Hi, I bought a spyderco medium ceramic sharpening stone, and to my disappointment it's not flat. I'm a beginner knife sharpener and I was recommended this stone as a one-stone solution to learn on, but so far I haven't been able to sharpen any blade, maybe because the stone itself is not flat.
How can I level it in the most budget friendly and easy way possible?
Flattening a stone
Re: Flattening a stone
Hi Sparrisen,
Welcome to our forum.
The medium grit ceramic stone is as fired. It should be flat enough to sharpen a knife though. I do not know of any way that you could made it flat. Some have tried to use a diamond stone try to do so, but results are questionable and it ruins the diamond stone,
sal
Welcome to our forum.
The medium grit ceramic stone is as fired. It should be flat enough to sharpen a knife though. I do not know of any way that you could made it flat. Some have tried to use a diamond stone try to do so, but results are questionable and it ruins the diamond stone,
sal
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Deadboxhero
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Re: Flattening a stone
Sparrisen wrote: ↑Thu Dec 07, 2023 4:52 amHi, I bought a spyderco medium ceramic sharpening stone, and to my disappointment it's not flat. I'm a beginner knife sharpener and I was recommended this stone as a one-stone solution to learn on, but so far I haven't been able to sharpen any blade, maybe because the stone itself is not flat.
How can I level it in the most budget friendly and easy way possible?
As the saying goes, a picture is worth a thousand words.
It would be easy to see what the problem is by taking a picture of the knife being sharpened and the stone itself.
I think some important questions to ask are how is the knife being sharpened? What is the procedure? What knife is being sharpened?
We should rule out technique before equipment, especially when just getting started on the sharpening journey.
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WilliamMunny
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Re: Flattening a stone
I agree with Shaun, he knows what he is talking about. Even a stone with a small 1/16" dip or hump it would not stop you from getting a knife sharp. It might not be ideal but as long as you are hitting the apex of the edge at some point with the stone it will get reasonably sharp.
Listen to Sal that ceramic can't be flattened effectively. If you had a softer stone, like a Whetstone you could use sandpaper on a flat surface like glass or marble.
Provide some additional details, pictures and there will be a lot of people on here to help.
Listen to Sal that ceramic can't be flattened effectively. If you had a softer stone, like a Whetstone you could use sandpaper on a flat surface like glass or marble.
Provide some additional details, pictures and there will be a lot of people on here to help.
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Traditional.Sharpening
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Re: Flattening a stone
In my limited experience with the Medium 8x2", what Sal says is entirely correct for the most part. Diamond plates will be ruined in short order and results will be slow in flattening. They aren't made to handle this but there is a lapping plate design which was designed for this exact sort of thing. Nano Hone makes Diamond Button plates which are tough enough to handle these sintered ceramics/Arkansas stone/Norton Oilstone. I own the NL-10 and it has flattened both sides of my Medium stone. It took around an hour to get there though and it was done under lighter pressure to just let the diamonds do the cutting.
My example was flat enough to work right out of box, on either side. What I found was one side was slightly convex and the other was slightly concave. This will only be a problem potentially with some knives and also if you ever wanted to recondition the stone to make it cut more true to grit rating (it will wear smooth slowly over time). Once I flattened mine it's very easy to condition with a soft bonded Silicon Carbide waterstone around 200 grit, just light pressure for about 10 seconds is all that's needed to get it good and aggressive again. The problem with not being flat is that the lapping abrasive from that waterstone would only recondition parts of the stone well and leave the rest untouched.
In your case, without spending a lot on the NL-10/NL-8, I would suggest a float glass lapping plate and very coarse loose abrasive sprinkled over it. This is needed to generate high enough PSI contact pressure to actually cut into the hard stone effectively. Any other means of rubbing against other stones will wear the lapping stone far more than the ceramic stone and quickly change the shape of that stone. Lee Valley sells the glass and sheets you can adhere to the glass to act as a sacrificial barrier to extend the lifespan. Keep in mind the loose abrasive will continue to wear/crush rapidly and need to be rinsed and re-applied several times over the coarse of truing the stone. You could also use a ceramic tile or other hard/flat surface.
It's also worth noting that while you can certainly use the Spyderco Ceramics for quick touch-ups, they begin to be the wrong stone to begin working with when the edge is anything more than lightly blunted. I generally only use them with knives that are already slicing newsprint easily to bring out very high sharpness. Using a micro-bevel at that point it should only take a few passes per-side to get it razor sharp and anything more than that you'll just be pushing around the apex more than cutting it. For knives that are not mostly sharp, you would ideally use something like a softer waterstone to grind the edge bevel back thin enough at the apex to where you can transition to a finishing stone with very minimal work.
My example was flat enough to work right out of box, on either side. What I found was one side was slightly convex and the other was slightly concave. This will only be a problem potentially with some knives and also if you ever wanted to recondition the stone to make it cut more true to grit rating (it will wear smooth slowly over time). Once I flattened mine it's very easy to condition with a soft bonded Silicon Carbide waterstone around 200 grit, just light pressure for about 10 seconds is all that's needed to get it good and aggressive again. The problem with not being flat is that the lapping abrasive from that waterstone would only recondition parts of the stone well and leave the rest untouched.
In your case, without spending a lot on the NL-10/NL-8, I would suggest a float glass lapping plate and very coarse loose abrasive sprinkled over it. This is needed to generate high enough PSI contact pressure to actually cut into the hard stone effectively. Any other means of rubbing against other stones will wear the lapping stone far more than the ceramic stone and quickly change the shape of that stone. Lee Valley sells the glass and sheets you can adhere to the glass to act as a sacrificial barrier to extend the lifespan. Keep in mind the loose abrasive will continue to wear/crush rapidly and need to be rinsed and re-applied several times over the coarse of truing the stone. You could also use a ceramic tile or other hard/flat surface.
It's also worth noting that while you can certainly use the Spyderco Ceramics for quick touch-ups, they begin to be the wrong stone to begin working with when the edge is anything more than lightly blunted. I generally only use them with knives that are already slicing newsprint easily to bring out very high sharpness. Using a micro-bevel at that point it should only take a few passes per-side to get it razor sharp and anything more than that you'll just be pushing around the apex more than cutting it. For knives that are not mostly sharp, you would ideally use something like a softer waterstone to grind the edge bevel back thin enough at the apex to where you can transition to a finishing stone with very minimal work.
Re: Flattening a stone
This, 100%. I have tried it. Don't waste your time. At first, it might seem like it's working ok, but after the initial slurry rinses off, your diamonds will work exponentially slower because the ceramic has dulled them completelysal wrote: ↑Thu Dec 07, 2023 1:07 pmHi Sparrisen,
Welcome to our forum.
The medium grit ceramic stone is as fired. It should be flat enough to sharpen a knife though. I do not know of any way that you could made it flat. Some have tried to use a diamond stone try to do so, but results are questionable and it ruins the diamond stone,
sal
The warpage should only be extremely slight, and it won't affect knife sharpening. If you were trying to sharpen a straight razor, then it might be a dealbreaker
Re: Flattening a stone
If the medium stone is not working for you then perhaps sell it off and buy a diamond or CBN bench stone instead?