More on Unicorn Profile

[Jim Koepke]

Mike, grinder speed does matter. Ultimately it is a balance between speed, the hardness/softness of the buffer, and the cutting level of the compound used. Add to this the amount of time the blade is held against the buffer ... and, of course, the angle. All this makes it sound complicated, but it is not. It is something one sets up one time and adjusts to.

Regards from Perth

Derek

It feels as if a resonating voice is saying, "Use the Force Luke."

Sharpening at times seems almost a mystical ritual.

Creating a Unicorn edge may mystically make a half parabola that spreads the stress angles in a way to give the edge more lasting power.

Time for someone to break out an old calculus book.

jtk

[Michael J Evans]

I have a feeling I should invest in rikon... Their grinder sales are about to go way up.

[Curt Putnam]

I have a feeling I should invest in rikon... Their grinder sales are about to go way up.

Just did - from Acme Tool @ $99.99. Got here faster than the cotton wheel from Amazon.

[ken hatch]

Just did - from Acme Tool @ $99.99. Got here faster than the cotton wheel from Amazon.

Curt,

Put a CBN wheel on one end and the cotton wheel on the other. Like Derek I have a Tormek BGM-100 on the grinding side, that and a medium grit stone and you are set.

ken

[Curt Putnam]

Curt,

Put a CBN wheel on one end and the cotton wheel on the other. Like Derek I have a Tormek BGM-100 on the grinding side, that and a medium grit stone and you are set.

ken

Hi Ken,
Yes Derek was my inspiration. Been think about a grinder for a couple years now and the unicorn method caused me to jump. So now I have the Rikon equipped with a 1" Spartan CBN wheel (180 grit) and a 1" cotton wheel loaded with green compound. The BGM-100 is mounted and got tested with the SE-76 (chisel holder) this AM (temps hit triple digits by 11).

Question: The SE-76 is not going to work with my Marex mortise chisels. Got a jig recommendation?

[ken hatch]

Hi Ken,
Yes Derek was my inspiration. Been think about a grinder for a couple years now and the unicorn method caused me to jump. So now I have the Rikon equipped with a 1" Spartan CBN wheel (180 grit) and a 1" cotton wheel loaded with green compound. The BGM-100 is mounted and got tested with the SE-76 (chisel holder) this AM (temps hit triple digits by 11).

Question: The SE-76 is not going to work with my Marex mortise chisels. Got a jig recommendation?

Curt,

I know how it is, my truck thermometer showed 112F on my drive home from work today.

I haven't tried it on your mortise chisels but I have used the Tormek SVS-32 to hold odd shaped chisels. It is not precise like the SE-76 but it can sometimes work.

ken

[Daniel Culotta]

Trying to keep up with this and the other threads, and excited to try this soon. Last I read it sounded like the unicorn method didn't have as profound results on plane blades as it did on chisels. Is that still the consensus? Want to make sure I'm not wasting time trying it on plane irons if others have got mediocre or negative results there.

[Jim Koepke]

Trying to keep up with this and the other threads, and excited to try this soon. Last I read it sounded like the unicorn method didn't have as profound results on plane blades as it did on chisels. Is that still the consensus? Want to make sure I'm not wasting time trying it on plane irons if others have got mediocre or negative results there.

Daniel, On one of my plane blades given the unicorn treatment it was able to take a very fine shaving. It was thinner than the shavings this plane usually makes with a simple flat bevel. The plane has not been used much since then. So no report on edge longevity or the next time it needs sharpening.

My reluctance toward the unicorn technique is consideration of what will need to be done the next time sharpening is needed.

Will a simple return to the buffing wheel be enough to restore an edge?

How long will this work before the bevel has to be returned to flat bevel or reground.

What makes me even more curious is if this is really "something new" or did woodworkers discover this technique years ago and decide working on their stones and stropping was preferred in the long run?

It appears there are carvers who use buffing wheels on carving tools. Surely this approach was shared with non-carvers.

So why are there no magazine articles or other mention of the technique?

jtk

[Derek Cohen]

Last I read it sounded like the unicorn method didn't have as profound results on plane blades as it did on chisels. Is that still the consensus?

Daniel, David reports success with bevel down planes. He shows evidence of very fine shavings. I began with bevel up block planes and had success. This has been replicated by others. We are all moving slowly, via experimentation, to understanding the dynamics of adding a unicorn profile.

I have not found this as easy to do on BD and BU plane blades as simple block plane blades. Block planes are like chisels in that they are honed on the straight, and the surface quality is not the main area of interest; being sharp and holding this is most relevant.

The success of a bench plane, whether BD or BU, lies in the surface quality. The issue (for me) when unicorning a plane blade is that a high nano bevel can cause the BD plane to run out of clearance, while a high nano bevel on a BU plane can like using a scraper (lots of resistance). The other factor is creating the unicorn on a camber. David says he does it, while I have experienced the camber being exaggerated (blade cuts more in the centre), which is likely down to technique.

One other area to watch out for with planes is the chipbreaker. It seems to be reasonable to buff the leading edge. However, rounded leading edge is one thing (good), but a nano bevel is likely to end up with a seriously high leading edge angle, and I have experienced the plane refusing to cut.

