How to get an extra sharp edge?

S

SconnieBT

Joined
Oct 11, 2016
Messages
12
I've recently gotten into pocket knives. Bought a BM 940 and a used PM2 and because I wanted to be able to keep them sharp also picked up a used edge pro apex. I feel like I've got a nice edge on the blades, and for everyday uses they are working just fine. But being the perfectionist that I am, I wish they would shred paper better. I'm wondering how to get to that next level of sharp where you can actually push cut paper.
Using the edge pro I've used the sharpie to match the factory angles on the blades. I use 220, 400, 600, 1000, 2000, 3000, 6000 grit in progression. It gives me a mirror like edge which is great, but I still feel like the edge could be sharper. Should I buy a strop or are there any techniques on the edge pro that I need to do better on? Any and all suggestions welcome. Thanks.
e44996bea2935c0a2b7128d1d365edd2.jpg
0566cb9e67a083a0cd0dd3ceb5155286.jpg

Picture of my result on the 940.
 
Looks like you are not getting it fully apexed. Nice shiny mirror bevel but the very edge itself looks unfinished.
 
Let's move to the sharpening section (Maintenance, Tinkering & Embellishment), you will get more answers there.
 
What JC57 said. The edge bevel looks great, nice mirror job, but the apex looks like either you did not fully apex, or you have a microbevel at a different grit finish than the mirror polished bevels, but looks like not quite apexed. To be sure, form the burr (both sides).
 
I agree, not sure I'm apexing adequately. If I were to do the microbevel at a slightly larger angle, would I go through the same progression of grits? Also how many more degrees (approximately) should I increase the angle?

I have tried to feel the bur, but have never felt like I'm feeling it. Even if all the sharpie is being removed, I still don't feel the bur. Is there a learning curve to feeling the bur, or am I simply not feeling it cuz it's not there.
 
If you apex with a coarse grit stone, the burr is usually more obvious. I never really did "look" for a burr, rather I rake my finger tips across the edge to feel for it. Sometimes I will use the very edge of my fingernail, and if there's a burr there, the fingernail will hang on it.

But if you apex with a very fine stone, you may not see the burr at all, and maybe not even feel it at first. If you try those techniques, especially after a coarse stone, it may not have been raised just yet. Grind a little more, see where that gets ya.

As far as the microbevel and grit progression, that's purely up to you. I don't normally use microbevels, but if so, I would only use the final fine grit stone you want the apex finish to be at. (not supposed to end a sentence with a preposition, but lucky for me I'm not in English class). If you want your microbevel to be a mirror, like your back-bevel, then you might have to go thru the progression to get that nice mirror finish. But being that it is a MICRO bevel, the actual finish on it isn't too noticeable.
 
like samuraistuart rightly said, please be sure that you raise a full length burr on each side with your coarse stone--from your progression list that would be 220. Full length means from heel to tip. You raise a burr as an indication that you have removed enough steel and reached the edge's apex on the side you are working on.

Raising a burr on one side and doing the same on the reverse ensures that your edge is completely apexed. Remember that the majority of your sharpening will be with the coarse stone. The rest just build upon and refine that newly formed secondary bevel.

I have an EP Apex w/ a similar grit progression. I suggest you add a coarse diamond like an Atoma 140. It will form and shape your edge much quicker than the 220.
 
SconnieBT said:
I have a 120 as well. Just don't use it often unless I'm really reprofiling.
Click to expand...

Re.: 120 stone: Why don't you go ahead and use it for now? I sometimes use mine with low pressure to raise a burr and then progress. It might help you be sure that you are raising a burr, as it's easier to feel. It will also avoid buying diamond stones for now. Something to consider.
 
Go get yourself one of the 3.99 folders from Walmart or an old kitchen knife and then work with your coarse stone until you can feel your burr with your fingernail or finger. It will feel different on one side than the other. The key in using the cheap knife is that you will be willing to "grind" it more and can make mistakes without worry. Also the easier steel to sharpen may help a little also. I personally would not do a secondary bevel at first as it just adds a layer of complications and another set of things that can go wrong.

I never really got it until I tried to sharpen a piece of wood with sand paper like I would a knife and saw how the wood would feather at the edge as the fibers flexed up away from the grit.
 
Fyi, you dont have to even go to a very high grit to push cut paper. I am able to eaisly achieve a push cutting edge using the spyderco medium grit "brown" ceramic stone. I sometimes like going to the fine stone but for the most part i prefer the way it cuts with the coarser edge. Btw, i edc: 940-1.
 
Looks like you arent getting to the edge of the edge. Go to your coarsest stone and make sure you raise a full length burr down both sides of the blade.
 
I definitely understand the concept of a bur on the edge. I'm wondering if I need to flatten my stones? I bought the edge pro used and so I'm not sure how much wear the have. Could an arched stone be giving me the problems I'm having?
 
1. Always burr and make sure you fully deburr

2. Pull the angle back to a more acute edge.

3. Yes, a 1 micron diamond compound on a strop can enhance a sharp edge.

Also jus FYI, you don't need to progress through each of those grits.

