Opening up the Carbonext

[Soen]

Long after all the hype has died surrounding this knife I decided to purchase one to have a go with tool steel before I take the plunge into carbon and since the carbo next requires "opening up" I thought I would give it a go as a little sharpening project.

My knife arrive yesterday and I was very pleasantly surprised by two things;

1)the fit and finish was above my expectations

2)the OOTB edge can actually cut and I would classify it as "sharp" in the general use of the term

The FnF is perfectly acceptable. The tang and handle are seamless as are the rivets, the bolster protrudes ever so slightly above the handle, I mean slightly. The pakka wood is smooth a well finished with only few minor scratch marks to the rivet finishing. I would say the spine is semi rounded but the choil is completely unfinished. I compared the FnF with some of my german knives which are well known for there high FnF and I would say that they are comparable with the exception of the choil.

The handle is ever so slightly narrow, but not enough to cause me a problem when in a pinch grip. So both the FnF and handle size issues are if my carbonext is anything to go buy are massively over exaggerated imo.

The edge is the normal sharpness option and OOTB was capable of feathering a piece of A4, made short work of an few onions and potatoes, although it struggled with the bread. Nothing amazing, no less sharp or sharper than a $40 knife from your local hardware shop comes but certainly by no means was it blunt or unfinished as people seem to suggest. I was expecting a bevel put on by a course stone only, but the edge is actually polished.

Now my little surprises aside, I will be in the near future when I get a free afternoon spending some time touching up the FnF and putting my own edge on it. This will probably include some thinning. So I was just looking for some general advice on what edge, thinning ect that they would specifically recommend for the CN.

After I have finished opening her up, I'll post before and after in the show and tell forum and perhaps a vid if the level of sharpness warrants it.

Thanks in advance.
S

[doug8066]

Weli Soen, I think you will be pleased with the carbonext. I have had a carbonext 150 petty for about a year, and have just a few weeks ago bought a Carbonext 210 gyuto.
I like the carbonext knives very much. Why ? Well they have good f&f, and are good value for money.
But above all - they are very light with lovely tapered thin blades. Easy to sharpen and take a very keen edge - very close to the razor edge I can get on my Hiromoto AS knives.
But (repeating myself) where the carbonext knives really score is in their light and highly nimble weight in the hand. They feel like Superbikes compered to many other knives which feel like... well... like farm tractors.
Along with the razor edge, this agility makes a real difference to everyday use.

BTW - They arrive "sort of" sharp out of the box. But my experience of many brands Japanese Western style knives is that OOTB does not matter - fact is no manufacturer sharpens knives as well as we do, so I would never judge a knife on its OOTB edge sharpness. Sharpening is my(our) passion

[Soen]

Hi dough,

Yeah I agree my 240 is pretty light in the blade. It is a bit heavy in the handle, they could benifit from tampering the tang imo.

What bevel angels have you used/intend to use on your 210?

[Benuser]

Assuming you're fine with the heavy asymmetry that's common with our J-friends, and assuming you're free hand sharpening: start with thinning the right side at the lowest angle you're comfortable with. Don't hesitate to remove eventually the original edge. Go on till you raise a burr on the left side. Keep the left side as flat as possible, with a barely percievable bevel.
Create a 10-12 degree bevel on the right side, deburr the left side at 15 degree.
As the area behind the edge is very thin you don't have to worry to much about the angles. For this thinning work I prefer sandpaper on linen over stones. No flattening, cheap and fast. Use the Magic Marker Trick to see where you're abrading steel. Good luck!

[Soen]

Thank you Bensuer, I can't tell by your post if your just deburring on the left side or thinning at a very accuate angle. I took a closer look at the balde geometry last night and the CN is slight asymetrical in grind with a flatter back side, so imo it makes sense just to debur and thin asymeterically on the front edge.

[Benuser]

I wouldn't thin the left, flat side at all. Just deburr, essentially with edge trailing strokes, a few edge leading will be necessary though. So the edge will remain as thin as possible, and the flat side will remain as close as possible to the stuff you're cutting, allowing the thinnest slices, while the convex side will push away these slices and prevent sticking. That's the idea.

