What am I doing wrong??

[Jondllas311]

Hi guys,

I'm new to the forum, and I'm stuck. I recently purchased some DMT Dia-sharp stones. A combo coarse/fine and an extra fine. Granted, I'm new to this so I definitely could be doing something wrong...that's where I'm hoping someone can help.

When I finish with the Fine stone, I have a nice sharp edge. Every time I move to the Extra Fine stone my blade gets duller! I can't figure it out. I know the stones need to be broken in, but I've been sharpening for about 2 hours each day over the last week and nothing has changed. I was thinking that the stone may be defective/damaged because as soon as I opened it up it was clear that the top finish wasn't perfect.

It had some nicks and scratches in it brand new. I figured it wouldn't effect the sharpening but now I'm not so sure. It feels and sounds like crap. Like I can feel little imperfections slamming into my edge.

Am I just stupid and need to keep at it, or could there really be something wrong with my stone?

I've been following the advice of Jason on this forum. His posts and videos are what sold me on this stone system. I don't think it's my technique because I'm doing well with the coarse and fine stones. I'm really at a loss here.

Thanks for your help and please let me know what you think.

 

[HeavyHanded]

My best guess is that there is too much play/wooble in your mechanics. The margin of error is relative to the size of the abrasive, as you go to finer abrasives, the amount of play needs to be very small or the edge will have too much curvature - will be overly broad at the cutting edge.

When you go from the fine to the EF, mark the edge with a Sharpie and try to work from the shoulder to the cutting edge. If you just work it without a strategy (and unless your mechanical movements are very precise on their own), there is a tendency to elevate the spine for more feel - this broadens the edge.

You can also use those with a drop or two of mineral oil or even a bit of soapy water - tends to tame the stone a bit and improve tactile feedback. They do have a break in period, but the EF should not feel like it has large individual imperfections.

Is it possible for you to take a high resolution image of the surface and link it to your post?

Martin

 

[jackknife]

Jon, are you using any kind of marker to keep track of how you are doing with a consistent angle?

 

[Obsessed with Edges]

With diamond hones, the most common mistake is using too much pressure; even if you think it's too light already, go lighter. As compared to any other abrasive type (SiC, AlOx, natural stones), diamond is at least 2X-3X as hard as the hardest of the others, so pressure needs to be reduced in proportion to that (cut pressure to 1/2 or 1/3 of anything you've used before). Even at very fine grit, they're aggressive enough to do all that's needed with literally no more than the blade's own weight being exerted at the edge. Somewhat heavier pressure can be tolerated when just setting the bevels on a coarse diamond; but, at finer grits, too much pressure is an edge-killer.

As mentioned, it's also possible and somewhat likely that the held angle may be a bit inconsistent as well. If so, the effects of too much pressure will just be that much worse. At the refining stages of Fine/EF/EEF diamond, the touch needs to be featherlight and very steady.

2 hours' worth of sharpening at a stretch, with diamond hones, is also likely overkilling the edge, and I'd think fatigue will also be an issue as well. The hands will get too heavy and technique will be too sloppy, the longer it goes on. When refining with diamond hones, most refinement should be accomplished in the first minute or so of very light strokes; if it's taking much longer with no real improvement, there are other issues getting in the way (as mentioned above).

Edit:
BTW, if there are noticeable 'bumps' proud of the surface on the EF hone, sometimes they can be very gently burnished off with something like a ceramic hone. If they still won't come off, and the edge is obviously colliding with or being stopped by them, it may be a warranty issue for DMT to address. They've usually been pretty good about quickly replacing such hones. Cosmetic nicks or scratches going below the working plane of the diamond surface ordinarily shouldn't be a problem, UNLESS the nicks or scratches have penetrated through the nickel substrate to the steel plate underneath (may become a rusting issue, or the nickel may start chipping or peeling off).


David

 

[Jondllas311]

Thanks for all the feedback.

I'm new to this process, so it's highly likely that even though I think I'm holding me angle perfectly, in reality I'm probably not. I have been using a sharpie to mark the bevel and it's working.

I feel like Im using very light pressure. Basically, just the weight of the knife/blade itself with me guiding it along the stone. I've been using the coarse and fine stones dry but adding water and dishwashing soap as lubricant for the extra fine.

I've been using every knife I can get my hands on to practice with. Not one knife for the 2 hours per day. It's probably more like 5-6 knives being sharpened each day. These knives vary in steel quality from super cheap mystery steel (pretty sure it's just generic stainless) to SV30 on my hunting knife. The results are all the same...sharp with fine stones and duller with extra fine.

