DC4 -- ridges on ceramic side?!?

KarlMaldensNose

KarlMaldensNose

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Feb 3, 2009
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Like the title says, the Fallkniven DC4 I just got has very obvious ridges running across the ceramic side. Tooling/machining marks, I assume. And it's not just cosmetic, I can definitely feel them... it's like running your fingers over a little washboard. I have some serious concerns about the quality and effectiveness of this ceramic side.

I did alot of searching (on Google and BF) and apart from a couple forum members mentioning the ridges on their DC4 in passing there doesn't seem to be any other discussion of this. IIRC knifenut1013 had similar issues on a Spyderco ultrafine ceramic benchstone, and the company just wrote it off as nothing to be worried about. Does anyone know the outcome of that story?

Has anyone else experienced this on their DC4 or on other ceramics? Is this a problem? I can't see how it can not be a problem. How is it possible to create a smooth precision edge on a lumpy surface?!?
 
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Its designed like that, its what makes it cut at the grit stated. You can lap it with a fine diamond stone to smooth it out but it will also make it cut finer.
 
KarlMaldensNose said:
Has anyone else experienced this on their DC4 or on other ceramics? Is this a problem? I can't see how it can not be a problem. How is it possible to create a smooth precision edge on a lumpy surface?!?
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I have a DC4 like the one you describe. It hasnt caused any problems with my sharpening. Now i dont go around creating lasers out of my knives, but a trip on the DC4 will make any of my knives shave hair.

The DC4 is meant as a field sharpener, and it does that just fine.
 
They were out of the DC4 so I ordered a DC3. It has visible lines on it but I can't feel them. If there were ridges I would think a knife blade would run along the high spots and if you are also moving the knife from ricasso to tip that you wouldn't have much of a problem. It is a pretty fine ceramic so I don't think you will be removing enough material to have a negative effect as it is mainly for touch ups.

Anyone have any idea what grit the diamond side is?
 
I just received mine. It is the same. As flmtnbkr said, it will sharpen on the high points probably. Since your knife is straight, it can only rest on a plane. That will be either a totally flat sharpening medium or two high points on that medium
 
If it's designed like that then I guess I should have no issue with it.

I was kinda forgetting what its intended purpose is and why I bought it -- pack or pocket carry for quick field touch-ups.

FlaMtnBkr, it has a 25 micron diamond side. DMT lists 25 mic at 600 grit, but just about every other source lists it at somethng different, from as low as about 400 to as high as 2500.
 
dc4 is great pocket sharpener, with light pressure on both sides you can get a very very nice hair poppin' edge.

for the op question, i've had 2 dc3 and one dc4. 2 of them had very rough grooves on the ceramic side, that's how they are supposed to be one dc3 was almost smooth. don't know why.

the grooves won't affect sharpening just avoid getting the edge parallel to the grooves and it wil work fine.

don't know if a flat surface will cut finer but i doubt, i don't see why the same abrasive with the same grit rating will polish differently if your bevel only touches the edges of the rifts or a perfectly flat surface. correct me if i'm wrong.
 
Lapping a ceramic stone with a diamond hone will smooth the surface and make it cut finer. How do you think spyderco makes the UF? They lap a fine ceramic ;)
 
pwet said:
the grooves won't affect sharpening just avoid getting the edge parallel to the grooves and it wil work fine.
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I just discovered that. Running the edge parallel to the grooves I can really feel the blade jumping all over the place, and can hear it too. Gotta be bad for the edge as it smacks into an incline. Holding and running the blade even just a little diagonally/off-parallel makes all the difference.

pwet said:
don't know if a flat surface will cut finer but i doubt, i don't see why the same abrasive with the same grit rating will polish differently if your bevel only touches the edges of the rifts or a perfectly flat surface. correct me if i'm wrong.
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Maybe better that way, with ridges, that is. The depressions or low spots could act as a place for material/swarf/shavings to congregate out of the surface path that the edge travels along. Kinda like DMT polkadot Duosharp hones.

knifenut1013 said:
Lapping a ceramic stone with a diamond hone will smooth the surface and make it cut finer. How do you think spyderco makes the UF? They lap a fine ceramic ;)
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I remember learning about that too. I was pretty surprised. I'll probably leave this one alone unless the ridges bug me. I have a tendency to hold and pull my blades perpendicularly across the stone/strop/whatever on plain edge-trailing and edge-leading strokes.
 
I have a DC3, and this is the only falkniven stone I own so I have no other comparisons, but the ridges were deep and ran in an slight arch width-wise, so when sharpening the edge was alway parallel to them. It pretty much just dulled the knife, was very unforgiving, if the angle wasn't JUST RIGHT.

The best way to describe it is, like if they used a circular saw and sawed the stone as a slice out of a larger bar, and the saw left teeth marks.

I used a extra course DMT pocket stone to lap the ridges off, and it works rather well now. I always thought the ridges on mine were a defect, especially since they looked like saw marks.
 
I have had two DC3's, the first of which was returned for a bubbled diamond side. I lapped the ceramic of each of them on a fine diamond surface. I assumed because of the arc to the ridges that they were pre-firing machining marks. I didn't like the way they felt in-hand so off they came.
 