[Soen]

Good stuff, wasn't sure if you was trying to match blade geometry with edge geometry. Yeah I I would have done a few edge leading just to create a small bevel to debur off. I give it a go this weekend, thanks for you input Benuser, it's been helpful.

[Benuser]

You're welcome, Soen.
Please let us know how it worked out.

[doug8066]

Hi dough,

Yeah I agree my 240 is pretty light in the blade. It is a bit heavy in the handle, they could benifit from tampering the tang imo.

What bevel angels have you used/intend to use on your 210?

Sorry - a little bit late in replying. The angle is usually about 10 - 15 degrees per side. That is the cutting edge of course.
The rest of the blade, behind the cutting edge, is ground to about 8 -10 degrees, certainly thinner than the cutting edge.
BTW this is the standard angle I use on most of my knives.
And in case you were wondering - my sharpening ritual currently is Bester 1200, Norton 4000, Norton 8000, Naniwa 10,000, then maybe a GENTLE strop on CrO / hard leather or 0.5micron diamond on artist's particle board.
Real killer sharp.
I test for sharpness by using the Murray Carter 3 finger test for a start (not useful when your fingers are wet) but mostly I use the Chad Ward hair catch test.
This test consists of very gently holding the knife above & behind your head, then bringing the blade edge GENTLY down until it contacts your hair. The blade should be almost parallel to your hair surface. As the blade edge contacts the hair, a really sharp edge will grab instantly. A dull or not quite razor sharp edge will slide off the hair. This process sounds very dangerous but is not. Once you have experienced a really sharp edge this way, you will never forget it.
After this test I might slice a potato to double check, but there really is no need to.

[Soen]

Haven't had the chance to work on it yet. So your not too late

I would be rebeveling/thinning on a 600 Chosera, and sharpening on a 1200 bester, 5000 Naniwa and then a on a 8000 grit and 35,000 grit mircofinishing film (trailing strokes only on the last to avoid riping the paper).

[Soen]

Update.

I thinned the front side this weekend. I got rather cocky and went for 4-5 degees. The edge is quite neat and even and the taper is now much more progressive at the tip, but I had to take the painters tape off half way through. I found it created more problem than it fixes, but consequently there is quite a bit of scratching on the blade face, so I going to have to refinishing with some wet and dry. I was planning on starting on 240, 320 by working the knife face on a mouse matt.

I am a little concerned what refinishing will do to the kanji logo, though. Anyone refinished the front face on a logo'd knife before?

[thombrogan]

I am a little concerned what refinishing will do to the kanji logo, though. Anyone refinished the front face on a logo'd knife before?

Yep. If it's engraved, 220 or 240 wet/dry shouldn't touch it. If it's laser-etched, all bets are off.

[Benuser]

Are the scratches that deep you need sandpaper in the P200 range? I would first try the cosmetic approach: coarse ScotchBrite. Otherwise P700, then ScotchBrite. A light touch, in one direction only. You will have to treat the entire blade.

[Soen]

Well the marks are for the Chosera 600 mainly that the area just prior where the belly progresses to the tip, i.e the part that I personally find hardest to keep angled constant. But it's quite bad, it was only from a momemntary lasp of concentration but that's all it takes.

I'll try a stotch brite first, but I can't see that working. I have some quality wet and dry comming in the post between 340 and 1000, I'll try high first and work down and then back up to get to the finish I want. I'll do the back face a well to keep the finish consistant.

I also shoe shine the choil and spine whilst I am at it.

Extra work but hopefully it will be worth it

[Soen]

Started refinishing last night, the brite pad didn't cut the mustard. I used 240 wet n dry in the end. Still have a few little scratches that need taking care of, but I'll do that after I round the choil and spine.

I not sure how I scratched it so deeply, I can only guess it because I don't wet and dry the stone after the 140 atoma.

[bob13bob]

I bought one 240mm gyuto over a year ago. The ootb edge was sucky.

I jsut bought 2 210mm gyutos and and a petty. These came with a great edge. All three could smoothly shave hair off my arm. No need for me to touch with my stones for awhile.