Winston's View/Test of the Unicorn (tiny rounded tip) Edge

[D_W]

https://vimeo.com/444232624

I posted about this method below - shallowing the bevel of a chisel and rounding over the tip. More or less (not all the way around, just the last few thousandths.

Winston Chang started experimenting with this immediately when I posted about this on a US forum and he's been using a drill with a smaller lower speed and softer buff.

Interestingly, his profile ends up being shorter and steeper due to the combination of the lower cutting power and choice of a finer abrasive. His cost outlay is far lower than mine (about $10 for the arbor, wheel and some little buffing sticks). I'm sure he's beyond that now, but I do seem to have a lot of trouble convincing people to spend $53 on a buffer here in the states.

Unlike me, he put a nice orderly video of all of this together after the fact. Buck brothers hardware store chisels here are on the soft side - the tips will bend without breaking. They're sold in a pack new for about $20 at home depot (or were) and have the heavy acetate handles.

A good indication that what's done at the edge precisely isn't really that important as long as it's some kind of rounding (longer and more gradual like mine, or shorter and more blunt like winston's) and eliminates the very tip of the chisel where failure starts.

 

[D_W]

I have a long article summarizing what I do, why, etc, but at the beginning is a clear set of steps to create this bevel. When winston talks about setting up a chisel with a shallower bevel, he's referring to the draft article that's been passed around (or that I passed around).

The article is getting the editor treatment this week or next week by a professional editor in the states (luckily, he's a professional editor AND a professional woodworker who has done paying work that's fine in nature). It'll be up on wood central when it's done, but there's little more to it than what's shown in the video until or unless you run into problems.

 

[Droogs]

Very interesting David, I will give this a go when I get back into the wksp as anything that minimizes time away from the bench is a damn good thing. Let your friend know a well made info video as well

 

[Rorschach]

Wow that is fascinating!

I do a fairly similar process on my kitchen knives, using a deburring wheel and an MDF wheel to get a similar style result (slightly bigger convex area of course). For chisels and planes though I have also used a diamond stone, guide and then an MDF strop. I might have to try this method though.

I wonder if stropping on a thick leather strop gives a similar effect?

 

[D_W]

I think rolling the very last tip of the edge on a fine stone and then stropping works great (I have done it for years, but each time I mention it, it sort of falls on deaf ears because it sounds gimmicky or "there's too much - 'if it's freehand, then i probably won't do it right so I won't try'".

Same with a strop - you can find a combination with a strop that will do the same thing (and I'd bet paul sellers has sort of mastered this looking back at what he's doing, and his students do less well - but i'm not a huge fan of his sharpening method because students are sharpening too much on the bevel and not enough on the edge - I get tools to refit - mostly planes - from fans of pauls, and if the geometry isn't funny, the edge is left unfinished and lots of unneeded parts are wonderfully finished).

Point with all of that being that you can do all of this with a strop, you can almost get the same effect with an extremely fine tiny 34 or 35 degree microbevel, but the buffer does it better. IT seems immune from grit contamination in the shop (mine literally sits below the grinder) and it does the work in seconds. After faffing on and off for years finding ways to accommodate edges, it's kind of a blow to my selective ego that the buffer does it better and faster than I can.

Faster and requiring less smarts means that people will do it every time, not just know how they could if they weren't feeling too lazy to do it well.

 

[D_W]

The uptake on this so far, by the way, is most people find if they have a chisel set up and sharpened already that just sticking it in the buffer makes it feel sharper and have the edge last a lot longer.

That much is true. The two part of this is that you start to realize that you can ease the angles back from where they were originally set and the chisel becomes even easier and smoother to use, but if the whole bevel thing sounds like a bridge too far, Bill Tindall here in the states (and others - derek cohen now also) have started at this with chisels that are just set up as normal and even there a gain is observed.

I started this far down the road with the hand-applied roll to the edge, and wanted it to work with planes after getting a request about that, thus for both of those cases, the lower bevels make sense to give you room or to reduce effort.

If the jones to try it can't wait, just find a chisel somewhere in the till and buff just the tip, for a few seconds.

 

[SammyQ]

Jacob.

Rounded bevels.

Just sayin'.

Sam

 

[D_W]

This is quite a bit different. But it does seem to be the case that a rounded bevel at the very tip is protective. Rounding the entire bevel is a natural way to site sharpen but unnecessary work, and lots of metal in places where it doesn't need to be (thus creating extra work chiseling).

Or as Bill T said on the US forum, you can create "buttholes between dovetails" with a very wedgy tip.

 

[D_W]

(there's nothing wrong with convex edges if the geometry is right, though - especially site sharpening. As for the rumor that japanese tools don't come with them, about half of the used japanese tools that I get from japan come with convex edges, so so much for that. I'd imagine there's jacobs over there running around on site with a carborudum stone convexing their chisels and getting abused by other site carpenters. The occurrence of perfectly or near perfectly flat chisels over there in used tools is much much higher, though).

