Boker ceramic blades: Any sharpening luck?

[Carl64]

I had seen them for sale many times before, but they were always kind of blunt so I never bought one. I recently got a financially good deal on one (I kind of wish I had something else now, even for the same price), so I took it to see if I could sharpen it up.

Using diamond sharpeners (ceramic and stones didn't make much sense) and a Smith's sharpening rig, I got a nice even bevel on the edge but the damn thing won't get sharp at all. I was very careful to not put too much pressure on it, and I even tried a relatively fine sharpener. The edge is continuously blunt, and if you shine a flashlight on it you can see the bluntness from the edge. It's about as sharp as when I got it, but not as smooth feeling. Not sharp enough to cut anything.

I have one more diamond stone to try (not handy right now) that is finer. It's a DMT that feels smooth to touch, you almost can't tell which side is which. But the blunt part of the edge looks to be far thicker than the grit of the stone, so I don't think that will help.

Has anyone bought a new one that actually came sharp enough to use?

 

[Cliff Stamp]

Kyocera's can actually be shaving sharp. I have not found a way to get a nice coarse edge on ceramics yet, but if you apply a very fine polish you can get them very sharp again. I described how I did it in detail in the OK-45 review. The best way it to cut an acute primary bevel with an x-coarse stone and then apply a micro-bevel for honing as the machinability of ceramics is horrible so it takes forever to hone the full edge bevel.

-Cliff

 

[Nimick]

I have had luck with cliff's method. I've had better luck paying the 8 bucks+shipping and sending it back to boker.

might I ask where you found this good deal? just so I know wether or not the same one I've been eyeing for the past 5 months. (it saves me the trip if it is.)

 

[Carl64]

The best way it to cut an acute primary bevel with an x-coarse stone and then apply a micro-bevel for honing as the machinability of ceramics is horrible so it takes forever to hone the full edge bevel.

It didn't look like grinding away ceramic was too difficult, but maybe my finer stone is not doing its job. I'll try your method when I can get my hands on the super fine DMT, which is actually more aggressive than other stones despite its finer grit.

 

[Carl64]

might I ask where you found this good deal? just so I know wether or not the same one I've been eyeing for the past 5 months. (it saves me the trip if it is.)

It was a Boker Gamma (the tiny liner lock with Zytel handle) at a local shop. They had it marked for $70 I think (common price, but I always thought too much), but I did some trading with them and it worked out I traded in $30 worth for it. I have been going there for years and this knife was sitting there unsold for most of that time, so they were rather happy to switch it for almost anything else.

 

[Nimick]

It was a Boker Gamma (the tiny liner lock with Zytel handle) at a local shop. They had it marked for $70 I think (common price, but I always thought too much), but I did some trading with them and it worked out I traded in $30 worth for it. I have been going there for years and this knife was sitting there unsold for most of that time, so they were rather happy to switch it for almost anything else.

shoot, It's not the same one. now I'm going to have to go buy it

 

[DGG]

Send them back to Boker who will sharpen them for free.

Great knives which rarely ever need sharpening, IMHO. The downside is their brittleness so you never want to pry with them.

Ceramic is just below diamond on the Moh's scale of hardness. It is number 9 like saphires. It is what Spyderco makes the sharpening rods for their Sharpmaker out of. I have never tried to sharpen mine myself. I have only sent them back one time for sharpening. The ones I have are mostly used in the kitchen and they get a lot of use cutting up veggies, etc.

http://www.knifecenter.com/kc_new/store_detail.html?s=BOC0

https://www.bokerusa.com/default2.asp

 

[yuzuha]

If I remember correctly, ceramic blades are made of zirconium oxide which is around 8.5 or so Mohs. Aluminum oxide and silicon carbide are both harder, though AlO would be slower going than SiC. You can sharpen them on diamond hones (careful with the angle and pressure) but you must then polish out the scratches or they can become stress points that will cause chipping or fracture. You can polishing them on some of the fine artificial waterstones as many of them are aluminum oxide. Or you can try 3M microfinishing film (they make it in AlO, SiC and even diamond... the diamond ones are used for polishing the ends of fiber optic cables before putting on the connectors) or you can use diamond spray/paste on some sort of lap or strop to try and polish out the scratches.

 

[STR]

My Boker ceramic folder came pretty sharp; not shaving sharp but sharp enough to use and I have used it some in the kitchen and for some light tasks around the house. I tried to sell it twice on the forums and didn't even get any takers. I won't buy another one. I have not tried to sharpen it but it really doesn't need it just yet. I figure after reading this thread that I'll pay the money and send it to Boker to mess with when the time comes rather than try myself. I always had it in the back of my mind that a diamond pad like the EZLap extra fine would do the trick but I guess not. I think diamonds are one of the few things harder than ceramic. I would think it is some kind of diamond sharpener that Boker uses but it is probably a motor driven wheel or belt of some kind.

Perhaps a silicon carbide belt would do the trick?

STR

 

[DGG]

If I remember correctly, ceramic blades are made of zirconium oxide which is around 8.5 or so Mohs. Aluminum oxide and silicon carbide are both harder, though AlO would be slower going than SiC. You can sharpen them on diamond hones (careful with the angle and pressure) but you must then polish out the scratches or they can become stress points that will cause chipping or fracture. You can polishing them on some of the fine artificial waterstones as many of them are aluminum oxide. Or you can try 3M microfinishing film (they make it in AlO, SiC and even diamond... the diamond ones are used for polishing the ends of fiber optic cables before putting on the connectors) or you can use diamond spray/paste on some sort of lap or strop to try and polish out the scratches.

Yuzuha-

The Moh's scale is really not what you need for testing ceramic hardness but it is understood by many folks as a point of hardness reference. The Vickers scale is much better.

http://moremetallography.com/ceramics/ceramics.htm

 

[Cougar Allen]