Removing large particles from DMT / Atoma plates?

[croyleje]

Hello I recently purchased some new DMT and Atoma plates to replace a couple that had basically worn out. However out of the 6 plates all but one of them leaves an odd scratch that is well beyond the grit rating. I have had to break in plates before and I have even found an odd grit in DMT plates by running my hand over them but these new plates I can’t feel anything. I can angle the the plates to avoid the area but would prefer a more consistent fix. I also saw that one plate maker supplies a piece of hardened steel to break there plates in with has anyone tried that? Well if anyone else has had this issue ideas would be welcomed and hope everyone is doing well.

Jason

 

[*stefan*]

Yes I had this issue on one out of 2 dia-flat DMT bought used from an auction site.
The plates were hardly used at all.

One really scratchy.
I noticed that in the scratchy end there was a point that collected JNAT slurry when lapping so thought that might be the issue.

Put the plate on the floor, looked with a loupe and took a small screwdriver for glasses and put some force on this spot.

Back to lapping but still scratchy and collecting JNAT slurry at the same location.

Repeated 4-5 times, rather heavy force. Last time the screwdriver slipped after a while and I scratched the plate perhaps 5 cm( 2 inches). but this was with the corner with the pictured very small screwdriver. So that was no issue ( hardly any area to count really on this large plate). Could not see that I made a scratch.

Then there was no JNAT slurry collection and no scratching any longer.

The 95 micron plate dia-flat ( smaller particle than 120 micron) seems to contain a mix of small but also the same size particle as the 120 micron dia-flat plate.

Love them both and use them a lot. Think the 95 micron is faster, don't know why, smaller particle in mix with probably 120 micron particles. Both is fast thought.

The first DMT dia-flat I bought was also scratching heavily and I sent it back and got a new one.
This one is almost worn out. Used it a lot for many years.

Because of the large size it is possible to use it with wet /dry sanding paper for lapping.

 

[H Brad Boonshaft]

Yea, totally normal, a few high diamonds. Sharpening a couple large kitchen knives will dislodge any high diamonds or swarf.

I have an old cleaver that I use to burnish hard stones, that will knock off any high grit, followed by lapping a 1k stone or a few laps on a hard ark for smoothness.

Clean old plates with Barkeepers Friend make a paste on a wet plate covering the whole plate and let sit 10-15 minutes. Then scrub with a stiff brush, a nylon stripping or fingernail brush.

Barkeepers is Oxalic Acid and will clean off most imbedded swarf and rust. It will also revive a tired (swarf loaded) plate, some of my plates are over 10 years old.

I give my diamond plates a Barkeeper’s soak and scrubbing every 6 months or so.

 

[Gamma]

I get new diamond plates fairly often. These days I just lap with them and if I need to dress the stone with w/d afterwards that's what I do. After a few lapping sessions the plate's surface evens out. Final finish lapping is always done with an old worn plate or 500x w/d anyway - usually. I only use the new plates to start things off. Not a fan or believer in forced break-in methods.

 

[croyleje]

Thanks everyone for the information it's been years since the last time I bought plates and I don't remember having to do this but I wasn't flattening stones then either so probably never noticed like I do now again thank you everyone it is truly appreciated.

 

[Slash McCoy]

I don't use DMT very much. I have a F plate somewhere and a credit card hone too, but no idea what they are buried under. When I want the furious aggression of a diamond plate, I use the cheapo set from Harbor Freight. They are not super flat but they can strip away unwanted steel in a hurry.

BUT, there are two equally good approaches to treating a new DMT. One is as @H Brad Boonshaft suggests, honing a big heavy straight SS edge on it to knock the proud diamonds loose. The other equally valid method is as @Gamma describes, to just do nothing, and just let it break in naturally on those blades that need a lot of heavy work done and not so much finesse, and eventually it will wear itself in. Once it is work slickened it will treat a razor's bevel or a knife's bevel with firm kindness.

A good quality diamond plate has one thing, an unchanging thing, going for it. If it is flat to begin with, it will always be reasonably flat. It can only dish just so much, on the order of a couple of microns I guess.

Like I say, I personally am not a fan and don't use them. But if you understand them, they can be useful.