PM-V11 ones. I've always struggled to get a good edge on these using a 1000grit diamond stone, 6000 grit Cerax ceramic and honing with green compound on a piece of MDF. I also find using the honing guide time consuming and fiddly, so last night I decided to hollow grind these chisels as an aid to freehand sharpening.
I decided to grind them to 25 degrees overall which given the nature of a hollow grind of course means at the point the angle is somewhat less than that, then gave them a quick freehand hone on the diamond stone which gives a small secondary bevel once again at 25 degrees, then on to the green compound on a buffing wheel. To say the results were encouraging is a major understatement, this is the first time I've ever got these chisels to feel truly sharp. I can't yet comment on edge durability since I've only tried them so far for some gentle paring, but given my sharpening frustrations thus far with these chisels I'm already thinking this is a major advancement for me and my only modest sharpening skills.
I'm sure I can get even better at this, but even at this point it's a big thumbs up for me, and that's putting it mildly, to be honest I'm bloody delighted to be able to finally get these rather expensive chisels to work properly.
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18th October 2021, 04:12 AM #137GOLD MEMBER
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Excellent news. Rather than how the edges feel, always test them in the woods that you intend to work with. That's where it really matters.
I have good sized pieces of every wood that I like to carve and I'm forever testing the quality of my sharpening efforts in those woods.
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18th October 2021, 12:31 PM #138
Yeah, I still feel I'm in the foothills of the sharpening mountain with a great deal to learn but this is definitely a step forward. Not only are the chisels sharper but I really like being able to stop work when the chisel seems to need a touch up and do that touch up in a minute rather than farting around pulling out the honing guide, soaking the ceramic stone and all that other stuff which really seems to disrupt my work flow. Quicker touch ups means I do them more often as well.
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18th October 2021, 01:00 PM #139
The unicorn method is not expected to get an edge sharper. It is aimed at making the edge stronger - to last longer.
If you are achieving a sharper edge, then there is a problem with your sharpening technique.
Further, continued buffing without returning to a stone will eventually just round the edge and dull it.
Regards from Perth
Derek
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18th October 2021, 02:05 PM #140
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18th October 2021, 04:35 PM #141
Hi Biggus
My comment was not aimed at you, but for all who see this as a "get sharper" method. It is not. It is a "stay sharp" method.
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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18th October 2021, 05:57 PM #142
I can easily see why an edge might feel sharper and that is the use of a lower primary bevel recommended by this method and the consequent decrease in what DW calls 'wedging', in my case going from a 30 degree primary bevel and a secondary bevel a degree or two higher than that as catered for by the secondary bevel function on the Veritas honing guide, so say 32 degrees, to a 25 degree hollow grind overall which is then freehand honed to a true 25 degrees, a drop in seven degrees that must have an appreciable difference when taking anything but the finest shavings with the chisel.
I have watched DW's video and am aware of the aim of this method, and it's also difficult to pin down exactly what is the reason the chisels feel sharper since I've changed several variables at once, nevertheless the difference is real. Some other readers who like myself operate at less than master level may have experienced frustrations much like mine, and that's why I posted my findings. I would never have reground my chisels to that primary angle if I were not having a go at the so called unicorn method, and if that's the reason the chisels feel sharper then it may be a collateral bonus of adopting this method even though it's not the primary aim.
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18th October 2021, 07:06 PM #143
Biggus, a lower primary bevel (20-25 degrees) will enhance penetration. This is where the impression of sharper comes from. The nano edge is higher, say 40 degrees, but this is too small to impede penetration. The edge is not actually sharper - how could it be at a higher angle?
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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18th October 2021, 08:09 PM #144
Didn't you read my comment, "I can easily see why an edge might feel sharper and that is the use of a lower primary bevel recommended by this method". Surely I've made myself clear here by they key word "feel". I'm out of this conversation, any reasonable reading of what I've posted should make what I'm trying to say clear, but you seem determined to misread those comments. What a pain!
