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Edge: 30 versus 40
- Thread starter Alvin Hom
- Start date
Alvin Hom said:
Well, BOTH.
Truthfully, I do about 15 degrees (30 inclusive) for the initial bevel, then I polish that bevel and make it shaving sharp for good measure.
THEN
I hit the edge with a sharpie (So I can see what's going on) and put the secondary bevel on at about 20 degrees (40 inclusive). I shape the second bevel until about 1/4 to 1/2 the witdh of the first bevel sharpie is gone, then I hone to shave.
THEN
I either hone it with an ultrafine stone at 20+ degrees or strop to get rid of the burr.
Time consuming yes, but after I do the initial bevel, I can do 20 degree touch ups for a very long time.
(Sharpie ink comes off with a little alcohol)
Sorry to give you such an unhelpful answer.. generally the thinner the better if you are slicing, and a little thicker if it will see abuse (cleaving bone etc).
Edit:
Alvin Hom said:
"Sharper has little to do with the angle.. .any angle can have a shaving sharp edge, But the thinner the bevel (and blade), the easier the blade can go through material and the smoother the cut. (This is why Victorinox blades slice so well, even though the steel is mediocre.)
It is questionable whether it would wear faster, less resistance at 30 deg, but more behind the edge at 40. It probably depends more on how tough the stuff is that you cut.
30 degree is plenty for any kind of work with decent steel, if you use 'carbon " in stead of "stainless" then you can go 30 or lower even. 40 is seen as "safety " "idiot proof" measure but for any quality steel you can safely go with 30. Knive is meant to cut after all- why is SAK, opinel, Moras etc all have less than 30, more like 24 even though they have "cheaper " steels then American makers?
Martin
Martin
- Joined
- Jun 29, 2003
- Messages
- 428
The first question I ask myself is: what edge angle is already on my knife from the factory? If it's 40, it obviously won't cut as efficiently as a 30 degree edge, but I don't have the patience (or the diamond rods) to put a whole new edge on it. More likely, I'd take some metal off the shoulders of the edge bevel with the 30 degree rods (as explained in the manual and video) - it's a lot less work than re-doing the whole edge, and it makes a big difference in cutting efficiency. Most recently I did this on an AG Russell "fruit testing knife". I was expecting it to cut as efficiently as a kitchen knife, but the edge grind was too chunky. I took the shoulders down a bit, and didn't even touch the edge (probably closer to 40 degrees than 30) and now it cuts very well.
Now, one of the first things I look at when I'm thinking about a new knife is the edge grind. Too thick for my purposes and I'll pass, no matter how much I like the knife otherwise. Other members love a good sharpening challenge, but I think life's too short to be re-doing edges on every knife I buy.
Now, one of the first things I look at when I'm thinking about a new knife is the edge grind. Too thick for my purposes and I'll pass, no matter how much I like the knife otherwise. Other members love a good sharpening challenge, but I think life's too short to be re-doing edges on every knife I buy.
I just use the 40 to ....refine..... the 30.
It seems to be more uniform and actually sharper. I spend more time on the 30 to get the thin nice slicey part and then using the 40 much more lightly, refine any irregularities that may have cropped into the 30 session.
So in essence I am just "sharpening" a sharp edge. And it usually ends up that way. The 40 finish seems to take out the tendency to "dig in" and actually add some control to light cuts and incidentally preserve that 30 work with the very slight strengthening of the 40.
I am light on the 40. But just enough for me.
It seems to be more uniform and actually sharper. I spend more time on the 30 to get the thin nice slicey part and then using the 40 much more lightly, refine any irregularities that may have cropped into the 30 session.
So in essence I am just "sharpening" a sharp edge. And it usually ends up that way. The 40 finish seems to take out the tendency to "dig in" and actually add some control to light cuts and incidentally preserve that 30 work with the very slight strengthening of the 40.
I am light on the 40. But just enough for me.
- Joined
- Apr 27, 1999
- Messages
- 6,117
Under normal use a 30-degree edge will stay sharper longer than a 40-degree edge. As a 30-degree edge wears down it gets wider slower than a 40-degree edge. The advantage of a 40-degree edge is if you use your blade hard or abuse it. If you are chopping into tough material like knots in a wood or bone the 40-degree edge is less likely to fold over or chip.
