Lesson Learned

Well today I put my knife on my DMT 1200 and I'd swear it left scratch marks .

I don't understand why as it's a stinking diamond plate! It's not like I took the knife to a Norton, but I guess even with a DMT, it's not a good idea to use a knife on the same hone you use for a razor?

That is interesting. Very interesting. Since a honing medium, by its very definition, should be harder than what it hones, one would think that not possible. How severe are the scratches? Can you feel them with a fingernail?

I will try the same thing with my 1.2K DMT.

I can't feel them with a fingernail, but when the hone is wet with clean water, there are shiny spots where the blade was run in an arc (curved knife). It still seems to be able to remove a ton of material though, and I ran a razor across it and it's working okay. I'm mostly concerned that there isn't any diamond in those shiny spots (i.e. just nickel left) and that it might lead to uneven hone wear on blades as they are honed.

I noticed somewhat similar lines when lapping my 12k on my D8X (220 grit). It still works like a charm for lapping duties though . I don't run my hones dry, but I'm starting to think these DMT's may be a bit more fragile than one might think.

I decided to get one of those "pocket" dmt's for knives. Amazon had a set of 3 for 20 bucks. Sure they are smaller, but I can live with that, knives don't demand what razors do.

Well here's a thought, how do they adhere the diamond to the rest of the plate?

gollum83 said:

Well here's a thought, how do they adhere the diamond to the rest of the plate?

Click to expand...

It's my understanding that it is embedded in the nickel. Whether it's adhesive or added when the nickel is still hot is something that I'm not sure of.

SavantStrike said:

Well today I put my knife on my DMT 1200 and I'd swear it left scratch marks .

I don't understand why as it's a stinking diamond plate! It's not like I took the knife to a Norton, but I guess even with a DMT, it's not a good idea to use a knife on the same hone you use for a razor?

Click to expand...

The red 600 mesh DMT in my avatar has seen heavy use on both knives and razors; on knives for 22 years plus. I have a 1200 with almost as much use on it.

They still work and look fine. If your diamonds are popping off, I suspect one of two possibilities:

• too much pressure.
• defective plate.

I have tested a 325 and it is easy to scratch up if you use too much pressure; especially with a small, hard, pointed tool.

I haven't had any problems using the same DMTs on knives, woodworking tools, and razors; yet.

SavantStrike said:

It's my understanding that it is embedded in the nickel. Whether it's adhesive or added when the nickel is still hot is something that I'm not sure of.

Click to expand...

Well it would be interesting to know how the plate is manufactured. It could be the weak link. I have work with diamond films before, and they can be quite brittle along the grain boundaries separating individual crystals.

Sticky said:

The red 600 mesh DMT in my avatar has seen heavy use on both knives and razors; on knives for 22 years plus. I have a 1200 with almost as much use on it.

They still work and look fine. If your diamonds are popping off, I suspect one of two possibilities:

• too much pressure.
• defective plate.

I have tested a 325 and it is easy to scratch up if you use too much pressure; especially with a small, hard, pointed tool.

I haven't had any problems using the same DMTs on knives, woodworking tools, and razors; yet.

Click to expand...

I was afraid of that.

If it still seems to do a good job on a razor, I guess that means it's good enough right?

I'm going to get the 20 dollar mini and just use that for knives. I have done no such damage with a razor. I use very little pressure when doing a razor, when I do the knives it's a different story I guess.

It's kinda' easy to use too much pressure with a knife when you get to the belly, since only a small part of the knife's edge is then bearing on the hone at one time. That's why, for most knife honers, the belly will get sharp before (or after) the straight part of the edge does. Often a small modification in technique will sort it out.

.....

Have you tried cleaning the dmt? Use a powdered cleaner like borax? Or is it Comet...??? I use barkeeper's friend. Anyway, it should come off and the shinyness should go away.

leighton said:

.....

Have you tried cleaning the dmt? Use a powdered cleaner like borax? Or is it Comet...??? I use barkeeper's friend. Anyway, it should come off and the shinyness should go away.

Click to expand...

I usually just rub the DMT with my fingers under water and the swarf will come up after a minute or so. I did this yesterday and most of the shinyness went away, but a small amount of it is still there. I suppose I may have not gotten it completely clean, or there are small indeed patches of diamond missing.

There is still a lot of hone left in it and I expect it to outlast me if I keep taking care of it. I don't think I'll be putting any more knives on it though. I just don't sharpen that many knives that it's too much of a hassle to use a small portable DMT to do the knives with and keep the D8E for just razors.

I think Shiny nailed it on the head though. The belly of the blade made too much contact with too much pressure vs the rest of the knife. Of course this was the first time I even tried to sharpen a knife.

The plate had little scratches on it coming straight from the factory. DMT's aren't 100 percent perfect, just 98 percent. I don't believe any DMT has a completely uniform surface even when brand new, but they have enough surface area that small patches with less abrasive on them will not affect the outcome.

Try cleaning it with the powdered abrasive and a scotch pad.