DMT continuous and mirror finish questions

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prime77

Joined
Oct 11, 2006
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After reading many threads praising the DMT continuous stones I decided to give them a shot and see what I could get out of them. I got the coarse, fine, and extra fine stones and went to work on reprofiling my Manix2 to 15 degrees per side. Let me throw my praise out there for these stones. They make sharpening so easy. They cut fast and clean. The scratch pattern is very nice and even with all three stones and make for a short time of sharpening. I was able to bring the bevels to the edge with the coarse stone much faster than I anticipated. Even just with the coarse I was able to make the Manix2 nice and sharp. I then followed with the fine and extra fine. All three stones made for a really sharp knife but I wanted it sharper and with a mirror finish. I don't have the extra, extra fine DMT stone so I used my Spyderco Ultra fine stones, then used strops with white, and green compounds and then finished with Mothers mag and aluminum polish on a leather strop. After all this I got the Manix2 amazing sharp. I can shave hair with ease off my arm and treetop really well. I can get it to whittle hair too. but still no mirror finish. Any advice? Did I just not use the fine and extra fine stones long enough? Do I need the EEF stone? I have used the same stropping process after using my Sharpmaker and got a nice mirror finish. Here is some shots to show the experts what my finished result was. Any advice would be appreciated. Thanks
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Your last picture tells the complete story, your using excessive pressure and not using the F and EF stones long enough. The heavy scratches in your finish are from the C stone. I probably sound like a broken record with this pressure thing but in a sence you hardly need to touch the diamonds for them to work. See if you can "float" the edge on the surface of the stone.

The lighter the touch the less depth the diamonds scratch the surface of the steel. Because of this I use a method of decreasing pressure that seems to work very welll, I also tend to pyramid the abrasives, work up to EF then go back to F then continue up again. The coarse stones cut deep and take extra effort to remove by the "fine" stones, using the F stone longer will do the same thing it will just take time though.

Good pic's BTW, once the stones break-in and you get a feel for them you will be surprised just how sharp the EF stone will make a edge. Hair splitting with the right touch and not a burr to be found :D
 
Excellent post prime77. Good questions with good pics.

knifenut1013 said:
Your last picture tells the complete story, your using excessive pressure and not using the F and EF stones long enough.
:D
Click to expand...

Mors Kochanski suggests that as you progress through the grits, you will likely have to multiply the number of strokes by three (3) to remove the scratches from the previous stone. As an example, if you took you 30 strokes on the course stone, it would take ~90 strokes on the fine stones, ~ 300 strokes on the extra-fine stone, and so on and so forth. I have tried to follow this as a general rule or guideline and it seems to work fairly well. Is this your experience using the DMT continuous stones? I have the DMT continouos 8" stones as well and like them very much.


knifenut1013 said:
The lighter the touch the less depth the diamonds scratch the surface of the steel. Because of this I use a method of decreasing pressure that seems to work very welll, I also tend to pyramid the abrasives, work up to EF then go back to F then continue up again. The coarse stones cut deep and take extra effort to remove by the "fine" stones, using the F stone longer will do the same thing it will just take time though.:D
Click to expand...

I am also interested in the technique of decreasing pressure. Can you expand on that?

Sincerely,
Mark
 
Its as simple as it sounds, start with normal pressure and continue to decrease until it feels like your brushing a feather across the stone.

The x3 sounds good but your not going to need that much with diamonds. Maybe just double.
 
knifenut1013, thank you for responding and for your advice. I have tried to read all your posts on sharpening here. My goal is to be able to do what you did to the Umnumzaan in that one thread. A guy has to dream right. :D. I will take your advice here and go back through the F and EF twice and see what I can do. I'll try and post the results.
 
I went back to the F and EF stones and then the strops and have made a noticeable improvement in mirror finish. While not a perfect mirror it's progress. I tried for a very light touch like you mentioned knifenut1013. Watching the scratch pattern I understand what your saying now. Like everything in life it's a learning progress. There is still some of the scratch pattern left but she is really nice and sharp. I'll keep at it.

