How do i get this razor sharp?

5

5211

Joined
May 7, 2008
Messages
28
hi guys i'm new at knives so i need a bit of help

i recently got 2 knives

the bm 930 and bm 943

about 3 weeks apart from each other

when i got the 930 i noticed that it wasn't razor sharp (basically you can't even do that paper cut test)

and now today i got the 943 which can.. thinking something was wrong i went to inspect the edge and on close examination this is what it came down to

the 930 metal is thicker than the 943 but the tip was the main concern :eek:


how do i fix it.. (picture drawn is the actual cutting edge and what it looks like)

bmblade.jpg


should i take it to a professional to sharpen it / fix it or can i do it myself? i don't want to ruin the blade as i'm new at this.

i know to sharpen it .. but at what angle? it's thicker meter and it seems to be on a wider angle compared to the 943..

it's as if the 943 has a 30degree edge where as the 930 has a 40ish degree edge

well any advice would be appriciated
 
I'm sure you'll get lots of good advice as soon as people wake up and see this :)

I'm just moving it to our Maintenance forum where we do most of our sharpening.
 
Hey 5211, The bevels are off on the 930. First thing to do is to determine the bevel angle. You didn't mention what type of sharpener you have/use. In this case, a Sharpmaker is probably best because using a Sharpie, you can get a good read on the bevels.

Read this thread, and see if that makes sense.

Once you get the bevels down to the correct inclusive degree reading, all you should need is some work with fine or ultra fine ceramics or stones, then some stropping with a light compound to get that mirror finish.

This will give you a start, but as Esav said, someone with a lot more knowledge than I have will come along to give you the finer points.
 
You are going to have to thin out the edges and get the bevels equal on each side, Reprofile. Sounds like fun you say. If you are good a sharpening you should go ahead and do it yourself and if you want you can return the knife to Benchmade Lifesharp, pay Benchmade $5.00 and get it done that way. I have had several Benchmades that needed to be reprofiled and I have done them myself. I drop it main bevel to 10-15 deg per side to start with till I get it thined out then if you want you can put a micro bevel on at about 20 deg. I free hand my knives so those degree setting are rather +/_.
Anyway if you should do it yourself you will need to start off with a coarse stone and progress on up to fine and even finer depending on the finish you want.
Blades from the factory are usually done somewhat freehand on a belt so there is no guarantee that the bevel is dead nuts even on each side. So if you do it yourself just keep the bevels as even as possible.
I probably have not helped you much but in a nut shell that is how you go about doing it.
 
How do you fix that?

Very carefully! :D

All kidding aside, contact Benchmade and tell them the nature of the problem. If that fails, I suppose you could have it reground and reprofiled by a professional like Tom Krein. That looks beyond the ability of a SharpMaker to remedy...
 
well i live in Australia so i don't think i want to send it back.. it'll cost 2 much to send there and back.. ordering the knife cost me 40bucks aus for delivery ..

just a question.. what is reprofiling?
 
Reprofiling?? Changing the bevel at the cutting edge. Ok I will try to explain this so it makes sense to you and me both. I have the 940 so I will try to go through this in order. I just finished reprofiling the 940.
Look at your thumb studs on the blade and keep that in mind as a guide as we put that knife on a bench stone to reprofile. Lay the knife on the stone keeping the thumb studs just high enough off the stone so they do not get ground down. Then move the blade from heel to point and repeat this move on each side until you have the bevel even on both sides. When you think you have it even look down at the cutting edge, all you should see is the sides of the knife, not the actual cutting edge itself. If you can't see anything but the sides you are starting to getting close. Grab a paper and see if you can cut that paper with just light pressure on the blade. If it cuts the paper you are doing fine. Try it out on some wood and see how that cuts. After you get this first edge to your liking you can then add a micro bevel. What is a micro bevel you say. A micro bevel will be a bevel that is formed when you increase the angle to the stone while sharpening. Just raise the blade a little more than you had been doing in the reprofiling process. If you have reprofiled correctly it wont take long to get a good micro bevel. Now you dont have to micro bevel if you dont want to but the micro bevel will creat a somewhat stronger edge for you.
You might want to try all this out on some beater knife before you do your BM. And if you are going to reprofile you will need a corase stone, if you dont have a coare stone you can get some coarse sanding paper, and lay it out flat on a flat surface and get with it. You will want to use an automotive grade sand paper. Start with something like 250 grit to start with.
Now I guess I have you really wondering what is that dude talking about. I hope this has helped you somewhat but I may have really confused you too.
Have a good day mate.

Hopefully someone who can write better than I will chime in and explain this in a much clearer fashion. Come on guys help him out.
 
Do a search under knife sharpening and find articles about knife sharpening by Joe Talmadge. That will help you.
 
white dog.. no no .. its very readable and i think i understand what you're talking about

i've tried to sharpen a povo 2c chinese stainless steal knife but no matter how i do it i can't seem to get it to cut paper... its cutting but not as well as my new bm 943... can it be the stone?

can you or anyone please explain the 250 grit etc stone? what is 1000 or whatever and what kind of stone should i use?
 
