My CNAT Lapping Journey

So I finally got my hands on that CNAT. In a decent shape, but there are a few saw marks left on each side.

Attachment 264437

And oh boy does this thing not soak water!

Attachment 264438

Using the roughest wet or dry sandpaper I could get (400), I got to work. This thing takes forever to lap!
Attachment 264439
Attachment 264440

Obviously, I couldn't let all that nice slurry go to waste, so I tried sharpening two knives. The first one was already sharp (with my trusty Lansky 1000 ceramic hone) and the polishing from this hone made it a bit better. My wife was happy about that.
I also tried sharpening another knife 'from scratch', and the resulting edge is nothing to write home about - so that goes along the lines of what we know about those hones.

So, at the end of the day, I had a smooth sandpaper and my hone still had rough spots on <5% of its surface.
Score: CNAT: 1, Me: 0

On day 2, I tried a different strategy: a 120/320 hone that is almost the same size.
Attachment 264441

On the plus side, the rough spots are almost all gone and it worked faster. On the minus side, I got some extra scratches on the hone.
Score: CNAT: 2, Me: 0

I'm expecting that stone will be done lapping on its next encounter with the sandpaper.

In other observations: the stone dries fast, even after 30 minutes soaking. And its mud doesn't dissolve in water easily. In fact, I could dip the hone with some mud on it and most of that mud will be left on the hone. And the bucket that hosted the hone and its watered down mud still has marks that don't leave with a brushing and some soap.

The mud/slurry made with sand paper also has grit particulate from the paper. Something to keep in mind.

They are hard little buggers. Hard is good, when polished up it should impart a nice edge.

They can be used as a splash 'n go hone. No need to soak for extended periods of time.

These are fun to play with.

Flatten only one side, Write something clever with a waterproof marker on the back.
Perhaps the date and what it is. Just not a grit number.

Find a scrap of mild steel to worry the surface with. You can take a cut off of bar steel
or square tube steel and common sand to speed the surface tidy process.
I wore out a bit of wet sidewalk to get mine flat enough for a visit to sandpaper then a DMT.
Not many are fine enough to shave off but as you discovered they are nice for
touching up a lot of kitchen knives.

They also make nice "stands" for other hones to get them up off the counter.
Use some newspaper as the first layer to catch the grit then the CNAT then a no slip mat and
then your favorite hone. Damp newsprint paper is non slip catches water and grit.
Do watch out for ink transfer to a fancy countertop that we do not want grit from
honing to scratch.

have fun.

Yes! That's what I use mine for. A stand.

My cnat is the reason I bought a DMT. Went through quite a few sheets of sandpaper before i ordered it. The DMT was well broken in by the time I was done lapping.

A 60-grit belt for a belt sander, if you have a hand held, chuck it in a vice upside down, rig a vacuum to catch most of the dust and wear a respirator, and a fan blowing away from your face.

This is the fastest way and will leave a smooth surface, but will trash the belt. Let the belt do the work and use light pressure. Use a straight edge and measure the thickness to create a flat, surface parallel to the other side.

Or 60 grit Silicone Carbide, a steel cookie sheet from the dollar store and a flat piece of cement, (garage floor) will get you flat in 20 minutes or less. Mark a grid with a sharpie and use your body weight. GOTGRIT.com will have all the grits from 60-500, ($15) then go to Wet and Dry once flat.

Stay on the 60 grit, adding a half teaspoon at a time with a squirt of water. The cookie sheet will contain the mess.

Do not use a diamond plate, you will trash it.

Many $50 + diamond plates have been trashed trying to flatten those $20 stones!

Quote:

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Originally Posted by kelbro

Many $50 + diamond plates have been trashed trying to flatten those $20 stones!

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It was an Arkie that did my DMT in. The Cnat just broke it in. Glad I don't have to fiddle with either of them anymore. They'll be flat for a good long while.

