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Sharpening Global with Spyderco

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  • mliew Jun 27, 2009 05:08 PM
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I just got my Spyderco Tri-angle Sharpmaker 204 and have been practicing with some of my cheap knives. I'm not sure though if I should be using it on my Global knife or not.

1. I read that the factory angle for Global knives is about 15 degrees and the edge is convex. With the Sharpmaker it seems I should be using the 30 degree rod setting to achieve the 15 degree angle. Is this right?

2. In all of the pictures in the manual the knives have a straight edge. Is it ok to use the Sharpmaker on the convex edge of my Global knife or will that ruin the edge?

Any other tips or suggestions?

Thanks.

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  1. Hmm, seems nobody knows? Anyone have any suggestions as to how to sharpen convex knives in general? Seems to not be a whole lot of information on the internet regarding convex edges. Doing some research most people seem to do it by hand with sandpaper tacked to a mouse pad but I don't think I have enough skill to try that, especially not with an expensive global knife.

    Was hoping there might be a more foolproof way of sharpening a convex knife.

    3 Replies
    1. re: mliew

      I'm afraid I don't know the Spyderco but in general Global knives call for caution. I don't think I'd risk mine. I use the MinoSharp and have done for 8 years on all my Global knives and they are perfect and sharp. Occasionally I've shipped them to Global but not often. There are people who don't believe in the MinoSharp though personally I think it's likely they have never used it! It is made for Global knives and as I say my 8 years of experience with it have been positive.

      1. re: mliew

        I'm not familiar with the spyderco set up so I can't comment but convex edge is done by not holding a constant angle and rolling up. It is difficult to do on a hard stone or surface. Easier, well for those with experience, done on softer whetstones.

        Quote from Knife Sharpening Tips
        by Joe Talmadge

        http://www.worldknives.com/info/knife... Worth a read or two!

        "The Moran (Convex) Edge
        Named after Bill Moran and featured on many of Blackjack's knives, the Moran edge (aka convex edge) is, well, convex. Usually, an edge is a straight bevel over the last millimeter or two of the knife. With a convex edge, the edge continuously curves towards the very point. The advantage is that there's more metal behind the edge, so you end up with a very sharp but strong edge, which needs to be felt to be believed. Knifemakers typically create this edge with a slack belt, which leads us to the disadvantage: if you don't have a slack belt grinder and the know-how, you'll need to return your knife to the maker for sharpening periodically."

        1. re: mliew

          Just sharpen the thing. It's a tool. You're supposed to cut things with it. You're not supposed to panic about it. There's nothing magical about a convex edge. What's nice about it is that it's easy to touch up -- because the bevel right at the edge is quite obtuse, not much of the knife (measuring from the edge to the spine) needs to touch the abrasive to reach the edge. The sharpmaker will do fine on it. Eventually, you'll turn the convex into more of a V-grind, but it'll take years. And you're not going to hold a terribly exact angle on it, so it will end up with something convexish, anyway. Again: it's a tool, not a holy relic. The actual angle at which the two bevels of a knife meet has very little to do with its keenness or it's suitability for a particular purpose. Keenness is strictly a function how thick the edge is. (Ever cut yourself with a piece of paper? That's a 180 degree included edge. Microtome blades, back when they were sharpened, were often sharpened with a 90 included angle. They cut cells in half. They're plenty sharp, because the edge is thin enough.) Suitability for a purpose is much more about the geometry of the knife from the bevel to the spine: slicers tend towards thin, meat cleavers thick. You're not going to change that without working at it, for hours and hours, with the sharpmaker. Work on the keen edge, which the sharpmaker (it really should be called the sharpkeeper, it's great for keeping edges sharp, not so much for major sharpening) is quite suitable for.

        2. Thanks for the suggestions everyone. I originally thought about going with the Minosharp but reviews on it were pretty mixed. Also I already have one of the Chefs Choice pull through sharpeners and while it did a decent job I was never able to get a scary sharp edge on any of my knives with it. I figured the Minosharp would be more or less the same kind of thing.

          dscheidt: I guess you're right about not worrying so much about it. Even with the knives I sharpened already I can see that I wasn't really reshaping the angle of the blade even with 50+ strokes. I used the Sharpmaker on one of my cheap cleavers with a convex edge and it cuts really nicely now. I guess without higher grit I couldn't do too much damage with the Sharpmaker.

          2 Replies
          1. re: mliew

            I use the Spyderco on my Global...it seems to work great...

            1. re: mliew

              A convex edge does make for a strong edge but in all honesty I wouldn't worry about it unless you plan on sending the knife out to Global or other professional to maintian the convex edge. You can sharpen to a flat edge using your spyderco and it will still be shaving sharp and you can maintain that yourself. Again try to read up on the basics of knive sharpening. It's not so scary and you have only a small chance of really screwing up but even then it can be fixed.

            2. So I went ahead and sharpened my Global knife with my Sharpmaker just now and it seems to have done a pretty good job, however one of the main things I was hoping to fix is to straighten out the edge. If I look closely at the edge I can see that its not completely smooth and there are very small dings in the blade. How can I remove those? Seems like if I keep sharpening in a V shape it's not going to get rid of those.

              14 Replies
              1. re: mliew

                I use a fine ceramic steel to straighten the edge on my Globals.

                1. re: tanuki soup

                  Sorry, I guess I should have worded my post a little better. By straighten the edge I don't mean straightening like you would with a steel. I mean that if you look at the edge of the knife from the side of the blade the edge along the bottom looks "wavy" because of the little dings in the blade.

