Ceramic rod/stone restoration

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Barmaley

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Dec 31, 2016
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I got some reference to this issue in another thread but since it is not related to the previous thread title I decided to start a focused new topic.

I got a few ceramic rods which I bought from Ebay but they are too coarse which is not the best application for a rod. I read on this forums before that it is possible to restore Spyderco ceramic stones after they get blunt. I decided to try to do it to a rod and I scrubbed it with a course SiC grit. The rod got very smooth but it lost abrasive property since the surface got bold.
FortyTwoBlades said:
However, if it's a sintered ceramic rod (like a Spyderco ceramic) then you'll NEED diamond, as the difference of hardness between SiC and aluminum oxide is only very slight.
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The Knife Life said:
You can still use a flat diamond plate to refresh the round ceramic rod, just scrub it up and down the length of the ceramic rod and slowly rotate the ceramic every several strokes up and down.
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I tried to scrub the rod for about 10 minutes with a diamond plate but it did absolutely nothing to the stone. I was applying very light pressure since I did not want to damage the plate. Unfortunately I did not see any abrasiveness on a smooth surface of the rod. Do I need to press harder or use some oil?
 
Ceramics are very hard. It will take time. You would start with a coarse or even x-coarse grit and keep the stones wet. I would use water. Increasing pressure won't make the diamonds cut faster (same thing when sharpening) but will destroy the hone.
It can be done but not within minutes.
 
Thank you Papilio! Since ceramic is so hard, can I destroy the diamond plate? Will it be cheaper just to buy a new ceramic stone?

Does somebody have a knowledge about the process of the ceramic stone making, what do they do at a factory? Is the surface grit comes ready after the baking process or the stones are machined after baking is done?

When looking at a finished sintered ceramic product designed for another use other then sharpening (like electric insulators or heating protective tubes) the surface of the parts feels very abrasive. Can diamond machining at DYI settings provide the same abrasive properties as factory made stones and rods?
 
You can wear out a diamond plate. The better ones will survive this procedure most likely. The cheap ones are ready for the bin after you use them for that purpose. It could be wise to buy another rod instead of destroying an expensive diamond plate. Depends on the condition of the diamond hone.
Spyderco UF is machined to a finer grit (it is the same stone as the Fine).
Not all ceramics are the same quality. A.G. Russell talked about ceramics on his YouTube channel. In one of this videos he talks about the quality of different ceramics (don't know which video it was exactly). Maybe that helps.



 
Ceramic rods seem to run the gamut, in terms of quality. Sometimes the inexpensive ones can be pretty good - but many of them can also be almost unusable in their 'as finished' condition. They can be either too bumpy or irregular on the surface, or they don't cut the steel as cleanly, with persistent burring issues and running into a 'wall' in terms of how refined they can make an edge.

And some 'ceramic' rods are actually just a metal rod with a ceramic coating. I have at least one old v-crock setup with rods like that. Over time, the coating comes off and reveals shiny metal underneath.

If it were me, I'd likely not bother working too hard to refinish them. Some rods that start out kind of questionable in their performance might eventually break-in and settle into something better with use, kind of like many sharpening stones. I have at least a couple of them like that - I hated them early on, but they seemed to find their 'niche' after some time and became more worthwhile. I've occasionally used a diamond hone to knock down irregular bumps on them, but haven't found it worthwhile to attempt complete refinishing with a diamond hone - I have tried that a few times, and almost always ended up regretting it, as they finish out in a condition much less agressive than I'd hoped for.
 
Sintering is a process of binderless fusion where granular material is heated and subjected to enormous pressure to cause those grains to fuse into a solid, essentially like artificial sedimentary stone. Usually the ceramic grains are of varied size to assist in their clinging and fusing to one another, but average very fine, at around 3µm and not in excess of 14µm. Most sintered ceramics are sold in the as-pressed state because finish machining them is VERY slow and expensive. Sintered ceramics behave, generally, more like a file than they do something like sandpaper, and changes in the surface finish have a huge impact on how they cut. Diamond will cut sintered aluminum oxide or silicon carbide but will have a very difficult time of it, since cut speed is greatly impacted by how large of a difference in hardness there is between the abrasive and medium, and the gap between the two in this case is much smaller than it is for most things being abraded.
 
Interesting topic. I had noticed that a couple ofmy Spyderco gray colored stones had some rough spots on their corners. I took out a Dia-Sharp medium 6" plate and wet both the rod and the plate and slowly ran the plate over the edge. It worked! No apparent damage to either the rods or the plates, although you can see where the gray ceramic left some color on the plate. A wet 3M maroon Scotch Brite pad and Ajax seemed to remove most of the ceramic media from the plate
 
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