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Thread: More on Unicorn Profile

  1. #1
    Join Date
    Feb 2012
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    More on Unicorn Profile

    I'm still crippling around on a bad wheel so not much is happening in the shop even sharpening is too much some days. There have been a few days where whisky and a elevated foot was all I could do. On one of the good days I did install a stitched cotton wheel on the grinder and have taken a couple of my old Freud Chrome Vanadium chisels (BTW, they were the first "good" chisels I bought from the Garret Wade catalog many years ago) and ground a Unicorn profile then buffed on the buffing wheel with green stuff.

    chiselUnicornEdge.jpg

    First go, David Weaver may be on to something. First it is very quick, grind a bevel on the grinder, hone a secondary with a Washita, Medium India or other quick 1000 grit or so stone. Use whatever you have handy, then maybe 15 to 30 seconds on the buffing wheel. The chisel comes out very sharp and the edge is long lasting, maybe longer lasting and sharper than off a polishing stone.

    That's the good news, the process seems to work, it is very quick, and the equipment is inexpensive. That may also be the bad news. What do I do with the tens of thousands USDs I have in sharpening stones when to get a sharper, longer lasting edge all you need is a grinder with a buffing wheel, a little green stuff, and a $30 USD India stone. Also maybe a meal or two of crow.


    Check out the Unicorn profile posts on Wood Central, wear your masks and stay safe,


    ken

  2. #2
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    Thanks for the update Ken. Which cotton wheel did you go with? Using any smear on the wheel?
    David

  3. #3
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    Quote Originally Posted by David Eisenhauer View Post
    Thanks for the update Ken. Which cotton wheel did you go with? Using any smear on the wheel?
    David,

    Just one from Amazon, I think listed as best seller which usually means cheap. Yep, a green stick from IIRC WoodCraft.

    ken

  4. #4
    Join Date
    Aug 2012
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    Check out the carvers and knife people. Power strops and wheels all over the place. Used for all those carving tool shapes.

  5. #5
    Join Date
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    Michiana
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    When I was in high school woodshop in the '70s, we used a grinder, then a buffer to sharpen lathe tools. It left a razor sharp polished edge that would peel off the wood like it was soap.
    Sharp solves all manner of problems.

  6. #6
    Join Date
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    The technique discussed by DW arose from buffing some carving tools and some rigorous experiments.

    Short version - edge retention is longer, sharpening time shorter.

  7. #7
    At least you still got your plane irons to use on stones. Are there any downsides?

  8. #8
    Join Date
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    Quote Originally Posted by Matt Riegerix View Post
    At least you still got your plane irons to use on stones. Are there any downsides?
    Matt,

    I'm still reading and playing but first impressions are there are no downsides. On that time will tell. The folks over on Wood Central have been working at this a lot longer than I have. Winston Chang in a reply to another SMC thread said he had spent the weekend converting his chisels which implies no downsides.

    I have a feeling the stones will gather dust even for the plane irons if results hold. Whatever the JNATs sure are pretty and make a beautiful bevel and the years I've spent learning the skill to use 'em all will still be there. Maybe.

    BTW, Crow in browned butter and a little garlic is really good.

    ken

  9. #9
    Matt - they've been doing it to irons as well.

  10. #10
    Join Date
    Feb 2004
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    Note that buffing an edge is different with the unicorn method and sharpening carving gouges, or sharpening per se. The unicorn edge is a slightly rounded edge - I have referred to it as a nano bevel, alghough it us rounded in shape from buffing. The aim here is not to sharpen - although the chisels get very sharp. - but the increase the cutting angle at the very edge, and thereby strengthen the edge to hold it for a longer time.

    There has been some experimentation on plane blades. I reported that block plane blades work well. This had been interesting for me as cutting end grain posed no problem and, with the rounded edge at a higher cutting angle, chamfering edges was less vulnerable to tear out. Plane blades are another story. I am not comfortable with this yet - the performance is too hit-and-miss. Also, be careful with buffing the leading edge of chipbreakers. Mine at at 50 degrees. I buffed a couple, and this must have increased the angle significantly as the planes stopped cutting. They were fine when the leading edges were returned to 50 degrees.

