comparing diamonds to stones

[Curtis Niedermier]

So I sharpen with a set of three DMT DiaSharp bench stones: coarse, fine and extra-fine. The extra-fine is 1200 mesh, 9 micron. I'm trying to compare that to the Shapton Professional Series stones. Do I just compare the grit number of the Shaptons to the mesh number of the DMTs? I'm tossing around getting a finer stone from Shapton to use for my final polishing/honing, but don't really know how the extra-fine DMT compares.

[Jim Matthews]

You can use a lapping plate with diamond paste and get the same sort of wear that the Diamond Plates offer.

I bought the finest Atoma plate, and apply a little 3 micron paste as the lubricant.
Stropping is my final step, regardless.

That's the most effective way for me to remove the wire edge.

http://www.sharpeningsupplies.com/Sharpening-Stone-Grit-Chart-W21C60.aspx

FYI - I migrated to the Diamond plates after taking a course, and sold off my Shaptons (which I was prone to gouge due to rough handling).
I find the diamond plates MUCH faster than any other method I've used.

I suspect a good set of oil stones would be equally quick, but would still require flattening - which isn't necessary with a diamond plate.

[David Weaver]

It's similar to a 2k grit shapton when broken in, but the finish on the edge isn't quite as good.

You can do like jim says and refine it a fair amount with compound on a strop. Anything is fine, even something like autosol, though most strop compounds need to be wiped off of whatever you're sharpening, and autosol especially does.

[Andrae Covington]

So I sharpen with a set of three DMT DiaSharp bench stones: coarse, fine and extra-fine. The extra-fine is 1200 mesh, 9 micron. I'm trying to compare that to the Shapton Professional Series stones. Do I just compare the grit number of the Shaptons to the mesh number of the DMTs? I'm tossing around getting a finer stone from Shapton to use for my final polishing/honing, but don't really know how the extra-fine DMT compares.

Comparing the microns is the most reliable method IMO, as different companies use different grit and mesh standards. As David said though, there still can be differences in the edge you get. The DMT Extra Fine is 9µ, the Extra Extra Fine 3µ, and the Shapton 4000 3.68µ according to info I've seen, so the latter two are roughly comparable and would be finer than your Extra Fine. Shapton of course makes even finer 6000, 8000, and so on.

[David Barnett]

Comparing the microns is the most reliable method IMO, as different companies use different grit and mesh standards. As David said though, there still can be differences in the edge you get.

There are differences in the resultant scratch patterns dependent upon the abrasives used, both natural and manmade, the binding of those abrasives, crystal presentation, friability, wear characteristics, and so on.

An easy-to-see example are scratch patterns left by monocrystalline diamond compared with polycrystalline diamond of the same rough micron range. The multifaceted polycrystalline diamond leaves a smoother scratch pattern with less depth and less variation in depth, wears far better than the blockier monocrystalline—you can see why in side-by-side photographs (http://www.metallographic.com/Newsletters/PC-diamond-newsletter3.PDF)—especially when plated onto a flat substrate, and cuts more consistently throughout its life. For most lapping and consumable applications the cheaper monocrystalline will serve well, but there are applications where the polycrystalline hexagonal habit is much preferred.

[Steve Voigt]

There are differences in the resultant scratch patterns dependent upon the abrasives used, both natural and manmade, the binding of those abrasives, crystal presentation, friability, wear characteristics, and so on.


David, to me the difference is this: Diamonds leave horrible deep scratches comparable to stones that are double or triple the micron size.
I had a chance to pick up an eze lap "super-fine" (1200 grit) plate for a good price, so i did. They don't give the micron size, but various sources I've seen suggest around 8-12 microns,which is similar to a hard arkansas stone. I was shocked though--repulsed actually--at the violence this thing did to my poor carbon steel. I know you're supposed to break them in a little, and I did, but that only helped so much. Five minutes was enough to learn my lesson. I'll stick with my India stones and novaculite from now on.
I can see how the diamonds would be helpful for things like HSS, but for plain old high carbon steel, I don't think it's a good match. Just my experience, admittedly quite limited on the diamond end of things.

[John Sanford]

Everything you want to know you can find here: http://www.hocktools.com/perfectedge.htm

[Winton Applegate]

Everything you want to know you can find here

and all the stuff that isn't there is here
http://www.finewoodworking.com/how-to/article/sharp-and-sharper.aspx

:D

Just kidding, I haven't been to the Hockmeister but the FWW article is great stuff too.

[David Barnett]

David, to me the difference is this: Diamonds leave horrible deep scratches comparable to stones that are double or triple the micron size.

That's a rather sweeping statement, Steve, and does not accord with my experience these last twenty years, but I do not doubt your experience.