From what I see you got e really good and hard one. Properly prepared it should provide a great high grit polishing surface. Euclid has presented to you just what you need to make it really flat, then you will need to burnish it. Ideally prepare two surfaces, one burnished, that will serve as your final water only surface, and one that is a bit rougher, as you would use slurry in it, and/or finish knifes in it. Never slurry on the burnished side. My VG10 and Aus 10 japanese kitchen knifes too, in addition to my razors, love the cnat. I know many people love to trash these stones....and yes, there are quite a bit of bad ones around, but the harder ones,found at times, if you look, at Woodcraft stores..... prepared right, are a treasure. My cnat is now part of my Escher/Thuri sequence. From 8k synth or coticule, I go to a Escher 11k, Vintage Thuri 12-13k, then to CNAT, then to an Escher 13k. The Cnat pushes the edge much higher to a 14-15 k....than any of the thuris/eschers, but while smooth, is a bit agresive, so going back to Escher gives a very smooooth, and very sharp, close to my Nakayama Asagi 5 sharpness level. Prior to using my well prepared CNAT, using thuris/esher edges after using nakayama, ozuku asagi edges you felt you were missing a bit in sharpness on some Fridour/inox/ice or swedish steel razors. On old carbon steel thuris do fine, no need for anything else. The cnat has made my thuris on all blades luxurious.....as now you truly appreciate their smooth profile without missing at all on sharpness.

Quote:

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Originally Posted by fxt913

From what I see you got e really good and hard one. Properly prepared it should provide a great high grit polishing surface. Euclid has presented to you just what you need to make it really flat, then you will need to burnish it. Ideally prepare two surfaces, one burnished, that will serve as your final water only surface, and one that is a bit rougher, as you would use slurry in it, and/or finish knifes in it. Never slurry on the burnished side.

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Just making sure I got this right... Here's how I'd accomplish that. (I'm tempted to go for Euclid's suggestion, but I will try to do with what I have right now)
For finishing the 'slurry' side, I just keep rubbing with the 400 side sandpaper until even.
For finishing the 'burnished' side, I rub with the 400 side sandpaper until even. Then use my small 600 and then 1000 diamond hones (but not much, so that I don't un-flatten it). Then rub with the flat part of a chisel.
And use a permanent marker on a rough side to indicate which side is which one :)

Quote:

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Originally Posted by malaverdiere

Just making sure I got this right... Here's how I'd accomplish that. (I'm tempted to go for Euclid's suggestion, but I will try to do with what I have right now)
For finishing the 'slurry' side, I just keep rubbing with the 400 side sandpaper until even.
For finishing the 'burnished' side, I rub with the 400 side sandpaper until even. Then use my small 600 and then 1000 diamond hones (but not much, so that I don't un-flatten it). Then rub with the flat part of a chisel.
And use a permanent marker on a rough side to indicate which side is which one :)

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Just need the 600 and 1K enough to get rid of the 400 grit scratches. But thats pretty much it.

Quote:

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Originally Posted by malaverdiere

Just making sure I got this right... Here's how I'd accomplish that. (I'm tempted to go for Euclid's suggestion, but I will try to do with what I have right now)
For finishing the 'slurry' side, I just keep rubbing with the 400 side sandpaper until even.
For finishing the 'burnished' side, I rub with the 400 side sandpaper until even. Then use my small 600 and then 1000 diamond hones (but not much, so that I don't un-flatten it). Then rub with the flat part of a chisel.
And use a permanent marker on a rough side to indicate which side is which one :)

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I think you got it just right! I would get up to 1K and FLAT on both sides first.... then burnish one side with chisels, a hard nagura used dry, a hard high grit stone dry, and/or my favorite way: hone some chinese cleaver/chef knifes and make them stupid sharp. Then burnish with a hard stone(coticule, hard arkansas, hard carborundum barber hone etc...you get the point). That will do it. The slurry side needs nothing beyong getting it flat up to 1k. The rubing/nagura stone you use will take care of the rest.

Hint: a decent japanese awasedo tomonagura works BEST to finish (before going to water only side), if you got one....as they break down to smaller flakes, and gets the edge to higher grits, otherwise a thuri nagura works well too, and smooths the edge, up to its grit level, whatever that happens to be. The cnat nagura makes the stone behave as a midrange one, 6-8k, as the slurry does not break, but you can use that if midrange work is needed!

And use a permanent marker on a rough side to indicate which side is which one :)[/QUOTE]

No need to put any marker on the honing surface, just put an arrow on the side pointing towards the burnished side. Or just bevel/flatten the corners a bit more on the burnished side for a visual cue.

