Convex Edges with a Gen 3 Pro
- This topic has 20 replies, 5 voices, and was last updated 12/21/2018 at 7:54 pm by
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This is the long-promised video of my method of using the Gen 3 Pro angle selector to produce a convex edge.
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Tom, thank you for the time and effort it took to make this very informative and illustrative video. And thank you for your service.
I’d like to comment on Tom’s technique, for Wicked Edge users. Tom as he mentioned around 19 mins into the video has physical limitations between his left and right sides. Due to this he has found it to be safer and more effective, for him, to work one side of the knife at a time while counting his strokes to keep his paddle work even and balanced to achieve the sharpest edge he can.
For those without his difficulties, the edge most stone work at the apex, 23º in his video, can be done if you choose, alternately, left-right-left-right edge leading strokes to help remove any remnants of a burr formation and to help achieve the keenest apex. The subsequent angles down to 19º used to create the convex bevel can be applied with either method, separate as Tom did these or alternately, as they are on either side of the knife and do not reach the apex.
Marc
(MarcH's Rack-Its)Thanks, Marc, but to be clear the 23 and 19 are the detent markings on the base plate. The actual angles were 17.00 at the 23 detent and about 13.60 at the 19 detent. I failed to note in the video that I had also modified the vise height by adding a 3/4″ ABS spacer between the base and the vise. You can see it in the video as a white (ivory, actually) block. I originally added the block as an experiment to increase the amount of stroke length when sharpening narrower blades, but it also reduced the angles reachable with the range of detent settings. This is further exacerbated by the width of the blades. On blades as wide as the one in the video, the highest angle possible is only about 21 to 22 dps. I left the spacer in because I’ve never had the need to go over 20 dps. My modified extra-long micro-adjusts help to correct for this limitation.
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Ian it is a “give<>take” situation. Yes the Gen 3 Pro helps you apply convex bevels quickly, easily and efficiently. But it falls short in other areas.
The WE130 allows you to apply a larger array and variety of edges. All your regular “V” grinds, along with, asymmetrical and uneven ground bevels, easily. But it will take a lot of time, effort and adjusting to apply a convex bevel. But it can get it done.
The bottom line is you have to decide which model best fits your needs. That’s why some of us have more then one model WEPS!
Marc
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I’ve done at least a dozen knives now with the convex profile. Like almost everybody else, the first thing I do with any knife I sharpen is test them by slicing a sheet of paper. The convex knives clearly slice through paper more easily than they would with the same apex angle and a standard flat bevel profile. Even more interesting (and telling) is that they very noticeably make less noise as they pass through the paper.
Now I’m wondering how a convex profile would work on a chisel-edged blade. I’m thinking of a particular chisel-edged cleaver I seldom use. God, this is fun. And yes, I know I need to get a life. Unfortunately, this is the only one available.
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Tom,
After watching your video, I decided to try it on my PM2 EDC. The method worked very well and it came out just like you said. I took some pictures with the laser protractor to illustrate the bevel that I got. I used a restored RH36 WWII era fixed blade sharpened at 20 DPS with a single bevel, a CRKT with a double bevel, and my PM2 with the convex bevel to illustrate
For the convex bevel I started ~13 and ended at ~19. I started with the WE 1000 diamond grit and then went to Chosera 1000, 2000, 3000, 5000, 10000. I did 25 strokes per side. On the Gen 3, 24=19 degrees at the knife and I went down to 18.5.
12 stops X 6 grits X 25 strokes per side = I didn’t have much to do on Saturday night.
Ed K.
Ed: I don’t know if I should be pleased with your effort, or feel guilty for having eaten up a chunk of your life. Why did you decide to use 25 strokes? When I used more than a few strokes on the first step, I found that I quickly wiped out the apex bevel. It doesn’t change the result other than reducing the apex angle by the step change – maybe 0.4 degrees.
What did you think of the resulting edge? Does the PM2 seem to cut better?
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Tom: I haven’t had a knife to sharpen in about 3 weeks. So, I looked at it like a practice session to keep my muscle memory and form. Also, I was using very very fine grits as I wanted a really polished edge and the blade steel is CPM S110V.
When looking at the pictures the tighter and brighter the dot shows a bevel that is precise and very polished. In the convex picture you see each dot individually at each step. Certainly not required for use but again I was working on my form.
I bought a new Victorinox kitchen knife a few months ago. First thing I did was test the edge. It was right at 130 grams which is really sharp for a factory edge. When I put the laser on it the display was a “smudge” from about 13-17 degrees if my memory serves. That didn’t make sense at the time but when I looked at it under the microscope it was a convexed edge and not polished at all. If I have time I’ll post a laser picture of that knife.
I keep the PM2 sharp all the time. It sliced newspaper like usual and I have a bad case of Tinnitus so I couldn’t hear a difference in the sound. It’s my EDC so I’ll let you know how it performs cutting cardboard etcetera.
Ed K.
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Tom,
Finally got around to trying your method for a convex edge. I started at 20 Deg with angle cube , 20.5 Deg Detent on Gen 3 Pro. I tried it on a cheap brand knife a Home 360 5″ slicer. I am very pleased with the result, was disappointed that i didn’t have any Tomatoes to slice though!!!! It does slice paper very well. Only thing i did different was at the beginning of each grit i used angle cube to make sure i was at 20 Deg to start the progression. I will try on my Chicago Cutlery set, my Messermeister Meridian Elite knives(might start at a lower angle with these). Shouldn’t the Edge last longer (as long as wife doesen’t use them Ha Ha!) with a convex edge?
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Tom,
So, I pulled the Victorinox out of the drawer and checked it on the sharpness tester. The first picture has the sharpness scores – well
belowabove the delivered factory edge. <span style=”color: #ff0000;”>Below 300 is a an edge many people would be very happy using. When I sharpen a reading below 200 is good and my target is 130-150. </span>I’ve used it about 10 times since I bought it and have never sharpened it. I did try to steel the edge but as you see the angled scratches in the second picture I missed the mark. The third picture is the laser reflection of the Victorinox edge.I’ve got some time off this week and I’m going to sharpen it with a convex edge (not 25 strokes per side) and post the “after’ pictures.
The fourth picture is the edge of the PM2 after the convex sharpening. Looking at the shadow I kind of see the convex curve.
Is that curve similar to your microscopic view of your blade?
Ed K.
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Ed: I took a video of my factory-edge Victorinox and put it on Youtube. It shows that they produce a really good convex edge by polishing the heck out of the belt-sanded bevels. I was (and still am) impressed.
The goniometer shows almost exactly what I would have predicted. The apex bevel is there and the shoulders have been polished.
The steeling scratches are what I see on knives brought to me by friends and family. I ask them to stop using a steel and switch to a ceramic if they must. Generally, they don’t do a lot of damage, but it hurts my eyes to look at it with the microscope.
I can’t really make out the edge in your microphoto of the PM2…
PinkFloyd: I think the theory is that a really sharp knife will cut with less damaging force being applied to the edge, but I think not much. Wives are a much bigger part of that equation.
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Tom,
I agree the video shows a nice smooth convex bevel. I also watched your “using a microscope” video as well. I worked on the Victorinox this evening and got good results but not quite a perfect convex on both sides. First two pictures are the original bevel and the edge apex. Next two pictures are the convex bevel and the sharpened edge apex.
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