Scratches when using DMT 325 as lapping stone

At the advice of a very well respected source, I ordered a DMT 325 to lap my shapton 16K. It arrived a few days ago, and today (well, yesterday, technically) was the first time I cad a chance to actually use it. It certainly seemed to lap just fine, but it left a bunch of scratches and gouges in the Shapton, a couple of them deep enough to feel with the edge of my fingernail; I can't imagine that to be good for honing. Has anyone else had a similar experience? Am I doing something wrong?

Here are some picks, I rubbed pencil graphite over the scratches to make them more visible:Attachment 264568

Attachment 264569

Before using a DMT325 to lap any hone, you should take a large screwdriver shank and run it vigorously across the plate to knock down any loose diamond bits. Once I did this procedure, I had no issues lapping my Naniwa Super Stones. However, I did run into some scratch issues a few weeks ago and had to redo this procedure again.

Too bad the Shapton DGLP costs nearly $400, but that is the lapping plate I would use if I had the coin for Shaptons. :shrug:

That is super helpful, thank you!

I have abused the hell out of my dmt and there's stil one dang diamond scratching my hones.

Doesn't affect the edge, a good phrase I stole from someone; "Think of it as negative honing space, it's below the surface where the blade is riding."

If the screw driver does not work use some smooth concrete like in a basement.

Screw driver shank, hone a chisel or something similarly hard. Lapping a hard natural a bit can help too.

I was never happy with the scratches left behind by the DMT though. I know it's supposed to just be 'negative space' and not effect how they hone, but it bugs me all the same. So I typically wind up chasing the DMT with sand paper up to 1 or 2K depending on the stone, and I use my Naniwa red brick to refresh the honing surface when it gets clogged with swarf. No scratches, I'm a much happier camper.

Quote:

---

Originally Posted by Marshal

Screw driver shank, hone a chisel or something similarly hard. Lapping a hard natural a bit can help too.

I was never happy with the scratches left behind by the DMT though. I know it's supposed to just be 'negative space' and not effect how they hone, but it bugs me all the same. So I typically wind up chasing the DMT with sand paper up to 1 or 2K depending on the stone, and I use my Naniwa red brick to refresh the honing surface when it gets clogged with swarf. No scratches, I'm a much happier camper.

---

I agree, as far as my naturals are concerned, particularly the slow and harder ones, need all the space I can get. Coticules just look better with a nice smooth surface, plus gouging out garnets gives me the willies

For synthetics, it bothers me a little, but i try to ignore it in favor of laziness

I usually use my well used 850 Smiths diamond hone after the 320 to take out the scratches, 1000 grit wet/dry on a hard surface would probably work as well

Thanks for all the suggestions! I sharpened on of my "rough work" knives on the DMT, then hit the Shapton again, and the result were much improved. I also adjusted the lapping technique a bit, favoring a very small lapping movement, and just letting the weight of the Shapton rest on the DMT, rather than pressing at all, which I think helped. It's a lot less aggressive, and probably will take a lot longer when I'm doing an actual flattening, but I guess that's the price I pay for getting a $50 not-really-a-lapping-plate rather than popping $400 for the actual Shapton plate. I can live with that.

“but I guess that's the price I pay for getting a $50 not-really-a-lapping-plate rather than popping $400 for the actual Shapton plate. I can live with that.”


No, you don’t need a $400 plate to lap a stone, most any flat diamond plate will work.

They all, even Atoma’s can use some smoothing out, sharpen a couple of knives, or bevel the edges of a stone or two to knock off any high diamonds, usually the edges.

I would not worry about your stone it will flatten out with time and refreshing. You can finish lap them with other lower grit stones.

Unless you are honing 'professionally', you won't need to lap a Shapton very often. They do not require any pressure to do their magic and they are pretty hard.