Thread: DMT Issues

Just received all my hones in the mail yesterday and excitedly got to lapping them. I got a DMT 8E (1200), a Norton 4/8, and a C12k. Started out by running a few kitchen knives over the DMT to start breaking it in., then went to the C12k, figuring if the DMT wasn't completely broken in yet, a nice hard stone would help bridge the gap. It was SLOW work. The 1200 is a pretty slow cutter for stones as warped as all of mine turned out to be.

Once I finished up lapping everything beveled all the edges I started honing. I noticed I was getting a lot of drag on the edges of my DMT. Part of it was likely technique, but I suspect there was more at play. Now I didn't bevel the edges on the DMT. Is that even possible? What would I do it with? And now I'm reading the post from JimmyHAD that the DMT isn't necessarily perfectly flat. Are my hones likely not flat now too?

Originally Posted by kenneyty

Just received all my hones in the mail yesterday and excitedly got to lapping them. I got a DMT 8E (1200), a Norton 4/8, and a C12k. Started out by running a few kitchen knives over the DMT to start breaking it in., then went to the C12k, figuring if the DMT wasn't completely broken in yet, a nice hard stone would help bridge the gap. It was SLOW work. The 1200 is a pretty slow cutter for stones as warped as all of mine turned out to be.

Once I finished up lapping everything beveled all the edges I started honing. I noticed I was getting a lot of drag on the edges of my DMT. Part of it was likely technique, but I suspect there was more at play. Now I didn't bevel the edges on the DMT. Is that even possible? What would I do it with? And now I'm reading the post from JimmyHAD that the DMT isn't necessarily perfectly flat. Are my hones likely not flat now too?

Yeah, the DMT's have kind of a raspy feel to them when you're honing. It does get better when they are very broken in, yet even then they aren't really as smooth as say a shapton or a BBW/coticule. You can't really bevel the edge of a DMT, but you can break it in more than the rest of the surface. I took the skinny edge of my Chinese12k, and *really* went after the outside 1/2 inch of the DMT edges. So much so, that there is no longer any nickel/diamond left at all at the very edges.

Even if your DMT isn't *perfectly* flat, chances are it's certainly flat enough for honing and lapping.

The surface of a new DMT looks very dull and grey (obvsiously )... if you start seeing a change in the surface (if it looks like it has lighter spots in it), you are starting to wear through the nickel plating that contains the diamonds. The reason I mention this is that DMT doesn't recommend using anything finer than their DMT C rated plates for lapping. The abrasives in the stones you're lapping can/do remove the nickel/diamond plating on the DMT. So if you start seeing lighter spots in the surface of your DMT, you're getting close to the wear limit of the nickel.

I started using a couple of drops of dish soap on the water when I use a DMT for honing. It really does help get rid of that raspy feel on mine.

I did return two diamond plates to DMT. According to my high end machinist's straight edge they weren't 100% flat. They agreed with me on my 325 and replaced it. They didn't agree with me on my 1200 and they sent it back to me.

I didn't agree so I took my 1200 to a friend who is a 30 year pro machinist. He looked at it with the straight edge and said that he was amazed at how flat that it was and that for his money he couldn't imagine something being made flatter then that. So I guess this flatness thing is relative.

DMT recommends the DMT X for lapping water stones. They told me that if you already have a D8C go ahead and use it but only under running water in the sink. Any DMT finer then that is not recommended for lapping .

Edit; Since my friend looked at it I have used the 1200 a bunch and it is doing a fine job.

I currently have 11 DMTs in various grits. Mine have all passed the straightedge test and seem to work ok. Defects do happen though, if in doubt try a straightedge or surface plate with indicator.

I also use a drop of dish soap with water on the DMT D8E when using that on the rare occasion that I need that type of aggressive abrasive to set a bevel on a razor. Even broken in, the D8E compared to other peaceful stones like the Shapton 1k, feels like I'm honing on a sidewalk with a dentist drill in my mouth. It sounds so harsh that I can't believe the edge isn't trashed when I'm done. But, when I need to use it, it has worked for me so far.

Chris L

Originally Posted by kenneyty

Once I finished up lapping everything

Did you use the DMT8E to lap the Norton 4/8K? It is risky, you can strip off the nickel plating that holds the diamonds onto the DMT. I made that mistake, I think I got away with it but the DMT is broken in now.

Originally Posted by Sticky

Defects do happen though

Also mailmen sometimes treat "Do not bend" as a challenge...

Originally Posted by Rajagra

Also mailmen sometimes treat "Do not bend" as a challenge...

ROFL. Looks like the UK has imported some US postal workers over there...

DARN THIS POSTAL WORKER BEND DMT I CAN'T believe this .I always thought usps is the worse i think i made mistake uk postal carrier is in same level

if i would you i take that dmt to post office and ask Please show to you how they did it?Must use some machines

I've now heard several comments that it's risky to use the 8E to lap, which I find pretty frustrating because the only reason I bought it was that I was instructed by several people in chat that I should buy it for that specific reason.

I'll have to post some pics tonight- there's some color variation on the DMT now- grey in the middle, a few patches of silver on the outside edges- even a couple of rusty spots from leaving it in water too long.
*sigh*

Originally Posted by kenneyty

even a couple of rusty spots from leaving it in water too long.
*sigh*

Do you mean having water on the surface too long or do you mean you were soaking your DMT?

Chris L