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DMT "stones"

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Mary, or anyone else using DMT exclusively,

I switched from ark stones to DMT about 6 months ago, and I have been extremely happy since. My question is that the abrasiveness of the stones don't seem as robust, I guess, since when I bought mine. Is there a wear life for the stones, or has anyone found that they need to replace them after a certain amount of usage?

Thanks much for any feedback.

Hi Matthew,

There is a "wearing in" time. When you first have an 8000 grit DMT, it is probably more like a 4000 or 5000 grit. It takes a bit for it to break down to an 8000 grit. I have had mine for several years, and once it is broken in, it has not changed. It's as smooth as glass, but still is pretty aggressive. I have not heard about it wearing so fine that it needs to be replaced. They are great stones, aren't they?

Glad to hear that you have had and used yours for years. I've searched around and read about the breaking in, but wasn't prepared for the amount of difference I could see and feel while sharpening.

And they are really great stones. I doubt I'll ever go back to ark stones...I've saved so much time during the sharpening process since I switched.

I am very interested in these 8000 grit DMT stones, ever since I sharpened my carving tools to take a weekend class with Mary and discovered when I arrived that my tools were not sharp enough!  I used my translucent Arkansas stone for each tool, and I am pretty sure my technique was ok; I decided it was the stone.  I have been doing a little research on DMT as I am considering buying the 8000 stone, and Deneb Pulchaski (sorry if I spelled his last name wrong) from Lie Nielsen thinks DMT is not consistent; that some stones are not as good as others.  He says the quality varies and some do not provide the finish that they claim.  Has anyone else had any problems with DMT?  Matthew, do you feel your stone is sharper now or duller now than when it was new?  You asked about a wear life, so I wondered if you were finding the stones are not as sharp now?  Of course, Deneb is promoting Lie Nielsen's water stones, so I am not sure how much faith to put into his opinions.  I was interested in your statement that you would not go back to Arkansas stones; is it worth the expense, then?

I discovered DMT has a 1200 grit diamond stone for carvers and turners called the Wave.  It is a rigid plate that has a basic rectangular shape but is bent in a few directions to provide constantly changing curves.  A video demonstrated matching the curve of your gouge to the same curve on the "Wave", and taking a few short light strokes at that spot.  If it were offered as an 8000 grit, I'd probably buy it right away, but it may not provide much more sharpness than my translucent does now, so I hesitate.

Mary, have you heard of anyone with an 8000 grit DMT stone who feels the stone is not as advertised?    I am wondering if I should get the Wave and the 8000 both, and use the Wave first then the 8000 grit?  Or, since most of my tools are "translucent sharp", can I get away with only the 8000 for all my sharpening?

I asked a DMT rep about leaving puddles of water on the stone.  He said that it was not a problem at all, except, the metal from the carving tool may be on the stone and mixed with water, can turn rusty.  Not the metal from the stone itself.  But the metal and rust from the tools mixed with water can become embedded in the stone and cause it to be less sharp.  The remedy is to clean the stone with an abrasive such as Comet or Ajax, and rinse well.  There is no permanent damage, just a temporary clogging of the spaces that makes the stones less abrasive until cleaned.  Other than that, you can leave water on the stone for an indefinite period and it will not damage the stone.  This is all just a quote from him; I have no first hand knowledge at all.

My chisels and plane irons are super sharp and I have no issues at all with them - I sharpen on the translucent and sometimes strop them.  But this same method does not get my carving tools as sharp as they need to be, so I am seriously looking into buying an 8000 grit diamond stone. Eager for more information!

Hi Joyce,

Let's see if I can answer all this without writing (another) book.

First of all about the "wave". I have one of those, and with it being a 1200 grit, I find it too aggressive to be used as a slip stone for the insides of gouges. It will remove a lot of metal. It's great if you want to re-shape the inside of a gouge, or want to create an inside bevel, but not for simply removing the burr or wire edge during the sharpening process. I have spoken with DMT to see if they can produce an 8000 grit wave and am still waiting.

I'm cautious about their recommendation to never leave water on the stones. My 1200 has several little "pits" on the stone. I assume this is because I often bring these to classes and water is sometimes left on them all day. But assumptions can be dangerous. It could simply be that somebody gouged that part of the stone with the corner of their gouge (would hate to see what the gouge looked like after that). But there is definitely a damaged area which creates a very tiny, but rough point that you can feel when you run your hands along the stone. Small, but still pretty major when you are trying to sharpen a gouge.

Most of the diamond stones take a few weeks or month to "break in". My estimate is that the 8000 grit stone is about a 4000 to 6000 grit stone at first. It is then worn down to an 8000 grit. Once it is broken in, I have not found it to change.

Whether you use the Arkansas stones, water stones, ceramic stones or the diamond stones, you should be able to acquire a razor sharp edge to your carving gouges if you use very fine grit stones. I used black Arkansas stones for the first 20 years of carving, and they worked great to sharpen carving gouges. The main reason I changed to diamond stones was the speed. I cut my sharpening time in half.

