Which DMT Stone to use?

Re: Which DMT Stone to use?

Greg Sloop

>I've got the combinations.

Coarse/Extra Coarse

Fine/Extra Fine

If the edge is in decent shape, literally like 10-15 seconds on each one. (But I'm probably a dope too, though it seems to get anything sharp enough to trim the hair on my hunched back.)

I really like them because they seem pretty dope proof. I don't have to flatten them, or worry about transferring the slurry to the next stone, etc.

Perfect for a scatter-brain like myself.

Re: Which DMT Stone to use?

Steve S, coastal Georgia

>I've got the double-sided one, blue dot (coarse) on one side and green dot (fine) on the other. Usually I put a hollow grind on my bevels which makes it even quicker to touch up an edge, especially when freehanding it. Lift the blade a degree or two for the final 2-3 strokes on the fine side to put on a microbevel. I finish on a leather strop with Lee Valley's green honing compound. The whole process takes probably less than a minute.

The edges pass the arm-hair shaving test, and they cut soft pine end grain cleanly. Sharp enough for most of what I do.

Steve

Mine didnt last

Robin Frierson

>I am on my second one, the first one didnt last long using it on steel. Its wore out in less than 1yr. My second one is only used to flatten my Shaptons and appears to be holding up.

I believe

Dan Donaldson

>Steve Knight had the same issue. The DMT's did not hold up to flattening steel.

Re: Which DMT Stone to use?

Eric Kuehne

>Jack,

I have the same stones as Greg. They're fine for basic sharpening but I hone with 3000 and 8000 grit water stones. I too really like the simplicity of the DMT's and the fact that I can use the XC to flatten my water stones.

That being said I am looking into a faster solution for flattening.

To answer your question directly I have and like the large combination stones. While they are good and I would buy then again I don't consider them to be a complete solution.

Good luck,

Eric in the dreary Silicon Valley

Are DMT "stones" guaranteed flat?

Dave (Arlington, VA)

>Hi All -

A month or so ago I emailed DMT through the email address on their website. I noted that the packaging on their stones say that the stones are "flat," but I couldn't find any statements or references to a flatness standard on their packaging. So, in the email I asked a couple of questions: (1) what is the standard they use for determining (or declaring) their stones to be flat, (2 )do they guarantee that their stones meet that standard, and (3) could a stone be returned (and either refunded or be replaced) if the stone was found to be out of "flat" to whatever standard they use.

I emailed them twice...a week or so apart. I never received a reply of any kind. Not even an acknowledgement. I'm not sure what to conclude about their "flat" claim, though I have developed an opinion about their customer-service orientation.

On the basis of this, I decided not to buy one or more of their stones.

Regards -

Dave

Re: I believe

Steve S, coastal Georgia

>Mine's been going over 4 years now and seems to be holding ok. It definitely doesn't cut as fast as it did when brand new but it still works for the way I sharpen. It does cut slower when it clogs but I scrub it with ajax powder and an old toothbrush every now and then which seems to restore it.

Keep in mind I'm just a weekend wood hacker, I'm sure I'd probably have worn it out if I was using it daily. Also with hollow grinding there's not as much steel to be removed which I think contributes to the longevity. For initial lapping blade backs I use a piece of aluminum zirconia 80 grit glued to MDF to get most of the flattening done, and finish with the DMT.

I figure this stone's going to wear out in a few more years, and I'd be tempted to try a different brand to see if it holds up better. For me at least, the diamond stones have been a lot less hassle than scary sharp paper, and you don't have to flatten them like waterstones. YMMV

Steve

Re: Are DMT "stones" guaranteed flat?

Don Clark

>Dave,

I had good luck with their customer service. I had purchased an "extra coarse" stone and it wore out in about a year of moderate use, including some plane iron flattening. I wrote to them complaining and they sent me a new stone and asked only that I return the worn stone.

However, I think you did the right thing by not buying the stone, because with relatively light use, my replacement has already lost most of the diamonds in a couple of areas. I now use it mostly for flattening waterstones and oilstones.

The extra coarse seems to be worse at letting go of its diamonds than the finer grits. Both of these stones seemed plenty flat, although I never tried to measure the flatness.

Don

Re: Are DMT "stones" guaranteed flat?

Steve knight

>the finer the stone the longer it lasts. but it cuts slower of course. the problem is tool steel breaks or wears off the tips of the diamonds fast. no one has really told me why this happens. but you can cut carbide or stone ofr a hell of a lot longer then you can tool steels.

they just don't get along. plus I never found diamond to cut all that fast for the most part. unless it was on my makita.

Thanks, Don

Dave (Arlington, VA)

>Thanks, Don, for the positive words about your experience with DMT's customer service. Sounds like they did well by you.

I have decided to hold off on diamond stones for a while and see how my foray into waterstones turns out.

Again, thanks for your post.

Regards -

Dave

That is a mystery

Dave (Arlington, VA)

>Steve -

I had noticed in other posts the point that you make: DMT stones don't last as long with tool steel as they do with stones. This too has been something of a mystery to me since the stones are supposed to be harder than the steel. Perhaps its in the stone's binder. That is, while the stones are harder than the steel the particles of stone abrasives "break off" easier than the tiny pieces of steel and are therefore not as hard on the stone.

Who knows!

In any case, thanks for the post.

Regards -

Dave

Solid Solubility???

Paul M. in San Diego

>I received this as a forwarded email, so I don't know the original source. It's way over my head, but perhaps some metal-heads here can make sense of it.

----------------------------------------------

Usually, whenever you form an alloy, of say nickel and copper or aluminum and copper, you end up melting these metals together in the required percentages and form an alloy. There is a upper limit governed by what is called as a Lever rule for certain percentage of one type of metal soluble in another. Copper and Nickel have unlimited solid

solubility where as iron and carbon have limited solubility. But the interesting part is iron and carbon are virtually soluble even at very low temperatures and this can be very easily seen from studying their phase diagram. Here is the link for Fe-C phase diagram. Even a very low percentage of carbon is sufficient to form an iron-carbon alloy.

http://www.matter.org.uk/steelmatter/metallurgy/6_2_4.html

Here is another link for Fe-C phase diagram and the theory behind it.

http://www.mmat.ubc.ca/courses/mmat380/lectures/2004/Lecture2-Steel(completel).pdf

Thus, the bottom line is carbon can sink into iron at even very low temperatures to form a stable Fe3C phase and even very low percentage of carbon in the range of 0.005 is sufficient to form a stable phase. When you rub diamond against iron or steel containing iron you are essentially generating some temperature at the point of contact and enabling a reaction between the two. Thus, even though diamond is the hardest material, it has to succumb to iron's natural ability to eat it.