Flattening coarse stones

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captaincaed

captaincaed

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Hey sharpeners,
I’m wondering about how people efficiently flatten coarse synthetic stones. I have a big pink brick that always seems to need flattening. I typically use JKI diamond plate to flatten most stones. However, it doesn’t seem to play well with the pink brick. It cuts slowly, and gets worn out pretty quickly.

I’ve heard about using float glass or granite plus sand paper along with either silicon carbide powder or lapidary diamond can also be efficient.

Is this a good route to go? If so, what’s a good resource for these powders? I have no sense of what the price should even be, but I’ve heard it’s not too expensive.

Cheers
CC
 
if you can swing a nanohone plate, theyre worth it.

I have a dedicated Atoma 140 that has managed to keep its teeth because I dont use it on knives and it suffices. When it quits being effective Im just going to shell out for a nanohone.
 
captaincaed said:
Are you talking along the lines of the NL-5 or NL-10? Pricey! But if they’re super robust, maybe…
https://nanohone.com/collections/lapping-plates
Click to expand...

them's the ones, though I think you want to look at the 4 for coarse stones.

Forty has spoken highly of them and that alone is enough for me. My Atoma is sufficing but the second I have an excuse Ill probably just shell out for an NL-8 or 10. Theyre pricey, yes, but for me they would be a relatively small investment compared to some of my natural stones and I gotta think it's gonna last multiple times what an Atoma plate will, so from a financial perspective it's probably about break even but you get a lot of usability improvements IMO (there is no way that design is gonna suck down onto a stone, although to be fair an Atoma 140 wont either, but a 1200 sure will)
 
SiC 'oil' stones work exceptionally well, if they haven't got oil in them. Far harder wearing than diamond plates and a tiny fraction of the cost.

This is what I do all heavy-duty lapping with now, then touch up on an atoma.
 
I use 60/90 SiC powder with a SiC flattening stone for rough grid stones. A cheap combination that works well.
 
Loose SiC, 3m pro grade 60 grit sandpaper, nanohone nl-4 (I'm not sure about long term durability. I know it survived lapping a coarse and medium crystolon and fine India AND a pass around on Reddit, for whatever that's worth) or keep using the diamond plate.
 
SiC powder on a tempered piece of glass or a flat glossy floor tile.

It's very cheap. Can't imagine the 200,- nanohone plates beat the 15,- powder container price/effectivity wise.
I got about 250 gram for 15,- euro
knivesandtools.com

The downsides, it's messy compared to a flattening stone and it requires a little more setup.
 
captaincaed said:
Hey sharpeners,
I’m wondering about how people efficiently flatten coarse synthetic stones. I have a big pink brick that always seems to need flattening. I typically use JKI diamond plate to flatten most stones. However, it doesn’t seem to play well with the pink brick. It cuts slowly, and gets worn out pretty quickly.

I’ve heard about using float glass or granite plus sand paper along with either silicon carbide powder or lapidary diamond can also be efficient.

Is this a good route to go? If so, what’s a good resource for these powders? I have no sense of what the price should even be, but I’ve heard it’s not too expensive.

Cheers
CC
Click to expand...

My dealer sells a 1/2 lb. bag of 60 grit Silicon Carbide powder for $8.49 Cdn, roughly $7. U.S. For the average home sharpener, you'll probably have enough to last you a lifetime. In a typical flattening session, you need very little powder,,,, 1/2 teaspoon is often more than enough.

If you want to get into "reference-grade" lapping plates, be aware that some manufacturers specifically state that they should not be used for coarse stones below 500 grit. (see Shapton DGLP). I've got a DGLP, and frankly, I don't see much point at all in going that route for routine flattening/dressing.

For regular use, there's also 60-80 grade wet/dry Silicon Carbide paper, adhered to any flat and non-absorbent substrate. You could use a ceramic floor tile,,, a piece of tempered glass. etc. Use the paper under a steady flow of water if possible,,, and, apply zero pressure to the stone. Let your fingers gently guide the stone loosely in a figure-8 pattern. The stones' own weight will give you the flatness you're looking for.

You can also use grooved flattening plates. I have a large Naniwa 220, and a smaller Norton, and those might be all you need in certain circumstances. Best used under a light but steady water-flow.



1628802001101.png
 
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HumbleHomeCook said:
I am not intending to be flippant or dismissive of the original question, quite the contrary, but I've been warming up to sandpaper for course work over stones. I'm not saying I'm committed yet, but I've been having good initial results and it's just so much easier.
Click to expand...

100% agreed, as long as it's Silicon Carbide wet/dry. It can be a real time-saver, and dirt cheap.
 
cotedupy said:
SiC 'oil' stones work exceptionally well, if they haven't got oil in them. Far harder wearing than diamond plates and a tiny fraction of the cost.

This is what I do all heavy-duty lapping with now, then touch up on an atoma.
Click to expand...

That's a really interesting idea!

M1k3 said:
Loose SiC, 3m pro grade 60 grit sandpaper, nanohone nl-4 (I'm not sure about long term durability. I know it survived lapping a coarse and medium crystolon and fine India AND a pass around on Reddit, for whatever that's worth) or keep using the diamond plate.
Click to expand...

Surviving a passaround is no small feat. If I do decide to go that way, it's a strong endorsement.

Thank you all for the experiences. Sounds like the first stop is sandpaper and powder.
 
captaincaed said:
That's a really interesting idea!
Click to expand...

I have quite a lot of them that have come as part of job lots along with more interesting things, and when they're flat and degreased they're seriously good for it. You could use the 'fine' side to finish the lapping, but I tend to go to a diamond plate to make sure it's properly flat.

It's certainly worth trying if you have one already - less messy and faffy than sandaper or SiC powder.
 
cotedupy said:
SiC 'oil' stones work exceptionally well, if they haven't got oil in them. Far harder wearing than diamond plates and a tiny fraction of the cost.

This is what I do all heavy-duty lapping with now, then touch up on an atoma.
Click to expand...

What type of oil stone would you recommend for lapping other stones with? I've been using my King 300 to lap some of my other stones with. It works but it's tedious work, and there's a lot of slurry to clean up during and after.

Thanks.
 
Grayswandir said:
What type of oil stone would you recommend for lapping other stones with? I've been using my King 300 to lap some of my other stones with. It works but it's tedious work, and there's a lot of slurry to clean up during and after.

Thanks.
Click to expand...

Any old (or new) SiC/Crystolon/Carborundum, as long as it's flat and not impregnated. This kind of affair:

IMG-2351.jpg


(That one at the top back for instance has a load of Coticule dust on it atm. Which I might wash off and add to my slurry cup now that I think about it.)
 
No doubt. Aren't they synthetic diamond stones anyway, from way back when? I've seen some marketed specifically for straight razors. Back in the day it was advertised as a miracle stone (I guess they all were, lots of snake oil being sold in the late 19th century and into the early 20th century).

Thank you.
 
Coarse belt in a 2x72 for anything dished. Beyond that I use loose SiC on a flat surface. Loose SiC will be amongst the cheapest abrasive you’ll buy. You’ll want to start down the route of leather wheels impregnated with grit for glazing like the old Sheffield craftsmen before you know it
 
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