Only Sharp Knives Are Interesting- the Sharpening Thread

Lorien said:
one thing to concentrate on is the amount of pressure you're applying. There has to be a fair amount, especially at lower grits. As i progress into higher grits, I use less pressure. Learning how to sharpen isn't easy, it requires sensitivity. Just keep at it and eventually it'll click.
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I'm fine sharpening on a bench stone, just can't get the hang of using the DMT like a file. I'm probably just not consistent enough with my angles.
I appreciate the advice! Thanks!
 
David Mary said:
To me the blue and red both feel like mediumish
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Yeah, one thing that DMT states (and users can confirm), is that the comparable grit will be finer with use.

My ~3 decade old Red/Fine still cuts well, but with thousands of passes on it, it feels smoother than the newer Red side of my double sided, that only has hundreds of passes.
 
carnifex knifeworks said:
I'm fine sharpening on a bench stone, just can't get the hang of using the DMT like a file. I'm probably just not consistent enough with my angles.
I appreciate the advice! Thanks!
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it's much easier to maintain both consistent pressure and angle of approach with a benchstone than it is with a handheld stone like one would have in the field. I generally do all my sharpening and maintenance at home for that reason and also since it seems my multi day back country trips have more or less come to an end for now :(
 
Lorien said:
it's much easier to maintain both consistent pressure and angle of approach with a benchstone than it is with a handheld stone like one would have in the field. I generally do all my sharpening and maintenance at home for that reason and also since it seems my multi day back country trips have more or less come to an end for now :(
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Agreed. Sharpening in a controlled environment is much easier than in the field.
 
For field use I have always liked the puck shaped stones better than file shaped ones. It just feels more natural in hand for me when using them the way Lorien did in the opening post.

I keep the reference from the back of a DMT rod in my bench box, it's a handy reminder. I feel like I have these in just about every field bag, tool box and vehicle we own but these are the ones I use at my bench most often.

If you want to test drive an amazing stone try the Gold Series stones from KME. Early on they had DMT making their stones, but they weren't holding up for his heaviest users. They are made in the US using their own formula and I swear I cannot kill them.

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Received the new diamond plates.
What i have learned from this struggle?
The plates are everything. Thought i had good enough plates. Not even close.
Had one Med Course that was even leaving a wavy finish.
Now i must decide.
Pay for the new set of plates - Ouch
Or
Just move on to belt sander. 1x30 can be had fairly affordably.
This is a tough call. Been using fixed angle for years.
Maybe it is time to move on.

First i got some knives.
Then i sharpened them.
Then i got better knives and boarded a struggle bus.
 
Belt grinder is always going to be faster. And if you slack belt sharpen, limit pressure, and dip frequently, you don't have to worry about creating enough heat to hurt the heat treatment. One helpful cue for this is to make passes that don't throw sparks. You can always apply a plate/stone ground microbevel afterwards as well.
 
And use ceramic belts, 120 grit for reprofiling, and 220 for cleaning up. I suppose you could go beyond that if you wanted to make "pretty" edges, but this will work just fine for excellent performing working edges.
 
David Mary said:
Belt grinder is always going to be faster. And if you slack belt sharpen, limit pressure, and dip frequently, you don't have to worry about creating enough heat to hurt the heat treatment. One helpful cue for this is to make passes that don't throw sparks. You can always apply a plate/stone ground microbevel afterwards as well.
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Just a quick reminder that Nathan has previously detailed that powered setups/belt grinders can negatively affect the D3V heat treat.

He's stated that they have theirs set slow enough that you can read the belt, and it's continuously water cooled.

In one of his posts on it, he mentioned having done the calculations to confirm that you can easily overheat the very apex of the edge (where the mass of the metal is tiny), without ever feeling that heat with your fingertips, and although you can get the edge super sharp for things like slicing paper or shaving hair, that it will negatively impact the edge retention in harder use, that he specifically developed the D3V protocol for.
 
Even if the belt is fast moving and not water cooled one can sharpen properly. To make an analogy: would you hold your finger on a hot stove element for ten seconds? Of course not. But you can touch it for a split second with no molecular change to your flesh. So with powered sharpening, the key is patience and not leaning on the blade as you grind, and consistency in quick passes and frequent cooling.
 
One last thing on this: that all goes out the window if you use the grinder’s platen. The extra pressure from the unyielding platen under the belt is going to multiply force, which will accelerate heat production.
 
Nathan the Machinist said:
Powered grinding can easily burn the very apex of the edge. Delta protocol is more sensitive to this than most. It does not take much to lose the structure that gives us the properties that we want at the very leading edge which is where it really counts.

I do sharpen powered, but the belt is moving slow enough you can read it, and it is dripping wet. Places that sharpen with powered grinders will tell you "don't worry the edge doesn't even get hot". They don't know wtf they're talking about.

I did the math once and I found that you could raise the temperature of the leading .005" edge to 1,000° and it would cool off into the blade before you could touch it and it would not raise the temperature of the blade by 1° . You would never know that you burned it, and you wouldn't understand why your edge retention isn't right.

So I strongly encourage people do not use powered grinding on Delta 3V. I do it, but I'm doing this in production. I'm doing it at low speed and under flood coolant. Most places doing powered sharpening are not doing it right. And it's perfectly fine for a production knife with a shit heat treat, but you do not want to subject a CPK to that.
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I didn’t realize Delta3V was more susceptible to friction generated heat production than other blade steels. My advice above works for me on a dozen or more steels I have used it on.
 
David Mary said:
I didn’t realize Delta3V was more susceptible to friction generated heat production than other blade steels. My advice above works for me on a dozen or more steels I have used it on.
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Yeah, Nate's mentioned that he developed the Delta low-temp tweak for the heat treat because he wasn't satisfied with the edge retention with the industry standard heat treat, but one side effect of the low temp tweak is that he advised not subjecting D3V to temps above 400f (IIRC), which the very apex of the edge can exceed very easily on a powered grinder (and which many places would exceed if someone tried sending a CPK in for DLC coating, which I asked about some time ago. IIRC, the place I asked would subject the knife to ~500f when doing the DLC coating).
 
Lorien said:
I don't mind using my 2x72 for sharpening, but I always follow up with a bench or handheld sharpeny thing
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This is my philosophy as well, and why I always use variable speed for belt sharpening.

IMO those 1x30's spin way too fast. As noted in previous posts, I always finish my edges with a non powered micro bevel that strengthens the thinned edge, performs final deburring and cuts away edge that may have been affected by power sharpening.
 
Well, The nerdy tests a measurable difference.
knifesteelnerds.com

Does Sharpening with a Grinder Ruin Your Edge? - Knife Steel Nerds

You have to sharpen a new knife a few times to get it cutting well. Right? Or do you? Are knife manufacturers improperly sharpening their knives?
knifesteelnerds.com knifesteelnerds.com

Been looking at many approaches.
Tormek - Paper wheel on grinder motor - Mouse trap.

Wet, slow, belt, may be the answer for efficient ability to process anything.
Am going to have to invest. As my diamond plates have failed.

Great feedback so far. Thanks
 
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