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Gyuto - a new profile - WIP

Discussion in 'Brock Cutlery' started by Mark Brock, Dec 10, 2016.

  1. Mark Brock

    Mark Brock Professional Craftsman

    Here is a WIP Gyuto with a new profile style for me. I think this would be considered a westernized blade style.
    I appreciate comments and suggestions if you have any to give.

    We have to start with my trusty do everything grinder. I love this machine. Built like a tank and just a rock solid tool for shaping and grinding my knives.

    [​IMG]

    This is the new design I'm working on with a full distal taper and a thin convex blade geometry.
    Pics below show it as compared to what I typically make.

    [​IMG]

    [​IMG]

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    This is the basic profiling stage with a flat grind. I'll be taking this to the rotary platen for a convex final geometry, thinner tip than it has above, and about .01 or slightly less at the edge.

    Comparison, old vs new:

    [​IMG]

    Thanks for having a look!
     
  2. Lefty

    Lefty Founding Member

    Looks great! Sometimes it's really quiet around here...not sure why. Anyways, I'd use the hell out of it, with that profile. I'm looking forward to seeing how it turns out.
     
  3. chefcomesback

    chefcomesback Founding Member

    Looks nice


    Sent from my iPhone using Tapatalk
     
  4. Mark Brock

    Mark Brock Professional Craftsman

    Thanks guys!

    Now the hand sanding begins. There is something soothing about this stage if you let yourself have the time.

    [​IMG]
     
  5. Looks nice! So how thin it is behind the edge? Can you take a picture of tip thinness?
     
  6. Mark Brock

    Mark Brock Professional Craftsman

    Hi Anton,
    I hit .010 at the edge which is what I tend to shoot for. The taper on this one goes from 2.38mm over the heal to 1.66mm 2 inches from the tip. It tapers down to the tip from there naturally with the grind.
    Here is a pic with the 2 inch mark noted.

    [​IMG]



    Choil shot

    [​IMG]
     
  7. Mark Brock

    Mark Brock Professional Craftsman

    Here is how the hand sanding finish works. It starts off with the belt finish. In this case I stopped at 150 grit. I do all my post heat treat grinding wet to keep from spoiling the temper.
    This is the finish at 150.

    [​IMG]


    From there I start at 320 grit, progressing to 400, 600, 800, 1200.

    Here is a shot of 1200 taking out the 800 grit scratches. The standard way to hand sand is to cut a 45 path with one grit, then alternate opposite with the next so you can see the scratch pattern that needs to come out.
    I use a light machine oil for this entire process.

    [​IMG]

    A steady hand and straight strokes are required to keep the finish even and the pattern consistent. This is one of the sins of hand sanding, the dreaded fishhook scratches. This is caused from an abrupt stop in the sanding stroke.
    You can get away with this at the lower grits to some extent as it will all be coming off on the next grit. But you can't do this in the final grit without causing yourself a lot of grief.

    [​IMG]

    The final grit gets the 45 deg routine, then gets the longitudinal clean up strokes, so basically you are doing the last grit twice.
    One method I learned through hours of sanding is that as the paper clogs it stops cutting for the most part, which is bad when you need to remove scratches.
    But it is very good when all of your scratches are gone. At this point, with the grit filled with metal shavings and sand particles, it becomes a great burnishing tool.
    You must still keep the strokes full and even, but the more you use this last bit the smoother your surface will become. It won't produce a buffed mirror look, you will still have the line pattern of 1200 grit, but the lines will be reduces somewhat and it will have a mirror like appearance.
    This shows the top half burnished while the bottom half is just 1200 grit lines. It's difficult to get a good pic at this point.

    [​IMG]
     
  8. Mark Brock

    Mark Brock Professional Craftsman

    Hey, I also wanted to say that I can take the edge down to any thinness, including 0. Do you have a preference yourself?
     
  9. Photos can be deceiving especially when we talk about thickness. Personally I'd prefer a thinner knife in the edge and right behind it, but as always, there's a lot to do with personal preferences, technique of cutting etc. It's an art to find the balance between making knife super thin and retaining good food release and but without feeling flimsy at the same time.

