DMT D8C 325 DISAPPOINMENT!

After following all of the pros and cons of different flattening stones on this board, I decided to try the ever popular D8C.
Got and went to work on a few bad blades. It did good. Then tried lapping my JNat and Nortons and before long, the D8C was smooth as smooth as my strop. Cleaning it is also a bear. The thing developed a black shadow around the middle of the hone and I took for granted it was metal from honing some blades. I tried everything I could think of to clean it. But the bottom line is, I don't know how a diamond hone could get so smooth after just a couple weeks. It's like honing on a Norton 8000. Can anyone give me the scoop of what I've dome wrong? I do clean after each use by the way. All comments and suggestions welcome.

What were you doing when you were lapping? Mainly, were you lapping under running water? If you let a slurry build up, it can rip the diamonds out of the nickel that bonds them to the surface, which leaves you with a steel plate. You can see the color change when this happens, and I am guessing that may be what happened.

Always lap under running water. Never let a slurry build (rinse the DMT and the hone you are lapping periodically). I clean my DMT after each lapping so I don't get grit contamination; usually rubbing it under running water with my hand works, but scotch brite or similar also works.

I have the same D8C 325, bought in December 2010, so 2 months , I lapped
a Swaty hone and a coticule, and maybe honed 3 razors at all. Half of the plate is now smoth like not a diamond is there. I will try to talk with DMT to see if they have some kind of warranty on them. I also clean the plate as per DMT . I think , despite they indications, for lapping stones you need a 220 or even less grit.Or just this batch went wrong?
Regards
Livio

Quote:

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Originally Posted by livio

I have the same D8C 325, bought in December 2010, so 2 months , I lapped
a Swaty hone and a coticule, and maybe honed 3 razors at all. Half of the plate is now smoth like not a diamond is there. I will try to talk with DMT to see if they have some kind of warranty on them. I also clean the plate as per DMT . I think , despite they indications, for lapping stones you need a 220 or even less grit.Or just this batch went wrong?
Regards
Livio

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Does it still cut? My guess is that you only broke the hone in, and there isn't any problem with it.

Yes is still cut, but just about 3/4 of the plate. And on the sides the color is changing, it can't be cleaned anymore. You can feel with your fingers,
on one side still have the diamonds and one side is just metal.
I think this one was for learning, next one it will be for really working.
It may be becuse the slurry on the hones wash away the diamonds,I don't really know, but for sure in not about breaking in .
Thank you
Livio

Give them a call. Here is the webpage with their contact info. IME dia sharp (DMT) has real good customer service and if the problem is the plate's material or workmanship they'll give you a new plate. :gl:

You know I really hate to post this on the open forum because somebody will say it is wrong :(

You have to trust the numbers behind this statement OK???

You guys either have the worst DMT's ever made, or you did something terribly wrong... :shrug:

1. Small rule, never lap a stone that is lower then double the grit rating of the plate... :nono:

2. clean the plates, I use Comet/Ajax and a stiff nylon brush

3. I have honestly lapped hundreds of Barber's hones on my DMT 120 and 325 and I don't even want to count how much lapping has been done besides that on my 325...

Clean the plates, check the plates for diamonds with a piece of Glass, see if you actually ripped the diamonds out, I doubt it, but it is possible...

Then follow Jimmy's advice above :)

1. I always lap under running water.
2. If the diamonds come out that easily, it isn't worth using
3. If the honing didn't kill the plate, then the aggressive cleaning I am doing to it surely will.

I am thinking it must be a defective DMT. I do/did everything right including rinsing the thing extremely well after use. There is no way after just a few uses that the DMT or ANY lapping stone should be bald. On to Plan B.

Thank you for the DMT C.S. info

Thank you very much for the contact info. I call them and they said to send the plate for a check up and maybe changing. I will keep posting as soon I have more info. They really stay behind they product.
Regards
Livio

How much pressure were you using while lapping?

I agree with Glen. You can choose to believe me or not. I have four DMT's including the D8xx and D8c. I"ve used the D8C countless times, lapped hundreds of Coticules, and hundreds of C12k slurries. It still works great. Yes, it is smooth, but it works, it's broken in. As Dylan pointed out, I always do so under running water. It has no build up. I clean it after each use. Works fine, lasts a long time....

I did not put a lot of pressure. The Swaty take about 1 hour both faces,and coticule 45 min . It was done under running water.
Livio

I have had absolutely no problem with any of my DMTs. I have 8" Coarse, 8" fine, 8" extra fine and 8" extra extra fine. With the 325 I sharpen everything from my axes, to damaged knives, initial bevel setting on used chisels, and everything else in between. I've had them for over 2 years and they still cut like they were new.

Don't give up on DMTs, they can take a joke and are the best lapping stone I've used. Your plate is not ruined. I agree that the continuous-surface 8 x 3" plates do load up during lapping, and can be difficult to clean. The best cleaning method I've found is Barkeeper's Friend liquid, and my fingertips, repeatedly rubbing and rinsing under running water.

Some time back, I switched to using the continuous surface plates for razor honing only, and now use only a big perforated Duo-Sharp plate for lapping (coarse on one side, extra-coarse on the other). The perforated surface really seems to avoid loading up when lapping under running water, and cleaning is far easier because they don't load up in the first place. They can really remove material in a hurry with pressure, but leave little surface scratching when used with light pressure.

