DMT Diamond Stones

replicated my experience

Bill Tindall, E. TN

>....which is why we now use diamond powder on cast iron. You may be successful recharging the stone with diamond paste. I am trying it and it seems to be working.

Re: DMT Diamond Stones

Christopher Schwarz

>I'm no expert on diamond abrasives, but I have used them for about eight years on an almost-daily basis in our shop. We have about 10 stones so I think we have a good sample of what's out there.

The DMT people have told me that their stones cut much more aggressively at first as you "break in" the stone. If I remember correctly, during the break-in period you're knocking down any loose, irregularly shaped or poorly attached diamond media.

You can damage them. The DMT techs I've talked to say that excessive pressure during sharpening will damage the nickel media the diamonds are imbedded in. But it takes a lot of abuse.

You're right that they cut wicked fast at first, and it's seductive to think they always will cut that way. But they don't. Like a new car, they eventually settle in at a lower performance level.

However, I think that lower performance level is very good. My DMT stones do all my flat-grinding at home (I don't own a grinder). They true all my sharpening stones. They tune up my router bits and knives and 100 other tasks. I consider them essential equipment for my work (YMMV).

Chances are your stone is simply broken in, not broken. If you're not satisfied or unsure of it, I encourage you to send it back to DMT. I once sent them a black stone with the same complaint. They cleaned it for me and confirmed that it was OK.

I know there are other people on this board who have a low opinion of diamond stones, but I am not one of them. Treat them with care, don't expect too much and use them for the appropriate task.

Chris

With of Without Water?

Todd Stock

>Although DMT says the stones may be used dry, I've had much better luck using them wet. I think the swarf stays suspended in water, keeping the stone from loading up.

I don't see any difference in the cutting action between wet or dry - just the delay in loading up the surface.

Mineral Spirits

Christopher Schwarz

>I really like using mineral spirits on diamond stones. The liquid evaporates much more slowly, it seems to carry away the swarf better and you aren't introducing water into the equation. My DMTs look like they're right out of the box still.

Chris

Re: DMT Diamond Stones

Jim in Burlington Ontario

>I have the same experience and wondered wether to take it back or not. Maybe I need to buy the really course one and when it breaks in it will still cut fast. My other thoughts are buying the Veritas Mk2 power sharpener.

Re: replicated my experience

Jim in Burlington Ontario

>Hi Bill do you have a source for diamond powder. I have seen the paste in little tubes but it's pretty expensive. Thanks Jim

Re: DMT Diamond Stones

Lyn J. Mangiameli

>I have 7 (8 if you count both sides of a Duosharp) full size diamond "stones", and I nearly a dozen smaller flat, rod, and file shaped ones. The large ones are all DMT which are perforated; the smaller ones come from a range of manufacturers, including DMT

You experience generally describes mine. I've tried them wet, dry, scrubbed them with cleanser, you name it, and I've found that the effective life of these things is very short. My guess is that many of the individual diamonds embedded in the nickel get stripped off, some don't get fully exposed, and the remaining ones in a position to be effective get fractured and "rounded" such that they no longer cut aggressively and thus give that polishing appearance you observed. These are just speculations based on my observations, but someone with the right microscope should be able to confirm or rebut this objectively.

I will buy no more full size stones, but will continue to buy rods as there are no good substitutes for these in waterstones or free diamonds.

I wish my experience was different (after all, I've spent a lot of money on them), and I've tried hard to have the Diamond "stones" live up to there marketing, but I just can't get decent life out of them. For what I spent on the Diamond "stones" I could have easily purchased a basic set of Shapton waterstones, or a Veritas QPSS, or a basic Tormek, all of which do work for me.

Diamond Stones

Wiley Horne--Glendora CA

>Hi,

I have 3 almost-slick Norton stones, which started out 1200 and 600. I've tried em both wet and dry--but they get played out quite quickly no matter what I do. Right now, I'm doing what Bill Tindall recommended and am using the slick plates with diamond paste--they seem to be doing pretty well that way.

By the way, I'm also using diamond paste on an old 'surgical black' oil stone, and that is a great way to touch up blades on the fly while you're working at the bench.

If I had it to do all over again, I would not invest in expensive diamond stones. I do like diamond paste, however, and here the issue is to find a good substrate for the paste. David Barnett mentioned a few months back that MSC sells 6-inch cast iron rounds pretty cheap, about an inch thick, that could be flattened and used as a substrate.

Lyn's reviews have convinced me that the LV motorized system is a good way to go for bevels, if you don't already have a big investment in stones.