Quote:

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Originally Posted by fxt913

No need to put any marker on the honing surface, just put an arrow on the side pointing towards the burnished side. Or just bevel/flatten the corners a bit more on the burnished side for a visual cue.

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Good point. I round the edges of the burnished side of my stones. The side I leave a little roughed up just gets an angular bevel.

Quote:

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Originally Posted by fxt913

I think you got it just right! I would get up to 1K and FLAT on both sides first.... then burnish one side with chisels, a hard nagura used dry, a hard high grit stone dry, and/or my favorite way: hone some chinese cleaver/chef knifes and make them stupid sharp. Then burnish with a hard stone(coticule, hard arkansas, hard carborundum barber hone etc...you get the point). That will do it. The slurry side needs nothing beyong getting it flat up to 1k. The rubing/nagura stone you use will take care of the rest.

Hint: a decent japanese awasedo tomonagura works BEST to finish (before going to water only side), if you got one....as they break down to smaller flakes, and gets the edge to higher grits, otherwise a thuri nagura works well too, and smooths the edge, up to its grit level, whatever that happens to be. The cnat nagura makes the stone behave as a midrange one, 6-8k, as the slurry does not break, but you can use that if midrange work is needed!

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That sounds a bit overkill (and expensive, and tempting - but that is another problem).

So I used the sandpaper on a ceramic tile again, and got a nice flat surface.

The I usedy small 600 and 1000 diamond and got lots of scratches. Then I used the back of a small chisel. And there are many scratches left. Did I degrade my lapping job by any chance?

I would have stuck to the sand paper and not used the diamond plates on the stone. At least not on the surface I was intent on burnishing. Diamonds tend to cut fast because they also cut fairly deep. So I might do the initial flattening with a diamond plate, but after that I transition to sand paper and let that do the rest of the work.

Quote:

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Originally Posted by Marshal

I would have stuck to the sand paper and not used the diamond plates on the stone. At least not on the surface I was intent on burnishing. Diamonds tend to cut fast because they also cut fairly deep. So I might do the initial flattening with a diamond plate, but after that I transition to sand paper and let that do the rest of the work.

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So I can go back to the sand paper to remove the scratches. Then I could use my small AlOx hones from the Lansky set (600 and 1000) to finish the burnishing?

I'd hold off on the burnishing for now. If your scratches are relatively small and in the direction of honing, it should still cut finely.

I've had the best luck with those boxes in terms of cnats - it suggests that the stone originated from woodwell tool (mujingfang) and all of the ones I've gotten will not release particles without you wanting to. That's important.

If a cnat gets a little slow, it's fine to use a little pressure on it like you would an ark, it won't hurt an edge. A little means that you're mindful not to flex the razor and alter geometry, but you don't have to let the weight of the razor go back and forth on those stones 500 times.

For anyone else who gets one of the 8x3 stones, if one of the sides is a little high, you can just hit it with a diamond hone until you have a workable patch. If the last 1/2 inch of the edges is low in some areas, it's not a big deal, the stone will finish the same.

Quote:

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Originally Posted by malaverdiere

So I can go back to the sand paper to remove the scratches. Then I could use my small AlOx hones from the Lansky set (600 and 1000) to finish the burnishing?

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If you use sand paper to get it scratch free, going back to the AlOx hones is likely to just scratch it up again rather than burnish it. Typically I'll use sand paper up to 2K grit, then use my Norton 4K and 8K hones. After that if I want a finer surface I'll either polish the stone with CrOx, burnish it with the tomo nagura that came with my Jnat, or find a hard steel tool that I can use to scrub the surface and burnish it even finer. Honestly after the 2K sand paper you can probably skip right to any of the burnishing steps if that's what you're trying to accomplish with your stone, I just have fun playing with them and once they're flat and scratch free the rest of the polishing phases go by pretty quickly.

Quote:

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Originally Posted by Marshal

If you use sand paper to get it scratch free, going back to the AlOx hones is likely to just scratch it up again rather than burnish it. Typically I'll use sand paper up to 2K grit, then use my Norton 4K and 8K hones. After that if I want a finer surface I'll either polish the stone with CrOx, burnish it with the tomo nagura that came with my Jnat, or find a hard steel tool that I can use to scrub the surface and burnish it even finer. Honestly after the 2K sand paper you can probably skip right to any of the burnishing steps if that's what you're trying to accomplish with your stone, I just have fun playing with them and once they're flat and scratch free the rest of the polishing phases go by pretty quickly.

