Why not JUST diamond stones?

[Jim Belair]

I just bought a 220 grit DiaSharp stone for rough reshaping work and flattening my waterstones (Norton 1000/4000/8000). I really like it! Since (as I understand it) they don't wear and stay forever flat, I wonder why use anything but diamond stones? Pricewise they are comparable, and available up to 8000 grit. When my 1000 Norton wears out why shouldn't I just replace it with a DiaSharp?

Jim

[Sam Takeuchi]

1. They wear out. When they are new, they cut pretty aggressively, too aggressively even for the git. Along the way, it settles down to usable level, but performance gradually deteriorates over time. At one point, it gets too worn out and don't cut for worth a damn. Depending on how much you use it, you can wear out a diamond stone in a year or decade, but it's an inevitable life cycle of a diamond stone.

2. More often than not, they aren't flat. They come 'flat enough for the spec' flat, not necessarily flat needed for a lot of tasks. There are very small number of option when it comes to buying truly flat diamond stones and in the end, performance, price and all that don't really balance out.

3. It's not often recommended to use diamond stone used for flattening for any other tasks. It goes back to the point 1, they do wear out and doing so will cause uneven wear which would make that particular diamond stone unsuitable for flattening. The problem with it is that you can't do anything to fix your diamond stone once wear out, or not flat (you can return it if you feel cheated).

In the end, other sharpening mediums have more or less better performance efficiency throughout their usable life as performance don't deteriorate as they wear out. I started out thinking the same years ago and bought a few diamond stones, DiaSharp at that. Honestly, as far as sharpening performance, they didn't impress me then and they don't impress me now. Now I have a few worn out steel plates that used to be diamond stones, that's neither flat nor useful in anyway whatsoever.

[John Coloccia]

I like the DMT Duos better than the Diasharps. I find them to be flatter and just work better. The course/fine (red/blue) Duo would make a fine replacement for your 1000 stone, I believe. Just my opinion.

[Mike Henderson]

I never really looked but I thought diamond stones came in coarser grits than you need to finish your sharpening. I use a diamond stone to do rough sharpening and to flatten my water stones and that approach works well for me. I bought the DMT "stones" and they've lasted quite a number of years now, and probably will last several more years.

Mike

[john lampros]

The Diamond may not wear out but its what bonds the diamond to the steel that is the weak spot. I have a monster diamond lapping plate that I only use for truing plane bottoms and I use it sparingly. Every once in a while I flatten finishing stones on it. but they do wear out.

[David Wong]

I have atoma diamond plates, primarily for flattening my waterstones, but I sometimes use them for fixing big chips in the blades. I have plates in 140, 400, and 1200 grit. I do not like them for sharpening because the blades tend to skate very fast on top of the diamonds. For freehand sharpening, I don't get enough feedback for the bevel position on the plate, and the diamonds can do a lot of damage before you realize it. I also had some difficulty with the diamond stones causing chipping of the cutting edge. Probably related to poor technique in keeping the bevel flat to the diamond plate.

[Sam Takeuchi]

The Diamond may not wear out but its what bonds the diamond to the steel that is the weak spot.

They do wear out. They break down slowly. Basically when it's new, diamond particles are pretty pointy and sharp, hence the aggressive cut in the beginning. Eventually sharp and pointy grits break down and settle into relatively ok cutting performance during which is the intended grit/performance I believe, until it is worn past that range and become frustratingly less effective. Worn out diamond stone cut VERY slowly. If you buy a relatively reputable stone, they should even come with a literature explaining 'break in' process and it goes on about how takes some sharpening session before reaching optimal cutting performance, etc (I remember my DiaSharp came with one).

I know there are couple of ways diamond grit are bonded onto the plate, I can't remember details now, but I vaguely remember people mentioning certain type of particle bonding on cheaper stones having pretty weak grip and prone to premature wear, or in worst case, spots coming off altogether on the plate. Diamond stone I used for flattening for a couple of years had that 'bald spots' after about a year. It was a cheap diamond stone, but as flat as one could ask for and it lasted about 1.5 years.

