KnifeForums.com - Intelligent Discussion for the knife enthusiast
Recent Members
Welcome them to our community!
Recent Topics
Recent Pictures
thumb_1406560141-DSC_0018.JPG
thumb_1406365749-175-Honduran-Hunter-f.jpg
thumb_1406244502-apple1.jpg
thumb_1406242071-IMAG0183.jpg
thumb_1406138951-1.JPG
thumb_1405723916-IMG_1451.jpg
thumb_1405631397-6.JPG
thumb_1404764053-004.JPG
thumb_1404657528-DSC_0483.JPG
thumb_1404465179-190720104842.jpg
Current Quote
"Security is mostly a superstition. It does not exist in nature... Life is either a daring adventure or nothing."
~ Helen Keller
375 Online Now
26 viewable users (
    ) and 0 hidden plus 349 guests are online now.
    Username Post: Convex vs. flat vs. hollow grind        (Topic#1142)
    jgtiffany
    Member
    *
    06-30-01 05:25.00 - Post#1142    



    Can anyone tell me the relative advantages/disadvantages of using a convex grind for the blade's edge? I recently read an article extolling the convex grind as superior in every way, but I have read other articles and books that say flat or hollow ground is the only way to go.

    I was also wondering if anyone could tell me (or point me to some reference materials) how to put a convex grind on a blade. That way I could experiment with it myself.

    Thanks!

    Jim

    Where are we going, and why am I in this handbasket?

    ------------------
    This sentense contains threee errors.

     


    Jerry Hossom
    Master Member KnifeNut!
    *
    06-30-01 05:47.00 - Post#1143    


        In response to jgtiffany

    I think it basically has to do with what you are trying to cut, though this is probably one of the most contentious subjects in knifemaking. Whatever you hear about it, all anyone can offer is an opinion, including me.

    If you are cutting wood, convex is hard to beat since it provides its own wedge to help in the cutting. Also, the sides of the blade are generally prevented by that same wedge from rubbing against the material being cut as it penetrates, thereby reducing friction. It produces the heaviest blade, removing the least amount of steel, and is the most difficult to sharpen without equipment.

    If you are cutting rope or wood or most anything else for that matter, a flat grind is probably the best all around grind. The edge on a flat grind can be made convex to give you some of the advantages of the convex grind, yet the primary grind itself can be pretty fine allowing for very delicate cutting as well. While the blade is generally heavier than a hollow ground blade it can be lightened with a distal taper (ie tapering towards the point).

    The hollow grind can produce the finest edge and is therefore very good for cutting flesh and most non-rigid or softer materials. It can fail utterly in the wood chopping test, because the top of the hollow grind acts like a barrier to any further penetration. Since the center of the blade is hollowed out, the overall blade weight can be the lightest without reducing the thickness of the blade's spine. Hollow ground blades are probably the easiest to sharpen over time, because the blade thickness remains thin even after the primary edge is sharpened away.

    Ask most knifemakers and they will tell you that the one they best know how to grind is clearly the best to have. And most have had many years to completely rationalize that opinion...

    ------------------
    http://www.hossom.com

    “A fear of weapons is a sign of retarded sexual and emotional maturity" Sigmund Freud


     
    jgtiffany
    Member
    *
    07-02-01 03:53.00 - Post#1144    


        In response to Jerry Hossom

    Thanks for the information, Jerry. That does clear up some of the confusion. I think you're right about each knifemaker having a "pet" technique. The Razor Edge Book of Sharpening, for example, opines that the hollow grind is best for everything, including _axes_, with the flat grind being second, and that the convex grind is useless. Go figure.

    I read your post about convex grinding and I was wondering how to create/sharpen a convex grind without a belt grinder?

    I may be able to get my hands on a belt sander eventually, but not right now. I have an 8" bench grinder and a couple of Razor Edge sharpening guides.
    Thanks.

    Jim

    Where are we going, and why am I in this handbasket?

    [This message has been edited by jgtiffany (edited July 02, 2001).]

    Where are we going, and why am I in this handbasket?

    This sentense contains threee errors.



     
    Jerry Hossom
    Master Member KnifeNut!
    *
    07-02-01 05:59.00 - Post#1145    


        In response to jgtiffany

    Since a convex edge is pretty durable, touching it up with a ceramic stick once in awhile is usually sufficient. Obviously it will eventually wear and need some regrinding.

    Some folks say you can simply use wet and dry paper on a semi-solid surface like hard rubber to sharpen convex edges. That might work if the rubber is pretty hard.

    BTW, You can get sharpening wheels for your bench grinder. These are laminated cardboad wheels with abrasive on one and polishing compound on the other. These are what you see being used by the guy who is at every gun show sharpening knives for $2-3 each. Most knifemaking supply houses sell them.

    To use them for making a convex edge...

    After you lay in your bevels with your present sharpening system, use the sharpening rough wheel to round over the angle at the top of the bevel, then polish the bevel down to the edge, just until you raise a small wire bead on the edge. Polish that off with the other wheel and you'll have a pretty decent convex edge.

    ------------------
    http://www.hossom.com

    “A fear of weapons is a sign of retarded sexual and emotional maturity" Sigmund Freud


     
    R.W.Clark
    Journeyman KnifeNut!
    *
    07-02-01 06:26.00 - Post#1146    


        In response to Jerry Hossom

    I totally agree with Jerry. All three have their place. I flat grind only because it is a nice middle ground.

    Its kinda like asking which is the best vehicle. Should you get the Porsche, the SUV or the Mack truck. All depends on what you want. I will always chose the SUV, but to each his own.

    ------------------
    R.W.Clark

    Proud Member : California Knifemakers Association

    The sword that cuts down evil brings life to those upon which evil would prey.

    [red]R.W.Clark[/red] www.rwclarkknives.com President, California Knifemakers Association


     
    RDT
    Master Member KnifeNut!
    *
    07-02-01 14:35.00 - Post#1147    


        In response to R.W.Clark

    I love the Hollow grind, I like flat as well but Jerry is correct. It's all a matter of what knife to use for each occasion. I don't chop much wood. I like knives for light utility and light duty like rope, boxes and for the use of self defense. Therefore I go with the hollow as it is just so easy to sharpen and damn ! is it sharp. There will almost always be the thin area of steel on the blade so that it will always retain a good sharpening ability. Convex in my opinion works on impact that is why it's good for chopping but it is not usually good for delicate tasks. Good luck !.....RDT

    ------------------

    DERESPINA_KNIVES@HOTMAIL.COM Karambit specialist ! www.derespinaknives.com


     


    Icon Legend Permissions & Sharing Options Topic Options
    Print Topic


    2430 Views
    KnifeForums.com - Intelligent Discussion for the knife enthusiast
    KnifePromotions

    arenaro@verizon.net

    FusionBB™ Version 3.2 | ©2003-2014 InteractivePHP, Inc.
    Execution time: 0.274 seconds.   Total Queries: 114   Zlib Compression is on.
    All times are (GMT-12.0). Current time is 02:25.16
    Top