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I understand that your path is optimal, but since I'd like to avoid buying more stuff, I need a suboptimal path :)

So, 400 grit sandpaper to remove the scratches, then what?

I have a variety of handyman tools (including wrenches, screwdrivers, a small chisel, etc.) , a few small AlOx hones from Lansky (70-1000 grit), a few small diamond hones from DMD (320-1000 grit), a large coarse/medium hone, some green compound (particle size unknown), and small strops (balsa and leather on paddle).

If the hones are a no-go, then I suppose my options are to use a big wrench (on the smooth side) and the green compound on the paddle strop. Does that make sense?

Could always try to hones on a side to see if they scratch or polish. Otherwise I'd just go with the wrench and the compound.

So I finally got around to do it.
I flattened my hone. I also did the same the CNAT a little bit to remove the scratches. Here's the set-up.
Attachment 270991

Then I used the 1k Lansky hone and light slurry formed. Then I went to town with the wrench. It was doing an annoying 'eee-eee' sound on every stroke.
My CNAT certainly feels smooth, but not glassy (like I've seen for well-burnished coticules). The result:
Attachment 270992

So my question is: should I move on with the CrOx, or I have more work to do?

I still see some scratches on that stone. Are those from the 1K, or are they left over from something else? Id from the 1K, do you have 2K sandpaper or something similar you could use to work them out? Or better still, did it come with a slurry stone? Those can also be used to work scratches out.

I don't think CrOx on that surface would be very helpful so I'd look to get it a little smoother first. At least scratch-free.

You could also try honing a razor on it to see if you even feel the need to burnish it any further.

I'm not sure those are scratches per se. I guess I have to take pics from a few angles.
That being said, I'm sure there were no scratches from the 1k hone.

One observation. The wrench I used had lots of small grooves - most likely something meant to increase grip. By the time I stopped, most of those on the contact surface were gone - leaving me with a smooth surface - except for a few spots. Perhaps that indicates inadequate flattening?

Obviously 'try honing a razor' is a test I'm trying to postpone, since I never honed one yet :)

I think it's more likely that the wrench wasn't flat. Those bumps are from casting, and on cheaper wrenches aren't cleaned up. You don't see that on pricey wrenches like snap on, Mac, and Matco. It's to save money on production, not increase your grip, so you can probably imagine how flat the wrench is.

When I used a wrench to burnish, I used the polished surface they stamped the company name and size into. But I guess technically any surface of the tool will do the job as the idea at this phase is to knock down any high spots and reduce cutting speed in favor of a finer finish.

I guess if those aren't scratches you can move on to CrOx and see what you get.

Quote:

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Originally Posted by malaverdiere

So I finally got around to do it.
I flattened my hone. I also did the same the CNAT a little bit to remove the scratches. Here's the set-up.

Then I used the 1k Lansky hone and light slurry formed. Then I went to town with the wrench. It was doing an annoying 'eee-eee' sound on every stroke.
My CNAT certainly feels smooth, but not glassy (like I've seen for well-burnished coticules). The result:


So my question is: should I move on with the CrOx, or I have more work to do?

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Some CNATs will never get glassy.

Just worry it with some 'flat steel' The deep scratches that you might see that run the length
of the rock are a do not care as long as the bulk of the surface is flat and burnished.

If you have lucked into a good CNAT that works as a good finisher do not be too concerned
if it dishes even as much as a dime. In my opinion a finisher with a light touch is allowed
to produce a micro bevel in its own way. Keep your bit of steel handy to worry and burnish the
hone flat where the razor does not so it never dishes more than a dime (or less).

CrOx burnished on the surface might help. It is unlikely to hurt. If all else fails try
vaseline and allow swarf to build up from your burnishing steel.

Finishers are a mystery.... if you have one you like KEEP it.

I have a small block of CNAT that I have been using to clean my Nanawa 4k and 12k hones.
It is picking up a polish. If you have a modern fine hone wipe any fine slurry onto the
CNAT and worry it with sacrificial steel and see what happens.