[george wilson]

I just bought a 260 grit and a 600 grit 6" wheel for my Sunnen horizontal/vertical grinder. These wheels cut on their side,not on their edges. I may buy the 1200 grit also. These are very useful especially for carbide,but at 200 rpm,they are slow enough to use for steel.

I bought a white titanium oxide ceramic knife blade from Woodcraft supply. You put on your own handle,but they are only $25.00. It stayed sharp(was very sharp new) for quite a while,but started getting a few nicks i the edge. With the diamond wheels I was able to get rid of the nicks and put on a decent enough edge that I can cut 1/16" tomato slices with it. I need to go to diamond paste to get a really sharp,polished edge. I'll make a wheel out of brass some time,for the diamond compound.

I use these wheels very gently because it is true that they will wear out from the diamonds fracturing or breaking loose from the nickel matrix.

I have been using diamond bench stones to start out the sharpening of chisels,etc.. We have a stone where I worked that was one of the very first ones to come out. It is still working!

Be sure to not put much pressure on your diamonds. How long they last is partly the technique you use.

BY THE WAY: NEVER buy those ceramic knives that have a stainless steel core,and a very thin coating of ceramic. The ceramic does not bond well at all to the stainless steel core,and it flakes off. You do not want to be eating razor sharp shards of ceramic. I had bought 2 of the black bladed coated stainless blades at Woodcraft. They began to flake off soon,and we no longer use it.

[Simon Frez-Albrecht]

My sharpening kit right now consists of a 2x6" coarse/fine DMT plate, and a strop with two different compounds. I believe the fine side of the DMT is rated at 600 grit, with the coarse maybe 220 or 320. I get razor sharp, hair popping edges by sharpening the edges on the fine DMT and then stropping to slightly polish and remove the burr.

Soon I would like to get a couple of nice Japanese stones, like the set that Stu is selling, but it will have to wait. In the meantime I can pare end grain, get glassy surfaces off of a plane, etc. I almost don't want to spend the money to upgrade for what is probably a very small gain in performance in what is largely a hobby, but I also really want wicked edges.

I came to woodworking through green wood working (knife and axe), which I arrived at after being into knives for a while. My sharpening kit for knives is a 1x30 belt sander, which is fine as long as you aren't looking for flat. When I started sharpening up my planes and chisels, I used the glass and sandpaper because it's cheap and was quick to put together, but when I got my DMT I realized just how much that method was dubbing the backs of my blades. Using spray adhesive instead of water to stick the sandpaper down could have something to do with it, but I haven't tested to see.

[Don Dorn]

I'm sure they do wear out, but I use two Diasharps - one 600 and an 8000. I use Cosmans free hand method and normally sharpen blades at least a couple times per week. I've had these for a bit over a year and they still work great and I'm not spending any more time than I ever did. When it eventually does, I'll probably replace because the convenience of not having to soak and flatten water stones is worth it. While I can't prove it, I think that not using great pressure and letting the diamonds do the work extends the life of them.

[Archie England]

I'm sure they do wear out, but I use two Diasharps - one 600 and an 8000. I use Cosmans free hand method and normally sharpen blades at least a couple times per week. I've had these for a bit over a year and they still work great and I'm not spending any more time than I ever did. When it eventually does, I'll probably replace because the convenience of not having to soak and flatten water stones is worth it. While I can't prove it, I think that not using great pressure and letting the diamonds do the work extends the life of them.

At the lower end (300-600) I find my waterstones work as efficiently and quickly as my DMTs. At the medium, fine, and extra fine levels, I far prefer the blade sharpness from my upper grit waterstones to what the DMTs produce. AND, I'm flattening a bunch of blade backs that really accelerate the deterioration of every sharpening medium. My Sigma Power and Chosera stones have handled this brute work with barely a notice, and the sharpness, and speed of achieving that sharpness, are outstanding. Sure, if I'm cutting a new bevel completely, I'll start with a grinder; otherwise, I'm free handing all my sharpening on the water stones. Once I tried the Chosera 400 as opposed to my DMT lower grits, I've never gone back to the DMTs on a regular basis. However, there's probably a bunch of woodworkers who'll swear by their scary sharpen method, too.

