Think I have an uneven edge. Some input please?

M

mdc5162

Joined
Nov 3, 2010
Messages
611
I have a couple questions to the sharpening inclined around here. The blade I am talking about is S30V. I have a smiths guided system with diamond hones and I used it to sharpen and reprofile the knife. I know this isnt perfect but its what I have and works good for me for now.

Basically when I try to shave hair when I try to shave down my arm it will shave hair but when I go up my arm it does not. Is this due to uneven sharpening?

After done with the guided system I was still wanting more so I freehanded it on the hones they provided 750, and 1000 grit and saw improvements but still have the above problem.

Basically I am asking the above question. Also I noticed that one bevel is a bit larger than the other so I assume they are different angles, (almost positive from eying up the edge). Should I fix this before trying to fix the other question?

Just for your info I normally maintain my knives by stropping on 2000 grit sandpaper or 800 grit if its bad.
 
have you checked for a burr on the side that wont shave or is it the same side you are trying?
 
Yes I have checked for a burr and made passes through wood to remove any burr if there was. (I didnt detect any when I check the finished product but of course I raised a burr when sharpening.)

I dont understand what you mean when saying "or is it the same side you are trying" going down my arm shaves the hair, going up my arm does not.
 
If there is no burr... you are tearing the hair when you go down your arm... cutting with the grain.

It's not sharp enough to cut against the grain going up your arm.... you need to finish sharpening it and it will go both ways.
 
For me sound and feel of shaving my face tell me how sharp I've gone, if I hear the hairs popping off, it's not completely sharp and I'll feel it tugging a bit.

Sharp is much less noise and there's no tugging I can feel.

A similar analogue is the hair on the back of my hand, thin pliable skin.

Technique can play a part as well.
 
Okay so because it can not shave up my arm, it is indicating it still need work. It actually can shave the hair off the back of my hand better than the thinner hair on my arm. And it can cut "S" curves in paper. Dont think it can shave my face though.
 
I don't think you're taking care of the burr on S30V with the wood unless it's a hard wood. This might be misleading since when you have a small burr left over, it may shave hair when the left-face of the blade is facing downward, but not when the right-face of the blade is facing downward ( say if you shaved with the grain on one arm, switched hands and did so on the other, or shaved down the grain on one arm, and then turned the knife over and shaved upward against the grain ).

On the other hand if you did get rid of the burr on the wood, with S30V you may have tore off a little bit of your honed edge so you should strop after removing the burr from the wood. This might be the case if it can't shave against the grain, but will shave with the grain with either side of the blade-face being up or down. Reason being is that it's just easier to shave hair with the grain than against.

You should try to work on scrubbing the burr off on the hones themselves with gradually lessening pressure ( all the way down until you're just barely grazing the hone surface ) and maybe to pick up a strop of some sort.
 
Thanks for the tips. I do decrease pressure and amount of passes when I am on the guided system to knock off the burr but I also heard passes through wood were also beneficial. The wood might be soft as I am using the under side of a cheap desk. I didnt know I could knock off the honed edge with the wood.

I tried to shave hair again both arms, up and down and it worked this time with a slight change in angle on the side that I perceived as a steeper angle to the edge. I think most of the error lies within the error in the guided system.

Since this is an expensive knife I am a little hesitant to freehand it on sandpaper but I did get good results with a cheaper knife using 8CR13MOV.

Basically this is a right hand knife and I believe the bevel on the lock bar side is more shallow and the bevel on the scale side is steeper. Hope that brings a little clarity.
 
S30V is known for initially taking a very fine edge, then some of that edge will 'fracture' off with some cutting, leaving a coarser and much more durable working edge that lasts a long time. If there is much of a burr at all, after sharpening, I've found on this steel at least, it can be taken off relatively easily in this 'fracturing' way. I noticed this with the first S30V blade I sharpened. I was testing cutting performance by cutting into a phone book. I noticed, after a few cuts this way, the edge suddenly had a little more 'bite' to it (cutting very aggessively, and felt somewhat coarser after the fact). For real-world cutting tasks, this is a good thing. Doesn't shave as well, though. If the blade isn't shaving, I wouldn't necessarily worry too much about that. Try it out at some other tasks, like cutting wood, leather and cardboard, and see how well it does that, and for how long.

If the blade is very thick (1/8" or more), the uneven bevels can be pretty common and more noticeable. Oftentimes, it's just due to an asymmetrical grind on the blade itself, with more metal on one side (relative to the centerline). This can make the blade 'thicker' on one side, meaning more metal will be removed at a given sharpening angle, on that side. That will result in a wider bevel on one side.
 
Thanks very much for your imput. The blade is pretty much 1/8 at the top and a 3/4 hollow grind to the bevel. This is an edc knife for me and the edge is more than acceptable, I am just trying to further my technique. I have heard this about S30V before and I guess I shouldnt be comparing it to my S90V para2. (oops).

I do understand what you mean asymmetrical grind and that may be it but I think if i get the bevel more even the slicing may improve. Although I am sure there is a strong possibility that it is just in my head and stroping this on 800 then 2000 grit isnt gonna help. Then again it might lol.
 
mdc5162 said:
Thanks very much for your imput. The blade is pretty much 1/8 at the top and a 3/4 hollow grind to the bevel. This is an edc knife for me and the edge is more than acceptable, I am just trying to further my technique. I have heard this about S30V before and I guess I shouldnt be comparing it to my S90V para2. (oops).

I do understand what you mean asymmetrical grind and that may be it but I think if i get the bevel more even the slicing may improve. Although I am sure there is a strong possibility that it is just in my head and stroping this on 800 then 2000 grit isnt gonna help. Then again it might lol.
Click to expand...

S30V is also the one that really illustrated 'abrasion resistance' to me. The very large and very hard carbides in this steel make it much tougher to abrade (sharpen or file) metal away. I've learned to be very PATIENT with this steel. On thick blades, the more metal you remove from the bevel, the wider the bevel gets. The contact area under the hone gets much broader, so the going gets a lot slower. I have a couple of S30V folders that aren't quite as sharp as I'd like, and I go back to them periodically with sandpaper and/or a diamond hone. Gets a little better each time. But, it does take time.
 
Yes that is a very true statement! I noticed that too when I first sharpened an Umnum I had with the guided system. At first it was going fast and I was thinking this will take 5 min but then once you get more then half way of reprofiling and edge the time really starts to increase. It does take patience and a block of time. I may have premied it a bit, but better here than other places. :D
 
You must log in or register to reply here.
Back
Top