Zero secondary bevel sharpening?

[TikTock]

I am finishing my second fixed blade and it is coming out great. I was wondering about alternate sharpeing styles to the typical guided stone secondary 17 degree sharpening. Id rather go for a straight main zero degree secondary bevel. I was thinking slightly convex, worked with 800 grit sandpaer on a piece of glass. Would I be able to get this razor-sharp-enough-to-split-hairs? This knife is a thin slicer, so wont be intended for heavy thick cutting, so i want a thin, sharper blade. What are my options for keeping a smooth, uninterrupted looking bevel?

[Go4it]

I am sort of confused in what you are asking. You have me confused with all the different bevel types.
But it sounds like you are asking if there is a way for the blades primary bevel to also be the cutting edge and replace a seperate edge bevel, as well as, asking if this will result in a razor sharp blade?

If this is so, I recommend trying what the Japanese do when they polish their weapons. The japanese polish is not so much just to make the blade shiny but also to put the edge on the weapon and reveal the grain in the metal work. Most traditional japanese weapons do not use an edge bevel to create the edge. Additionally, since the blade's primary bevel is the edge, when designing a weapon, the width of the bevel, the blade, and the spine are all determined on how sharp vs how durable the blade will be.

To briefly explain how it is done. Stones are used for all sharpening and polishing. And all sharpening and polishing are done by hand. The japanese believe that machine grinding and polishing smears the grain and blurs the clarity of the hamon (which is, one of many, points of quality for their blades). Additionally, they believe machines will not produce a truly sharp edge. Their faith is in human skill, not machinery. Continuing on, the initial rough forming is done much the same as what we would do on an edge bevel, but done on the main bevel. The finer grits are done with smaller polishing stones. These polishing stones are formed into small flat square pieces and attach them to pieces of wood so they can run them over the blade in small circular motions. Progressively getting to finer and finer grits. The final stone grit is supposed to be around 12000 grit. This produces an extremely sharp edge, a remarkebly clear grain (to polish metal to just make it shiny, they will burnish). Because the grain is "open" they treat with oil imediately. It is very time consuming and will cost anywhere from 2,000- 6,000 dollars.

There is much more to the process that the Japanese will go in to endless detail. They have artisans who spend their whole careers doing only that portion of a blades production, care, or restoration. For my purposes it is much more detail than I need.

This is what I do (and have seen done, since this is a borrowed technique) when overhauling a blade. Those who do this often, get the japanese wet stones. But for a single experiment, sandpaper can be used. I glue the sandpaper to some Micarta blocks that are about 1" x 1" x 1/4" with some light contact cement or rubber cement. I make numerous blocks of each grit, as the paper can wear fast. I then go down, rinsing the blocks frequently with water to keep the paper clean, rubbing the blade till all the marks from previous grits are removed. I will go from 180 grit to start until I end with 6000 grit paper. I clean the blade and change water each grit. I use the same amount of passes and motions on each side for each grit. It is very important to pay attention to what you are doing. You will be working very closely to an edge that will become very sharp.

I do not have access to a lot of power tools in my production, so I personnally like doing this method. I am not so much concerned with time as results. I use it just to polish the blade and use a traditionaly western edge bevel. I like the clearness of the grain the most.

Hope you found this explanation enlightening

[TikTock]

WOW, thanks!

Yes, when i re-read my initial post is a bit fuzzy. What I wanted to know was the feasability of yes, having the prmary bevel extend directly to the edge. I calculate that on a 1/8" piece of steel, with my bevel running 3/4" up towards the spine, and a completely dead flat grind, my edge angle would be almost exactly 12 degrees. Thats awful thin, but for the knife, it may be acceptable considering 15 degrees is a normally acceptable edge bevel. Thanks for your post, very informative. I have a Waki that is hand polished like you describe....amasing watermelon seed edge that I would never want slicing across anything attached to my body....

I will experiment....

[AwP]

Scandanavian knives also don't have a secondary bevel but they do it differently then the japanese, they do a flar grind. It makes resharpening easier since you lay the whole large bevel on the stone or sandpaprt or whatever.

[TikTock]

Thats how I got the idea....I am going for a crazy time-intensive hand rubbing on this blade, and ive watched the edge get thinner and thinner from my dangerously thin HT grind thickness. As i progressed slowly and thoroughly from 220 through 800 the edge is now a sliver that is approaching sharpening thickness. With a minor amount of work, it will be scary sharp with no second bevel, or i can create a second bevel and thicken up the area directly behind it. Given the thin grind and overall sleekness of the blade and design, im leaning towards a thin convex edge but wanted to know my options.

[dudeinthehut]

I recently hollow ground a dual edge fighter so thin in most places that I created the very edge you speak of.

After polishing, both edges were wicked sharp in almost every spot. I was going to rework the edge in the traditional way in order to straighten up the edge as it is now just slightly wavy.

However, you have me thinking that a pure polished look (with no satin textured edge) would be awesome on this long elegant fighter.

Hmmm...

Andy

[tonn]

Originally Posted by AwP

Scandanavian knives also don't have a secondary bevel but they do it differently then the japanese, they do a flar grind. It makes resharpening easier since you lay the whole large bevel on the stone or sandpaprt or whatever.

As far as I know - at least in Finland - they grind the blade to allmost sharp condition and then make a tiny secondary bevel - allmost invisible - with fine stone. And it isn't easy to resharpen for you have to take off much more (hardened) steel to!

[AwP]

Well I guess any grind by a Scandanavian is a scandanavian grind , but the primary flat grind without the secondary is what I've usually heard of refered to as a scandanavian. I didn't mean easier effort wise, I mean easier to keep the proper bevel degree, which alot of people have problems with doing freehand when the bevel is small.

[tonn]

Originally Posted by AwP

Well I guess any grind by a Scandanavian is a scandanavian grind , but the primary flat grind without the secondary is what I've usually heard of refered to as a scandanavian. I didn't mean easier effort wise, I mean easier to keep the proper bevel degree, which alot of people have problems with doing freehand when the bevel is small.

What I've heard is a first hand information from some of the top makers in Finland.
Not all knives are sharpened in that way but when knives with best edge holding are inspected, some secondary bevel is discovered. Don't try to find it in factory knives
What comes to resharpening - in theory it's easyer to keep a proper degree with large bevel, in real life that flat bevel become convex very soon. And imagine doing it in the field!

To TikTock
It's all about a geometry! If you blade geometry allows you to make a single bevel- do it!
But be sure it's not too weak!

[Coutel]

Originally Posted by tonn

What I've heard is a first hand information from some of the top makers in Finland.
Not all knives are sharpened in that way but when knives with best edge holding are inspected, some secondary bevel is discovered. Don't try to find it in factory knives
!

I think you will find that some Scandinavian makers will have a secondary and some dont ( flat to zero edge)....it can be regional by country according to tradition. ..... A flat zero edge scandinavian grind is great for wood carving, but can be too weak for hunting (likely to chip)...hence sometines a secondary bevel is added for strength.