Thread: DMT dilemma

Do you know anybody with a surface grinder and diamond wheel? It just may be worth it for ceramic stones.

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,

If anyone is interested, I'd be willing to try lapping one of these on my DMT 120. The stories I'm hearing are sounding a lot like the barber hone stories, so I'm thinking the coarser hone may do the trick.

Just thought I'd offer.

Josh

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 Chrisl

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.

Although the woodworking forum I referred to is a very tight knit group, they've been listening to my diamond lapping plate and ceramic stone questions with interest. I'm asking for more specific info on the Shapton Diamond on Glass Lapping Plate and its performance.

Interestingly, one person DID mention that the Shapton higher grit stones, when lapped extremely flat are prone to strong stiction if an edge is honed perpendicular to the length of a stone. It's recommended that a plane iron (or razor in our case) be drawn at a 45 degree angle on the stone instead.

Any polished and perfectly flat surface would exhibit the same sort of stiction. Gage blocks made from hardened steel and which are truly flat and polished need to be wrung apart after use as two surfaces which are flat will not permit air to enter, thus the stiction. The very high grit Shaptons are simply displaying the same tendency when a largish bevel is honed and polished to the same flatness as the hone. This of course does verify the claims for the accuracy of the Diamond Glass reference plate and it's ablility to flatten the 15k and 30k hones.

I just finished flattening my blue and yellow coticule on a DMT 325. After both were dry I placed them together and got a fairly good stiction between them. Nothing like a pair of gage blocks mind you but good enough to indicate that my DMT is quite flat. The scratches left from the DMT are enough to allow air to migrate in between the two stones. Had I carried on, using a finer grit but equally flat DMT, the stiction between the two hones would increase. After all is said and done though, considering the narrow bevel we use for shaving, this issue of extreme flatness quickly becomes a case of diminishing returns, measurable to be sure but insignificant in actual use/performance for our purpose.

As for lapping ceramic hones.... it's the surface scratches on the hones that determine the the way a ceramic hone cuts, not the size of the grit it was made from. I realize that the coarser grit in the medium brown Spyderco IS coarser and can be seen with the naked eye as it is almost porous due to it's different binder/grit combination but the Fine and Ultra Fine would seem to be the same ceramic substance with a differing pattern ground into their surface as they do not shed their grit as it gets worn but rather remains as manufactured. By lapping one of these hones, you are essentially changing their cutting behavior to whatever pattern your particular diamond hone displays and the method in which you use it. This of course does not mean it won't work because it does, but much of it's cutting action will be determined on how the user flattens the ceramic hone (circular or crisscross movments on the diamond hone) and to an extent the diamond grit size as well as how worn it is... A fresh diamond hone will have sharper tips on the grit and will presumably create sharper edged scratches than a worn hone with more rounded tips on the diamond grit. Lots of variables and the reason why I won't flatten my Spyderco hone... I just cannot predict the outcome, so if it works as is, I'm not going to fix it.



Regards

Christian