    In my collection I have very good cutters with S-grinds, awesome cutters with convex grind, really nice wide bevel cutters with almost zero convexity, so there's no silver bullet for me. Experiment and see what works for you :)
     
  10. Mark Brock

    Mark Brock Professional Craftsman

    Thanks Anton. I have a similar collection, although i have yet to do any exotic S grind work. I have a 14 inch wheel that I plan to test out at some point.
    But of course you are right. Personal preference and the job at hand dictate the best edge geometry. My wife has a thin laser Gyuto and a somewhat thicker convex ground blade as well.
    She loves the laser on standard veggie prep, and won't use anything but the thicker convex blade for splitting things like winter squash. It all has it's place.
     
  11. Ya that profile looks spectacular. Also hand sanding is hard work cant wait to see the finished package.
     
  12. Lefty

    Lefty Founding Member

    I always say grind it to zero, and add a bevel to help the cut. @CrisAnderson27 has the best examples of this geometry I've ever seen, but my @butch Harner knives can cut with no edge, like nobody's business.
     
  13. Lefty

    Lefty Founding Member

    Also, this knife looks incredibly promising. Really nice work, man.
     
  14. Mark Brock

    Mark Brock Professional Craftsman

    Thanks for the compliments! I am looking forward to testing this one out. The hand sanding has taken the edge a bit thinner still, so it is under .010.
    I have a few more of these to make so I might experiment with a zero edge grind and see how it pans out.

    I have studied Cris and Butches work. They are good makers and I have to say I respect both.
     
  15. Thanks for sharing all the cool wip pics! Love to see what people are doing in their shops! :cool1

    I think we discussed a little bit on another forum about kitchen knife geometry and profiles. My personal preference from my experience is that my favorite knives look like they were ground extremely close to zero behind the edge before sharpening. Less than 0.01" is pretty much getting close to zero, and how it cuts probably depends on how acute the cutting edge is. For a gyuto which is general purpose, I like it to push cut hard stuff like carrots without much resistance initiating the cut. Even a beefy convex blade with proper geometry at the edge can do this, but one that is too thick behind the edge will hang up with resistance on initiating the cut.

    You may have seen it, but Cris Anderson recently put an instagram video of cutting potatoes with a few of his knives unsharpened.

    I agree there are plenty of different geometries and profiles that can work, and it's probably a matter of matching up the best one for a particular customer's preferences. On customs I've ordered, I usually detail what I cut the most in the kitchen as well as how I hold the knife and what types of cutting movements I tend use. Then I wait and see what they come up with.
     
  16. Mark Brock

    Mark Brock Professional Craftsman

    Hi MB. I did see Chris' video on unsharpened veggie cutting. I will try a few in the next round taken to zero edge. This one is getting about done.
    I think it's pretty interesting that you give your technique and style to a knife maker and have them figure out the best config for you. It makes sense, but maybe backwards a bit from what we usually see.
    I'm not familiar with custom orders. I've done a couple of custom knives, but there was no real blade geometry specified so I was free to do what I like.

    To get back to the WIP. Here I'm trying out some different materials. This is macassar ebony and manzanita with a silver bullion ingot spacer. These are 3 of my favorite materials.
    This manzanita just isn't a long enough piece to make a handle from, but it has such great color and grain...

    [​IMG]

    Here I am milling out the tang slot in the ebony. This helps ensure a nice snug mechanical fit. This leaves just the right size gap for epoxy.

    [​IMG]
     
  17. Mark Brock

    Mark Brock Professional Craftsman

    Here is the finished product.
    I ended up going with Macassar ebony, manzanita burl and silver ingot spacer with red oak on the rear with medullary ray pattern. This is stabilized oak with tons of character from top to side to bottom.
    Experimenting a bit with handle shape. Oval config. I would classify this handle for hands small to medium.
    AEBL @62 hardness
    185 mm blade
    336 overall lenth
    47mm tall at heal
    2.33 mm thickness at spine
    less than .01 behind the edge.
    good distal taper with a thin tip.

    Blade is a burnished satin to 1200 grit.

    Thanks!

    [​IMG]

    [​IMG]

    [​IMG]
     
  18. cassca

    cassca Vendor

    i love that !
     
  19. Mark Brock

    Mark Brock Professional Craftsman

    Thanks Bryan!
    Hey, I was looking at your suji post where you show 4 platens. You actually use a concave platen? I haven't seen that before.
     
  20. cassca

    cassca Vendor

    it's not me ;-)
     

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