[Bruce Haugen]

I'm not going to summarize any of the discussion on this topic, but let me point you to multiple, extensive discussions on the use of diamond paste in grits from 30 microns to .5 microns (and smaller) on a cast iron substrate on Wood Central. Just do a search on the hand tool forum. A lot of people with extensive experience who really know what they're talking about have discussed the dickens out of this subject.

[Sam Takeuchi]

I'm not going to summarize any of the discussion on this topic, but let me point you to multiple, extensive discussions on the use of diamond paste in grits from 30 microns to .5 microns (and smaller) on a cast iron substrate on Wood Central. Just do a search on the hand tool forum. A lot of people with extensive experience who really know what they're talking about have discussed the dickens out of this subject.

Except the OP's question was concerning diamond stones, not diamond paste on substrate. I don't think advantages and disadvantages of diamond paste on substrate and diamond stone are interchangeable. In my opinion, the only thing they have in common is abrasive material, the rest function differently. While I agree that discussion on sharpening with diamond paste on substrate is very interesting and method itself is very effective, I don't think that fit into the scope of original question here.

[Bruce Haugen]

Except the OP's question was concerning diamond stones, not diamond paste on substrate. I don't think advantages and disadvantages of diamond paste on substrate and diamond stone are interchangeable. In my opinion, the only thing they have in common is abrasive material, the rest function differently. While I agree that discussion on sharpening with diamond paste on substrate is very interesting and method itself is very effective, I don't think that fit into the scope of original question here.

Sam, I'm merely pointing out a method that can be considerably cheaper both in the short and long runs. Certainly that is something worth considering, don't you think? Besides, the abrasive material is not the only thing they have in common. The sharpening effect functions exactly the same. Not to mention which, but several other sharpening media have been mentioned, too.

[Sam Takeuchi]

Sam, I'm merely pointing out a method that can be considerably cheaper both in the short and long runs. Certainly that is something worth considering, don't you think? Besides, the abrasive material is not the only thing they have in common. The sharpening effect functions exactly the same. Not to mention which, but several other sharpening media have been mentioned, too.

I agree that it is cheaper and I think it's more versatile than diamond stone. I think it's a much better alternative than using diamond stone for the purpose OP brought up. I do have to clear one thing, I'm not disputing how diamond grits abrade steel much unlike other abrasive. What I consider difference in function is the way diamond stone has no way to refresh its cutting property and follows linear decline in performance over a period of time (however long that may be) while other sharpening mediums are able to retain relatively consistent performance throughout their usable life. To me that's function, being able to abrade steel the way it was intended for throughout their usable life.

Generally speaking, I would agree that technique is the key to preventing premature wear on diamond stones, but these days, I wouldn't generalize to say so. There's just too many low quality diamond stones floating around, some of them are bound to lose plating or pop grits no matter what people do. I say this because I know not everyone is going to end up with diamond stone from reputable manufacturers and some of them will be dealing with "bald spots" on the diamond stones soon or later. It's not just low quality stones that could have problems, even reputable manufacurers' products can be duds, too. My DiaSharp trio were stunning failures, one has two humps (you can even feel them), one is cupped length wise and the third one is the flattest, but not really that flat either. I'm not being super critical here either. There is not much you can do when you get duds like that, either just suck it up and use them or return them. There is no way to fix them. With 3 duds, it's hard to put much faith in replacement being any better.

I know quite a few people recommend DuoSharp, as John suggested earlier, but I have no first hand experience with it. That cheap diamond stone I used for flattening waterstones was beautifully dead flat and even with plating coming off on spots, it was pleasure to use until it wore out. The problem is, though, there is no guarantee that the exact same make of this diamond stone will be as flat or good. As for sharpening, I have diamond paste sharpening setup for M2 blades, but I wouldn't consider diamond stones to be its equal. With paste, simply there is better control over the whole setup and performance than diamond stones.