Ok after talking to fallkniven, I think I understand now....

You'll never use the ceramic side by itself. All sharpening happens on the diamond side, the ceramic acts as like a chef steel, to break the burr off or align it. The burr "catches" on the ridges...
 
I've been told the ridges are due to the manufacturing process. A saw spinning at low rpms leaves those types of marks
 
Jack Shen said:
Ok after talking to fallkniven, I think I understand now....

You'll never use the ceramic side by itself. All sharpening happens on the diamond side, the ceramic acts as like a chef steel, to break the burr off or align it. The burr "catches" on the ridges...
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oh nice.

sorry but that sounds like cr*p to me. if the ridges are there on purpose why do they vary in size from a stone to the other ? why my first dc3 (2+ years old)is almost smooth while my DC4 has very deep and straight ridges and my brother's is between the two but with more radiused ridges (like half circles)? why everyone who uses it for long says that the newer ones have waaay more ridges than before ?

nah don't buy it, it's just lack of QC and it's really too bad because this stone is just a perfect field solution otherwise, diamonds cut fast enough, ceramic is a bit of a gap but enough to clean the edge and i carry a piece of cardboard impregnated with 3 micron compound in the pouch ...

the ridges don't bother me that much but trying to say it's there on purpose when it's not and when the ridges can ruin your edge if not carefull pisses me of quite a bit.
 
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tabeeb762 said:
I've been told the ridges are due to the manufacturing process. A saw spinning at low rpms leaves those types of marks
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Exactly my conclusion. They are making those stones by the thousands. The ceramic somewhere in the process , has to be cut to size. They probably don't grind the saw marks out , as it's most likely not cost-effective to do ,so they leave it. I have no problems with my 4 Fallkniven stones. All have the same marks.
 
I had one with the ridges, this is a tooling mark that should have been removed. I lapped it with a DMT, worked much better. Subsequent DC4's that I bought were very smooth. I think these slipped through QC.
 
pwet said:
oh nice.

sorry but that sounds like cr*p to me. if the ridges are there on purpose why do they vary in size from a stone to the other ? why my first dc3 (2+ years old)is almost smooth while my DC4 has very deep and straight ridges and my brother's is between the two but with more radiused ridges (like half circles)? why everyone who uses it for long says that the newer ones have waaay more ridges than before ?

nah don't buy it, it's just lack of QC and it's really too bad because this stone is just a perfect field solution otherwise, diamonds cut fast enough, ceramic is a bit of a gap but enough to clean the edge and i carry a piece of cardboard impregnated with 3 micron compound in the pouch ...

the ridges don't bother me that much but trying to say it's there on purpose when it's not and when the ridges can ruin your edge if not carefull pisses me of quite a bit.
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well since you put it that way, it does really seem like fallkniven is doing some damage control over some bad QC.

I had an idea the other night, dunno how well it'll work or even possible.
Here it goes, I was thinking about getting a fine spyderco pocket stone, and epoxying a fine DMT stone of a similiar size to the other side, is this just a stupid idea? I think if the ceramic on a dc3/dc4 was more like the spyderco ceramics, it'd be ideal.

before lapping, the ridges were completely negating whatever work was done on the yellow side.

*sigh* I thought I had found the ultimate pocket sharpener, I'm kinda unwilling to shell out another $20-$30 just to see if mine was an exception to the norm.


here is what I sent them:

What are the ridges on the ceramic side of the DC3 for? Is my stone defective? They seem to be actually dulling my knife as opposed to sharpening it. The ridges look like teeth marks from a circular saw, as if the stone was cut from a larger bar.

here is the response I got from Fallkniven:

Dear Jack,

First of all, thanks for using our products.

Your stone is NOT defective, it is meant to look that way.

Please use your stone as it is.

Normally, you will use the yellow/diamond stone for almost all sharpening, only when you wish to get a razorblade sharpness, you go for the dark/ceramic stone.

No water or oil is needed.

Best regards

Peter Hjortberger



I'm soooooo confused now ...lol
 
zyhano said:
I just received mine. It is the same. As flmtnbkr said, it will sharpen on the high points probably. Since your knife is straight, it can only rest on a plane. That will be either a totally flat sharpening medium or two high points on that medium
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please re-read that quote by me.

Guys, with all respect to you all, but I have no trouble sharpening on my dc-4 with the ridges present. Maybe it's because it's a smaller stone that some have trouble with it.
I do agree that the stone should be flat. there is no reason for those ridges. QC must go a step up.

I find the first answer that is stated here by Jack shen strange. Jack, are those the exact words of fallkniven company, since I doubt that?
 
I've used a fallkniven DC4 for quite a long time now, and mine had the ridges that others here have talked about. I didn't get the performance i wanted out of it, so i lapped it on my dmt big coarse benchstone. Now, it works a treat. I do main sharpening with the diamond side, then i do a few light strokes on the ceramic side, to "polish" it up a little. Works well on all my knives. I've recently ordered a DC3, so i guess i'll see then if that one needs lapping aswell.

Anyway. There's no reason not to lap the DC3/4 if you're not happy with the ridges, because in my experience, the ridges doesn't add anything to a sharpening experience. Infact, it may make it more difficult for you to maintain your edge. As always, YMMV.
 
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