It appears there are carvers who use buffing wheels on carving tools. Surely this approach was shared with non-carvers.

So why are there no magazine articles or other mention of the technique?

Jim, as I have mentioned before, a carver is likely to be buffing the bevel to polish it to a high level of sharpness. To do this, the bevel angle is maintained. The unicorn bevel is not aimed at sharpness, per se, but to improving edge holding. Sharpness is a bye product (I buff with the angle of the buff - which sharpens - and then increase the buffing angle, which creates the unicorn profile). The unicorn is a higher nano bevel, and this is unique to the unicorn edge (I am not suggesting that David invented it, but that it is the target here).

Note: David has written a fuller article on this process, which is on the WoodCentral website (which I cannot link to - silly rule here ... which are all in this game together).

Regards from Perth

Derek

[Warren Mickley]

Wood sculptors often use a buffing wheel. Some do most of their sharpening on the wheel, with occasional grinding or honing. On the other hand, for carving we need a more precise geometry, so we use slip stones and strops. None of the carvers I know use a buffing wheel at all.

[Winston Chang]

Daniel, David reports success with bevel down planes. He shows evidence of very fine shavings. I began with bevel up block planes and had success. This has been replicated by others. We are all moving slowly, via experimentation, to understanding the dynamics of adding a unicorn profile.

I have not found this as easy to do on BD and BU plane blades as simple block plane blades. Block planes are like chisels in that they are honed on the straight, and the surface quality is not the main area of interest; being sharp and holding this is most relevant.

The success of a bench plane, whether BD or BU, lies in the surface quality. The issue (for me) when unicorning a plane blade is that a high nano bevel can cause the BD plane to run out of clearance, while a high nano bevel on a BU plane can like using a scraper (lots of resistance). The other factor is creating the unicorn on a camber. David says he does it, while I have experienced the camber being exaggerated (blade cuts more in the centre), which is likely down to technique.

Derek, I'm a bit surprised you've had trouble with bevel-up planes. I've been buffing blades for my Veritas low-angle jack and low-angle block planes, and they both leave a very, very smooth surface on the softwoods and hardwoods I've tried (white pine, yellow pine, cherry, red oak). I'd even say that the surface is as good or better than the best surface quality I've been able to get with any other plane. To me, the sharpness and uniformity of the edge is a big benefit of unicorning plane blades. The straightness and smoothness of the edge is better than what I can achieve by hand sharpening, and that translates to better surface quality.


It sounds like perhaps the angle at the edge is too high in your case? If so, you'll probably want to do less buffing, and that may require getting the blade closer to a finished condition on stones before taking it to the buffer.


Here's one way I've been doing it for bevel-up planes:


- Hone a 25-degree bevel on the blade with a Shapton Pro 1000.
- Work the back of the blade on a fine stone (I use a Sigma Power 6000) to ensure any existing damage is removed.
- Lightly work the bevel and then the back on the fine stone to help minimize the burr. (For a good edge, the buffer at a minimum needs to remove the burr, so if there's less burr, you can get away with less buffing, and therefore less angle increase.)
- Buff the bevel side of the blade.




For bevel-down planes, I've also had good results, but it is possible to have clearance issues. I know you've read David's article and seen the section about bevel-down planes, but for those who haven't, the procedure is basically the same as the one I described above. The surface quality that I've been able to get is, again, extremely good, and sharpening is easier and faster, since I don't need to go to the finer stone, and I don't have to be as careful about perfecting the edge -- the buffing wheel takes care of that.

[Derek Cohen]

Derek, I'm a bit surprised you've had trouble with bevel-up planes. I've been buffing blades for my Veritas low-angle jack and low-angle block planes, and they both leave a very, very smooth surface on the softwoods and hardwoods I've tried (white pine, yellow pine, cherry, red oak). I'd even say that the surface is as good or better than the best surface quality I've been able to get with any other plane. To me, the sharpness and uniformity of the edge is a big benefit of unicorning plane blades. The straightness and smoothness of the edge is better than what I can achieve by hand sharpening, and that translates to better surface quality.


It sounds like perhaps the angle at the edge is too high in your case? If so, you'll probably want to do less buffing, and that may require getting the blade closer to a finished condition on stones before taking it to the buffer.


Here's one way I've been doing it for bevel-up planes:


- Hone a 25-degree bevel on the blade with a Shapton Pro 1000.
- Work the back of the blade on a fine stone (I use a Sigma Power 6000) to ensure any existing damage is removed.
- Lightly work the bevel and then the back on the fine stone to help minimize the burr. (For a good edge, the buffer at a minimum needs to remove the burr, so if there's less burr, you can get away with less buffing, and therefore less angle increase.)
- Buff the bevel side of the blade.




For bevel-down planes, I've also had good results, but it is possible to have clearance issues. I know you've read David's article and seen the section about bevel-down planes, but for those who haven't, the procedure is basically the same as the one I described above. The surface quality that I've been able to get is, again, extremely good, and sharpening is easier and faster, since I don't need to go to the finer stone, and I don't have to be as careful about perfecting the edge -- the buffing wheel takes care of that.