I had a chance to pick up an eze lap "super-fine" (1200 grit) plate for a good price, so i did. They don't give the micron size, but various sources I've seen suggest around 8-12 microns,which is similar to a hard arkansas stone.

1200-grit diamond is variously stated in a fairly wide micron range. I won't delve into the reasons for this but consider that DMT monocrystalline diamond is given as 9µ whereas non-DMT products can range as high as 15µ.


I was shocked though--repulsed actually--at the violence this thing did to my poor carbon steel. I know you're supposed to break them in a little, and I did, but that only helped so much.

I'm truly sorry you had such disappointing results, however, you're not supposed to "break them in a little" but rather a lot, and quite aggressively. Aside from sacrificial diamond plates, laps and loose diamond, for breaking-in I've used carbide tool blanks, boron nitride bars and split boules of synthetic corundum—flame-fusion sapphire, ruby—all significantly faster and more satisfying than even the hardest HSS. The half-boules are far and away the most effective non-diamond break-in medium for me. (They also make terrific burnishers for card scrapers.)

Although a diamond plate will eventually settle in with hardened water or oil-quenched carbon steels, it will be a long while indeed and I would not recommend such a break-in schedule which would likely exceed most anyone's patience.

The problem stems from understandable but unrealistic expectations regarding diamond plates. Having purchased a new diamond plate, most everyone expects it to cut at the stated grit size comparable to another sharpening medium of the same micron range. When one buys a 600-grit diamond plate, how it cuts early on is how many expect and wish it to cut throughout its life. The way your 1200-grit plate cut did indeed do violence and until well broken-in, would continue to do so for quite some time before finally arriving at that point where it gives a consistent scratch pattern with satisfying tactile feedback.

I have a nineteen year old Eze-Lap 600-grit that cuts like a dream with a velvety feel and can take any blade or iron, vintage to modern off my 7" grinder to my 1µ (14000-grit) lap in a very few strokes, with no interim steps, a regimen I've been repeating for the last fifteen years. Derek Cohen has a nicely broken-in 600-grit Eze-Lap plate he says cuts like a 2000-grit non-diamond stone.

One problem that persists is how most manufacturers who make diamond products for woodworkers apparently avoid explaining how new diamond plates require more than a cursory break-in and the best ways to do so. Frequently I'm offered a plate that's just starting to calm down as the owner perceives it no longer cuts the way it did when new, and who now eschews all things diamond.


I can see how the diamonds would be helpful for things like HSS, but for plain old high carbon steel, I don't think it's a good match.

I still have chert stones, novaculite and otherwise, but tend to use them for simple high-carbon steel carving tools and vintage gravers but successfully use diamond for all other woodworking tools from antique irons and chisels to HSS and carbide blades and cutters.

I'm certainly not saying diamond plates are the only way or even the best way to sharpen, but they've sure cut down my sharpening time and for someone who chooses more modern, harder and tougher steels or who doesn't wish to invest in ever-more-expensive natural and man-made stones, it bears consideration.

[David Weaver]

I have a 600 hone that also cuts like derek describes, and a 1200 that cuts finer, which I haven't used that much but I have used hard when I do (to get it to settle in). There is an enormous world of difference between the ezelap and what the DMT does (where the DMT essentially leaves deep grooves, even as it's no longer cutting fast).

Since going to all carbon steel, I don't use the ezelaps much, but I do use them for random odd jobs (like card scrapers) and other stuff around the house when you want something that will tolerate anything (oh yeah, and for the first step on an HSS skew now that my shaptons are gone).

I think the charts about novaculites have done them a disservice. A hard arkansas that is relatively close to the meaning of that definition should be able to be driven way up into polishing stone range, whereas the edge left by the ezelap is one that you can use, but it's never got the refinement that a burnished or polished edge will have.

Still love the jasper as an edge refiner, too.

[Steve Voigt]

That's a rather sweeping statement, Steve, and does not accord with my experience these last twenty years…


Dave, as usual thanks for the very detailed and informative post. Yes, I was being a bit hyperbolic! Obviously, you and many others have had great success with diamonds; I shouldn't have implied otherwise.
Still, everything you've written confirms that a new diamond plate will cut much more aggressively than any stone of comparable micron size, for a long time. As you suggest, I don't have the time or patience for that break-in schedule.
Perhaps the more useful thing I gleaned from this and other experiences is that micron size alone is not a useful comparison, unless one is sticking with similar media. Going by microns alone, a hard black or trans ark shouldn't be a fine finishing stone, but it obviously is.

[David Barnett]

There is an enormous world of difference between the ezelap and what the DMT does (where the DMT essentially leaves deep grooves, even as it's no longer cutting fast).

That's my experience. The Eze-Lap gets better with time (my first is nearing its twentieth year of continuous use), settles in and stays that way, whereas my three DMT 'stones' gave up the ghost in their first year and continue to cut in the manner you've described, which takes them out of any lineup for edge tools.