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Can't really tell until I get to my home computer but it looks much better. Remember though the EF is still a 1200 mesh/grit hone, it only gonna get so polished.

I'd strongly suggest DMT compound, you can use it directly after the EF stone and have perfect mirror finishes. Or you can get a EEF stone and not worry about stropping ;)
 
knifenut1013 said:
Or you can get a EEF stone and not worry about stropping ;)
Click to expand...
Or you can get an EEF stone and strop :)
the EEF is about 3 micron, so stropping at 1 micron dmt paste or .5 micron Cr2O3 is still an option. The stropping does make the mirror finish more mirror than without the stropping. But at EEF, it can be made amazingly sharp.
 
knifenut1013 said:
Its as simple as it sounds, start with normal pressure and continue to decrease until it feels like your brushing a feather across the stone.

The x3 sounds good but your not going to need that much with diamonds. Maybe just double.
Click to expand...

Thank you very kindly for your reply. I must say that I have learned quite a bit from you on this forum! :)

Sincerely,
Mark
 
I'd strongly suggest DMT compound, you can use it directly after the EF stone and have perfect mirror finishes. Or you can get a EEF stone and not worry about stropping
Click to expand...

I thought I may have to get some DMT compounds. Thanks again for the advice. I'm really pleased with the results so far.
 
I still at it trying to get that perfect mirror edge. I'm close. I got some DMT paste and went at it. I have a very reflective edge but still have some scratches that can be seen under magnification. Do I still have to spend more time with the fine and extra fine stones? The thing is even without the perfect mirror this is the sharpest I have ever been able to get a knife.

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I was able for the first time whittle a whittle of hair if that makes sense.:rolleyes:

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Very reflective edge but still scratches.
 
Pressure and moving on too early... but besides that it looks good.

Remember your stones still need time to break-in.

You are also experiencing what I call angle creep, as you sharpen you unknowingly increase you angle to hit the cutting edge. This leaves you with deeper scratches near the shoulder of the blade. Your edge is sharp though so USE IT first :D

For touch-up try to start with your finest stone if possible, it extends the life of your knife, makes getting it sharp again a quicker process, and will help with those unsightly scratches.

Try taking another photo of the edge with a darker backing, it will help clear up the image and give it detail.
 
knifenut1013 said:
You are also experiencing what I call angle creep, as you sharpen you unknowingly increase you angle to hit the cutting edge. This leaves you with deeper scratches near the shoulder of the blade.
.
Click to expand...

another couple of good tips. It's these small telltale signs that really provide you with the visual feedback that is part of the way to being a better sharpener.

Also: angle creep (changing the angle) can be seen in the light because of the different angle of reflection you will see. a perfect straight V-edge will have uniform reflection on the edge.

It would be interesting to create a post about the 'visual' side of things when sharpening. The kind of details that make you understand what's going on.
 
On top of the info you've already got, maybe you should spring for the xx-fine DMT stone? :)
 
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knifenut1013 said:
You are also experiencing what I call angle creep, as you sharpen you unknowingly increase you angle to hit the cutting edge. This leaves you with deeper scratches near the shoulder of the blade. Your edge is sharp though so USE IT first :D
Click to expand...

I'm under the impression that this is unavoidable. Would you agree? I've never been able to help doing this at least a little bit for every knife I've ever had and sharpened by hand.
 
Well knifenut1013 I took your advice and got results. I took my Endura down to 15 degrees per side. I used light strokes. Using lighter strokes towards the end of each stone. Then went on to the 6, 3, and 1 micron DMT paste on hardwood. Then finished on a leather strop with green compound. It's so close to a perfect mirror edge. Only some slight scratches visible under magnification. I am very happy with the results. Thank you for answering my questions. Here are some shots.

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Some slight scratches seen under high magnification.

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Now I have another question for you knifenut. This is what I wooden strops look like after some use. I have been storing then is a ziplock bag like DMT says. Are they still good to use? At what point do they stop being of any use?

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