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18th October 2021, 10:01 PM #145
Biggus, you asked a question and I answered it! ...
I have watched DW's video and am aware of the aim of this method, and it's also difficult to pin down exactly what is the reason the chisels feel sharper since I've changed several variables at once,
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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19th October 2021, 12:05 AM #146GOLD MEMBER
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You can do a range of things, but one of the truths about the method is that it leaves an even edge that you can't really duplicate by hand in any reasonable amount of time. Even sharpening deflects the edge a little bit and stropping (which is a good thing if there's a burr to remove or an edge to refine) will not leave a dead straight edge.
So the method isn't a method per se, it's a range of things you can do with the buffer. You can improve the edge by just finishing it with the buffer and not changing geometry much, or you can do a good bit more ("the full uni").
there is less friction and an easier cut through wood even on early strokes with an incannel gouge than anything I can sharpen by hand short of sitting down with a gaggle of sticks with compounds for 10 minutes. IT's also possible to buff the incannel gouge hard and make it not seem sharper, but it would at that point be almost impossible to damage the edge without prying.
The one thing that derek said is the case, though - if the buffed bit is left on, or only partially removed, it has a chance of growing. But you'll feel if that's the case- it'll feel more dull.
This is a video done with a japanese plane and oilstones and then linde A on a buffing wheel. I used to use japanese planes more, but they're a royal pain when an iron picks up a nick and what's the point if you just sharpen them quick and coarse? So you get stuck in a 7-8 minute cycle of heavy hand work to grind out a nick and refine the edge.
If the bevel is maintained with a grind on oilstones (it's fine to grind japanese tools on a grinder), then a touch up of the tip with a fine india and a washita and then a quick buff, you get a sharpness that most people won't match.
https://i.imgur.com/JyFkURR.mp4
Even on really cheap irons, like a $3 hardware store iron (but I don't think this one was with linde A buff - it could be). Linde A is super uniform 0.3 micron alumina.
https://i.imgur.com/ePvayfb.jpg
So, do remove anything left as an artifact when you hone each time, and then use your discretion with how much buffer - the less you use, the easier it is to refresh, but you will find the balance between durability and alien sharpness (and also find that stuff like the linde A isn't necessary - but I was just experimenting).
For planes, clearance enters the discussion and I think it's harder for people to get the hang of buffing the bevel side only. If that's the case, you can just buff some on both sides of the bevel (not much on the back side, but a little) with the bevel side more tangent, or just skip it. Only on a plane can you manage to wear off the initial edge evenly (so long as you can avoid damage). But if the wood is really hard, the cut is interrupted or any contaminants are around (in the wood or otherwise, then the balance of edge life goes back to some modification). Here's a plain carbon steel iron worn - you can see that some wear when planing does "the uni" for you, just a little less neatly.
https://i.imgur.com/z4QRWVU.jpg
(that's a very high magnification edge. The little bumps are most likely iron carbides and they're about 1 or 2 microns)
I've noticed on some undertempered irons, as well as some that are softer, if you can minimize the damage to the apex and just plane through it, if the iron is relatively plain steel, it will wear off sometimes and very small nicking will go away. The higher the carbide volume in steel, the less likely it is in my experience that the damage will just "wear off" rather than persist and gather buddies along the way.
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19th October 2021, 12:07 AM #147GOLD MEMBER
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in terms of penetrating wood, there may be something about a tiny rounded bevel that's more efficient (less friction, more split off of a properly sized shaving, etc) than an apex of two planes, but I've never looked into that - sometimes it's fine to know that something's working with less effort and not have to figure out why - stuff is going on at tiny levels and I'm not a fan of supposing reasons and then concluding they're likely just because they're the only ones supposed).
Obviously, a fat rounded bevel can also feel not too sharp, which is another reason I don't like supposing much. You suppose something without further purpose and then you find the words stated elsewhere in nothing remotely close to what you said.