A 250 grit would be very coarse, as you go up the scale like 600 that is fine, 1000 is very fine and so on. The lower the number the more coarse and the higher the finer it gets. 600 grit will give you a very nice working edge.Some of that Chinese stuff just wont take an edge but it is ok for practice.

Don't get discouraged while trying to reprofile. It may take you several sessions.
 
5211 said:
...can you or anyone please explain the 250 grit etc stone? what is 1000 or whatever and what kind of stone should i use?
Click to expand...

Stones are rated in terms of grit numbers (like sand paper). Think of it like the number of individual grit particles it takes to cover a given area. If the grit particles are larger, it takes fewer of them to cover the given area, thus a lower grit number. The larger the grit number, the smaller the actual size of the grit particles. This is easy to see/feel on various grits of sand paper.

The grit particles actually scratch away steel when you pass the steel over them. Larger particles make wider/deeper scratches, therefore they cut faster. A basic sharpening technique begins with a low grit # stone (larger particles) to create a sharp edge. Then progress to a higher grit # stones (smaller particles) to refine the edge (reducing the size of the scratches).

Stones are also described in terms of the type of grit that comprises them. The type of grit also effects the speed/efficiency of their cutting. There is too much contention over the "best" type of grit to discuss now.

Books about sharpening will explain this and sharpening techniques in much greater detail than you will get from single posts here. Try one of the following:

The Razon Edge Book Of Sharpening by John Juranitch

The Complete Guide To Sharpening by Leonared Lee
 
cheers guys.. for all your help i guess i'll have to find a few dull knives to practice on and also buy some stones tomorrow..
 
DMT diamond stones are good stuff and Northon stones are good also. The diamond stones work very well, simple clean up also. The diamond stuff works very well with a lot of the newer super steels. If you can find it get a combo stone that has a coarse grit on one side and a finer grit on the other side.
Good luck.
 
Just wanted to add that it's actually not necessary to have both sides with equal angles in order to be sharp. It just makes is nicer to use and look at. Every Emerson model purposefully comes with different angles and they can get extremely sharp.
 
Kaizen1 said:
Just wanted to add that it's actually not necessary to have both sides with equal angles in order to be sharp. It just makes is nicer to use and look at. Every Emerson model purposefully comes with different angles and they can get extremely sharp.
Click to expand...

Is true. Just make the two sides meet in the middle, and it'll be sharp.
 
Kaizen1 said:
Just wanted to add that it's actually not necessary to have both sides with equal angles in order to be sharp. It just makes is nicer to use and look at. Every Emerson model purposefully comes with different angles and they can get extremely sharp.
Click to expand...

Yep, I got a PE Delica 4 that was very sharp, but one side was 15 degrees and the other side was 20. So I reprofiled the 20 degree side, but being new to this, I only worried about getting the 20 degree side down to 15. I was successful in doing that, but ended up with an edge that had equal angles on both sides, but met off-center. It is very sharp, but yes, it would definitely look better if both sides were even. For now, I've decided to concentrate my sharpening efforts on one side over time, in order to let it gradually work its way back to center, although I just ordered my first benchstones, so in a sharpening frenzy I may forget all about that gradual stuff and even that sucker up!!! :D
 
DainBramage said:
Yep, I got a PE Delica 4 that was very sharp, but one side was 15 degrees and the other side was 20. So I reprofiled the 20 degree side, but being new to this, I only worried about getting the 20 degree side down to 15. I was successful in doing that, but ended up with an edge that had equal angles on both sides, but met off-center. It is very sharp, but yes, it would definitely look better if both sides were even. For now, I've decided to concentrate my sharpening efforts on one side over time, in order to let it gradually work its way back to center, although I just ordered my first benchstones, so in a sharpening frenzy I may forget all about that gradual stuff and even that sucker up!!! :D
Click to expand...

Unless you're going to be sharpening it at the smaller angle, the only thing that will happen is you'll be continually creating a burr on one side. If you do sharpen it at the steeper angle, you won't reached the edge until the excess metal is gone, which is okay if the blade stays sharp all the while.

I'm reprofiling the blade on my Leatherman Wave and I work on it maybe 30-90 seconds at a time a few times a week. If you're doing something like that, you should be okay. I don't really use the blade on it so I don't have to worry about keeping the edge sharp until the reprofiling is done.
 
Kaizen1 said:
Unless you're going to be sharpening it at the smaller angle, the only thing that will happen is you'll be continually creating a burr on one side. If you do sharpen it at the steeper angle, you won't reached the edge until the excess metal is gone, which is okay if the blade stays sharp all the while.
Click to expand...

No, both angles are now at 15 degrees. I guess I should have said that I'm going to concentrate PRIMARILY on one side when possible... but that won't include ignoring the burr. To be honest, I'm guessing that once I get comfortable with my new benchstones, I'll just even it up!
 
DainBramage said:
...I'm going to concentrate PRIMARILY on one side when possible... but that won't include ignoring the burr...
Click to expand...

That is what I would do. Sharpen as necessary on the one side. Remove the burr. Just a touch on the other side. The edge will eventually move to the center.:)
 
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