I use the big 10 X 4" Duo-Sharp like the one pictured below. They've gotten a little pricey now, but I lucked out and got mine on sale for only $20 more than a regular 8 x 3 plate over a year ago. The big 10 X 4 size really helps. I do x-coarse, then coarse, then move up through 600 grit and 1000 grit wet/dry sandpaper, the sheets laid right on top of the big Duo-Sharp as a base. Works beautifully.

http://theconsumerlink.com/imagesEdp...GY/p55497b.jpg
http://theconsumerlink.com/zoom.asp?...NINGTECHNOLOGY

I'm pretty sure the only thing DMT recommends for a lapping plate is the extra coarse.

I think I've gouged out some of the diamonds in a 1cm strip along one of the short edges - there is something very shiny peeking through and it develops rust spots there if I leave it to dry propped with that side down, so I'd say it's the steel backing. I attribute that to user error, I've probably lapped around 10 barbers hones on it, three sides of a chinese, and a dozens of belgians, thuringians, nortons, naniwas.... I am sure I can lap at least a dozen more barber hones on it, but since my honing interests have changed, I can't forsee lapping anything but the naniwa supers, so that dmt is definitely more than enough for the rest of my life.

I've always used the comet/ajax (whatever I have at the moment) to clean up the steel of my DMTs and that works really well. I don't bother with detergents after lapping though - most of the mud goes down the drain and any leftovers don't affect the honing and go away next time anyways.

I always wondered about those perforated plates. I have a continous and it's been weird since I've used it to lap. I take it from what you are saying, they're good for lapping, but not for razors?

Thanks

Quote:

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Originally Posted by FatboySlim

Don't give up on DMTs, they can take a joke and are the best lapping stone I've used. Your plate is not ruined. I agree that the continuous-surface 8 x 3" plates do load up during lapping, and can be difficult to clean. The best cleaning method I've found is Barkeeper's Friend liquid, and my fingertips, repeatedly rubbing and rinsing under running water.

Some time back, I switched to using the continuous surface plates for razor honing only, and now use only a big perforated Duo-Sharp plate for lapping (coarse on one side, extra-coarse on the other). The perforated surface really seems to avoid loading up when lapping under running water, and cleaning is far easier because they don't load up in the first place. They can really remove material in a hurry with pressure, but leave little surface scratching when used with light pressure.

I use the big 10 X 4" Duo-Sharp like the one pictured below. They've gotten a little pricey now, but I lucked out and got mine on sale for only $20 more than a regular 8 x 3 plate over a year ago. The big 10 X 4 size really helps. I do x-coarse, then coarse, then move up through 600 grit and 1000 grit wet/dry sandpaper, the sheets laid right on top of the big Duo-Sharp as a base. Works beautifully.

http://theconsumerlink.com/imagesEdp...GY/p55497b.jpg
http://theconsumerlink.com/zoom.asp?...NINGTECHNOLOGY

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Quote:

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Originally Posted by Zomax

After following all of the pros and cons of different flattening stones on this board, I decided to try the ever popular D8C.
Got and went to work on a few bad blades. It did good. Then tried lapping my JNat and Nortons and before long, the D8C was smooth as smooth as my strop. Cleaning it is also a bear. The thing developed a black shadow around the middle of the hone and I took for granted it was metal from honing some blades. I tried everything I could think of to clean it. But the bottom line is, I don't know how a diamond hone could get so smooth after just a couple weeks. It's like honing on a Norton 8000. Can anyone give me the scoop of what I've dome wrong? I do clean after each use by the way. All comments and suggestions welcome.

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This is why the only DMT that should be used for lapping is the DMTXXC all others are just a waste of time and money when it comes to lapping and offer no benefit.

Excellent thread!:tu

I just purchased a set of DMT's, 125-8000, that includes 2 of the 11" 220 grit. The 220 will be the main hone lapping plates. I had considered the perforated surface version and will probably purchase 2 of those as well in the 220 grit if they are available.
I had tried the 125 grit loaned to me from Bruce but I did not like the very deep scratches it created so I settled on the 220 grit.

A number of years ago I purchased a 400 grit & 1200 grit EZE Lap diamond hone set and learned that they get destroyed by lapping hones on them.

Frankly, the next thing I will have is a cast iron machinists lapping plate to do those jobs.

Quote:

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Originally Posted by pelicano

I always wondered about those perforated plates. I have a continous and it's been weird since I've used it to lap. I take it from what you are saying, they're good for lapping, but not for razors?

Thanks

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To be honest, I don't really know if the perforated plate should only be used for lapping, and continuous plate only for razors. But that's how it's shaken out for me trying both. The perforated plate is just less hassle and more effective for lapping in my experience.

I've lapped a number of stones with a coarse continuous plate, but I've never put a razor on my coarse perforated plate at the same grit. I'm pretty sure it would work fine, but something about running a razor's edge (even a damaged razor) across a perforated diamond plate just gives me the willies.

Quote:

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Originally Posted by FatboySlim

To be honest, I don't really know if the perforated plate should only be used for lapping, and continuous plate only for razors. But that's how it's shaken out for me trying both. The perforated plate is just less hassle and more effective for lapping in my experience.

I've lapped a number of stones with a coarse continuous plate, but I've never put a razor on my coarse perforated plate at the same grit. I'm pretty sure it would work fine, but something about running a razor's edge (even a damaged razor) across a perforated diamond plate just gives me the willies.

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If your perforated plate is well broken in it is okay for damaged razors. I tried and was able to take out a few chips from a couple of blades I did not care about. I agree the continuous plates are better for blades, but the others do work. And, yes, it feels creepy the first time you try it.

My DMT 325 is gray and grungy but still works just fine. I have a DMT 1200 for bevel setting that I like and alternate between that and a couple of 1K stones.