Can one put a too thin edge on a knife?

[marthinus]

hi everyone. I have been experimenting with my 440c blade and tried to put a very fine angle say about between 10* and 15* per side (free hand sharpening), but found that I am struggling to get a good shaving sharpness. Could it be that the steel does not like that thin a edge? I know people say M4 loves thin edges, but the properties differ quite a bit.

Thank you in advance for any help.

 

[Kbrasmodeler]

When you thin the edge, you increase the amount of material you must remove to sharpen. I don't know your experience in sharpening. Are you sure you are getting all the way to the edge? Try the sharpie test, or look at the edge under a magnifier, to see if you are removing the old bevel. Sometimes it looks like you are getting to the edge, then you look under a magnifier, and you still have remnants of the old edge. I find that if I work to a burr, progressively use finer grit, and then strop, the angle is not as important. Also, the edge seems to get better with further touch-ups, as it gets more refined. Hope this helps.

 

[mbhanzo]

The thin edges with the correct finish
should be very sharp and cut very well
but the edge obviously will be more fragile.

 

[BryFry]

the edge obviously will be more fragile.

+1 to that. I've gotten carried away before and put a very accute edge on a knife only to find out that the steel was not able to cope with the thin edge, (edge would roll if used hard) I found the only fix is to create a more obtuse micro-bevel, that is "sturdier"

-just something to keep in mind.

 

[Roger999]

You can have an edge too thin, but 10-15degrees/side sounds fine for a knife with decent steel.

 

[shecky]

If you depend on a blade to have significant lateral strength, yes, the edge can be made too thin. Then again, lateral strength isn't always necessary on knives other than choppers and prybars.

An edge 10-15 degrees per side isn't even close to acute in my book. I'd just as soon take it down to 10 degrees inclusive, and then you can start referring about acute.

Thinness is a different thing altogether. Many pocket knives have fairly thick edge bevels. The edge bevel is the portion of the blade grind where it finally terminates in a cutting edge. Coincidentally, I also find many stock edge bevels way too thick out of the box. It's not uncommon for my knives to be reprofiled such that the edge bevel is both thinned out and the angle made more acute.

If you're having trouble with a 10-15 degree angle, my first guess is that you are probably not actually sharpening the cutting edge, but rather mostly grinding the trailing part of the edge bevel. This seems a common problem with sharpening, and gets more common as the edge angle is less acute. In an effort to preserve the edge angle, there is a tendency to not remove enough steel from the actual cutting edge. And the edge cannot be made sharp unless steel is removed from the cutting edge. This is actually another reason I prefer very thin edges. It makes sharpening much less ambiguous. And quicker, since there's less material to remove.

 

[Gespenst]

I run 10 per side on most of my blades with a 15 degree micro bevel (and I do mean micro). On my stockmans I finish the main clip point at 800 grit and the others at 1000 plus some time on the strop and have no issues with durability in 440.

That said, the quality of the steel and heat treat can have as much of an impact on what angles will work well for your applications as the steel type. For example, Benchmade 440 holds an edge rather well while Chinese 440 tends to be rather soft so edge retention becomes an issue.

Just another .02

Try marking the blade with a sharpie to see if you have made it to the edge.