So to be back to the very original question as to why not go with all diamond stones, in my experience and opinion, it's because it's not all good and flowery. I think it has its place, like for flattening waterstones and maybe even back of chisels and plane blades if you get a hold of flat ones, but that's as far as I'd go. Basically for tasks you can wear it down evenly.

[Steve Friedman]

I like the DMT Duos better than the Diasharps. I find them to be flatter and just work better. The course/fine (red/blue) Duo would make a fine replacement for your 1000 stone, I believe. Just my opinion.
That's interesting. I never knew that, but DMT website seems to confirm that the Duo-Sharps are flatter. I have both and maybe that's why I haven't used the Dia-Sharps since getting the Duo-Sharps. But, I just ordered the XX Coarse 120 grit Dia-Sharp to flatten backs because the Duo-Sharps don't come that coarse. How do you check a diamond plate for flatness since the surface isn't smooth? I see that DMT will replace any of their products that are not flat.

Thanks,

Steve

[John Coloccia]

That's interesting. I never knew that, but DMT website seems to confirm that the Duo-Sharps are flatter. I have both and maybe that's why I haven't used the Dia-Sharps since getting the Duo-Sharps. But, I just ordered the XX Coarse 120 grit Dia-Sharp to flatten backs because the Duo-Sharps don't come that coarse. How do you check a diamond plate for flatness since the surface isn't smooth? I see that DMT will replace any of their products that are not flat.

Thanks,

Steve

You just have to do your best and maybe even just eyeball it. Your eye can be pretty accurate at detecting deviations from straight. The Diasharp I have is far enough out of flat that I can easily eyeball the warp. I suppose I should have it replaced but I never got around to it.

[David Weaver]

I also like the duos over the diasharps - I don't know how many duosharps i've come across, maybe 4 (I pushed them on other folks who were using sandpaper to flatten their stones, when I could find a duo with one of the sides at 325 grit for $55 on amazon). Every single one of them has been dead flat.

To use diamond stones only and then find out that you got one that is 4 thousandths hollow, and find out the next is 4 thousandths proud would create a lot of extra work flattening backs of tools - though it wouldn't really affect anything else if you microbevel or hollow grind.

I never found great favor in their feel or the way they cut deep narrow grooves. My experience with the finer ones is that when the diamonds start to dull some, they still cut a bevel well, but if you put a big flat surface on them, like the back of a chisel, you are forced to apply more pressure than you'd like to, which only speeds up the process of them becoming more marginal.

As a bevel sharpener and a stone dressing tool, though, they're great, and nice to have around for sharpening things that would put a rut in ceramic or waterstones.

[David Weaver]

The Diasharp I have is far enough out of flat that I can easily eyeball the warp.

I have two generic copies of koyama hones that were called "XL Sharp" or something that are also out of flat, and can see it. I could see it immediately after taking them out of the package and sighting them. They are at most out about 3 to 4 thousandths over 4 inches, but it's enough to cause problems with them flattening things. If I couldn't see deviation sighting them, then I probably wouldn't worry about them, either

[Jim Belair]

Thanks for all the input. The fact that they may not be all that flat and that they do wear out pretty well blows both my points out of the water! I had hear that one needs to go easy on them and that the feel changes from initial. The ability to renew a waterstone to original performance until it is used up has some merit.

I'll stick with my coarse DiaSharp for edgeshaping and stone flattening and leave the waterstones to sharpening.

Cheers
Jim B

[george wilson]

It is a bit problematic determining the flatness of the metal diamond stones. They are wrapped in plastic when you pick them out. Even when you take them out of the plastic,a straight edge doesn't rest flat on the stones,because the diamonds hold it up off the metal. As was said,it is mostly an eyeball gauge process choosing one.

[Andrae Covington]

Thanks for all the input. The fact that they may not be all that flat and that they do wear out pretty well blows both my points out of the water! I had hear that one needs to go easy on them and that the feel changes from initial. The ability to renew a waterstone to original performance until it is used up has some merit.

I'll stick with my coarse DiaSharp for edgeshaping and stone flattening and leave the waterstones to sharpening.

