Convex bevel width; primary bevel scratching
- This topic has 24 replies, 5 voices, and was last updated 11/07/2018 at 12:03 am by
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Just to re-affirm what Marc points out… even with the improved fit between handles and guide rods, there is still a significant change in angle between pressure applied below the edge and pressure applied above it. The stone will “rock” about the edge as a lever on its fulcrum. It can be close to one full degree on my rigs. If I see that I’m not erasing the scratches from the previous grit near the apex, I usually can simply move my hand up on the handle to correct the error. Even my bushing-equipped handles, which have nearly zero slop will show an angle change of several tenths.
Angle change and Organic’s comment about preserving your fingertips has been part of my sermon for a number of years now. Fingers below the edge – good. Fingers above the edge – bad. Try placing your thumb in the second groove from the bottom. That should place you index and middle fingers in the second and bottom grooves. Then stick with it, for consistency. And when setting your angle with an AngleCube, try to apply the same amount of pressure at the same point on the handles
I just checked, and with knife contacting center of stone, there’s .3° change between top and bottom pressure… Just spent 10 minutes staring at the WE, going “…huh.”
I sure as sin’ll be holding from the bottom now, but it complicates using the cube on the 1.5k stone. I’ve always taken readings from top closest corner. I didn’t find any difference between cube reading top or bottom of stone, but is there some hidden danger at reading angles at the bottom?
Tips are going to be more challenging. I see the safety benefits of grip bottom. The only real bad cut I’ve gotten is scrubbing the tip, sliding off, then pulling back. Tip carved a good miniature version of a fillet mignon steak out. But, gripping bottom feels a lot less stable. Stone wants to roll on the blade off parallel. Just slow it down for tips?
Feels like I just leveled up in a video game, and all the same monsters just got harder. Good trade for consistency, though.
That’s a good idea, using the “slop” as extra reach when needed.
Off to go redo all the knives in the house. No wonder my convexing was getting scratched. You all are career-savers.
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Drew, remember the angle setting of your bevel is “relative” to that knife individual knife clamped in that orientation and that specific position in the vice jaws. It is a relative angle not a true or real angle. All that matters to match that angle again is consistency. It truly doesn’t matter where or how you place the magnetic digital cube on the stone as long as you do it the same way consistently, each and every time you set the angle on that same knife. You may find that on some knives it’s easier to place the digital cube at the bottom of the stone. As long as you do it for each knife, again, the same way consistently, it’ll give you repeatable relative angle settings. I try to do everything the same way all the time for simplicity of the consistency. If I have to change up my technique or method, I note this in my sharpening log, where i can record specific comments on sharpening each particular knife.
In reality a bevel you sharpened to 15º per side with your Wicked Edge may be different from my 15º bevel on my Wicked Edge. It may measure with a Catra device at a true 14º or a true 15.5º. It really doesn’t matter. If the bevel angle we applied using our individual Wicked Edge Systems, that we measured to be 15º is sharp and it cuts and works well for us, this is all that matters. If it measures at something other than 15º with a true measuring device it doesn’t make the edge any less sharp or a bad angle. Too much emphasis is placed in the angle number when we knife sharpen. Like it gives bragging rights or make the knife better. All that matters is the knife’s performance. And that is very personally subjective also!
You may want to look into these safety tools.
Marc
(MarcH's Rack-Its)For the benefit of the newbies on this forum, Mark76 was Mark de Weger, who lived in the Netherlands. Mark was a good friend and mentor to many of us here. We lost him last Christmas Eve at the age of 50, far too early for a good soul.
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Pps, tc: I tried the .5° stepdown. The knives I had to work with were freakishly soft steeled CuisineArts. Even the 1.5k stones were too aggressive, and I kept wiping my bevels out… You, my friend, have got to have a surgical hand. I’ll try it again when I refresh these edges in a few weeks, but you may simply be a specialist at a difficult technique. Hat tip.
Not likely to be a highly develop level of skill. The amount of material to remove with each step is highly dependent on the thickness of the edge at the bevel shoulders. The thinner the blade, the fewer and lighter your convexing strokes should be. Try very light strokes and start out with very few strokes. Change the direction of the strokes to make it easier to see the transition point. Watch the new bevel and how closely it approaches the apex. Stop when you see the new bevel reaching about one half to two thirds of the way up the main bevel. Then take the number of strokes (and how much pressure) it took to get there as an indicator of what to do with all successive steps.
Because the first step will be initially hitting the shoulder of the bevel, its facet will seem to grow in width very rapidly, hence my use of only 3 or 4 strokes at each step, beginning immediately after you’ve stoned the main bevel at the apex.
I use “half-degree increments” because I follow the detents in the Gen 3 Pro. I don’t use my angle cube at all during the convexing process.. I rely on the detents to give me repeatable step angles. It doesn’t matter if it 0.4 or 0.7 degrees per step. You could probably get the same, or very similar results by making half as many adjustments, stepping one degree at a time, but with more strokes per step. If you’re using a standard rig (not a Gen 3 Pro or commercial rig) you can use the 1-degree detents in the angle bar. Just remember where the detent was for the main bevel.
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