Since going to all carbon steel, I don't use the ezelaps much, but I do use them for random odd jobs (like card scrapers) and other stuff around the house when you want something that will tolerate anything (oh yeah, and for the first step on an HSS skew now that my shaptons are gone).

It's now rare that I use anything but high-carbon tool steel for woodworking, but I use diamond pretty much all the time. All the HSS and tungsten-carbide is used for jewelry work and micromachining, although high-carbon steels are mainstays for repousse, stonesetting, engraving gold and silver, and so on.


I think the charts about novaculites have done them a disservice. A hard arkansas that is relatively close to the meaning of that definition should be able to be driven way up into polishing stone range, whereas the edge left by the ezelap is one that you can use, but it's never got the refinement that a burnished or polished edge will have.

Still love the jasper as an edge refiner, too.

I agree that hard arkansas bench stones (trans and trans-black) can take most high-carbon edge tools into polishing range. I use them most often for freehand sharpening plain steel gravers (sweeping motion) with rapid final passes on jasper. The first few sweeps on jasper usually leaves a streak. Subtle, but it makes a difference you can see and feel in the cut (non-ferrous metals) and lasts longer between retouches. I do use diamond laps with jigs for sharpening and polishing most everything else; HSS, GlenSteel, C-Max, Carbalt™.

[David Barnett]

Dave, as usual thanks for the very detailed and informative post. Yes, I was being a bit hyperbolic! Obviously, you and many others have had great success with diamonds; I shouldn't have implied otherwise.

Hey, I'd be frustrated, too, and would've likely groused hyperbolically and blasphemed obscenely.


Still, everything you've written confirms that a new diamond plate will cut much more aggressively than any stone of comparable micron size, for a long time.

Right. Easily so.


As you suggest, I don't have the time or patience for that break-in schedule.

Depending on the cutting characteristics of the new plate, technique and what you have on hand, it can be done in under an hour or so. Otherwise, gradual breaking-in by sharpening simpler tool steels can take days or weeks.


Perhaps the more useful thing I gleaned from this and other experiences is that micron size alone is not a useful comparison, unless one is sticking with similar media. Going by microns alone, a hard black or trans ark shouldn't be a fine finishing stone, but it obviously is.

Absolutely. I even have cherts that cut differently in one zone than another on the same stone. Good Arkansas stones are a joy when matched with the appropriate steel. I sure love my older trans ark carving slips for hand-forged gouges in simple tool steel.

[Daniel Rode]

I use a combination of DMT diamond stones and Shapton Pro 15k finishing stone. This has been working well for me. The DMT coarse is good for removing a lot of material, flattening chisel back and flattening the shapton. I don't use it much in day-to-day sharpening except to flatten the 15k. Unless the edge is badly chipped, I start with the X-fine to raise a burr, move on the the X-X-fine (5k DMT) and then finish up on the shapton. It's not uncommon for me to quickly refresh the edge by skipping the X-fine or even just going directly to the 15k shapton. I also have a DMT medium but it's not much used. One could go directly from the X-fine to the 15k and get good results as well.

I bought the 15 Shapton Pro because it was thicker and cheaper than the 16k Shapton glass stone. I couldn't find any reason to spend more to get less.

Mine may not be the ideal method or stones but for me, it's fast and consistent.


So I sharpen with a set of three DMT DiaSharp bench stones: coarse, fine and extra-fine. The extra-fine is 1200 mesh, 9 micron. I'm trying to compare that to the Shapton Professional Series stones. Do I just compare the grit number of the Shaptons to the mesh number of the DMTs? I'm tossing around getting a finer stone from Shapton to use for my final polishing/honing, but don't really know how the extra-fine DMT compares.

[Curt Putnam]

Curtis, All I can do is tell you what works for me. I use diamonds for the coarser work (regrinding bevels, etc.) My 1200 stone is now pretty well worn. I find that this makes a good transition point to my waterstones. I've got the 3 stone set from Stu. The 1K stone matches up to the 1200 stone pretty well - by which I mean only a few strokes and the edge looks as if it been completely done on the waterstone. A few strokes each on the 6K & 13K and done. For the fine edges, the diamonds are not needed, the 3 waterstones are all that are required.

I'm about to do a couple new (to me) things with diamond. I've got the DMT Wave for curved edges. I'm also going to try cutting into MDF with those edges and then spritzing with DMT's polishing spray. Hoping that will work.

In the main, my diamond stones get used for things like scraper blades because I would destroy my waterstones with them. I do use an 8K Norton for final polish in some cases, strops in others. The other guys can tell you all that's wrong with my wandering approach but at the moment it works for me. Simple and effective. IMO & YMMV

Curt