Just to clarify, how sharp should the knife get using just coarse and fine stones? Sharp enough to pass the paper test? If so, then my knives aren't getting that sharp after the fine stone. They're sharp, but not SUPER sharp.

My process also includes a leather strop with green "micro fine" compound. There was a also a big learning curve with that, but I've gotten to where I can definitely tell a difference after stropping.

More than likely I think it all points back to my technique being the real issue. I'm definitely not getting the results I want in only a couple of minutes. I'm doing lots of strokes. Even though I "think" I'm using light pressure, I'm probably using too much. I'll keep plugging away and working on my technique. It's just frustrating because I "feel" like I'm doing everything right and I'm just not seeing the results.

I do think this EF stone is pretty rough. I'll give it about a week to see if it starts breaking in better. If not I'll probably give DMT a call. I don't have a camera that would take a high resolution image to show you, but it doesn't look exactly right to my eyes.

Thanks again guys. I really appreciate it.

 

[Squashfan]

Do you know what a burr is and how to check for one? It has been a long time since I used diamond but I seem to remember having the same problem when I went to an ultra fine diamond. IIRC, it was because I hadn't removed a very, very small burr.
Don't give up, this is hard but not impossible.

 

[smo1898]

I used to have this happen to me but with water stones not DMT. The solution I found was using significantly less pressure on the extra fine stones.

 

[Obsessed with Edges]

Thanks for all the feedback.

I'm new to this process, so it's highly likely that even though I think I'm holding me angle perfectly, in reality I'm probably not. I have been using a sharpie to mark the bevel and it's working.

I feel like Im using very light pressure. Basically, just the weight of the knife/blade itself with me guiding it along the stone. I've been using the coarse and fine stones dry but adding water and dishwashing soap as lubricant for the extra fine.

I've been using every knife I can get my hands on to practice with. Not one knife for the 2 hours per day. It's probably more like 5-6 knives being sharpened each day. These knives vary in steel quality from super cheap mystery steel (pretty sure it's just generic stainless) to SV30 on my hunting knife. The results are all the same...sharp with fine stones and duller with extra fine.

Just to clarify, how sharp should the knife get using just coarse and fine stones? Sharp enough to pass the paper test? If so, then my knives aren't getting that sharp after the fine stone. They're sharp, but not SUPER sharp.

My process also includes a leather strop with green "micro fine" compound. There was a also a big learning curve with that, but I've gotten to where I can definitely tell a difference after stropping.

More than likely I think it all points back to my technique being the real issue. I'm definitely not getting the results I want in only a couple of minutes. I'm doing lots of strokes. Even though I "think" I'm using light pressure, I'm probably using too much. I'll keep plugging away and working on my technique. It's just frustrating because I "feel" like I'm doing everything right and I'm just not seeing the results.

I do think this EF stone is pretty rough. I'll give it about a week to see if it starts breaking in better. If not I'll probably give DMT a call. I don't have a camera that would take a high resolution image to show you, but it doesn't look exactly right to my eyes.

Thanks again guys. I really appreciate it.

The bolded part above, and especially the underlined portion, is the strongest clue. When used to fullest potential, edges should be at least paper-slicing sharp from the Coarse (could even be GREAT paper-slicing edges), and shaving or hair-popping from the Fine. In skilled hands, even shaving or hair-popping is possible from the Coarse DMT. If the edge isn't yet passing the paper-cutting after the Fine, it likely isn't fully apexed; in which case, the EF would likely just be rounding off or taking the 'sharp-feeling' teeth away from the rough 'Fine' edge, but not actually refining it. This leaves the edge as you're seeing it, which is too wide or incompletely-apexed and missing it's 'bite'; therefore the impression that it's duller than perceived from the earlier toothy edge.

Make absolutely sure you create a full-length burr with the Coarse, before moving to the Fine; that's the cue that the edge is about as thin as you can make it, and indeed fully-apexed. Even with a burr, paper-cutting should be passable coming off the Coarse, albeit with some possible snagging from the burrs.


David

 

[FTR-14c]

Just for kicks, you could try skipping the extra fine and jump right from the fine stone to the strop for burr removal and finish?
You may end up with a super sharp, slightly toothy edge that cuts like crazy.

