Weird "feel" and results when using extra fine sharpening (DMT) stone

How much pressure are you using when you're using the fine stones? If you're using inconsistent pressure, you will notice parts that look more rough because the stone isnt coming into contact with that area leafing it "unfinished" and unpolished.

Ps, next time you may wanna post this in Maintenance, Tinkering, and Embelishment; you will get more of the answers you're looking for.
 
Technique for the most part is the same when moving up the grits if you have proper technique. From the sounds of it I think you need work on it. It sounds like you have a problem with keeping a consistent angle when sharpening and possibly a few other things come to mind but I want more info to confirm that. Head on over to the maintenance sub-forum and provide us with more details (we'll ask for what you don't give us, don't worry) and we'll tear apart what you're doing step by step and turn you into a sharpening guru if you let us.

That maintenance tinkering and embellishment sub-forum is where the sharpening guru's hand out and frequent so you get a lot better answers (by a huge) margin over there than general most likely.
 
I've found that over time the DMT stones wear and parts of the stone will have a finer effective grit than other parts. It is possible that you may be putting more pressure on a particular area of the stone as you sharpen, and that section is giving you a finer scratch pattern than other parts. For me it is the center of the stone that is finer, and the corners are noticeably coarser.
 
Before you're going to your fine stones, are you sure that you have an even burr along the entire edge? When using more coarse stones to create a burr, you can use a little more pressure, but when removing the burr on a finer stone, always use very light pressure.
 
Cynic2701 said:
I've found that over time the DMT stones wear and parts of the stone will have a finer effective grit than other parts. It is possible that you may be putting more pressure on a particular area of the stone as you sharpen, and that section is giving you a finer scratch pattern than other parts. For me it is the center of the stone that is finer, and the corners are noticeably coarser.
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The stone could also just be "clogged". Using a rubber eraser on the stone then running it under water with soap will make it feel like new again. However, if you do all that and the stone still has no bite, then it just can't take anymore
 
I make sure the DMT is clean
DMT recommends kitchen cleaner like Comet
I use it with a toothbrush and cold water

I use the sharpie method
Take a permanent marker like a sharpie and color the edge of the blade
The edge that is being sharpened
Sharpen with a couple of strokes across the edge with the Extra Fine
The sharpening will take off the marker and show you exactly where you are sharpening and what sharpening angle you need to change

Recolor the edge
sharpen with the fine
Check for a burr
work both sides to remove the burr

Repeat for Extra Fine

That should bring you to sharp
 
Sound like your angles are wrong. Using my aligner guide I can shave off the EF, and shave even better off the EEF. Watch the pressure, keep the angles right, make sure you fully refined the edge on the previous grit, and clean your stones.
 
I have those stones. The edge will get so smooth that it feels dull and won't cut as effectively as an edge with a bit of a bite. That is exactly why I parked my DMT Fine and Extra fine, and Extra extra fine stones and stop at the blue, coarse. It has much better bite on the stuff I typically cut. I have gone all the way up to mirrored like normally only seen with guided systems like Wicked edge ( I have 2 different guided systems) but I find that aside from being fun and impressive it doesn't really help. Try cutting ropes, especially synthetic, or skinning & caping an animal with coarse, very dirty hair and the coarse-ish edge does a bit better. Likewise ropes, tomatos, and meat ( muscle & tendons).

Try the same sharpening but stop at black, or blue DMT's, or Norton Silicone Carbide stones coarse/fine.

Joe
 
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I'm going to throw in for technique. Take a look at the areas where you're getting good results off the (E)EF, compare to where the edge isn't so nice, and try to determine if there's a relationship to your mechanics.

The margin of error when freehanding is determined largely by the size of the abrasive. You can have some wooble at the larger grit size and the bevel will still appear flat and cut well. As the size of the abrasive starts to shrink, the amount of angle wobble shrinks as well and can wind up resulting in intermittent and somewhat poor contact along the cutting edge.

Also, the irregularities along the edge shrink too, and will result in an edge with better push cutting qualities and diminishing draw cutting qualities (though with diamond plates they tend to stay pretty toothy right up the EEF on most steels). What you expect of the finer edge in terms of cutting might have to be adjusted.

Between the above two conditions, many folk will tend to see noticeable shift in their edges as they get much above a medium/fine edge finish, is a fairly common observation. For most EDU the medium/fine finish is ideal anyway as it gives a nice blend of the two cutting characteristics and tends to have greater longevity with less maintenance.

A few drops of soapy water or mineral oil can sometimes increase tactile feedback on those plates and help a little with any technique issues.

Martin
 
Possibly the curve of the blade is where you're having problem?

I'd suggest take one of the knife, start over, share how it goes from each grit. Without a definitive knife such as steel, size, and how much pressure, more description on how you move it across and how you get to the curved part, etc., it's a guesswork. Picture will help too.

I also suggest go to HeavyHanded washboard link, watch the video and check the manual he created. It is very useful as much of the tips are applicable for DMT as well.