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19th October 2021, 03:39 AM #148GOLD MEMBER
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A more rule of thumb response than what I provided above, as too many options at the outset may not be great.
* if you have success with the method and performance is good, then work it up to consistency and speed so that you assume that 99.9% of the time you walk away from the buffer, it'd be a waste of time to even test an edge
* after that, if you want to chase other aspects (increasing sharpness, etc), you can do those, too, with the buffer - and you may find that chasing the sharp edge vs. just durable and sharp is also useful).
If you're going to chase *really high levels* of sharpness, the buffer is going to give them to you far more easily and practically than stones, and there are few stones that can match a lighter buffing in fineness even without time considered.
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19th October 2021, 05:36 AM #149GOLD MEMBER
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Every steel is very plastic when very thin. There is simple proof of that fact. I decided not to ignore that.
The deal with any sharpening technique is to get an edge adequate for the intended work.
In Leonard Lee's book: The Complete Guide to Sharpening, there are two pages of scanning electron microscope images
of various sharpened steel edges.
Based on those factual observations, I decided to rethink most of what I do for carving sharp edges for very soft woods.
I abandoned all stones, water and diamond. For some 8+ years now, I use nothing but 3M fine automotive silicon carbide
wet&dry sandpapers up to 1,500 grit (measured @ 3 micron), finished with a brief honing using CrOx/AlOx on a very hard strop.
I never "buff" anything. The CrOx is about 0.5 micron and the AlOx is about 0.25 micron. Steels are too soft to let us do much else.
The honing compound is a mix of very fine abrasives, that's the end step for all I do, adzes included.
Please scrape my dogma off your boots.
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19th October 2021, 05:55 AM #150GOLD MEMBER
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for planes, if you start off with a more refined edge, you'll get more edge life. If you can get the same geometry as a fine stone with those oxides and same finish, then the result will be the same.
Another person here more than a decade ago put together a test showing increased edge life with finer and finer abrasives, but I felt that the test was a little too idealized. In the end, I ended up proving the same thing that he did - that edge refinement for planing will result in extra edge life if there's no damage. The whole idea of the unicorn thing, and really the objective of avoiding damage in general is to get all of the edge life out of an edge. The damage, when it occurs due to anything other than dirt or silica, occurs on the early apex. If the edge is banged up, life suffers, but even if it's just toothy, life suffers (and ease through the cut is drastically different - when I used 2.5 micron diamonds (which is really a mix of 2-3 micron diamonds), the edge looked great. IT didn't last that long or feel that sharp after being spoiled by 1 micron diamonds.
The finest of the arkansas stones lasted between the two.
As far as buffing or honing with pastes, it makes no real difference.
Here's an edge finished after a washita stone with dursol (same as autosol more or less) on hardwood:
https://i.imgur.com/7m5tvAG.jpg
Then, the 1 micron buffed edge. I'd guess the tooth on this is stray particles bigger than a micron (with linde abrasive, very closely graded, this goes away, but it's really unnecessary).
https://i.imgur.com/XmxkY1k.jpg
Dursol is very good following a medium fine stone. The buffer is very good following a medium fine stone.
Really really fine stones like the SP13k and the shapton 30k following something that's not that refined - not as good (not because they can't finish a job, but because it takes much longer).
For something like 10 or 12 years, I didn't use a buffer to finish an edge because I"d tried spinning leather and spinning felt. they batter edges. It stuck in my mind that two extremely talented carvers/sculptors here in the states use only buffers (they aren't talented amateurs, they are professionals, in some cases winning smithsonian awards). It stuck in the back of my head that if I thought I couldn't use a buffer, then it's not that big of a deal, but I couldn't make the oversimplified statement that "an edge is only sharp if it's the intersection of two planes in a fine line". The initial edge is so transient that it's really more important how it initiates later wear.
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