Thread: DMT dilemma

Originally Posted by randydance062449

It is beginning to become apparent that the DMT is effective for waterstones/natural stones and razors but not so practical for ceramics. Just my two cents,

I have no experience with the Shapton ceramic on glass plates, but it's interesting to me that the cornerstone of that system is the Shapton diamond on glass lapping plate at approx 270-325 grit. The Shapton plate, according to their website says the diamonds bonded to the surface are polycrystalline vs. the monocrystalline on the DMTs. Does anyone know, are the Spyderco hones worlds harder than the Shapton ceramic on glass plates? I'm curious about this.

Ted Pella, Inc. site says polycrystalline diamonds are LESS friable yet DMT says they are MORE friable.

DMT's site says the less expensive monocrystalline like DMT uses are much better than polycrystalline diamonds like the Shapton plate which DMT says that the polycrystalline diamond "breaks apart and wears away easily with use." DMT says "sharpeners made with polycrystalline diamonds will wear out and need replacement".

I'm confused!!

Hmmmmm......I just looked at the Shapton site again about the diamond on glass lapping plate and I don't see it specifying mono or poly crystalline diamonds. I swear it mentioned polycrystalline somewhere on that site for that plate!

Over the years I have always heard (and read from different sources) that monocrystalline are less friable than the polycrystalline version. The mono is also more expensive, which might indicate some superiority.

Two reviews from woodworkers and knife nuts:

• Woodworkers post #5
• Knife Users post #3

I've owned an Eze Lap poly hone for about 10 years. It's in my desk drawer beside me right now. I almost never use it.

I've been heavily using a 4" DMT Fine machinist hone (actually 4 3/8") for over twenty years, it rides in my back pocket and in my current avatar. Based on proven performance, I'll stay w the mono version.

I would also love to see the results of lapping a Spyderco UF on the Shapton.

Originally Posted by Sticky

I would also love to see the results of lapping a Spyderco UF on the Shapton.

Sticky,

I'd love to see those results myself, but am unprepared to spend the 300 or so bucks it would take to try it. And then would likely be unprepared for dealing with the emotions washing over my weak psyche when I saw the Spyderco eat the Shapton lap for lunch. (I think this may be among the reasons my DMT is going south -- the Spyderco pointed and said, "go south young grit, go south.")

I have a post into the Shapton Japanese Woodworking forum asking the guys why they think the Shapton DGLP as they call it (Diamond on Glass Lapping Plate) is the cornerstone of the entire Shapton CERAMIC on glass stone system but the Spyderco UF Ceramic seems to eat DMTs, another diamond lapping plate for lunch. We'll see what kind of responses I get. Some of those guys also mention having/using DMTs so they may have a dual frame of reference.

I'm not conceding that the Spyderco hones hurt the DMT hones just yet. I've lapped an Arkansas hone on my DMTs, and if that sucker didn't kill them, I don't see how anything could.

The references I've seen to wrecking diamond hones usually involve sharpening with too much pressure. The pressure loosens the diamonds, and they start cutting away at the nickel plating, which is pretty soft. It might be possible to accomplish something similar by using a lot of pressure while lapping, but it would be hard to duplicate the amount of pressure you could exert with a knife edge.

I'll be interested to see what comes of this thread.

Josh

Originally Posted by JoshEarl

...
The references I've seen to wrecking diamond hones usually involve sharpening with too much pressure. ...

I'm with Josh on this one. I now have over 70 hours of wiping Spydercos over a DMT coarse (light pressure). The DMT is still working ok. So far the DMT is wearing me out first...

I'll also be watching with interest.

Originally Posted by Sticky

I'm with Josh on this one. I now have over 70 hours of wiping Spydercos over a DMT coarse (light pressure). The DMT is still working ok. So far the DMT is wearing me out first...

I'll also be watching with interest.

I feel for you. I spent about 30 hours lapping two sides (one wide/one narrow) of a Chinese 12K and it felt very strange to finally say "I'm done." Of course I wasn't entirely done because I hadn't yet reached the extreme corners but I decided it was good enough since I don't hone all the way to the edges anyway. Oddly, when I finally did quit, it felt strange to not be lapping the hone in every spare moment. I started to realize that I really missed it.