 

[bgentry]

David (Obsessed with Edges) is spot on. Your edge from the coarsest stone you use should slice paper. From the DMT C you should actually be able to slice phonebook paper if you're doing it really well. A minimum standard is that it should slice printer paper after the DMT C. Once you get the edge to that level, the work on the next stones (DMT F and EF) shouldn't take long at all, and you're going to be REALLY impressed with the edges you can get from them.

But it's all about that initial work with the coarse stone. Get it right and the magic will happen. Speed past the initial work and your subsequent work with finer stones is mostly wasted.

Brian.

 

[Jondllas311]

The bolded part above, and especially the underlined portion, is the strongest clue. When used to fullest potential, edges should be at least paper-slicing sharp from the Coarse (could even be GREAT paper-slicing edges), and shaving or hair-popping from the Fine. In skilled hands, even shaving or hair-popping is possible from the Coarse DMT. If the edge isn't yet passing the paper-cutting after the Fine, it likely isn't fully apexed; in which case, the EF would likely just be rounding off or taking the 'sharp-feeling' teeth away from the rough 'Fine' edge, but not actually refining it. This leaves the edge as you're seeing it, which is too wide or incompletely-apexed and missing it's 'bite'; therefore the impression that it's duller than perceived from the earlier toothy edge.

Make absolutely sure you create a full-length burr with the Coarse, before moving to the Fine; that's the cue that the edge is about as thin as you can make it, and indeed fully-apexed. Even with a burr, paper-cutting should be passable coming off the Coarse, albeit with some possible snagging from the burrs.


David

Thanks for all the feedback. Message received!

Lighter pressure on the blade
Secure the angle better
Get a complete burr on coarse stone
Do a proper paper test because my definition of sharp is apparently way off

About the burr...you should feel it on the opposite side of the blade (away from the stone). But it's really something you feel more than see, correct?

 

[HeavyHanded]

Thanks for all the feedback. Message received!

Lighter pressure on the blade
Secure the angle better
Get a complete burr on coarse stone
Do a proper paper test because my definition of sharp is apparently way off

About the burr...you should feel it on the opposite side of the blade (away from the stone). But it's really something you feel more than see, correct?

At the rough end you'll be able to feel it, as it gets smaller a visual detection will be needed. Working with water also seems to make a tactile detection more difficult - no sebaceous glands in fingers means water swells the skin.

Will also show in a cut test once you get a better feel for things. Strong overhead lighting is a big help - shine the light (hold the knife/tool such that light plays) along the primary bevel and slowly pivot the edge back and forth into/out of the path with the edge pointing straight down. The burr will appear as a very small halo/second line just off the cutting edge. It may or may not initially be all on the same side of the edge depending on how it has been worked.

 

[Jondllas311]

At the rough end you'll be able to feel it, as it gets smaller a visual detection will be needed. Working with water also seems to make a tactile detection more difficult - no sebaceous glands in fingers means water swells the skin.

Will also show in a cut test once you get a better feel for things. Strong overhead lighting is a big help - shine the light (hold the knife/tool such that light plays) along the primary bevel and slowly pivot the edge back and forth into/out of the path with the edge pointing straight down. The burr will appear as a very small halo/second line just off the cutting edge. It may or may not initially be all on the same side of the edge depending on how it has been worked.

This is really helpful as I had been looking directly into the leading edge of the blade to try and find the burr.

I basically went back to the drawing board and used all of the tips that have been shared. For kicks I decided to double check my angle...I was WAY off! What "felt" like 20 degrees was actually closer to 40!

I feel like an idiot. I'm completely starting over and resetting the bevel. I appreciate all the help that's been provided. I would have never figured this out on my own.

I'll report back tonight after I try to improve my results. Fingers crossed!

 

[BoboOfBodom]

No expert at all here...but several months ago I got some DMT stones...
There is a learning curve.
1 item to add to the excellent advice above: make sure your stones are not plugged up. I use a stiff nylon brush with Comet powder and rinse with water..PAT dry, don't wipe.

 

[kn4wd]

I agree with the wobble theory, also the burr without the burr you aren't sharpening at all. I own several dmt's and have never seen a bad one. it is most likely pilot error and not stone related.

 

[Obsessed with Edges]

Thanks for all the feedback. Message received!

Lighter pressure on the blade
Secure the angle better
Get a complete burr on coarse stone
Do a proper paper test because my definition of sharp is apparently way off

About the burr...you should feel it on the opposite side of the blade (away from the stone). But it's really something you feel more than see, correct?