Wiley

microscopy

Bill Tindall, E. TN

>the diamonds in mine looked all rounded and what was left was deeply embedded. I'll bet that a quick soak in something that dissolved some of the substrate (someone said nickel) would restore some life to the stone. Dilute nitric acid would do or maybe even electrolysis with leads reversed. No doubt some bold soul will try it and report results.

I have tried recharging with diamond paste. Seems to work ok. I have been doing it on the little ones I used for honeing gouge bevels as well as a 60 micron large bench stone I use for initial material removal. May not be as good as cast iron, or maybe it is. Any way, I was short a cast iron piece so I tried it. The 60 micron diamonds sound kind of crunchy so they may not be embedding well.

Re: microscopy

Greg Sloop

>Someone else asked this...but I'll ask again.

Where to get the 60 micron "crunchies?"

Is the price reasonable?

Thanks,

Greg

Harris Lapping Plates, very long

Patrick Gibbons

>Recently when I found them on sale (from a tip given here on this board) I bought the Harris plate kit. The kit consists of two cast iron plates, one with corrugations to allow runoff of the swarf for the coarse grits, and one with smooth faces for diamond paste of finer grits. The coarser grits are silicon carbide. There are four grits in all. The instructions talk about the difference between lapping and polishing. Before using this system I used diamond stones and scary sharp and a leather hone with green compound. My emphasis was always to achieve a mirror finish as so many articles and, indeed, so many here have counciled. The Harris system made the point to me that polished isn't necessarily flat and vice versa. I experienced the same problems with diamond stones that others speak about and I also experienced the rounding over of the leading arras as someone else has spoken about when using the diamond stones or scary sharp. The Harris lapping plates produce no such rounding over. I have used them for flattening the backs of chisels and plane blades. One charges the plate with abrasive but not so that there is an excess. This got me to thinking that my sharpening guide probably also picked up abrasive on the brass wheel about as easily as the cast iron does. This convinced me to go free hand whenever possible, saving the guide for reinstituting a proper angle as needed. This I still do on 80 grit wet/dry scary sharp. I purchased India and Arkansas stones from Joel and called him after first using them. I had used the Arkansas for hours and still not produced a mirror finish to my bevel. He corrected me that that was not the objective, but turning the burr was. It was then that the Harris system directions came back to me in an epiphany that mirror finish was the goal of scary sharp, not oilstones, or indeed diamond-charged lapping plates. I am still working on improving my freehand abilities. This learning curve effects my results. In the past I achieved reasonable sharpness with SS and diamond stones, sometimes quickly, sometimes not. But I sharpened more frequently. Using the oilstones is slower. But the edge retention appears to be longer. This is subjective. The backs of my tools are much flatter because of the Harris system and this might explain the better edge retention as much or more than the oilstones. While waterstones may be "better" meaning a sharper edge, I do not want to use water here in Houston where rust is a way of life and I don't want the added maintanance that water stones require. I also am tired of spending money for this and I have reliable results with what I'm using now. I will end with a question. Why have I not seen anything on these boards in two plus years about ceramic stones?

Consider these *LINK*

WoodburnBob

>I share your frustrations with relatively high priced diamond "stones". The same issue of fast apparent wear on the DMTs came up a couple times on BadgerPond; same problem, different people. It's a bigger problem for my coarse grit DMTs. I have several EZELaps that haven't lost abrasion...but they are less flat than I wish they were, and are too fine and slow for my taste. I've cycled back to some old time Carborundum stones.

Anyway, these cheapo junkers, illustrated at for example the Harbor Freight site, are the sleeper of the market. I think they are the Bic Razor of diamond sharpening.


http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=36799

Re: DMT Diamond Stones

Fred Krow

>I agree with your observations, the DMT 12" Coarse and Fine stones I purchased about 30 years ago are still working fine. Excessive pressure will make the diamonds break down very quickly and become smoother cutting. Let the stone do the cutting and use lubrication, I like mineral oil or glass cleaner without amonia, this helps float away the steel grit and prevents clogging.

Regards,

Fred

experienced same result

Bill Tindall, E. TN

>I followed your same path except I wound up with some cast iron plates and charged them with diamond powder or paste. And I got your same results, most positive. As I posted sometime ago, this is hands down the cheapest* fastest way to sharpen hard tool steels.

*cheapest if one can find inexpensive plates. I found some nice pieces at junk yard in their cast iron pile.

see new post above

Bill Tindall, E. TN

>