                  1. re: mliew

                    Sorry I misunderstood. I'm no knife guru, but it seems to me that the only way to get rid of dings such as those you describe is to hone the edge back. After a bit of practice on junk blades, I've found that I can get a nice even edge on my knives (including the Globals) by sharpening them on ceramic water stones.

                    1. re: mliew

                      I are talking micro chips in the edge? If so then they need to be sharpened out

                      1. re: scubadoo97

                        Yeah, the edge is chipped. So if I just keep sharpening in the V-pattern it should eventually take off enough metal to remove the chips?

                        1. re: mliew

                          When I get micro chips I will usually go straight to a 1000 grit stone. This will usually get rid of the chips in a few minutes of sharpening. I don't know the grit level of your rods but the coarser the better for chip removal if you are looking at saving time. You can then go back through finer rods to to achieve the level of refinement you're looking for. If you continue to have problems with chips you can add a secondary bevel which will make the edge stronger. To add a secondary bevel you want to increase the angle by maybe a few degrees on each side after your initial sharpening.

                          1. re: scubadoo97

                            Yeah I'm not sure of the grit of the stones that come with the Sharpmaker. All it says are medium and fine grit but the medium is pretty smooth so it can't be a very high number.

                            I guess I'll give it a try and maybe look into getting a high grit waterstone.

                            I've seen some people just use regular sandpaper as well. Is there any pro/con of using sandpaper over a stone?

                            1. re: mliew

                              the lower the grit the coarser the stone.

                              If you want to get into stones start with a 1000 grit. There are some combination stones that are 1000/4000. For most kitchen work 1000 grit is adequate. Lesser metals like in European knives don't benefit from much higher grits and not worth the time.

                              Again I would recommend an EdgePro as the best guide system out there.

                              I hadn't used mine in over a year but pulled it out just to play with it. I had a paring knife that I worked with first and put a very even 15* bevel on each side. That sucker can skin the zest off a lemon with no visible white pith. just razor sharp. Because I re-beveled it and went through the coarse to ultra fine stone it took around 20 min. I'll touch it up by hand but it did remind me why I bought it. The edge was nearly perfectly straight and even the entire lenght of the blade. The only thing I don't like is that I refuse to tape up my blades so they get scratched. I just rub them down with some wet dry 1500 grit sandpaper and if anal follow with metal posish. I stopped worrying about keeping my knifes pristine. More interested in sharp and it's a tool not a piece of art.

                              1. re: scubadoo97

                                Man, the edgepro costs at least £150!!

                                1. re: Soop

                                  But it's worth every penny

                  2. re: mliew

                    How are you storing your knife? Are you keeping it in a knife block or magnetic strip? Or are you throwing them in the drawer? Are you cutting through bones or frozen food? These could be the cause of your micro chips.

                    Again, over time, when you sharpen, these chips will disappear. If you want to get rid of them at once, then you have to sharpen w/ a coarser stone to grind out the chips. Spyderco isn't the best at that since it only comes w/ a med and fine rod. You can do it on a medium rod, but it'll just take a lot of time to grind it down.

                    1. re: aser

                      I keep it in a drawer in an edge guard (knifesafe). I sometimes cut slightly frozen (but mostly defrosted) meat and never through bone with my Global knife. Mostly I cut vegetables with it which I don't think should cause any chipping.

                      Maybe I'll look into getting something coarser to sharpen with. I think that Spyderco makes some coarser rods for the Sharpmaker but I'll have to do some research as to whether that's the best way to go.

                      1. re: mliew

                        What is your cutting surface btw? Preferably a soft end grain wood like maple. Just as long as it's not those glass or marble boards, they're HORRIBLE.

                        Finally, try not to wiggle when you're cutting through something. Very easy to chip your blade this way.

                        The best way to go is always a waterstone, but that also involves a learning curve. I'd say for now if it's not affecting the performance of your knife, those micro chips will eventually disappear once you sharpen regularly.

                        Assuming you don't develop new chips.

                        1. re: aser

                          I have an Epicurean cutting board that I use (I think the material is actually some kind of synthetic wood compound) as well as some plastic cutting boards, but I definitely don't use glass or marble.

                          So far it doesn't seem like the chips are affecting the way the knife cuts so maybe I'll take your advice and not worry about them for now.

                  3. I have collected perhaps a thousand knives and perform all my own sharpening on a Tormek rig out of Sweden. A sharp edge is a sharp edge, period, regardless of the blade contour. A convex grind is probably the strongest of all shapes since it retains the most metal near the edge. But that same characteristic also generates the most friction when cutting. Moran made more outdors knives, hunting knives you could say, than kitchen knives and hunting knives get rough use and must be durable, right? Thus the Moran edge. At the other extreme, the asian knife. with its single bevel, provides the most acute angle so the least resistance with cutting, also the most easily damaged if you abuse your knife. I prefer it. By the way, I employ the one-knife-kitchen philosophy of the old french chefs, its an asian knife.

                    1. I would get a sharpening stone and do it the old fashioned way. I know too many people that have messed up their globals by letting "professional knife sharpeners" sharpen them. They put the incorrect angle on them and the only way to get it back is to grind it down and sharpen it with the correct angle.

                      1. I see its old post but still relevant.

                        Sharpen away at 30. Eventually you'll loose the convex, but you will retain that last bevel, slowly wearing it back until you loose the convex.

                        Spyderco makes a number of grits on their rods, and highly recommend the ultra-fine ones.

                        Sharpening on a Sharpmaker generally is single bevel, unless you go from 30, then to 40 inclusive. At 40, just make a secondary mico-bevel. you now have a double bevel, but not yet fully convex.

                        A trick after that is to stop by an autobody shop and get some smooth grit, ranges 600 - 2,000 sandpaper.
                        Put it on a mouse pad and strop to make it more convex ;)

                        A