My suggestion - stay with the Arkansas stones that you have and really master the technique of sharpening. It sounds like something in the sharpening process may not be right. Maybe positioning of the bevel? Keeping the bevel consistent? Rotating it across the stone? Using the slip stone correctly? So many variables can happen. But ultimately, if you are unable to get that razor sharp edge with Arkansas stones, purchasing the diamond stones (probably) won't make a difference in the sharpness.

I'd love to help you get your tools sharp. Next time I'm in Maine you need to make a point of tackling me and bring your carving gouges with. I'd like to take a close look at them and investigate what the issue is. It's difficult to instruct via email and writing.

But...diamonds are a girl's best friend 🙂

Joyce,

What the Lie Nielson rep said about DMT consistency is something you can read about on many online reviews. I read about that same thing on Amazon, but chose to buy them anyways. I have the 8" plates in their offered grits, and out of the 5, I think I only am having trouble with the 8000 grit "extra-extra fine" plate. After Mary said it may take awhile to break in the stone, I took 7 plane irons to it to help speed that process along. It definitely helped, but it still seems a little rough. All of my other DMT plates didn't take this long. So, I don't know if I got a bad one, or if I need more patience and use.

All of their plates will "dull" a little, but they still work great. And yes, I'm still glad I left the ark stones. DMT is just faster overall...especially if you have a tool that is damaged pretty good. I haven't noticed any further loss of grit to the plates after that initial loss. I've only been using mine for a couple months now...I'll let you know in the future if that ever changes.

As for the wave...I looked very long and hard at it also and decided to pass. Once I got the correct sharpening technique on stones down to where I was no longer having tool troubles in harder woods, I decided to stick with that and look no further. Let me know if you ever get it and have a good review on it.

And definitely right on leaving the water on the DMT...as long as there's no metal swarf left on there, the water won't hurt. I always clean mine after just to make sure I always start with no clogged plate the next run.

Good luck and hope that helps!

Thank you both for your information.  This is very helpful!  I will pass on the "Wave", and focus on my technique on the stones I have, although I may give in to temptation at some point and get the 8000 diamond stone.  Years ago, I bought a diamond stone (without the holes) that did not "last" even a year before the diamonds seemed to be gone and I was left with a plain metal plate.  I don't remember the manufacturer.  So I was intrigued when Mary brought her 8000 diamond stone to our class. It seemed to be much more effective in sharpening the tools I brought with me. It almost acted as if the translucent Arkansas just was not hard enough.  I just reviewed all the sharpening videos, and will focus on the points you mentioned using my current stone. And, of course I would LOVE to take you up on your offer to get my carving tools sharp, Mary!  I doubt you will be making a trip to Maine in the winter, but actually if it is anything like the past few winters, we have had beautiful deep snow perfect for cross country skiing or snowshoeing and not to be missed!  Unless, of course, you are stranded in an airport as that snow arrives.

mary and DMT stone users,

I've been a gunsmith, stock carver , ivory carver, and violin maker for 35 + yrs. I have only sharpened with the Ark. stones.  Taking Mary's on-line classes trying to learn traditional style carving, a differnt animal altogether. Mary being full time proffesional vs me part time with a day job I bought the DMT "8000 grit".  upon using it the first time I was SHOCKED at how badly it scratched and nicked the edges of my chisels. NOT A HAPPY CAMPER!!!  I called DMT to complain and get more info.  DMT stones are listed in MESH not Grit,  they say that the mesh and grits are equal, but they'r not.  American Standard Machinest chart list 8000 mesh as 2500 grit. DMT also list there 8000 stone as 3 micron. = @ 4500 grit to 5000 grit. closer to Mary's observation.  Note; they do cut way faster than Ark's, cutting sharpening time in half.  I've been using my DMT for planing irons and carpenter chisels trying to wear them in more and using them on my carving chisels ONLY when they need some work, finnishing with my Ark, hard blk, then trans. followed by stroping.

There's my rant.  Sorry!  Not sold on DMT's just yet.

Mike Duncan  (old bear)

Michael, keep us up to date on how your testing turns out. My 8000 grit now feels like glass and creates a mirror finish, and still sharpens well. It's about 2 years old and I bring it to every class I teach and also use them for my own sharpening, so it's been well worn in. I doubt it will change much from this point on. You an still tell along the outer edges where tools have not really touched that it is slightly rougher, so there is definitely a "wearing in" period. I am hoping that these will last a lifetime, and with all the abuse I put them through, this should be a good test. Will report!

Mary,

I bought an 8000 grit stone,but didn't like it, It left a rough surface on my chisels, I complained to DMT and they sent me a new stone along with information regarding it's care, and that there is a break in period with that stone.

I have been working on my stone an hour at a time for the past few weeks and haven't seen much change. How long did it take to break your stone in , and what did you use to make sure it was smooth across its surface and not just the middle .

 

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