There are a couple reasons that Spyderco promotes the 40-degree edge. The first is to avoid complaints from inexperienced users. It takes a lot longer to sharpen to 30 degrees than to sharpen to 40 degrees. Even when the factory edge started out somewhere around 30 degrees a lot of novices don't have the patience to sharpen a dull blade to 30 degrees. They will complain that the sharpener just doesn't work. This is particularly possible with ceramic hones that just don't remove material very fast. This problem is compounded if the user has a saber-ground tactical blade that is more like 40 degrees to start with. The other reason to promote the 40-degree edge is that it can work very well as the final step of a process that started out at 30-degrees (to put on a slight microbevel).
Spyderco sort of gets around the issue of low performance from their recommended 40 degree edges by suggesting that the users "back bevel" the edges at 30 degrees. Most of us would probably call this back beveling honing or sharpening. A good way to get a fine edge on a knife is to sharpen it at a low angle and then do a few light strokes at a slightly higher angle as a finishing step. The edge is flexible enough that you may not even be able to see the microbevel under a magnifying glass, but it cleans up little surface irregularities and leaves a better edge than if you did all your work at one angle. I do this by sharpening (back beveling) at 30 degrees then slightly tipping my blade as I do a few light finishing strokes to finish at something like 35 degrees. For most uses it would work as well to do those last few "sharpening" strokes using the 40-degree rod position.
So some of this is symantics. What they call "back beveling" I call "sharpening". What they call "sharpening" I call "microbeveling". I just suggest that you extensively "back bevel" at 30-degrees before you "sharpen" at 40-degrees. I suggest this regardless of what angle the factory edge was set to. If necessary use a coarser bench hone or sanding belt to get the back bevel reduced or the knife just won't cut stiff material very effectively.
There are a couple reasons that Spyderco promotes the 40-degree edge. The first is to avoid complaints from inexperienced users. It takes a lot longer to sharpen to 30 degrees than to sharpen to 40 degrees. Even when the factory edge started out somewhere around 30 degrees a lot of novices don't have the patience to sharpen a dull blade to 30 degrees. They will complain that the sharpener just doesn't work. This is particularly possible with ceramic hones that just don't remove material very fast. This problem is compounded if the user has a saber-ground tactical blade that is more like 40 degrees to start with. The other reason to promote the 40-degree edge is that it can work very well as the final step of a process that started out at 30-degrees (to put on a slight microbevel).
Spyderco sort of gets around the issue of low performance from their recommended 40 degree edges by suggesting that the users "back bevel" the edges at 30 degrees. Most of us would probably call this back beveling honing or sharpening. A good way to get a fine edge on a knife is to sharpen it at a low angle and then do a few light strokes at a slightly higher angle as a finishing step. The edge is flexible enough that you may not even be able to see the microbevel under a magnifying glass, but it cleans up little surface irregularities and leaves a better edge than if you did all your work at one angle. I do this by sharpening (back beveling) at 30 degrees then slightly tipping my blade as I do a few light finishing strokes to finish at something like 35 degrees. For most uses it would work as well to do those last few "sharpening" strokes using the 40-degree rod position.
So some of this is symantics. What they call "back beveling" I call "sharpening". What they call "sharpening" I call "microbeveling". I just suggest that you extensively "back bevel" at 30-degrees before you "sharpen" at 40-degrees. I suggest this regardless of what angle the factory edge was set to. If necessary use a coarser bench hone or sanding belt to get the back bevel reduced or the knife just won't cut stiff material very effectively.
- Joined
- Sep 23, 1999
- Messages
- 3,831
The rule I go by is to go as thin as I can given what work I do with the knife. I have 2 chefs knives in my drawer, a very cheap Tramontina I got for $5 Canadian and a Wustof Trident that was a wedding present. The Wustof is around $175 Canadian in the stores. I find in the kitchen that the Wustof can handle a 30 degree edge no problem, but I can encounter very small chipping or edge bending with the cheaper blade.
Thinner edges cut much easier than thicker ones and make doing the same kind of work easier to do, generally speaking. So, sharpen at the 30 degree setting and see if you have any edge retention/chipping problems. If you encounter such problems, add the 40 degree microbevel.
Thinner edges cut much easier than thicker ones and make doing the same kind of work easier to do, generally speaking. So, sharpen at the 30 degree setting and see if you have any edge retention/chipping problems. If you encounter such problems, add the 40 degree microbevel.