DMT Disappointment

HeavyHanded

HeavyHanded

Joined
Jun 4, 2010
Messages
6,642
Just picked up a DMT extrafine interrupted surface stone with the intention of using it as a faster option for my soft Arkansas stone. The other diamond stones I own (Smith's coarse and fine) both did very well to be lapped on some steel (an old saw blade) when they were new. I found this to noticeably improve the surface and the cutting characteristics of these stones. They're diamonds on steel, what can it hurt? That's what they're made to do, so I did the same to the DMT. It appears to only be making good contact in lengthwise strips between the recessed dots. Across the stone, contact is only sporadic between the recesses. I can't imagine this is going to fix itself with use. For 56.00 bucks I'm not happy, will be calling DMT or trying to return it to the woodcrafting shop I bought it from (sans receipt - my bad). I know on the whole DMT makes excellent products, I've used one of their serrated edge hones for many years and it still cuts like new. Just thought I'd put it out there, take a close look before you buy - not that I'd have been able to see this defect with the naked eye. I should have bought one of their larger continuous-surface bench stones, but that's a lot of scratch. Does anybody else have experience with this condition on their DMT products? The Smith's by comparison have plates that are nearly twice as thick and I've used them to lap my Arkansas and waterstones with no visible hijinks.

FWIW
HH
 
It took a bit to wear the preliminary crud off of my DMT stones but after they were broken in they perform quite satisfactorily.
I'm a rather picky bugger and I'm satisfied with my DMT setup.
 
You are probably just seeing the steel loading up in the diamond surface, and it isn't showing much around the interruptions because much of it loads up in them rather than the abrasive surface. Unless you are getting stripes in your steel, I wouldn't sweat it in the least. Even then, I wouldn't be so sure you are not seeing imperfections in the steel surface rather than the diamond surface.

A thicker plate really doesn't matter if you aren't wearing the surface down. How thick does the plate need to be to support 30-40 microns or less? If you wear through it, there is something wrong, at least with the DMT style stuff.

If you call their tech line, there are people with a LOT of experience that will help you out...:thumbup: I talked to one guy who was awesome.
 
Unless you are getting stripes in your steel, I wouldn't sweat it in the least.
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Right you are Sir, no harm no foul. Ran a knife straight down the stone for 10 passes and a clearly visible wave pattern is being cut into the edge.

thicker plate really doesn't matter if you aren't wearing the surface down. How thick does the plate need to be to support 30-40 microns or less? If you wear through it, there is something wrong, at least with the DMT style stuff.
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A thicker plate will resist deforming if the dies that stamp it out are getting close to the end of their life. That's what it looks like has happened.
Your lapping with a EF stone?
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Just to remove the surface crud and bits of diamond that aren't firmly embedded in the nickel. Surely you've noticed these diamond stones perform better after an initial break-in.
 
Never lap with the EF or EEF stones you WILL destroy them!!!

The diamonds are too small at this point and when lapping a "soft" stone the opposing abrasive can get too far down into the surface of the diamond hone. I'm sure you can figure out from here what will happen.

Proper lapping of a diamond stone for break-in is to rub it with another EF or F stone under water or running water with THE LIGHTEST FREEKING PRESSURE YOU CAN USE. Using too much pressure in either lapping or sharpening with a diamond hone will cause permanent damage to these type of sharpening tools.

If the warp is visible then its defective and all you need to do is send it back for replacement, DMT will take care of you.

One more thing, when lapping if you see dark black streaks FYI that's the diamonds being removed from your stone.
 
knifenut1013 said:
Never lap with the EF or EEF stones you WILL destroy them!!!

The diamonds are too small at this point and when lapping a "soft" stone the opposing abrasive can get too far down into the surface of the diamond hone. I'm sure you can figure out from here what will happen.

Proper lapping of a diamond stone for break-in is to rub it with another EF or F stone under water or running water with THE LIGHTEST FREEKING PRESSURE YOU CAN USE. Using too much pressure in either lapping or sharpening with a diamond hone will cause permanent damage to these type of sharpening tools.

