Sharpening a convex d2 edge is killing me. Need some help

PURPLEDC

PURPLEDC

Joined
Apr 4, 2007
Messages
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Hey guys. So sharpening is probably my least favorite job. Its just not fun for me and I find I have to be in the mood if I am going to have any success. Well with that said I have an edge pro apex and I hate it. For me Its simply way too much work for minimal improvements. Nothing wrong with the sharpener especially if you like experimenting with angles. I really dont. I just like to try and improve existing edges to be as sharp as possible.

What I am struggling with is the concept of a hair popping edge. I have seen videos of knives that can cut a free standing hair but I have NEVER seen it in person. Either I am horrible at sharpening or I just have really tough hair. Now I can get my knives to slice phone book paper. But I have found everytime I can get a knife to push cut phone book paper, thats about all it will cut. Rope and cardboard seem to laugh at me with a polished edge.

Right now Im using a home made 4 sided strop and some grey, white, green and red compounds I purchased from a guy on the bay who claims to make his own stuff. The knife in question is a bastinelli made by lionsteel and has a german d2 variant for the steel. I took a strop to it as people kept saying things about D2 like it wont really take a polished edge due to its carbide size. Is this true? The edge feels really smooth. Not toothy at all. It cuts paracord good. Push cuts paper and phone book paper but on some materials like nylon rope it feels like it slips a bit instead of biting. Am I taking it too fine? Should I say screw the strop and just stick to a ceramic rod? Id really like to have one knife that is considered "scary" sharp but It seems I am very very lost on the most important aspect of knives. I have learned all sorts of techniques for modding and making knives except for the one thing that actually makes a knife a knife. It either shaves and wont cut much else or it cuts other things well and wont shave. Is there a good intro guide to sharpening? Its such a vast topic with so many forks that I am truly intimidated. But its time to learn this thing the right way.
 
D2 is a bear to reprofile should polish to a mirror through. I had it on my BM 51 it didn't seem to be a good razor edge holding steel, it only worked great at holding a working edge for a long time. Not my kind of steel.

For me I only have three knives I can bring to that level of performance. I feel it's mostly a matter of geometry. How thin the the steel is behind the edge.

Too much pressure on the strop can round the apex and cause the edge to lose its bite.
For me,
CBN compounds were a real break through for me to reach the highest level of sharpness.
 
If just stropping a factory edge (I didn't read that anything else had been done to it yet, besides stropping), that may not quite get it to hair-popping sharpness by itself; probably won't, in fact. And as mentioned, a typical leather strop is more likely to round off or overpolish a less-than-fully-apexed factory edge. Factory edges are seldom that sharp and will often need, or at least benefit greatly from, first thinning the edge geometry and then refining it further.

A convex in D2 can be thinned, and the convex maintained, by essentially 'stropping' the blade on wet/dry sandpaper over a firm or hard backing, like wood, or very thin/firm leather or fabric over wood, with the paper over that. Keep the angle conservatively LOW, to ensure more material is coming off the side of the blade, and not just rounding the apex and making it blunter. It can also be done on hard stones/hones, but that takes some practice to get a feel for it. For convexing D2, I've liked using a coarse/XC diamond hone to put a thinner (more acute) V-grind on it to create a crisp-as-possible apex, and then follow that with the sandpaper method mentioned above, to do the convexing of the shoulders of the V-grind and minimize altering the edge/apex too much, if at all.

D2 absolutely CAN take a wicked-sharp polished edge (my favorite D2 edges are finished like this), but it absolutely MUST be fully apexed from the beginning, before it'll start responding well to further refinement and polishing. Otherwise, it'll just get too smooth and rounded off at the apex; this is likely what you're seeing with the factory edge on yours, as you're likely stropping an incompletely-apexed edge. Finishing short of a full apex at the coarsest sharpening stage will guarantee an exercise in frustration in the following stages. Guaranteeing a full apex is most easily done with a diamond hone, because it'll handle the large chromium carbides much more easily, and leave the apex as crisp as can be. It should at least coarsely shave/pop hairs off the arm after the coarse step; if not, there's no point in going onto the next stage until it is.


David
 
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I can get D2 hair whittling sharp.

It is a bear to reprofile. Even with my belt sander.

I wonder if you might not be wrapping the edge.

I tend to get frustrated with my D2, and strop too vigorously. I have often had shaving, paper slicing edges that are not that great at cutting other mediums.

I try to make sure I am getting a little burr. I try not to over strop. And, I do a few passes on a diamond stone followed by some light passes on a ceramic.

D2 has tried my patience before.


I do find that a glass sheet and sand paper seem to work also.
 
Im not neccessarily going for a hair popping edge because i really dont want to reprofile. I chose my wording poorly. I am just looking to improve as much as i can without pulling out the apex. The strop i actually have patience for. It relaxes me and i can intentionally slow down and i dont use hardly any pressure at all. I start with 10-15 strokes a side and as i go to finer grits i get down to one stroke per side.

The reason i do multiples per side is i find i keep a consistent angle if i repeat the movement more times before swapping. But even though i always follow up with the same count for both sides i start to worry i may be working one side harder than the other because of the difference in my hold on the knife and naturally favoring the movement that comes more natural.

