Thread: DMT NEW PROBLEM.

This excerpt is from Craftsman Studio - Blog · Sharpening - Diamond Products (my highlighting)

• Flattening Waterstones: Customers often ask if it is appropriate to use DMT DiaSharp 8” diamond plates to flatten waterstones. On the surface this seems like a good idea, but in practical application, only the DMT Dia-Sharp D8XX 8×3x3/8 in. Diamond Plate is suitable for some waterstones. This is because the diamonds are large enough to create an “air break” between the surfaces of the waterstone and diamond plate so the two don’t stick together due to the surface attraction of the water. It should also be noted that waterstones will quickly remove the nickel holding the diamonds in place on finer DMT plates.

My thought is that the nickel surface on the higher grit DMT's is closer to the waterstones by enough to allow the waterstone's slurry to cut into the nickel. I'm guessing.

Please let us know what the DMT rep says,

So we can't lap our waterstones (naturals I speak of mainly) with the Shapton DGLP, we can't lap our waterstones with the DMT D8E or possibly even the D8C. What CAN we lap our waterstones with?

I sound like one of those infomercials overdramatically shrugging my shoulders with a look of utter despair on my face.

I have had no problems lapping using my D8C or finish lapping with the D8E although overall, I don't lap the naturals that often. The D8XX is a great lapper although the scratches it leaves are unacceptable to me for mid and fine grit stones.

I could see how stones could wreak havoc with the D8EE though. I use a lapped 8"x3" belgian blue if I want a nice smooth surface on my stones.

Chris L

Chris,

Here is the FAQ at the DMT website. See #18 for their recommendation for flattening Japanese waterstones.

When speaking to their rep on sending back a plate that wasn't up to spec for flatness I told him that I used the 325 for waterstones and he didn't say anything at all to discourage that. So far so good with the D8C and GDLP.

Not taking sides or trying to **** anyone off, but I have run into this a number of times the last few months. This may just be this companies’ policy. I can’t find it on any DMT sites.

Extra-Extra Coarse diamond (XX) - (120 micron / 120 mesh) for extreme removal of material and edge repair. They are well suited for flattening conventional and water stones such as those made by King and Norton. Using grits finer than this to flatten waterstones may damage the plate and is not covered by warranty.

Here is where I got this little gem.
DMT Dia-Sharp 8x3x3/8 in. Diamond Plates

I haven't had any problems while using a DMT D8C to lap everything up to 16k, including the hard "white" Spydercos. I'm also careful to avoid much slurry build up. The only thing I've lapped with the E 1200, except for breaking it in, is barber hones.

Thanks guys. The limitations of the DMT hones are now starting to fill in.
Good stuff to know.

On the low grit DMTs I imagine the "peaks" of the diamonds extend far above the hone's surface. This helps to keep whatever it is you are lapping off of the DMT base plate (nickel, did someone say?). Thus you get effective cutting and lapping of the waterstone, and no impact to the DMT plate.

When you get down to a 3um plate, that means the waterstone is very close to the DMT base plate, and as the 3um diamonds cut into the material to be lapped, the material to be lapped (in this case an abrasive hone itself) is busy lapping the nickel on the DMT base plate as well, undercutting the material that is holding the diamonds in place. It will thus errode the material, and the diamonds will be lost.


That's my understanding of the dynamic.

JimmyHAD's link to DMT under #18 does warn about slurry. In a quote from there: "Make sure there is plenty of water to flood the surfaces of the stones when flattening to wash away the slurry made by the flattening process."

Nickel has been a component of many steels for over a hundred years. We use slurry to cut steel... I never allow much slurry to build up while lapping, anyway. More slurry = faster cutting.

Once you think about it, it's easy to see how slurry can cut nickel. When lapping anything that makes much slurry, I'm going to start using a lot more water now.

hi_bud_gl: from your first post, it seems that slurry from your Charnley forest stone was cutting very little of the nickel from the 1200, but a lot from the 8000. Interesting cut-off point.

Good point Steven. FWIW, I use my DMT 325 ....or the GDLP in the kitchen sink with a steady stream of water running on the work. I stop frequently to clear the slurry. I have used these for months and lap often with no problem. I recently bought a DMT600 grit to further smooth out the hones that I lap with the 325. Both DMTs are holding up fine so far.

I have lapped such toughies as the Swaty and the Charnley Forest as well as the Chinese 12K with no visible or perceptible damage to the 325. I hold the stone in one hand and the plate in the other and do a kind of x pattern frequently flipping the stone end for end to try and keep the pressure even.

Originally Posted by Sticky

hi_bud_gl: from your first post, it seems that slurry from your Charnley forest stone was cutting very little of the nickel from the 1200, but a lot from the 8000. Interesting cut-off point.

when i use 325 and 1200 slurry was coming out from charnley but when i go 8000 slurry changed to black color =this was dmt's color not charnley's slurry.i mean now slurry was coming out from dmt odd