Try just the 250, 600, 2000, 6000,

Or 400, 1000, 3000, 6000.

Also remember that mirror finish edges don't last as long since your polishing out the teeth.


You get cleaner cuts, but your edge won't have much bite.

It will dull faster on cardboard and other utility cutting as well.

This also reduces the benefits of that s30v steel which would probably perform better with a toothy polish to really expose those vanadium carbides for a longer lasting more aggressive edge.

I'd recommend stopping at 1000 grit, with maybe some light stroping passes on the 3k.
 
SconnieBT said:
I definitely understand the concept of a bur on the edge. I'm wondering if I need to flatten my stones? I bought the edge pro used and so I'm not sure how much wear the have. Could an arched stone be giving me the problems I'm having?
Click to expand...

Maybe. But not the shape. Worn-out thinned stones would result in inconsistency and more importantly a steeper (greater) edge angle than a new stone. So if your lowest grit stone is thinner than higher grit stones, I guess the higher grit stones would not be able to reach the apex created by the lowest grit stone. To avoid it, you need to make sure that all the stones you use are similar in thickness. Or you can get a adjustment collar to compensate the thickness difference.


Miso
 
SconnieBT said:
I definitely understand the concept of a bur on the edge. I'm wondering if I need to flatten my stones? I bought the edge pro used and so I'm not sure how much wear the have. Could an arched stone be giving me the problems I'm having?
Click to expand...

I wouldn't think that is the case, otherwise you would have hit your apex due to the stone being dished.
 
SconnieBT said:
I definitely understand the concept of a bur on the edge. I'm wondering if I need to flatten my stones? I bought the edge pro used and so I'm not sure how much wear the have. Could an arched stone be giving me the problems I'm having?
Click to expand...

It can happen, the edge pro when used properly is very fussy about differing stone thickness and blade movement. If you are just using stock stones odds are good you created some decent dishing doing the first few(presumably dull) knives you used to practice on.


Check out this video by Dr Matt. Mostly regarding straight razors but alot of this information can be applied to knife sharpening.
[video=youtube;RAbAToeM5hU]https://www.youtube.com/watch?v=RAbAToeM5hU[/video]

You gotta get all the way to the edge of the edge.
 
I would do like dead box said and thin the edge down. If your 940 is anything like mine was its a pretty obtuse angle and matching it to a mirror polish won't don't much if anything to help it cut. I'd go to 15 a side fully apexed on the 120 then the 4 and then 6 and 1000 for just a few light passes and then try push cutting your paper. If it's not push cutting by the time the 6 is done I'd say you are using too much pressure
 
Don't rely solely on the sharpie trick. When you think you're dead on, go up a degree or so. I can effectively erase ink in one swipe and not hit the apex. It'll get you really close but you need to keep going once the ink is gone to make sure you're thinning the apex.

Think about it this way, the sharper the knife, the thinner the apex. Just because you removed the ink doesn't mean you actually thinned the apex. At the same time, just because you created a bur doesn't mean you thinned the apex. A burr just means that there's metal that's been scraped off the bevel still hanging on right at the apex.

It's really just matter of doing it enough until you realized what's happening at the apex and what works for you. It's easy to say remove the ink and create a burr because you will probably see those things when you sharpen a knife but that's not really the whole picture.

Your goal is to create the thinnest apex you can. With coarser stones your apex will be large because there's a lot of removed steel. With finer stones the burr will be smaller because it removes less steel per pass.

Your main goal shouldn't be to create a smaller and smaller burr but that will likely happen if you're doing it right. Your goal is to create a thinner and thinner apex.

Try to visualize looking at the edge from the tip at a microscopic level. You don't want a wide, trashy apex. You want a refined, thin apex. You don't need to go to super high grit levels to obtain that. You just need to realize what you can accomplish with each step of the sharpening process and how you can create a thin apex.

Having said all of that, I was getting really great edges way back in the day but stropping on the clean, worn out back of a normal leather belt held between my support hand and big toe really taught me that cleaning the trash off the apex was a thing.

Since I figured out what benefits that brought and how to best do it I can normally shave my face sans shaving cream with my freshly sharpened knives unless I was in a hurry or didn't feel like being all that anal. After sharpening my knives will always shave arm hair, though, regardless of how much time I spent.

Freehand my edges are arm hair shaving. With a guided system and about an hours worth of time most any of my knives can easily push cut paper. It's more like I could probably shave my head with a bunch of nicks. Even CPM 15V.

You have the right system and the right stones to create a superbly sharp edge. The rest is just practice and trying to figure things out. With the edge pro type system I found that some strong neodymium magnets under the blade keeping the blade in place really, really helped step up my game. I couldn't really produce anything that great with just my hand holding the blade in place. A clamping system easily solves that issue but usually isn't that great with blades that don't have a large flat to clamp on to.
 
You must log in or register to reply here.
Back
Top