Thread: Informal Diamond Plate Comparison

Its a lapping plate but the ad says if your concerned about flatness, get the dmt or atoma! Hmmmmm.

Well, if you're sharpening knives, the flatness isn't really going to be that much of an issue. You just want to be able to have lateral flatness on a stone, or close to it (and even then it doesn't matter that much).

So the folks sharpening knives could tolerate something that's 5 thousandths out of flat along the length without issue.

The truth is, we probably could, too, with razors. We want flatness laterally, but within a couple thousandths along the length of a stone is fine.

Where it's not fine is plane irons and chisels when your flattening the backs of the tools or polishing away wear on the backs of the tools and you've got a progression of stones that are not all the same definition of flat. You are working a very wide surface instead of a small bevel, and it's a flat surface. Even then, a skilled worker probably wouldn't care as long as they were using the same diamond hone. Where people care is when they pop out a starrett straight edge and start comparing with other forum members.

Or, if you have an out of flat coarse diamond hone and actually use it on the back of a chisel or plane, and then go to the next finer stone and find out that you're not able to work the whole surface of the chisel or plane because the stones don't match the profile on the diamond hone (and it really isn't preferable for the back of a chisel to be anything but dead flat).

I guess what I'm saying is that you could get that hone and probably use it just fine, even if it's a few thousandths out of flat, but they have to warn the spec browsers that it might not be perfect, even though spec browsers may not have any clue if it matters. Lee Valley put something in some of their literature a few years ago, they started lapping the backs of their plane iron to within some very fine spec, like half a thousandth or something. The owner of the company expressed frustration that novice purchasers would call and say this or that tool was off by a couple of thousandths, even if they had no way of actually being able to measure that, and he ultimately said that the lapping isn't necessary, but rather than try to convince users about why it wasn't, they just went with the "well, give them what they want" strategy.

Just as information. Both of my DMTs, 220 and 320 ( not the lapping plates) are off by up to 0.008+ when laid upon a granite surface plate. They would not return my emails when I tried to find if that was normal. So I use them and watch what they are accomplishing. I have done industrial lapping of tools and fixture parts by hand. The only time I am really concerned about having a dead flat hone is an absolutely straight blade razor. A smiley doesn't care that much as it is never all on the hone at the same time.

Those are the diasharps, right?

conventional wisdom (term loosely used) on the woodworking boards several years ago was that the diasharps were not very flat, but the plastic duosharps were very flat. I haven't yet seen a duosharp that wasn't flat, but at the time, some people were turned off by the fact that the diamond surface isn't continuous and the core is plastic instead of being attached to a milled steel plate.

I have no idea how they could get the diasharps so out of flat when nobody else seems to have a problem with it, unless they are just buying stock to a spec and not grinding it.

Originally Posted by DaveW

Those are the diasharps, right?
conventional wisdom (term loosely used) on the woodworking boards several years ago was that the diasharps were not very flat, but the plastic duosharps were very flat. I haven't yet seen a duosharp that wasn't flat, but at the time, some people were turned off by the fact that the diamond surface isn't continuous and the core is plastic instead of being attached to a milled steel plate.

I have no idea how they could get the diasharps so out of flat when nobody else seems to have a problem with it, unless they are just buying stock to a spec and not grinding it.

From some industrial experience, the electroplating can cause warpage of the substrate if the current is too high. Then heat is generated and perhaps at a different rate closest to the anode. It should not bother something as thick as the DMT plates though. As a machinist I have used the Diasharps for many years and they only went out of flat at the edges where they were sheared? to size. I used to grind the edges to a slight chamfer. I buy the cheap Chinese 6 inch two sided, plastic core, hones and do the same to them. I do not mean the HF ones that have holes in them. They are in no sense flat!
~Richard

It’s a 140 grit plate, not a finishing plate. It is just for hogging off material.

Perfectly flat is not that important, the razor will just ride on the high spots.
How did honers do it years ago?

Don't think guys on the range or covered wagons worried about how flat their stones were.

Bought a couple razors recently from a guy that honed on a King 1K and finished on a two sided barber hone, the edge on those two Sheffield’s was a fine shave.

Doubt any of his hones were Dead Flat… his 80+ year old hands may have had something to do with it.

I think if your using a progression of stones and ones off here, and the other one off there, you can very well have a problem. If your using one stone, it doesnt matter much as the blade will contour to the hone. My point of it all is the flattening stone should be flat.

Originally Posted by Euclid440

It’s a 140 grit plate, not a finishing plate. It is just for hogging off material.

Perfectly flat is not that important, the razor will just ride on the high spots.
How did honers do it years ago?

Don't think guys on the range or covered wagons worried about how flat their stones were.

Bought a couple razors recently from a guy that honed on a King 1K and finished on a two sided barber hone, the edge on those two Sheffield’s was a fine shave.

Doubt any of his hones were Dead Flat… his 80+ year old hands may have had something to do with it.

Most of the old stones I get would suggest that there isn't a whole lot of bevel setting going on historically, that's a newer thing. When razors were new, people probably did a lot of work to put on an initial edge and then used a finisher, strop and linen, with the finisher being used sparingly. I say that because many of the razor stones (naturals) that I have that are in long disuse have a bit of a hollow along their length but not in their width.

125 years ago, if a barber or individual (those being the minority of individuals who shaved every day back then) did anything, they probably used the exact same razor on the exact same stone and never needed more than the finisher, probably also preferring not to work all of the way to the edge if they could help it, an art that is lost these days where everyone wants to blast off the entire edge and then work through a progression again. We have people doing restoration style work every time they should just be maintaining.

Side comment, most of the finer craftsmen that I've met who have used oilstones and still do are meticulous about keeping them flat, but they keep them flat in use by honing the tools their honing over the sides of the stone (so as not to wear them hollow) and never letting a stone get more hollow than the camber they'd want on a tool. With waterstones, such a state is too transient. What I'm getting at is they do not use diamond hones or laps to keep their stones flat, but they do have a very precise condition of flatness or slight lack thereof that they prefer.

Carpenters is another thing entirely. Sometimes people argue with me (on the woodworking side) about what fine woodworkers did by comparing clapped out carpenters consumables, which is something else entirely.

The trouble with discussing all of this with a newbie is that they don't have the experience to know what counts and what doesn't, and therefore go scorched earth (and if their pockets support scorched earth, who am I to argue?).

I never, like the craftsmen I've talked to, never lap an oilstone once I've started using it. I can't stand to go from a perfectly fine cutting surface to one that's brash like a lapped oilstone is. The only exception is that the softer stones (washitas), I will rub together sometimes to get the surfaces excited without blasting grooves in them like happens with a diamond hone.

Isn't the idea of using figure 8's and rotating the stone 180 degrees suppose to counteract and not reproduce imperfections?

I've thought the same thing. Not many razors are truly straight, and the best of them may be worse than we ever let a hone get. And even with a truly straight straight razor - there are some - it would seem x strokes and turning the hone 180 degrees halfway through honing would probably negate any ill effects of a slight out-of-flatness.

Cheers, Steve

Originally Posted by Geezer

Just as information. Both of my DMTs, 220 and 320 ( not the lapping plates) are off by up to 0.008+ when laid upon a granite surface plate. They would not return my emails when I tried to find if that was normal. So I use them and watch what they are accomplishing. I have done industrial lapping of tools and fixture parts by hand. The only time I am really concerned about having a dead flat hone is an absolutely straight blade razor. A smiley doesn't care that much as it is never all on the hone at the same time.