Johnny_Z said:
Since the Spyderco Sharpmaker is so popular here I thought I'd order one and get my blades sharp. So I order one. When it arrives I look through the book, I watch the video and say to myself, "that doesn't look too hard.". So I take out the Vapor and get to sharpening.
My Vapor is now dull.
I mean insurance seminar dull.
This is supposed to be fool proof. Well I am one inventive fool, I outwitted the system. I am hopeless.
Oh woe is me...
From my posts on the 'other-forum':
(I did not copy other's responses, because I don't have permission).
I also don't know if linking to the other forum is taboo.
I think it might make sense anyway.
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Spyderco recommends 40 because even if the original blade was 30 (15 per side), sharpening at 40 will ensure that you get the very edge of almost any knife. The part of the edge that gets dull is right at the very edge, even though the edge bevel is visible a few milimeters from the edge, so if you touch up the very edge, the knife will be sharp again. If you do 40 degrees forever on a knife that was initially 30 degrees, then eventually you will only have the 40 degree bevel. You probably won't need to sharpen that often.
However, some Japanese knives have an edge _finer_ than 30 inclusive (15 per side). It depends on the knife though. This is also why I was wary of the 19 per side on the chef choice. Hopefully someone who knows your exact knife can advise.
If the original bevel is 30 degrees (15 per side) or less, then you are better off with the 30 degree setting.
Try the marker trick. Paint the edge with a permanent marker (comes of easily with rubbing alcohol later). Then do a few strokes on the sharpmaker at the 30 degree setting with the white rods (a few strokes won't mess up your knife regardless). Then check to see where the marker got rubbed off, that's where you are sharpening.
Let's say this is your blade (ignore the periods, spaces don't work right):
..|......|
..|......|
..\..../
...\../
....\/
Add the marker #
....|......|
....|......|
.#\..../#
..#\../#
...#\/#
1. If the marker is removed only at the very edge, then the blade has an edge bevel of less than 15 degrees.
....|......|
....|......|
.#\..../#
..#\../#
......\/
2. If the marker is removed only away from the edge (the 'shoulder'), then the bevel is greater than 15 degrees.
....|......|
....|......|
....\..../
..#\../#
...#\/#
3. If the marker is removed consistently from the very edge to the 'shoulder' of the bevel, then the original bevel is 15 degrees per side.
....|......|
....|......|
....\..../
.....\../
......\/
If you have #3 above, then the 30 degree sharpmaker is fine and you can sharpen away as per the instructions. You may have to use the browns first for a while before it gets sharp.
If you have #1 above, you can sharpen at the 30 sharpmaker. The very edge will be slightly more obtuse than before, but you will be able to get the very edge plenty sharp. You may only need the whites. The less material you remove the longer the original bevel will last. It will take a long time before you have to worry about that.
If you have #2 above, you can sharpen with the 40degree setting, and again the whites at 40 should do it (unless the edge bevel is greater than 20 per side, which is unlikely).
If your knife is chisel ground (shrpened on only one side),
....|...|
....|...|
....\..|
.....\.|
......\|
then the same #1 #2 #3 applies, but you only need to sharpen one side and then remove the burr on the other side with a few light strokes on the whites.
I like to check the edge by slicing paper every dozen or so strokes to see how it is going. When it glides through the paper with little resistance, it's good enough. If you cannot get there, ask more questions.
I hope this isn't too confusing. Hopefully others can advise as well.
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The grit size of the Spyderco Stones are not directly measureable, the ceramic is different than a natural stone or sandpaper.... Here's a thread where Sal (creater and owner of spyderco) explains and some guesses as to what grain size corresponds to the spyderco stones.
http://www.spyderco.com/forums/showthread.php?t=13424
http://208.63.68.209/SharpenGuide.htm#Grit
Enjoy. Do ask if you don't get the results you want.
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(Notes on back beveling)
Say the original knife was like this, with one bevel.
.|..........|..1.
.|..........|
.|..........|..2.
.\......../
..\....../
...\..../..3.
....\../
.....\/....4.
Assume this was 30 degrees to start.
If you sharpen forever at 40 degrees, enough material will be removed from points 3 and 4 to make it a 40 degree bevel.
We call the top of the bevel (#2 above) the 'shoulder' of the bevel.
If your knife has a 40 degree bevel and you want it to be 30, you would sharpen at 30. The sharpening would only happen at the shoulder until enough material was removed to bring the bevel back to 30.
Now, a 'back-bevel' is when you normally sharpen at (for example 40), but the edge is too obtuse to slice well. Then you can sharpen at 30 degrees just enough to remove the shoulder. Then you have a two-step (or two-angle) bevel. The one near the shoulder (point 2)is the smaller angle and called the 'back-bevel'.
.|..........|..1.
.|..........|
.\......../...2.
..\....../
....\../...3
.....V....4.
