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

I have a new DMT325 I got about 2 months ago. Assuming it's a flattening stone for all my hone stones, is it suppose to be "flat" or concave? Have I worn it down? (Using 1k, 4k,8k,12k & 16k hones)
I noticed yesterday, that the DMT is concave (low in the center) I can see light under the straight edge I'm using. Can I fix it & how? Or should I seek a replacement from the vendor? As I mentioned above, I've used it 8-10 times on my stones.

(UPDATE POST #8)

The regular dmt stones are not supposed to be flattening stones, we just use them for that purpose They have a "certified flat" stone that is super expensive, but I never saw the need to spend that kind of money on a flattening stone.
If it is that concave, then you probably got a lemon. I would contact them with pictures and see what they will do for you. I don't see anyway that a waterstone can wear a diamond plate...

Originally Posted by Ernie1980

The regular dmt stones are not supposed to be flattening stones, we just use them for that purpose They have a "certified flat" stone that is super expensive, but I never saw the need to spend that kind of money on a flattening stone.
If it is that concave, then you probably got a lemon. I would contact them with pictures and see what they will do for you. I don't see anyway that a waterstone can wear a diamond plate...

This is my thought as well. I was using the DMT to flatten the bottom of my scuttle, when I noticed the issue.
I put a steel ruler across the DMT and noticed light under the center portion. Probably about .004-.015.

Using s dial indicator I sent back two before I got a dead flat 325

.004 is awful close to flat.

Originally Posted by pixelfixed

Using s dial indicator I sent back two before I got a dead flat 325

What I did was take a Starrett pro machinist’s straight edge to the back side of the plate. My 325 wasn't flat, my 1200 wasn't either. I called dia sharp, sent them back on my dime. They sent me a new 325 and the old 1200.

They don't use a straight edge. I don't recall exactly how they come to gauge flat, but in their tolerances my old 325 was not flat, but the 1200 was. I later bought a 120, a 600 and a 8000. The 600 is dead flat with the straight edge, the others are not. Probably within their tolerances though.

So send it back and see what happens ..........

DMT must have improved over the last couple years. Mine were not flat. I contacted them and got no reply. I tried again with the same results. The Trend was also not flat.
Been a machinist most of my adult life and agree with JimmyHAD.
~Richard

Okay, now I'm back from work, so I can do more than an "eyeball guess".
Zeroed out the calipers and I've come out with -.0085 @ the center, decreasing steadily as you go out (L/R of center, -006, -0035, -.001, & at the edge .0005.

So, keep or send back? Will this much effect flatness of the hone enough to effect blade geometry and comfort. Or just over thinking?

When it comes to a stone being absolutely flat I think of what one of the best hone masters said. the stones need to be flat-ish. when a blade moves up or down the stone it moves to some extent from side to side so I would thing that all of the blade would get some of the hone. kind of like when I hone a smiling blade. as one person said .004 is pretty flat. Now I wore out a DMT325 on a chipped swaty. the diamond plates can wear out. when this happened to me I bit the bullet and bought another.

Originally Posted by rhensley

When it comes to a stone being absolutely flat I think of what one of the best hone masters said. the stones need to be flat-ish. when a blade moves up or down the stone it moves to some extent from side to side so I would thing that all of the blade would get some of the hone. kind of like when I hone a smiling blade. as one person said .004 is pretty flat. Now I wore out a DMT325 on a chipped swaty. the diamond plates can wear out. when this happened to me I bit the bullet and bought another.

I sent Best Sharpening Stones a request for reply/ course of action request, so lets see what they say. $31 isn't a ton of bread, but if it's suppose to be flat or to make something flat, then I assume it should be flat or flatish. If they tell me +/-.010 is okay, then I'm good.
If +/-.004 is acceptable, I can't believe honing 4 Stones twice (8X's) is enough to cause this kind of wear.