Thanks Winston. Interesting ideas there. They do make sense.

I need to experiment, but I have a good idea why it does not work for BU bench planes ...

The history of my using bevel up planes lies with a need for high cutting angles for interlocked West Australian timbers. It was BU Veritas or high angle HNT Gordon woodies. All needed a cutting angle of at least 60 degrees. For BU planes on a 12 degrees bed, as all know, this is a bevel around 50 degrees.

So here's the thing: if you have a 50 degree bevel, why introduce a Unicorn profile? Firstly, it is not necessary for edge endurance. Secondly, increasing the angle at the leading edge makes the plane behave horribly - like a scraper.

So I imagine that those who do unicorn a BU bench plane are using a lower bevel angle to begin. Winston, you are stating that you use a 25 degree bevel. How do you know what you are adding by way of cutting angle with the unicorn profile? Another 20 degrees? 30 degrees? That takes the cutting angle to around 45-50 degrees. It is too low for WA timbers.

The problem here is that BU bench planes require a somewhat OCD approach when you work with interlocked grain. Lesser woods do not test this issue. Just as a case in point, I love the streamers that David and Rob Cosman can produce. On the wood - Hard Maple - it just requires a sharp edge. I can replicate this with ease in my workshop. It is fun However, try the same set up on a wood like Jarrah, and it will be patchy, the shavings will struggle to straighten, and you will think that the plane blade is dull. Back to the Maple, and the streamers fly.

I use bevel down planes far more these days, and plan to do a little practice this weekend. It is needed in this area and there are a few ideas to try out - I will report back later.

Regards from Perth

Derek

[steven c newman]

Just stopped in at Lowes, today....between the wheels, and pair of large washers + Mil. Discount..$11.30

Kobalt brand. 2 wheels, one "Firm" and one "Medium"...with a leather washers sewn in....5/8" arbor hole. Two $0.37 cent 5/8" washers to help out..

One wheel is white, the other is yellow..may try the yellow first. ( need to find that green "crayon", too)

[Winston Chang]

Thanks Winston. Interesting ideas there. They do make sense.

I need to experiment, but I have a good idea why it does not work for BU bench planes ...

The history of my using bevel up planes lies with a need for high cutting angles for interlocked West Australian timbers. It was BU Veritas or high angle HNT Gordon woodies. All needed a cutting angle of at least 60 degrees. For BU planes on a 12 degrees bed, as all know, this is a bevel around 50 degrees.

So here's the thing: if you have a 50 degree bevel, why introduce a Unicorn profile? Firstly, it is not necessary for edge endurance. Secondly, increasing the angle at the leading edge makes the plane behave horribly - like a scraper.

So I imagine that those who do unicorn a BU bench plane are using a lower bevel angle to begin. Winston, you are stating that you use a 25 degree bevel. How do you know what you are adding by way of cutting angle with the unicorn profile? Another 20 degrees? 30 degrees? That takes the cutting angle to around 45-50 degrees. It is too low for WA timbers.

The problem here is that BU bench planes require a somewhat OCD approach when you work with interlocked grain. Lesser woods do not test this issue. Just as a case in point, I love the streamers that David and Rob Cosman can produce. On the wood - Hard Maple - it just requires a sharp edge. I can replicate this with ease in my workshop. It is fun However, try the same set up on a wood like Jarrah, and it will be patchy, the shavings will struggle to straighten, and you will think that the plane blade is dull. Back to the Maple, and the streamers fly.

I use bevel down planes far more these days, and plan to do a little practice this weekend. It is needed in this area and there are a few ideas to try out - I will report back later.

That makes sense that with the woods you're using, you have a different set of concerns than I do.

For me, using a 25-degree blade and buffing it seems to make it behave like a low angle blade in terms of surface quality (planing with the grain in softwood), but did result in some tearout when going against the grain. I also used a unicorned 32-degree blade, and it had better resistance to tearout, and only marginally worse surface quality in softwoods.

I don't know exact final angle was for my buffed 25-degree blades. Based on the previous blade profile pictures I've taken, I'm pretty sure it's at least 45 degrees, which results in a cutting angle of at least 57 degrees. Still, the surface quality is much better than what I'd normally expect from that cutting angle, so I think when you're talking about the angle of a nanobevel, the behavior (with respect to surface quality) isn't exactly the same as with a flat-honed blade at the same angle.

I agree that the blade durability won't be increased much if at all by buffing, if you're already using a 50 degree bevel. But the buffing wheel still has a big advantage in terms of being very fast and easy to get a good uniform edge. It almost feels like I'm cheating now when I use a buffing wheel to sharpen a blade for a bevel-up plane.

My guess is that you'll want to start with a different angle (maybe 35-40?) before taking it to the buffing wheel, but I don't know for sure. All that said, it might be that in the end, a bevel-down plane is still best for you.

[Winston Chang]

Just for fun, here's the surface of the white pine after planing it with the buffed 25 degree blade. Of course you can this kind of a surface without using a buffing wheel, but the buffing wheel makes it easier.

planed-white-pine-2.jpg