And this link might give you insight in what happens to the edge as you move along:www.bladeforums.com/forums/showthread.php/1014274-What-is-sharpening-a-knife-about
Sounds novice, but a good step by step reminder that serves as check points.
 
dogbertius said:
Good day,

I keep a spare DMT duo-sharp folding sharpening stone in my ruck when I'm out on hunts for repairing my blades (I carry, while in the woods, a Kabar USMC mk2 and Cold Steel Espada 62NX, beautiful blades), as well as fixing a badly mangled broadhead if I honestly feel it can be used again and not cause undue suffering for the buck that it hits.

I've sharpened about 70+ machetes, utility knives, chisels, etc, and have even practised with a stropping band of leather for a straight razor. Still, I find the "fine" and "extra fine" grit DMT stones seem to dull my blades more than sharpen them. For example, I have sharpened a couple santoku kitchen knives a few times with a DMT "fine" stone (25 micron / 600 mesh), and it easily passes the paper test and cleaves soft tomatoes just by resting the blade on them.

I've tried the finer stones at the same angle (ie: 20 degrees, blade cutting towards the stone), and it seems to make things worse. Small sections of the blade seem a bit sharper, and more polished, but I get small sections of the edge that seem like they were sharpened with an aluminum baseball bat.

Is there a general technique that is applied with finer stones that would help?

Thanks!
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dogbertius said:
Thank you for the advice on the appropriate forum. I looked over the topic list twice before posting.

With medium and fine grit, I just let the weight of the blade be enough pressure when drawing. Should I have to press harder when using finer grit?
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I'm betting there are some small variations in angle and/or pressure that are creating a fine burr, or rolling/blunting the increasingly-finer edge. The first bolded point in your quoted post above sort of hints at that, in that you are seeing some benefit from the EF in some parts, but other sections are noticeably irregular and rough.

And there's never any reason to press harder, under any circumstance; it'll always be counter-productive, if one is deliberately trying to do so. With pressure, it needs to be as light as possible, but steady and controlled enough to minimize those variations in angle, and to prevent too-light contact from allowing the blade to bounce or skip on the hone. As you get progressively finer in grit, and the edge becomes thinner and more refined, it becomes more important to 'feel' what's happening under the bevels as you make each stroke. I keep the pad of my index finger alongside the blade and just above the portion of edge being worked, so it's easier to feel flush contact on the hone. The feedback felt by doing this is what I rely upon to keep the bevel flush to the hone, and also makes it easier to feel if the angle is varying up or down. If the angle gets too steep (too obtuse), the edge can be felt digging into the hone (lots of drag), which erases the fine edge and might also create a burr. If the angle varies in the other direction (too acute), it'll start to feel as if the shoulder of the bevel is 'skating' loosely on the hone (and it is). When the angle is flush, there's a very nice 'buttery' smoothness to the contact; especially on the EF and EEF DMT hones. Try to focus on feeling for that 'buttery' sensation under your bevels, and results will usually improve.


David
 
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The Mastiff said:
I have those stones. The edge will get so smooth that it feels dull and won't cut as effectively as an edge with a bit of a bite. That is exactly why I parked my DMT Fine and Extra fine, and Extra extra fine stones and stop at the blue, coarse. It has much better bite on the stuff I typically cut. I have gone all the way up to mirrored like normally only seen with guided systems like Wicked edge ( I have 2 different guided systems) but I find that aside from being fun and impressive it doesn't really help. Try cutting ropes, especially synthetic, or skinning & caping an animal with coarse, very dirty hair and the coarse-ish edge does a bit better. Likewise ropes, tomatos, and meat ( muscle & tendons).

Try the same sharpening but stop at black, or blue DMT's, or Norton Silicone Carbide stones coarse/fine.

Joe
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I go from C to EEF and I have to entirely disagree. The edges I get are nearly mirror polished and have an insane amount of bite for the refinement level. I have an edge with a true mirror finish that isn't as aggressive as a cutter because it lacks the teeth diamonds leave. It you want to do extra bite I would suggest a knife with a vanadium carbide steel like S30V or M390. The ability to a grade the carbide makes those edges insanely aggressive. Diamonds are optimal on hard to sharpen steel, or higher carbide content steel. Something like 154cm sharpens up fine, but traditional stones are easier and a lot cheaper.
 
That's awesome. :)

You've discovered one of what I call the 7 Secrets Of Sharpening. Secret #1 in fact: How to feel the bevel on the stone. It's amazing when you feel it in action. Good job and good luck to you in your future sharpening.

Brian.
 
dogbertius said:
Care to share any other such secrets? :)
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I'm not sure I should hijack the thread, but I'll throw out #2 for you:

#2 Following the curve of the blade. This is difficult to say in words without a visual aid. If you watch where the edge of the edge contacts the stone, you'll see that you need to adjust your stroke as you go through the curved portion of the blade. Ken Schwartz correctly (and wisely) describes this as maintaining the same plane of the bevel against the stone throughout the stroke. Jason B has a very good demonstration of this concept at one point in his Les George sharpening video.

I've been planning to do a video series on my so called "7 Secrets of Sharpening" for a while, but haven't gotten around to it so far.

Brian.
 
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