30° then 40° or vice versa

Louis Cohen · #1

The Sharpmaker instructions recommend sharpening kitchen knives at 30° first, and then 40°. The Juravitch article at the link below says 40° with the coarse/medium stone and then finish with 30° and the fine stone. Which one is right?

http://www.ameritech.net/users/knives/J ... 977Feb.htm

sam the man.. · #2

40° on the 204s when you have a knife with the correct edge profile which is 15° on each side. Use the 30° only when you have a profile which is worn out or too wide.. Hope this helps.. And whenever in doubt, get a tutorial on the 204 instructional video!

Sam

have bone implant will travel..

Louis Cohen · #3

This diagram from the article showing 40° above and 30° at the tip makes sense. I'm having trouble visualizing the reverse - 30° above and then WIDENING to 40° at the tip. The diagram in the Sharpmaker manual on page 6 is labelled exactly this way, but it doesn't look it.

transistor · #4

If you go 40 first, then 30, all the 30 does is take the shoulders off the 40 degree bevel. If you go far enough to affect the edge you're at 30 and the 40 degree bevel is gone.

Try getting a good sharp edge at 30, then put a few strokes on at 40. Follow up with a good stropping. The back of any old leather belt will work fine. You can use a fine polishing compound if you want, but it isn't absolutely necessary. I don't. It is actually marginally less sharp this way than a 30 degree bevel all the way out, but the edge holds up MUCH better.

mac_heath · #5

I don't think it matters whether you start w/ 30 or 40. If you do both, you'll get the same bevel. The point of the 40 bevel at the edge is for strength.

Praise not the day before evening has come, a sword before it is tried, ice before it has been crossed, and beer before until it is drunk.

vampyrewolf · #6

it all depends on the steel being sharpened...

I sharpen my vg-10 to 30, and only 30...

I sharpen my ats-55 to 30(till it'll slice paper) and then toss a 40 on the edge and it's shaving...

my millie is the only 440V(S60V) edge I have to worry about... I just use the 30 slots on my 204, or really slow with the 303MF DoubleStuff stone...

other than that, they just get 40s... my 8A Spydercard, my 440C Q Standard, my ladybug...

I actaully have a convex on my SS Dragonfly inb ats-55... **** that was hard, but well worth it.

*Our greatest triumph comes not from NOT falling down, but from getting back up every time.*

Joe Talmadge · #7

mac_heath is right, in theory it doesn't matter. If you do 40 degrees first, the 30 degree step will knock off the shoulders (as per transistor), unless you go so far as to grind the 40 degree bevel completely off. If you go 30 degrees first, the 40 degree bevel will just put the final edge.

As a practical matter, I firmly believe the right answer is: 30 degrees first in order to thin the edge, the final 40 degree edge on top of that. Depending on how many strokes you take at 40 degrees, you can effect the performance and edge strength considerably. It's not possible to have such control if you've laid down the 40 degree edge first, then tried to creep down with the 30 degree angle.

Additionally, the 40 degree bevels are the final edge. If you do the 40 degree bevel first, then make a little slip on the 30 degree bevels, you'll hose the edge. No problems if you do 30 degrees first.

Joe

sam the man.. · #8

There you have it! Joe is THE man when it comes to sharpening your knives! <img src="spyder.gif" width=15 height=15 align=middle border=0><img src="smile.gif" width=15 height=15 align=middle border=0><img src="spyder.gif" width=15 height=15 align=middle border=0>

Sam

have bone implant will travel..

Louis Cohen · #9

So, Joe, how do you know how many strokes to take at 40° after doing the 30°? Do one side only and feel the burr, before switching? And which Sharpmaker steps for tho 40° would you recommend for kitchen knives?

MacHeath - great nick for this forum.

Thanks

Joe Talmadge · #10

Louis,

In all honesty, I tend to play it by ear, depending on what the knife is made out of, what I intend to do with it, and whether or not it chipped or indented badly last time I sharpened it.

I do have some general trends I follow...

My good-quality Henckel's knives, that my wife and mother-in-law absolutely torture, get a mostly 40-degree edge. The purpose of the 30 degree part is just to keep the edge thin enough that it won't be too difficult to sharpen next time.

My high-quality Japanese-made VG-10 chef's knives that I don't let anyone else use got a 30-degree edge, with just one or two light swipes at 40-degrees to knock off the burr. But then I noticed that the knives were chipping out a little, so now I'll put 10-ish swipes on the 40-degree stone.

I feel that for regular EDC use -- not super hard use, but not easy either -- a good quality ATS-34 blade should be able to handle a mostly-30-degree edge (10-15 swipes at 40 degrees maybe). I tend to sharpen my EDC folders down to total 30-degrees, then just a few swipes at 40 to knock off the burr. If the knives chip or roll too much, I'll put 10-20 swipes at 40 degrees next time. If they still can't handle it, I go buy a better knife -- at some point I won't accept lower performance just to accomodate a particular knife, when so many other knives are out there.

That of course is for regular EDC, for lighter use I definitely stick with 30-degrees (plus a couple swipes at 40), for hard use it can be reasonable to go more towards a 40 degree edge.

Joe

Louis Cohen · #11

A couple of weeks ago, I used the Sharpmaker diamond stones (and the regular stones) to put 30° edges on all the kitchen knives except the cleaver. They've been fine so far, even competitive with a brand new Global. I just did a quick touch-up on the chef's and paring knives (which get the most use)and recut the carver for Thanksgiving.

Our knives get pretty light use, just home cooking for two, so the 30° alone weems to work fine for us.

transistor · #12

Joe T. IS da' man! Good to see you here Joe!