Info on Primary and Secondary edges

[KAE1]

I've seen a few threads where people send pics of their knives and others comment that it's a convex, hollow or concave grind or that its got a secondary edge. As a newbie to proper knife sharpenning my question is - can you really see all this from a pic? In the Razor edge book of sharpening the entire edge is 1/16th of an inch and the primary edge is only 1/3rd of that (1/48th if my brain is working correctly - sunk a couple of bottles of vino watching glastonbury last night so probably not)- can that really be seen with the naked eye?
I put two edges on one of my blades with the Gatco professional but wasn't really confident so now I put just one edge - either 22 or 19 degrees.

Any comments/advice most welcome.

 

[Andy]

I think there may be a bit of confusion what what terms mean. Normally you have a primary bevel and a secondary (or edge bevel)
On most kitchen knives the primary bevel will start at the spine and there will be a secondary bevel of 1-2mm (at around 20degrees)
When people say scandi grind the normally mean a single bevel per side starting from 1/3 to 1/2 the way up the blade with no change in angles just by the edge.

It can get more complicated when people put a third bevel on, normally called a micro edge bevel. This will be tiny.

You can normally seen mostof them with the naed eye if you move the blade around in the light. If you hold a knife edge in the light you will sometimes get bits reflecting light. These are flat spots in the edge and it needs sharpening

 

[KAE1]

Thanks for reply Andy. So most knives have the very visible first bevel and then the 'edge' that is re honed on each sharpening.
To your point I was adding a third bevel or second edge by using two angles when sharpenng.

I am currently using 19 degrees on my opinel # 7 and 22 degrees on Clipper, Bamsen and SAK.
Do most people out there on the forum use only one angle/edge when sharpening and what angle are you using?

 

[spamel]

When I sharpen my Mora, it stays as the factory edge. My opi gets a secondary bevel put on now, I put the knife on the block and then lift it "so far"! I know how far as I guage it with my fingers and what feels right and it usually only takes a few passes to get it razor sharp again. Saying that, I haven't used my stones for about two months now and have just restropped the knives back to sharpness after use.

 

[C_Claycomb]

I know you are not asking this, but here are some links to sharpening stuff
http://www.bushcraftuk.com/downloads/pdf/knifeshexps.pdf

http://www.worldknives.com/info/knife-sharpening-tips-by-jay-talmadge-24.html

http://outdoors-magazine.com/s_article.php?id_article=91

Possibly the most thorough description on sharpening I have seen.
http://forums.egullet.org/index.php?showtopic=26036

Most folk on here don't have a guide system, so they won't know the angle they sharpen at. I certainly don't. I have a rough idea that I like about a 20degree inclusive angle, but that could go up to 25 or so. I just sharpen so the knife will cut the stuff I want to cut
I usually do a convex edge, but if not, then you could say I use the twin bevel method, the first bevel providing a bit of relief, lead in and setting up a wire edge, then second bevel to the cutting edge being a little steeper to strengthen the edge and remove the wire. I only do a few very light passes to create that edge bevel and it is almost imperceptible.

My recommendation would be not to get too attached to sharpening guides. They are like training wheels on a bike. You can get great results, and everything will look real neat and tidy, but if you don't learn free hand sharpening you limit yourself.

Just my opinion...

 

[KAE1]

Thanks for the links, I'll take the time to read through them.