My only fear on my strop is i didnt use a very thick piece of leather. I worry that since it is that thin it may be too rigid and that im just polishing the shoulder. But examining the edge with a loupe it appears to be working well. but i guess i cant expect too much if not willing to reprofile. But is there any reason it will push cut paper yet not respond well on cardboard?
 
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PURPLEDC said:
Im not neccessarily going for a hair popping edge because i really dont want to reprofile. I chose my wording poorly. I am just looking to improve as much as i can without pulling out the apex. The strop i actually have patience for. It relaxes me and i can intentionally slow down and i dont use hardly any pressure at all. I start with 10-15 strokes a side and as i go to finer grits i get down to one stroke per side.

The reason i do multiples per side is i find i keep a consistent angle if i repeat the movement more times before swapping. But even though i always follow up with the same count for both sides i start to worry i may be working one side harder than the other because of the difference in my hold on the knife and naturally favoring the movement that comes more natural.

My only fear on my strop is i didnt use a very thick piece of leather. I worry that since it is that thin it may be too rigid and that im just polishing the shoulder. But examining the edge with a loupe it appears to be working well. but i guess i cant expect too much if not willing to reprofile. But is there any reason it will push cut paper yet not respond well on cardboard?
Click to expand...

On those last two bolded points:

There'll never be a reason to worry about going too thin or too rigid on a strop; thinner and firmer is really what will work best, without exception; the objective being to minimize how much the stropping substrate rolls or conforms around the apex. Developing a 'feel' for stropping seems easier for most beginners on a 'softer' substrate, which feels more forgiving; but it's not really the best for the edge, because it increases the likelihood of rounding off the apex. The firmer or harder the strop is, so long as it's sufficiently smooth, the crisper the apex will be.

As for cardboard cutting, anything that causes the edge or the sides of the blade to snag or bind is what you want to eliminate. Cutting simple paper doesn't really present the same obstacles to cutting, as the apex itself is really the only thing doing the work there. Even stiff burrs along the edge can still seem 'sharp' and cut paper for a little while. For cardboard, the apex needs to be crisp, free of dents/dings and STRONG (no burrs that'll fold over), and the bevels or convex shouldn't snag or bind as the cardboard presses against or 'squeezes' the blade. I've always liked a polished convex for cardboard, as it'll be very SLICK going through the material, with no hard-edged shoulders (as on a V-grind) to dig in & bind, and no coarse grind lines to create friction against the cardboard. With a very crisp & strong apex and a polished convex, cutting can get scary-slick in cardboard; the blade will sail right through it.


David
 
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thanks for all the advice. I feel better about using the strop. Im not sure if I am having any of the issues or not that you are describing. I feel I have the knife at a point that I can live with it. I need to think about going to the next step because one of my weaknesses is I rush things and I try to get the end result without having to do the time. I dont want to jump in without some practice with a lesser knife. Baby steps for me with this.
 
Well said folks but there are two presenting issues here as I understand the post PURPLEDC. You want a hair popping edge and cut rope and cardboard. I agree that a true apex is absolutely vital first. Another member was having the same trouble here recently. That was the final solution to his problem.
Now hair popping and rope are are on opposite ends of the cutting world. Ankerson, our edge testing guru, puts a 400 grit edge on all the blades for testing. He makes sure they cut TP and then has at it.
If you want an edc edge, 400 will cut great. If you want to cut sushi, hair, etc. you need CBN or diamond honed edges. One size does not fit all. I use different edges/knives for different purposes.
Steels and heat treatments vary a lot to. Dozier sends back entire shipments of D2 that don't perform the way he wants them to.
A Japanese sharpener told me the steel picks the stones. Some do what you need them to, others don't.
Happy hunting.
 
PURPLEDC said:
Im not neccessarily going for a hair popping edge because i really dont want to reprofile. I chose my wording poorly. I am just looking to improve as much as i can without pulling out the apex. The strop i actually have patience for. It relaxes me and i can intentionally slow down and i dont use hardly any pressure at all. I start with 10-15 strokes a side and as i go to finer grits i get down to one stroke per side.

The reason i do multiples per side is i find i keep a consistent angle if i repeat the movement more times before swapping. But even though i always follow up with the same count for both sides i start to worry i may be working one side harder than the other because of the difference in my hold on the knife and naturally favoring the movement that comes more natural.

My only fear on my strop is i didnt use a very thick piece of leather. I worry that since it is that thin it may be too rigid and that im just polishing the shoulder. But examining the edge with a loupe it appears to be working well. but i guess i cant expect too much if not willing to reprofile. But is there any reason it will push cut paper yet not respond well on cardboard?
Click to expand...

D2 with large carbides is not a the best candidate for stropping for maintenance if you want the crispiest edge possible. Diamond lapping film as a strop, or just take it straight off your last stone and strop on paper lightly just to help with deburring. The edge is likely being polished over to a much more broad angle than you might think, causing it to hang up on thicker materials even as it is still capable of shaving arm hair, slicing paper etc.
 
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