    I have not reduced primary bevels on chisels to 20 degrees (yet - we’ll see). My paring chisels remain at 25 degrees and bench and mortice chisels are 30 degrees.

    Regards from Perth

    Derek

  11. #11
    There are no downsides for chisels that I can see. I'm still getting a handle on the technique for plane blades.

    David is satisfied with his method for (bevel-down) planes, and he mentioned that he's going to be selling off a lot of stones. Best to sell off your stones before word gets out and everyone realizes they don't need them anymore.

  12. #12
    Derek, have you found that the unicorn profile significantly benefits edge durability when planing end grain with a bevel-up plane? That's one thing I never liked about using a shooting board -- that it dulls the blade pretty quickly, especially since the damage is in one location on the blade (my shooting board isn't ramped). But if the blade lasts several times longer, then shooting regularly becomes much more appealing.

  13. #13
    Join Date
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    Winston, I compared the longevity of steel type and bevel orientation here: http://www.inthewoodshop.com/ToolRev...tingPlane.html

    and here: http://www.inthewoodshop.com/ToolRev...eirBlades.html

    The bottom line is that bed angle, rather than simply cutting angle, is a central factor in bevel wear. Higher beds create greater force on the edge, and this leads to greater wear. In short, even a lower bevel angle on a bevel up shooting plane (e.g. Veritas Shooting Plane) outlasted a higher bevel angle on a bevel down shooting plane (e.g. Lie Nielsen #51).

    It would be interesting to redo this with the unicorn profile, but it probably would not alter the results. What it may do is improve longevity of the edge. The brief experience to date profiling the Veritas blade has demonstrated that it cuts as well as the unprofiled edge.

    Regards from Perth

    Derek

  14. #14
    Pretty exciting stuff. Anyone have recommendations for a buffing wheel for a Rikon 80-805 slow speed grinder?

  15. #15
    Quote Originally Posted by Derek Cohen View Post
    Winston, I compared the longevity of steel type and bevel orientation here: http://www.inthewoodshop.com/ToolRev...tingPlane.html

    and here: http://www.inthewoodshop.com/ToolRev...eirBlades.html

    The bottom line is that bed angle, rather than simply cutting angle, is a central factor in bevel wear. Higher beds create greater force on the edge, and this leads to greater wear. In short, even a lower bevel angle on a bevel up shooting plane (e.g. Veritas Shooting Plane) outlasted a higher bevel angle on a bevel down shooting plane (e.g. Lie Nielsen #51).

    It would be interesting to redo this with the unicorn profile, but it probably would not alter the results. What it may do is improve longevity of the edge. The brief experience to date profiling the Veritas blade has demonstrated that it cuts as well as the unprofiled edge.
    Thanks for those articles. I had seen them a while back but it's good to see them again.

    My question was about the durability of a buffed edge when shooting with a bevel-up plane. (I'm not questioning your conclusions about bedding angle and edge damage.) My hope is that the unicorn profile in this situation can greatly increase edge durability, as it does for chisels used for chopping.

    In the close-up pictures you have of the blades, they all appear to have some degree of chipping. From the blade's point of view, shooting end grain with a bevel-up plane is similar to chopping across the grain with a chisel. We know from testing that buffing can effectively eliminate chipping for chisels doing chopping. It seems likely to me that buffing could also eliminate chipping for a plane used for shooting. If there's no chipping, then I'd expect the blade to be able to keep cutting longer, and gradually become more difficult as the edge gets rounded by abrasion.

    Note that I'm specifically talking about bevel-up planes. Buffing the blade for these planes increases the cutting angle, but hopefully with a small enough nanobevel that there's not an appreciable increase in resistance. With a bevel-up plane, the tiny nanobevel could be 45 degrees or even higher, which would result in a very durable edge. With a bevel-down plane, if you buff the blade so that it has a 45-degree nanobevel, there will be clearance problems.

    Hm, now that I think of it, maybe this is something that I should test out.

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