Convex edge on a sebbie?

[pbubsy]

I'd like to see the option on CRK blades to have a hollow, convex or flat primary. That would be sweet! I know I've seen some flat ground sebs around....does anyone know if that is something you can ask for or was it only in a special run?

 

[tsiloics]

Another approach you could take would be to put a compound secondary edge on, and then gradually round it out as you maintain on the strop. I've done that on hollow-ground primaries before. It's not a textbook convex edge, but it allows you to easily go back to a simple secondary edge without making the primaries look like crap.

I'll add my voice to the idea of sending the knife to Tom if you want the primaries reground/thinned/convexed.

 

[KeithAM]

All this talk about putting a convex edge on a Sebenza -- I know the primary grind is hollow, but I've always understood that the edges were convex from the factory.

 

[Lycosa]

Me Too, KeithAM!

 

[Justabuyer]

All this talk about putting a convex edge on a Sebenza -- I know the primary grind is hollow, but I've always understood that the edges were convex from the factory.

Since nothing is perfect I imagine all edges are convex if you measure at a high enough resolution. But that is not the intent of most edges. In fact many if not most sharpening operations work to try to avoid the natural tendency to form a convex edge.

Some of us have stopped doing that and have come to embrace the convex edge for its advantages. One of the greatest advantages in my mind is it lets you finally stop worry about edge angle altogether.

All HAND sharpeners form convex edges. Your choice to spend your life fighting it or to embrace it, work with the unavoidable process and take advantage of it.

 

[KeithAM]

Since nothing is perfect I imagine all edges are convex if you measure at a high enough resolution. But that is not the intent of most edges. In fact many if not most sharpening operations work to try to avoid the natural tendency to form a convex edge.

Some of us have stopped doing that and have come to embrace the convex edge for its advantages. One of the greatest advantages in my mind is it lets you finally stop worry about edge angle altogether.

All HAND sharpeners form convex edges. Your choice to spend your life fighting it or to embrace it, work with the unavoidable process and take advantage of it.

I believe CRK purposely gives Sebbies convex edge. My one-piece Mark IV appears convex too. And I don't think they are microscopically convex either. You can see it by the way it reflects light. So my point is you don't need to do anything to convex the edge of a Sebenza -- it comes convex from CRK with all of the advantages you state.

I just did a couple of searches on the subject and confirmed that it has long been widely understood that Sebenzas and other CRK knives come with convex edges.

BTW, I have a number of knives with convex edges which I maintain with a slack belt sander. I've also got a few Bark Rivers and Opinels which are fully convex. So I'm definitely fine with convex.

 

[steelfury]

I have a new sebenza and the edge is convex, although the primary grind is hollow.

There is nothing to stop you putting a convex edge on any blade grind be it hollow, flat or convex itself.

Of course if what people mean by a convex edge being a 'full convex from spine to cutting edge' in one smooth go , then that cannot easily be done a hollow grind unless you remove loads of metal, hence altering the grind entirely.

 

[Dinkum]

I convex everything, the Sebbie would take about 20 mins by hand to get to a #2000 finish.

Get a SAK and practice on that, I only say SAK because the steel is softer so you make progress faster, its really easy to do. I do suggest though that you get a thicker piece of EVA foam, (about 8-12mm) if you are going to reprofile, it makes things easier still.

 

[KeithAM]

I convex everything, the Sebbie would take about 20 mins by hand to get to a #2000 finish.

I'm not sure I follow you since not only do Sebenzas come with convex edges, but the edges are already polished finer than 2000.

 

[kdizzog6]

I'm not sure I follow you since not only do Sebenzas come with convex edges, but the edges are already polished finer than 2000.

I'm not sure I get it? I have never seen a sebenza with a factory polished convex edge? I have 2 brand new ones right in front of me? They both are hollow ginds with a V shaped edge that has grind marks on them? I convexed the edge on one of my sebenza's. Its the bottom one on the pic. I thinned out the edged, and made the edge roll gently back to the hollow gind in a rounded shape. The factory sebenza has a tiny little edge that has a v shape? Sorry for the crapy pic.

http://i513.photobucket.com/albums/t339/Kdizzog/Picture929.jpg

http://i513.photobucket.com/albums/t339/Kdizzog/Picture926.jpg

 

[giant1]

I don't agree that the sebbies come from factory with a convex edge. If you have a look at this page (Best way to keep a CRK knife sharp) on the CRK site it seems to confirm what I am saying

http://www.chrisreeve.com/faq.htm#

Since I started this post I have been doing a little more thinking and research and now I'm beginning to doubt the wisdom of changing the geometry of the edge. After all, my knife is sharp when I stick to the factory recommended procedure and it's easy enough to do. Further more if the makers of the knife decided that a bevel edge is the way to go who am I to question it??

I still want to have a go at putting a convex edge an a knife for the learning experience, but maybe I'll leave the sebbie as is until I know what Im doing.

 

[Justabuyer]

Further more if the makers of the knife decided that a bevel edge is the way to go who am I to question it??

I still want to have a go at putting a convex edge an a knife for the learning experience, but maybe I'll leave the sebbie as is until I know what Im doing.

I am not sure what you mean by who are you to question it?? You are the knifes owner. That trumps any Internet FAQ designed to calm the lowest common denominator end user.

The part about learning on less expensive knives is not a bad idea.

 

[giant1]

I am not sure what you mean by who are you to question it?? You are the knifes owner. That trumps any Internet FAQ designed to calm the lowest common denominator end user.

The part about learning on less expensive knives is not a bad idea.

haha, just saying there may be a small chance that the guys at CRK know just a bit more than me about making knives and which might be the best edge for the intended use and style of the knife

But I also agree with you that we all have a right as owners to do what we want (within reason) :thumbup:

 

[Dinkum]

Further more if the makers of the knife decided that a bevel edge is the way to go who am I to question it??

It's quick and easy to do, this probably has more bearing on the decision than anything else.

Convex lovers, once converted are like reformed smokers still, there is a reason for their love of the grind. Once I found 'the way' I convexed everything I own and I suspect the most often asked question on the Bark River and Fallkniven forums is 'If the geometry cuts so well, why don't more makers do this?' to which the answer is 'Becuase it can't be done quickly on a machine, it needs to be hand ground'

To me though my Sebbie looks like a micro bevel that has been buffed so it does look a wee bit convexed.