Regarding detecting the burr. My favorite means, and to me the most bullet-proof method, is in the cutting of thin paper, such as with phonebook pages. If you have a fully-apexed edge, it should first cut paper easily, but perhaps show some snagging (due to burrs). Assuming there are some burrs, they'll catch or snag at specific points along the edge, as you're slicing the paper. Cut into the paper SLOWLY, and watch how the edge interacts with it. The portions that are sharp and burr-free should easily and effortlessly cut; portions containing burrs will cause the paper to snag on the edge and roll over. If you also see areas where the edge is slipping over the edge of the paper without cutting or snagging, that could be an incomplete apex OR a burr that's completely folded over, leaving a rounded apex. All of these things to watch are specific indicators of what's going on; if you pay attention to all of them, they'll tell you exactly what needs to be fixed. When I 'test' edges this way, it's literally never failed me.

One other thing to test, if all the above passes, is to cut into some wood fairly deeply, then go back and do the paper tests again. That's a good way to see if there was still a weakened wire edge or burr that snuck past the earlier tests (can happen with burrs that aren't yet folded over, mimicking a 'sharp' edge). If there is a 'standing' burr, cutting into hardwood will either break it off or cause it to fold, after which you'll see the effects of a folded burr in the paper-cutting. As you get more experienced in sharpening to burr-free edges, you'll hopefully go back & forth between a few slices in paper, and a cut or two into some wood, without any degradation of sharpness. That tells you your edge is both sharp and durable, in which case it's READY.

The visual or fingertip 'feel' tests for burrs can highlight the more obvious ones, so there's no harm in still looking for that in a visual inspection or testing with the fingertips or nails. As one gets better at sharpening and refining edges, hopefully the size of the newly-formed burrs will steadily decrease, after which the cutting tests will catch anything that's still there. For guys like me, my aging eyes aren't making things any easier, in 'seeing' these things.


David

 

[Jondllas311]

Regarding detecting the burr. My favorite means, and to me the most bullet-proof method, is in the cutting of thin paper, such as with phonebook pages. If you have a fully-apexed edge, it should first cut paper easily, but perhaps show some snagging (due to burrs). Assuming there are some burrs, they'll catch or snag at specific points along the edge, as you're slicing the paper. Cut into the paper SLOWLY, and watch how the edge interacts with it. The portions that are sharp and burr-free should easily and effortlessly cut; portions containing burrs will cause the paper to snag on the edge and roll over. If you also see areas where the edge is slipping over the edge of the paper without cutting or snagging, that could be an incomplete apex OR a burr that's completely folded over, leaving a rounded apex. All of these things to watch are specific indicators of what's going on; if you pay attention to all of them, they'll tell you exactly what needs to be fixed. When I 'test' edges this way, it's literally never failed me.

One other thing to test, if all the above passes, is to cut into some wood fairly deeply, then go back and do the paper tests again. That's a good way to see if there was still a weakened wire edge or burr that snuck past the earlier tests (can happen with burrs that aren't yet folded over, mimicking a 'sharp' edge). If there is a 'standing' burr, cutting into hardwood will either break it off or cause it to fold, after which you'll see the effects of a folded burr in the paper-cutting. As you get more experienced in sharpening to burr-free edges, you'll hopefully go back & forth between a few slices in paper, and a cut or two into some wood, without any degradation of sharpness. That tells you your edge is both sharp and durable, in which case it's READY.

The visual or fingertip 'feel' tests for burrs can highlight the more obvious ones, so there's no harm in still looking for that in a visual inspection or testing with the fingertips or nails. As one gets better at sharpening and refining edges, hopefully the size of the newly-formed burrs will steadily decrease, after which the cutting tests will catch anything that's still there. For guys like me, my aging eyes aren't making things any easier, in 'seeing' these things.


David

Thank you for this detailed information. It was incredibly helpful. I used your paper test and the results have improved dramatically!

Thanks again to everyone who contributed. I know most of these questions have been posted before countless times but for some reason I never was able to put all the pieces together. Thanks for providing answers and not immediately flaming me!

It was definitely my technique and my blade angle. I focused on both and also on identifying the burr. The results are impressive for me being so new. Paper is now cut after all stones and the EF stone is perfectly fine. Clearly I was inconsistent with my blade angle before. I'm still not perfect - not by a long ways - but I'm getting the knife MUCH sharper than before. It's scary sharp.

I'll keep practicing and working on my technique. Hopefully I'll be able to hang with you pros soon!