If the warp is visible then its defective and all you need to do is send it back for replacement, DMT will take care of you.

One more thing, when lapping if you see dark black streaks FYI that's the diamonds being removed from your stone.
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I think he meant he was lapping the EF with an old saw blade, not another stone.
 
Either way, if the hone is flexing in use your using too much pressure and damaging your tool.

Diamonds are a "new breed" and require a different method of care. If the stone is defective then send it back thats what the warranty is for.

On a side note I too perfer a continuous stone, the poke-a-dot stones leave a different finish and are more sensitive to pressure changes.
 
Knifenut i have a question, i have a blue dmt aligner stone, it appears to show some vertical streaks in line withe the dots. is this bad?
 
Heiheit said:
I think he meant he was lapping the EF with an old saw blade, not another stone.
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I wouldn't feel comfortable lapping it with another stone. I took my old crosscut saw, put it flat on the bench, sprinkled a little water on it and put the DMT face-down. Did a few minutes of cloverleaf pattern using little more than the weight of the stone. Patterns were very clear when flipped back over - more or less disappeared when rinsed with water, but still visible if carefully looked over. The wavelike cut patterns in the knife edge are proof positive. I'm not doing anything crazy with the pressure etc, this is the third interrupted surface diamond stone I own - am familiar with some of the limitations. I'll be calling DMT on Monday, hopefully they'll make it good, if not I have a great tool for making a serpentine edge grind...

HH
 
I'll see if I can get a few - of the stone and more importantly of the grind pattern. I have a bad feeling that with my camera I'm going to have to really mess up a knife edge for it to show, for the stone I can just leave any pre-rinse metal residue on the stone and it should be pretty visible.
 
Just got a package in the mail from Mike at DMT. In it - a new EF interrupted surface 6" stone and a few goodies - diasharp card, one diafold and a file-looking doodad. Stone appears to have been selected (packaging was wide open) and came w/ a note thanking me for returning the defective stone and an apology for my trouble. All is well once again.

HH
 
I like DMT but have found I prefer eze-lap diamond goods...they just seem to give me better results and more controllable results then with the DMT pieces I use. I need to get some more though to see how it goes.
 
I just ran a quick side-by-side with the DMT EF, some 1500 grit Gatorgrit sandpaper, and compared both to the edge I produced recently with a hard Arkansas. As far as refinement of the grind pattern, all were about the same. The sandpaper looked the best, with the Arkansas coming in a close second and the DMT bringing up the rear, likely a result of the interrupted surface and the fact that there still seemed to be a little bit of the "corrugated" effect between the rows of relief holes (couldn't be my technique!...). Stropped the edges on some Flexcut gold, and they all could just shave some facial hair, easily pop arm hair, and cut newsprint across the grain with a smooth, barely audible hiss.


I've come to feel that Smith's does interrupted diamond stones better than DMT. I've never used a continuous surface DMT, but I can imagine they work very well. In any event, I have to give high marks to DMT's customer service even if it took five months to get squared away.

HH
 
HeavyHanded said:
I've come to feel that Smith's does interrupted diamond stones better than DMT.
HH
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I figured they're dirt cheap because it's just cheap diamond dust or powder sprinkled and glued to a base. Guess I'm wrong and I should give 'em a go? They just look so cheap, though!

Anyone else vouch for Smith's diamond?
 
KarlMaldensNose said:
I figured they're dirt cheap because it's just cheap diamond dust or powder sprinkled and glued to a base. Guess I'm wrong and I should give 'em a go? They just look so cheap, though!

Anyone else vouch for Smith's diamond?
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I'll vouch for having a Smith's and selling it as a "POS" IMHO, on evilbay last summer. The buyer left glowing positive feedback saying "okay".....:D That was mighty kind of him too. I got $15 plus shipping for the kit.
 
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