About ready to spring for the Spyderco ceramic stones...

[arnman]

Please be sure to report back about the Spydercos after using them for awhile. 

I will follow up after using a few times.  But first I have to say that I was all ready to start flattening them when my silicon carbide grit arrived in the mail.  I was convinced by someone else to call Spyderco to get their recommendations first.  Spyderco said you can send it in and they will take a look at it.  Of course, I have to pay shipping both ways.

I decided to go that route.  I am up to my neck in other projects right now, but I am very anxious to try them.

[arnman]

The Spyderco medium is very flat.  It seems to be dished 0.0015 in the center.  I could not fit the 0.0015 under the rule anywhere else on the stone.  I don't know if I can make it flatter than this.


The Ultra Fine is not as flat.  It is dished in the center.  I can barely fit a 0.003 guage under the rule, and there is resistance when I try to drag the guage.  That is not bad, but I think it should probably be better.  The other side was much worse - with a dip on one end.  I was able to fit a 0.006 guage under the rule.

I just got a call from Spyderco.  They claim both stones are within their tolerance.  For the medium, I am not surprised.  I think the UF is pushing the envelope.  They did offer to swap the UF with their "goldenstone" which is machined flat - but it has kind of a funny shape that I don't think would work best for my needs.

I decided to have them ship my stones back, and I will try to lap them if I feel it is necessary.  He could not offer any suggestions for lapping them flat.  In hindsight, I wish I had asked him what they use to machine their goldenstone flat.

[Mike Brady]

I just got a call from Spyderco.  They claim both stones are within their tolerance.  For the medium, I am not surprised.  I think the UF is pushing the envelope.  They did offer to swap the UF with their "goldenstone" which is machined flat - but it has kind of a funny shape that I don't think would work best for my needs.

I decided to have them ship my stones back, and I will try to lap them if I feel it is necessary.  He could not offer any suggestions for lapping them flat.  In hindsight, I wish I had asked him what they use to machine their goldenstone flat.

One thing I don't recall reading here is that Spyderco is a knife blade maker.  If you know their knives the machining is excellent and the price is high.  Coors makes those Spyderco stones for them in their labaratory/medical vessel production facility and the Spyderco and Coors facilities are on the same street in Golden.  The point is they don't need flat for their applications and don't need to make their stones flat.  That is up to you.  Did you happen to ask them about how to lap the ceramic?

[arnman]

I did ask them how to lap them, and also what their tolerances were. He said he did not have any knowledge of either one. I did not want to force the issue on either question.

[wch]

I just got a call from Spyderco.  They claim both stones are within their tolerance.  For the medium, I am not surprised.  I think the UF is pushing the envelope.  They did offer to swap the UF with their "goldenstone" which is machined flat - but it has kind of a funny shape that I don't think would work best for my needs.

I decided to have them ship my stones back, and I will try to lap them if I feel it is necessary.  He could not offer any suggestions for lapping them flat.  In hindsight, I wish I had asked him what they use to machine their goldenstone flat.

I have successfully used the three-plate method to make a set of three bricks that have very, very flat faces -- flat enough that no light will pass between a good straightedge and each brick. I know that I can see light in gaps that are smaller than .001 inch (as tested by a feeler gauge) so I'm certain that the flatness is better than .001 inch over the face of each brick. This is flatter than the diamond plate that I happen to own.

To summarize, if you have three "plates" numbered 1, 2, and 3, you lap 1 against 2, then 1 against 3, then 2 against 3, and repeat, until they are flat enough to meet your standard -- and it will eventually get there, without any special skill. I used 90-grit silicon carbide powder and soapy water as the abrasive. If you only lap two plates together, you can end up with a cylindrical or spherical surface, because those shapes can fit together perfectly. However, if you lap three plates together in rotation, then the only set of shapes that will fit together is three flat planes.

I learned of this method from this PDF on sharpening, translated from German (page 40): https://www.fine-tools.com/sharpening-ch...lades.html.

I know you only have two of the Spyderco ceramic stones. You would have to find a third "plate" to use. I suspect you'll have a hard time finding something as hard as the ceramic stones, but the same logic holds even if the third plate is a different material: the only shapes that will fit together are three planes, so I suspect that even if you use a different material, at worst it will take longer to achieve your desired flatness. (Note that I'm not an expert on this, though!) It took me about 30 minutes to do it with the bricks, which are probably much softer than the Spyderco's, but I'm certain they were also much less flat.

[arnman]

the three-plate method....  

That is an interesting technique.  I was planning to use glass plate.  I think I have 3/8 thick plates.  First I will try just using ceramic against glass, with the silicon carbide.

[Mike Brady]

No report yet of the Spyderco ceramic stone outcome?

[Axehandle]

My Spy ceramic stones were all dished too. I cleaned them up a bit with a diamond stone but they are still a tad dished. No big deal really.

Just expect it.

[Mike Brady]

My Spy ceramic stones were all dished too. I cleaned them up a bit with a diamond stone but they are still a tad dished. No big deal really.

Just expect it.

My reason for posting after the thread had been dormant for a month was to remind the OP that three pages of responses were devoted to his quest for Spyderco stones, and then....crickets....Where's the last chapter of the book?

This is some of the reason you see maybe a half dozen live topics on this forum on any given day.

Here are my questions:
How did the flattening go?  How much difference is their between the grades of stones that he got?  Do they work on A-2 steel?  Do they take any maintenance?  Do they replace any stones he already has or is the stack of stones just getting taller?

[arnman]

My reason for posting after the thread had been dormant for a month was to remind the OP that three pages of responses were devoted to his quest for Spyderco stones, and then....crickets....Where's the last chapter of the book?

This is some of the reason you see maybe a half dozen live topics on this forum on any given day.

Here are my questions:
How did the flattening go?  How much difference is their between the grades of stones that he got?  Do they work on A-2 steel?  Do they take any maintenance?  Do they replace any stones he already has or is the stack of stones just getting taller?

I just typed up a long post and hit Post, and it disappeared!  I will try to follow up soon.