how sharp is sharp enough to get a knife? I just sharped my knives to where they can shave facial hair easy enough, should i keep going or would the edge not last long at that sharpness?

Demonik5150

?

If it will shave hair cleanly.....it is plenty sharp enough......kinda hard to get any sharper than that.

sounds good to me

Max killz

i just like to keep them as sharp as possible so when i need them (cutting rope, boxes, tape, w/e else) there is no issue. I keep my emergency seatbelt knife sharp enough to replace my shaving razor

1+ You're golden then! 

Max killz

know a test beyond shaving hair?

To understand sharpness you must first understand the definition of an edge. An edge is the line of intersection of two surfaces. A highly sharpened edge is one where the two surfaces are highly polished to form a very fine edge. Sharpening is the means to that very fine edge.
 
There are countless ways of testing knives and tools for sharpness. We believe the easiest way to test sharpness is to use the tool or knife. If it does not cut fast and cleanly, it needs sharpening. On a kitchen knife, the knife should be able to cut vegetables with almost no downward pressure. On a woodworking tool, the tool should cut wood fibers cleanly without leaving marks or crushing the wood fibers. On a fillet or skinning knife, it should be able to cut very quickly without having to saw through the meat.
 
If you really want to get down to fine-tuned levels of sharpness there are a few more tests you can use. My personal favorite is to take a piece of paper and hold it vertically. If you try to cut it with a dull knife, the paper will crumple beneath the knife. A sharp knife will cut it cleanly when use a slicing motion to cut through the paper. A razor sharp knife can cut the paper cleanly by just pressing down on the edge of paper without any slicing at all.
 
Another test is to shave the hair on your arms. While we recommend caution using this method, it can be very useful. A dull or even moderately sharp knife will just fold over your arm hairs without cutting. A well sharpened knife will cut almost all of the hairs in one pass. A very sharp knife will cut all the hairs in its path. This level of sharpness can only be attained using the finest abrasive materials. 
 
Another factor effecting edge sharpness is the angle it is sharpened. The lower the angle, the sharper the blade becomes. However, the lower the angle, the weaker the edge becomes. Very low angle blades like a razor blade or a fillet knife will ultimately have a sharper edge than high angle tools such as an axe.
 
From: http://www.sharpeningsupplies.com/testing-sharpness.aspx

Max killz

I sharpen at about 22 degree edge, all can shave arm hair easily and the paper test is nothing

think i should go for 20-16 degree?

on most i start with an accusharp and then to stones for fine polishing or a sharpening rod

 
Ehh, I'd stay where you are bro. I mean, honestly I'm sure you're fine if you cut hair, and paper easily. I don't believe you'd need it much sharper... And like I said, at extreme degrees, it'll get really thin, and bend/get dull really quick.

The action of knife sharpening reduces the radius at the tip, since you can't go to an absolute zero without a laser-cutter, you got to make a call at some point due to deminishing returns and fabrication errors due to running the risk of not maintaining the apex.
 
Imagine the knife's cross-section at the tip, it starts out as a tall trapezoid and you shave off the upper fulcrum until you have something that looks like a triangle, but not quite.  It is easy to tilt the knife and suddenly losse the top of your triangle and have to re-sharpen, this makes it shorter and you're basically loosing material.
 
Through natural use and wear, you loose the top of the triangle but not from chipping or over-sharpening, rather microfragments of metal end up in your food or face over the months.

I like mine to be sharpened at a 90 degree angle.

Max killz

know a test beyond shaving hair?

 
Ever seen the video of dropping a silk cloth on an arabian sword? Yeah, if you reach that point, I would say you have managed overkill...
 
I just go to the point that I can shave arm hair, I always have a nice shaven spot on my wrist right before deer season :)

If it hurts just to look at it, then it is sharp enough.

ok so i just did the hanging toilet paper test and it made a clean slice through :-/ i think I'm done sharpening