Thread: Are DMT stones supose to be "flat"?

I would guess that would depend on the stones. I flattened and cleaned my naniwa hones several times with my DMT325 then made the decision to flatten and take the chip out of my swaty. That was a mistake on my part. the swaty was hard and the chip was too deep. now the chip is gone and DMT is wore out.

Originally Posted by rhensley

I would guess that would depend on the stones. I flattened and cleaned my naniwa hones several times with my DMT325 then made the decision to flatten and take the chip out of my swaty. That was a mistake on my part. the swaty was hard and the chip was too deep. now the chip is gone and DMT is wore out.

Well I may have to bit the bullet and buy another, I'm well past their 14 day, unused 100% garentee policy.

But I guess my real question is, are there any adverse issues with what I have to continue on, or should it be replaced?

I replaced mine. after the Swaty incident there were places or should I say spots that had no diamond at all. my new DMT325 I use after 3-5 blades on the stones. ecept for the 1K which gets more use than the others. I was told that most people over flatten there hones. I was told to watch the water line of the blade and that would tell you no. 1 if the hone was flat enough or if the hone is flat then the blade might be warped. After honing a blade if theres some black or dark spots on the hone I hold it under the faucet and rub with my hand until it's gone. anyway that's what I do.

I just checked the old dia sharp website, now it is dmtsharp.com . They used to have more info in their FAQ than they do now. The only plate they list a tolerance on is the lapping plate "On a special order basis, DMT is offering a 95 micron / 160 mesh lapping plate made with the same Diamond Hardcoat Technology™ and precision ground, hand certified flat to +/- 0.0005" plate as our standard Diaflat™ Model."

They used to have the tolerance posted for the 'sharpening' plates, such as the 325, but if they did, I didn't see it. If the vendor doesn't offer a replacement go to dmt's website and contact them. I found an old thread from 2010 where one guy said, "DMT advertises they start with a steel plate true flat to 0.001." I don't know if that is still the way it is.

I really don't have any way to measure my DMT325 or the hones I flatten with it but when i watch the water line that the blade makes when I'm honing the line seems to be straight and even and the edge seems to be good. When it all comes down to it I would guess that a good edge is really what I want.

A way to check flatness of a Diamond Hone ( or any other) is to set it on a nice marble counter-top and see if it wiggles corner to corner or end to end. Change the direction of it a few times and try it in other positions.. A rattle is more than a sheet of paper off. If a corner or end comes up, slide sheets of paper under it till it stops. Each sheet is about 0.003 inch.
And yes I have an accurate granite surface plate I use for mine. But, it does no good if the manufacturer says no.


If you are not honing a lot a cheap granite plate and wet dry sandpaper is plenty good.

If the manufacturer uses too much current in the diamond / nickle plating bath, the plate will heat fast and may warp. I also have found where the ends of plates were higher or more heavily plated.

~Richard

$31.00 DMT?

Are you using a 6 in stone?

Originally Posted by rhensley

I would guess that would depend on the stones. I flattened and cleaned my naniwa hones several times with my DMT325 then made the decision to flatten and take the chip out of my swaty. That was a mistake on my part. the swaty was hard and the chip was too deep. now the chip is gone and DMT is wore out.

Takes some Comet or Soft Scrub and a nail brush and work your DMT over with it. They often clog up and look dead but will come back to life. I have done a few hard barber hone recoveries and after the scrub the DMT is back.

Originally Posted by Euclid440

$31.00 DMT?

Are you using a 6 in stone?

Sorry, here is the correction; D8EE 8X3 120Gr for $47 & change, had a discount code.
So it's not a 325.

Really just personal preference never checked my plates, never had an issue. At most, you have an inch of razor width on the stone at a time, so it will just ride on the high and low spots as you move across it. We are not talking about that much variance. On a stone the plate will just ride on the high spots, it will not take the shape of the plate. Think about it, how flat is your strop?

Smooth is more important than dead flat, flat-ish is good enough. Most synthetic stones, move way more, swelling and shrinking than the variance of the plates, so does it really matter?

I remember years ago, someone wrote on this site words to the effect, if a hundred years ago, guys really worried about how dead flat their stones were?