 

[Rebel4ever]

Jondlss, what exactly did you do to get satisfaction with the level of sharpness? Several suggestions were made. Please share what you did...1,2,3, etc. I'm having the same problem and reading with interest your solution.

 

[Jondllas311]

Jondlss, what exactly did you do to get satisfaction with the level of sharpness? Several suggestions were made. Please share what you did...1,2,3, etc. I'm having the same problem and reading with interest your solution.

No problem. I pretty much followed all of the recommendations. First, I mentally started over and checked EVERYTHING to make sure it was all correct. I used the angle meter app on my iPhone to roughy estimate the angle to hold my blade. It's not perfect, but it was close enough to tell me that my original angle was WAY too steep.

Then I looked at my mechanics. I made myself focus on keeping the blade perfectly still. For a push stroke I lock my wrist on the hand holding the handle, put mu thumb behind the spine of the blade (to make sure I'm not moving it up or down and changing the angle), and I put my first finger and middle finger on the blade/stone. I followed the recommendations and I'm using LIGHT PRESSURE. Basically, the weight of the knife or less is all the pressure being put on the stone.

The actual motion I'm using is all arm and body. It's feels weird, but it works. And I'm forcing myself to slow down. I think initially I was trying to do things too quickly. It "felt" right to me, so I would automatically start moving the knife pretty fast along the stone. This was definitely causing problems because now I realize that the blade angle wasn't consistent.

I worked the coarse stone on one side of the blade and I regularly check for the burr using a flashlight. Holding the blade away from me, I shine a really bright flashlight with a focused beam along the blade and slowly move the blade until I see the burr. I'm still working on this, but to me it looks like there is some sort of fuzzy stone residue on the very edge of the blade (even though I wipe it off after taking it off the stone to check). Once I get the burr to show up along the entire length of the blade on that side, I switch and start doing the other side.

I do this 2-3 times basically moving the burr from one side of the blade to the other. I'll also do paper cut tests throughout this process just to check that what I'm seeing is really happening. For me, the hilt of the blade edge grabs the paper then the knife starts slicing the paper about halfway down the blade all the way to the tip. I'll keep working it on the stone until I'm satisfied.

This is the part I still need work on. I'm not exactly sure when to move to the next stone. I wait until the paper is cutting pretty well on the coarse then go to the fine. I repeat the process with the fine stone. I basically play with the stone and paper until I get it as sharp as I can before moving to the EF stone. Again, I'm not exactly sure when the ideal time to switch stones is.

The EF stone is really the same process. I might be using slightly lighter pressure. I'm really listening to the blade on the stone. It sounds different and you can hear when you make a mistake more than anything. Then I use the paper test and again get it as sharp as I can. When I'm happy I move to the strop.

I had to change the angle I use for stropping to match my corrected blade angle. Not a big deal because you can feel this on the leather. Super light pressure (knife weight only) and I slowly move it along the leather in a blade trailing stroke and alternate sides. This took some practice but for some reason I picked this up faster than the stones. I feel pretty god about my stropping stroke, but I do focus on stopping the blade and reverse rolling the knife to start the alternating stroke. That probably sounds weird, but I just focus on NEVER letting the edge of my blade roll on the leather. I think the natural stroke would be to slide and then "flick" the blade against the leather to turn the knife over. I make sure I never do this by stopping and rolling the spine of the blade on the leather to turn the knife over.

Then I paper test again after stropping. It's crazy how much better my knife is at cutting paper. And my thumb is covered in little micro cuts from testing the blade too. It's absolutely sharper than anything I had been able to achieve before. I hope this helps, but remember I'm just figuring this stuff out too. Some of what I describe could be totally wrong and I'm just getting lucky...I don't know.

It's obvious to me that this is a process where all of the elements have to be correct or the results simply won't be there. And these stones have completely changed my perception of "sharp". It has taken all of my previous perceptions and raised them to a point that I never experienced. The fun part for me will be perfecting this process and my technique. I know I'm still making mistakes and I need to better understand the burr/paper relationship and when to change to the next stone. If anyone has any tips on this please feel free to share. And thanks for your question Rebel. I'm glad to know that others were helped out by this thread.

 

[Jondllas311]

By the way - my screen name is supposed to be JonDallas311 but I had a typo when I registered. I can't figure out how to modify my screen name. So I guess I'm stuck with a typo in my name...stupid. What was I saying earlier about trying to do things too fast??