The biggest take away from this that I've figured in coming to this over a period of years, though, is that the idea that an edge is only sharp with an intersection of two planes isn't right.

There's severing, and wedging (at least), and then crumbling edges. IF wedging is half of the force, and the two plane edge never lasts in the first place, then why deal with coddling the very tip and compensating by increasing wedging?

 

[SammyQ]

"

This is quite a bit different"

Of course David, just my Celtic Irony surfacing in a gentle leg pull.

Saw your earlier stuff with excellent macrophotographs. "Respect" from a microscopist of 45 years.

Sam

 

[D_W]

I knew you were just yanking my chain a little bit.

Bill T and I (who I bounce ideas off of - and Bill never believes me, either - he always waits for someone else to have success with something that I propose before he'll lift a finger - figured that as soon as I started talking about rounded edges, one group would say:
* they won't be sharp

the other group would say:
* you're just copying paul sellers' method and using a buffer

I have gotten some of both so far.

as to the micro and macro photos - one thing that has become easier for a basement and garage shop jockey these days is finding affordable ways to take pictures of things. I sold japanese waterstones and fixed up razors for a little bit (not for profit, just for fun). the microscope is necessary to be one of the few honest sellers of japanese stones. Everyone who isn't honest lists all of their stones as "razor hones". a hand held scope that will tell someone all they need to know about sharpening is $11. My portable bench top scope is $425, including shipping and the camera. I have a slightly filthy lens at this point, it appears (the care to this point with photos has been zero), but other than that, I'm thrilled with the scope. At 150x, it's almost too close and it will do 600 optical. things are so magnified at that level that for sharpening and woodworking, it's hard for people to grasp what they're seeing - even at 150x that's somewhat true without descriptions.

 

[Rorschach]

Did a test today and here is my rather terrible photo of the rounded microbevel.

This is 25deg on a 400 grit diamond stone then about 2 seconds on my high speed soft buffing wheel. Feels great, will see how long it stands up to use.

 

[D_W]

that should do. I don't know what the lower limit of taste is for the refreshing stone (the 400 grit stone in your case).

I have used a strong 1k diamond hone that would normally be seen as kind of harsh - and with very good luck.

 

[Rorschach]

I will definitely go to at least 1000 next time, the stone was in the shop though and the microscope in the office so by the time I realised how awful the scratch pattern was I couldn't be bothered to go back and re-do it. It does show though that even 2 seconds on a buffer turns a really rough edge into a mirror smooth polish so if you were limited in your stone selection (on site for instance) this would still work quite well.

 

[D_W]

what you did is actually going to tell us something useful. Looking at the edge, it doesn't appear that there's really any detriment to it.

The key to this whole thing is really just cutting edge and then support (as is always the case). I don't think support needs to be that refined as long as it's not too shallow (I pushed the limit and used a 15 degree grind and a shallow secondary and then in that case, the strong edge just got pushed back into the secondary bevel - not enough support)

It's robust in straight on force - obviously it won't be that robust in prying or twisting, but we don't need to do that much of that.

On mortise chisels, it's very good at limiting unsightly failures at the edge until or unless one gets really rough and starts prying the chisel like they're pulling a drawbridge lever.

Success with a visual like yours shows (aside from me pushing the limit with the bevel) has been 100% so far.

 

[Rorschach]

Well I am glad it will be somewhat useful.

Unfortunately I won't be able to give a definitive report any time soon as I am not regular chisel user in my day to day work but I will do some testing when I can, probably just bench testing rather than an actual project.

It does make me wonder if this setup would work with a plane iron or my carving knife. I might test that out, my carving knife sees a lot of abuse from the type of work I do and the edge rarely lasts more than a few minutes before needing a strop. It is single edge sharpened like a chisel, similar angle too. I might try that tomorrow.

 

[D_W]

separate thread on the plane iron side, but no responses to it:
1) I found the tiny rounding to be protective of difficult wood and silica tainted wood (mahogany, khaya, limba, rosewood, cocobolo...anything that dents plane irons on a near microscopic level suddenly doesn't dent the iron and dull it nearly so quickly)
2) if it's used on the flat face of the iron, it will probably refine the edge some - I haven't gone there yet. If it's used on the bevel side, while it does improve edge toughness at the tip quite a lot, there is a small sacrifice in overall edge life (the edge will stay undamaged, but about 80% of the way through what would be normal edge life, you'll run out of clearance and the plane will begin to skate across difficult grain without increasing the shaving thickness).

For people who aren't very good at sharpening, they may not ever get that ideal duration in edge life, anyway.

Also, irons that are a bit soft and don't hold much of an initial edge suddenly don't have a tendency to lose the initial edge so quickly. I did quite a lot of planing on a silica-filled rosewood plane billet with a $3 iron that home depot used to sell in the US. IT held up well planing that rosewood. I'm not sure I have any wood that it wouldn't plane well now.