Cheers
Jim B

I only use diamond stones. I have DMT Dia-Sharp 8x3 plates in Extra Coarse (60 micron), Coarse (45 micron), Fine (25 micron), Extra Fine (9 micron), and Extra-Extra Fine (3 micron). I sometimes use green compound on a leather strop.

My experience aligns with what Sam Takeuchi and David Weaver have said. Fortunately most of mine are quite flat, but a couple are a little off. The real problem is the degradation over time, which I unwittingly accelerated by doing a considerable amount of flattening the backs of chisels and blades, and pressing too hard. My Extra Coarse and Coarse stones in particular cut much, much slower than they did at first. The other stones are slower than they used to be, but not that bad.

It is the only system I have used, other than occasional sandpaper on granite tile. I wanted to avoid the near-constant flattening process of water stones, which sounded like a real hassle to me. But slogging away on worn-down diamond stones is a hassle, so I'm not sure I did myself any favors. As any quality choice of stones is expensive, I am reluctant to now shell out more for a set of water stones, oil stones, fire stones, etc.:rolleyes: So I keep using what I have.

[Terry Beadle]

I have a DMT coarse/extra course and it's almost flat. I've used it for about 5 years. I did use it on some chisel/plane blade flattening but only for a little bit as I was apprised on this site of the need to only use it on the stones. It's still working fairly well. I use the extra course on stones of equal to or less than 1000 grit. I use the coarse side on stones above 1000. I find that the higher grit stones stay cleaner and flatter longer by the use of the coarse instead of the extra course. Probably my perception vs reality, but there it is.

This diamond stone is wearing, albight slowly. I do wish it was flatter but I make sure it's cleaned and dry and stored flat. Over the years this has helped the DMT to be flatter ( not by much ).

IMO the only thing you gain by using diamond stones to flatten water stones is the speed. If you use a same grit or slightly less grit water stone on a water stone to flatten them, you bag both in one effort. Therefore, IMO, you don't need the diamond stones but they are nice to have.

I notice Rob Cosman only uses another water stone to flatten another water stone and from the looks of his jointery, they must be working great !

In short, Mr. Covington, Mr. Weaver, and just about every one that's posted to this thread are right. A Diamond Stone has it's uses but it's not the every thing.

[Steve Friedman]

Has anyone used diamond paste to "recharge" a worn down Dia-Sharp? Just wondering.

Steve

[David Weaver]

Not yet, but there should be some merit to it if the plate is soft enough that whatever you sharpen on it will push the diamonds into the plate.

No clue how hard the surface of a beat DMT is.

Even better would be loose diamonds so that you don't have the lubricant discouraging the diamonds from digging in and putting a layer of lubricant between the iron to be sharpened and the beat diamond hone.

[Steve Friedman]

Thanks David,

Short of asking my wife to lend me some, where does one get loose diamonds? Are they sold in micron sizes? Also, without lubricant, don't they just roll around?

Steve

[David Weaver]

On ebay is the cheapest I've been able to find. Lapidary supply places sell them to folks who go through a lot more than we would sharpening things, so they're surprisingly cheap.

There are sellers on ebay who label in grit size and micron size and basically sell for somewhere in the ballpark of 25 cents per carat of diamond weight.

In terms of the diamonds rolling around, what you're doing when you deal with loose diamonds is finding a substrate that is soft enough for the diamonds to embed, but hard enough to keep them pointed in a direction that they can do damage, and hard enough to wear well. The result should be the same regardless of lubricant. In the case of something like cast iron as the substrate (instead of a diamond plate), the hardened plane iron will smash the diamonds into the cast iron and they will stick in it. Once they're stuck in it and in a stationary position, the bits that stick out of the cast iron will scratch the hardened iron, regardless of lubricant.

See item (on ebay):
320704507255

No affiliation to the guy/girl who sells them, just telling you where to get diamond powder the cheapest. I've purchased from him twice and found the diamonds to be just fine. You can fish around through their store to find the grit you want. No clue if finding 600 grit and throwing them on a DMT 600 grit side will give you comparable results to original. I use the loose diamonds only for flattening very poorly treated chisels and irons, and in something along the lines of 100-120 grit.