So when you 'back-bevel' you remove the shoulder at 2, and so the 'back-bevel' is 30 degrees and the edge bevel, 3 and 4, is at 40 degrees.
Softer steels are best sharpened at 40 degrees, so that there is more strength in the edge, but they can perform poorly because of the reistance of the shoulder, so a back-bevel at 30, making a two-step edge performs better but still has the strength of a 40 degree bevel.
Now, on a hard steel like a Japenese-style kitchen knife, the original bevel is probably less than 15(30), so that is essentially your 'back-bevel', and then you sharpen the very edge at 15(30) and you have a two-step edge already. No need to go to 40 degrees.
Now after a long time, your knife will only have a 15(30) degree bevel left because you have sharpened the original blade bevel away. Then you can back-bevel the shoulder at 12.5 or so to restore the original edge. You won't need to do this for a while, especially if you use the whites only.
If you did need to do this, the sharpmaker (204) has a slot for the stones on the end of the base, which is 12.5 degrees from _horizontal_ this can be used to sharpen scissors vertically, OR you can keep a blade horizontal and sharpen a 12.5 degree angle on it. Or you can just use a flat stone and us the smallest angle possible to remove the shoulder (back bevel). (note that the sharpmaker stones fit into the base to make a flat stone as well)
So on most softer steels or thicker knives 20(40sharpmaker) degrees is the _edge_ bevel and 15(30) degrees would be the back-bevel. On your thin hard knives 15(30) would be the edge bevel and 10-13 degrees would be the back-bevel.
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Yes the back bevel is always the smaller angle (near the shoulder).
It really doesn't make any difference which bevel you do first. If I have a new knife with a horrible edge, I start from scratch and do a 30 degree bevel first until it is sharp and add the 40 after because when it is sharp at 30, I know that 40 will only sharpen the very edge. It doesn't matter either way if you use the marker trick because you can see what you're doing.
Spyderco recommends that you do the 40 first and then the 30 to back bevel if the knife is not performing as well as you would like. This is because at 30 degrees you may have a lot of material to remove before you get an edge, and most cheap knives will be better off at 40 for the edge anyway. For a brand new knife, you really only need to be concerned about the very edge, unless the factory did a terrible job. Of course if the factory edge is less than 15(30), stick with 30 for the edge bevel.
As far a number of strokes, you should always alternate left/right (unless it's a chisel grind), and the number of strokes depends on how much sharpening is needed.
I have tests I use at each stage, using my thumbnail for the med stones and paper and shaving arm hairs with the whites. If you are only using the whites, you should quickly get to the point where you can get the knife started in paper and it should glide though, if it doesn't, go back to some more work on the whites or use the marker to see if the very edge is getting sharpened. You can count strokes, but you may need more or less. Once you can slice paper, food should be no problem at all.
If you have old kitchen knives, it's good to practice on those first (You may have to pick 40 and 30 for those). Also, there's no reason to require a double bevel. If a particular knife works well at 20(40), that's fine. A cheap knife may not hold a 15(30) degree edge for long enough, and 40 may offer too much resistance, which is why we compormise sometimes.
I am by no means a final authority on this, I've just spent a lot of time with my sharpmaker recently (attacking my awful kitchen knives) so it's fresh in my mind.
Take care,
Just a note, there is another type of edge which performs very very well, which is a convex edge. This can be produced with stropping on sandpaper which has been affixed to a mouse pad. I use this type of edge on many of my pocket knives. It looks like the double bevel above, but since you smooth out the angle transitions it glides through material. (I only do this for pocket knives like Swiss Army Knives because it is a lot of work, and SAKs are a softer steel which is easier to do this to and the SAKs perform better this way.)
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It's hard to say, it depends on how much material needs to be removed. Use the marker to see where you are sharpening. If you are creating the back bevel the marker will be removed only at the shoulder, and you just continue until the marker is removed about halfway to the edge or so.
If you are doing the edge only, you remove marker at the very edge until the knife is as sharp as you want it, making sure the maker is not removed too far away from the edge.
Either way, the marker will tell you, you cannot predict how many relative strokes it will take.
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Another reason that you "might" run a few strokes at 20(40) degrees is if you sharpened the edge bevel at 15(30) and want to cut off the "burr". A burr developes when you are sharpening and it is at the extreme edge and is a little bit of metal or a line of metal that is soft enough to flop back and forth as you sharpen. Then sharpening at a slightly larger angle will cut the burr off.
BUT, with a hard blade and the fine spyderco stones, the burr is so miniscule that you don't usually have to worry about it.
With a straight razor, you actually strop on leather to stretch out the burr and make it super super sharp (only lasts long enough to shave though).
I just wanted to cover all the bases.
This is entirely different from a back bevel (which is at the shoulder, not the edge).
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In case I missed something, check out Joe Talmadge's article on sharpening.
It's FAQ #9 and is a pdf:
http://www.edcknives.com/faqs.html
