Hamaguri Grinds on Blades

[Tekki]

I have recently read an article on knifenews about the up and coming 2018 catalog that we are all super excited to check out. But one thing that really stood out was that Eric mentioned that they perfected the production of hamaguri grinds, which made me excited. I know the first time I saw the Bob Lum tanto folder/fixed blade I was amazed by the beauty of how that hollow grind transitioned into the apple seed grind at the tip of the blade. I do hope that the new catalog or future releases has something similar. I would be interested how this style is going to be incorporated into their new designs, anyone have any extra information or some input?

[bearfacedkiller]

I am eager to see what models will feature it.

I also look forward to hearing how folks plan on sharpening them. I like the sandpaper on a mouse pad approach on the convex edges I have played with.

[dammyippon]

I love convex grinds. I use strops to touch them up and waterstones if the need a proper sharpening, which is pretty rare in my case.

[ZrowsN1s]

I am eager to see what models will feature it.

I also look forward to hearing how folks plan on sharpening them. I like the sandpaper on a mouse pad approach on the convex edges I have played with.

Are you familiar at all with Rockstead Knives? They make some expensive ZDP blades with apple seed grinds. They recommend getting a board and stapling some cloth from denim jeans onto the board, then smearing metal polish onto the denim, and using that to strop. For major sharpening they recommend you send it back to Japan.

Also for those of you with the KME system, they sell a curved rod attachment for sharpening convex edges. Never tried it though.

[bearfacedkiller]

Yes I am familiar with them. They are a bit out of my price range.

I like sharpening and enjoy doing it and would not send my knife half way around the world to have it sharpened. I do not like to let anybody sharpen my knives, not even the maker. Spyderco sharpened one of my knives when it was in for warranty work and I was rather disappointed.

I am not much of a stropper and I seldom do it. I realize some maintain knives just by stropping but I do not. Either way at some point it is going to need an actual sharpening.

[ZrowsN1s]

I agree I'm unlikely to send my knife to anyone else to sharpen (then again if you dropped 3k on a rockstead you might I suppose, waay out of my price range as well).
I can go a long time in between sharpenings by using strops, but you are right eventually they all need the stones. I may buy that KME attachment and try it out.

[sal]

Hi Tekki,

Welcome to our forum.

It is an expensive process so we'll have go wait and see reaction to the cost before going overboard.

I'm with you Darby. I still favor the mouse-pad, but we are working on some other methods. We'll hide-n-watch the market.

sal

[SpyderEdgeForever]

I have wondered about this grind before. I really like convex grinds and this seems almost perfect.
Sal, is it a more expensive process to grind this type of knife because it requires different tooling than say a hollow or flat grind?

What would you all think of a hamaguri ground knife with blade steel being lc200n? Would it be a good one?

[Brock O Lee]

I love convex grinds - watching this development with interest...

[Tekki]

Thanks for the reply Sal!!! I am deff interested to see what you guys have in store for us, as well as I would love to see a return of the bob lum tanto as well!!! I wasn't into spydercos or knives for that matter when they was initially released.

[anagarika]

Self sharpening a full convex will be a challenge, cosmetically, especially there is no clear line of division between primary grind and secondary (there’s none).

I like HeavyHanded approach (https://www.bladeforums.com/threads/con ... e.1533818/) and that’s how I do it, ignoring the cosmetic (it’s a work knife, a tool). Does that to my BCMW 52100 paring & utility. Mouse pad + sandpaper can work but need to be careful with rounding the apex. I’m sloppy so I don’t do that anymore.

[tonijedi]

Interesting news.
I also like the convex edge on my fallknivens. Initially I was using the mouse pad and sandpaper method but lately I found stropping is enough. I'd just use stones if a major chip or damage happened.

[JD Spydo]

I love convex grinds - watching this development with interest...

Convex grinds are a bit tricky to sharpen but the results are worth the wait. A few years back me and my good pal Spyderknut were at the Blade Show in Atlanta and we got to meet and talk to the King of the Convex Grind and that being the late Bill Moran. Mr. Moran went into detail as to why he liked convex grinds the best and I've been intrigued with them ever since.

If my memory serves me well I believe if I remember right that Spyderco's first run of the Spyderco MORAN fixed blades had the convex grind. Well at least that's what a couple of old timers told me anyway. I would love to see a C-60 Ayoob Sprint Run with a convex grind.

[Jazz]

I find them very annoying. Can someone tell me why they are so great, please?

[Evil D]

I find them very annoying. Can someone tell me why they are so great, please?

Well I suppose they can slice better. Some people find them very easy to maintain. They can have a stronger edge. They can be tougher.

[SpyderEdgeForever]

I find them very annoying. Can someone tell me why they are so great, please?

Well I suppose they can slice better. Some people find them very easy to maintain. They can have a stronger edge. They can be tougher.

That is why this is my favorite grind. However, practical experience and the experience of persons such as Jazz and David on here have taught me to have a renewed enjoyment of quality SPYDERCO-made hollow grind and saber hollow grind blades. I trust the strength and quality of Spyderco-made hollow ground knives.

[Brock O Lee]

I find them very annoying. Can someone tell me why they are so great, please?

When done right IMHO convexes should be very thin behind the edge. It's main benefit is to eliminate the thick shoulders created by the V edge, and that reduces binding in the cut, especially for rigid materials. To me a convex with a micro bevel serves the same purpose as a thin FFG "regrind" done by someone like Krein for instance, but it is free if you do it yourself and cuts even slightly better. :)

It is quite difficult to photograph, but here I have a Sage 2 and a Cruwear Manix. The Manix has a 13 dps V-edge with a 15 dps micro bevel, which is already an improvement over the typical 15-17 dps factory edge. The Sage has a nice flat convex and a 15 dps micro bevel.

Sage right:


Sage on top:




They are worlds apart in use compared to how easy they glide through material.

I'm not sure if you are "supposed" to have a micro bevel on a convex. I can understand that this is not ideal for wood. It works well for me on EDC knives, as it gives some strength to the thin edge without reducing cutting ability. It is easy to maintain the micro bevel on the SM. I do not strop them.

[Jazz]

Thanks, guys. Nice pics. I see what you're saying. I found sharpening them annoying, but there was no microbevel. With one would mean less annoying convex touch ups.

[anagarika]

Hi Jazz,

Depends on the zooming level, a full convex can be said tp have blended micro bevel .
If final apex angle is the same, it’s going to slice better because the shoulder up to spine will be thinner than flat or sabre.

There’s a lengthy discussion (and disagreement) on whether they slice better or more robust.
https://www.bladeforums.com/threads/the ... h.1180540/
The blue line represents if they are done to make it more robust. The red line represents when they are made more slicy. One is based on final apex angle (red), one based one spine thickness - blade width (blue) being the same with the Scandi grind.