Originally Posted by Utopian

I feel for you. I spent about 30 hours lapping two sides (one wide/one narrow) of a Chinese 12K and it felt very strange to finally say "I'm done." Of course I wasn't entirely done because I hadn't yet reached the extreme corners but I decided it was good enough since I don't hone all the way to the edges anyway. Oddly, when I finally did quit, it felt strange to not be lapping the hone in every spare moment. I started to realize that I really missed it.

Holy smoke! What hone were you using to lap the 12K for 30 hours if I might ask? If it was a DMT, that concerns me that it took that long (not questioning your lapping ability in any way, I say it concerns me because I'm wondering if maybe you're DMT is more broken in than mine and maybe I'll have to prepare to work mine that hard as time goes along). I got a 12K from Woodcraft just last week and lapped it on the DMT 325 grit. It took me an hour (I did lap only one surface and added beveled edges), about as long as it took for me to lap my Belgium Blue. Sure an hour isn't a long time in comparison to what you guys are describing, but it's alot longer than lapping a Norton!

Originally Posted by Sticky

Over the years I have always heard (and read from different sources) that monocrystalline are less friable than the polycrystalline version. The mono is also more expensive, which might indicate some superiority.

Two reviews from woodworkers and knife nuts:

• Woodworkers post #5
• Knife Users post #3

I've owned an Eze Lap poly hone for about 10 years. It's in my desk drawer beside me right now. I almost never use it.

I've been heavily using a 4" DMT Fine machinist hone (actually 4 3/8") for over twenty years, it rides in my back pocket and in my current avatar. Based on proven performance, I'll stay w the mono version.

I would also love to see the results of lapping a Spyderco UF on the Shapton.

Thanks for those linnks, Sticky. They were interesting. It's reassuring to know that some of those guys had been using the DMT even back then and thought they were a class A product.

I'm still left wondering why monocrystalline are supposed to be better than poly when poly is 4 times the price when purchased in paste form. On the Ted Pella site, they have this to say about poly vs. mono (underlining by me to highlight a statement that seems to contradict your posted links and DMT's FAQs:

The polycrystalline is typically used on hard to polish materials such as ceramics, tool steels, sapphire, and super alloys. It has more facets or cutting edges and keeps its cutting ability by being less friable (easily crumbled or pulverized) than the more common and less costly monocrystalline diamonds. Monocrystalline diamonds tend to have longer sharper edges and are more suitable for less hard materials such as brass or soft steel.
Polycrystalline diamond is somewhat spherical in shape and it has a greater number of cutting facets than monocrystalline diamond, therefore reducing subsurface deformation, giving more precise results when surfaces are etched.
Maybe the mono works better in the bonding process for the DMT plates? The DMT site shows illustrations of what look like shards of the mono diamond sticking out of the nickel substrate, almost like canine teeth. Maybe the poly that look more rhomboid (like the garnets in the belgian stones) although they have more cutting edges, wouldn't stick out as significantly from the nickel substrate?

At any rate, I like my DMT 325 grit and I can't wait for my DMT 1200 grit to be exchanged by DMT (I sent mine back since it had some surface blemishes that could be felt almost like raised nicks above the surface of the diamonds). The more the 1200 was broken in, the better it felt!

Originally Posted by Chrisl

Holy smoke! What hone were you using to lap the 12K for 30 hours if I might ask? If it was a DMT, that concerns me that it took that long (not questioning your lapping ability in any way, I say it concerns me because I'm wondering if maybe you're DMT is more broken in than mine and maybe I'll have to prepare to work mine that hard as time goes along). I got a 12K from Woodcraft just last week and lapped it on the DMT 325 grit. It took me an hour (I did lap only one surface and added beveled edges), about as long as it took for me to lap my Belgium Blue. Sure an hour isn't a long time in comparison to what you guys are describing, but it's alot longer than lapping a Norton!

I was using a DMT 325 that previously had lapped a Swaty, 2 carborundums, a norton 1000, a norton 4000, and a norton 8000. My 12K was convex--the center faces were highest in the center. That means as I lapped, the center became smooth and the edges were untouched. As lapping proceeded, the smooth center got larger and I was therefore lapping a progressively larger area and the progression out to the edges became slower. That is why I stopped when all but the last 1/2 inch of each corner was polished--the greater the polished area, the slower the lapping was going. Because I like to hone on narrow stones, on both the 12K and all three nortons were honed on a wide side and a narrow side.