How do I sharpen a brand new BM 940?

prng

prng

Ham and Cheese in between two crackers
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Jan 6, 2011
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I just purchased a new Benchmade 940. It's fairly sharp already but I'd like to sharpen it a little more.

I have a Spyderco Sharpmaker and I also have the diamond rods.

Should I go through the steps of putting a 30 degree back bevel using all three stones and then go to the 40 degrees with all three stones too? Any other suggestions? Should I just wait and occasionally use the fine stones?
 
If it's brand new, it should only take a few strokes with a fine or ultra fine rod (freehand) to get it really sharp. Or just the 40° angle on your Sharpmaker.

After many, many touch-ups, it'll eventually need reprofiling, which is when you use the 30° and the diamond rods.
 
Planterz said:
If it's brand new, it should only take a few strokes with a fine or ultra fine rod (freehand) to get it really sharp. Or just the 40° angle on your Sharpmaker.

After many, many touch-ups, it'll eventually need reprofiling, which is when you use the 30° and the diamond rods.
Click to expand...

:thumbup:
 
I'm having some problems with my Benchmade... The right side of the blade has a larger shiny bevel than the other side and this knife is not as sharp as my Endura ZDP-189, sure I can understand that, but even my Persistance is sharper. This thing tears paper, not cuts it. I don't know what the hell went wrong with it and I don't know what to do with it. I barely used it over the last few weeks and it's dull already.

I've tried sharpening it on my Sharpmaker multiple times and still a bad edge. Won't push cut paper, requires a lot of force compared to any other knife i have to cut an apple, etc.

How do I get this thing back to a decent edge?
 
prng said:
I'm having some problems with my Benchmade... The right side of the blade has a larger shiny bevel than the other side and this knife is not as sharp as my Endura ZDP-189, sure I can understand that, but even my Persistance is sharper. This thing tears paper, not cuts it. I don't know what the hell went wrong with it and I don't know what to do with it. I barely used it over the last few weeks and it's dull already.

I've tried sharpening it on my Sharpmaker multiple times and still a bad edge. Won't push cut paper, requires a lot of force compared to any other knife i have to cut an apple, etc.

How do I get this thing back to a decent edge?
Click to expand...


BM's usually have an obtuse edge with very little relief. You'll probably have to reprofile it.
 
cover the edge in sharpie and go at it with the diamond rods until the sharpies gone right at the edge and that should even out the bevels. Then you can finish it up and put a nice edge with the other stones. Its how I fix up all my BMs
 
dtownknifekid said:
cover the edge in sharpie and go at it with the diamond rods until the sharpies gone right at the edge and that should even out the bevels. Then you can finish it up and put a nice edge with the other stones. Its how I fix up all my BMs
Click to expand...

I tried this last time after posting and got a better edge but it's still nowhere near what I wanted. Is it possible to be hitting the sides of the bevel but not getting the tip? It looks like I'm just missing the very edge most of the length of the blade.

Either way, I'll try it out again. Should stick with 40 degrees or try for 30 first then try 40? How many strokes would I need on each stone set and each surface (edge vs flat of the stone)? What surface should I use to get rid of the sharpie when going at it with the diamonds?

With this reverse tanto blade, should I be trying to keep my wrist still completely not move with the curve of the knife while "cutting" the stones or should I move my wrist while cutting? How much pressure with the diamond rods is enough?

Could it be that I need the ultrafine rods for the sharpmaker to get it sharp enough?

Sorry for all of the questions, I'm new to the whole sharpening thing with different blade steels.
 
It's more about the angles than the steel. Planterz was correct in his post above.
 
It all depends on how obtuse the factory angles are, but stick with the 40 degree for now. I use the corners of the diamond rods and try to follow the curve with my wrist. I also use a very light pressure. It can take a few hundred strokes and a very long time but eventually the angles should be set. The sharpmaker does some things very well, but sadly reprofiling is not one of them. Be patient and eventually you will get your edge.
 
i reprofiled my benchmade 707 to 30 degrees on my sharpmaker. it took hours with the diamond stones. i believe you may not even hit the edge with the 40 degree setting so you will need to reprofile.
the ultra fine stones are not needed to get it sharp. it should easily shave after the fine stones
 
The Sharpmaker, as good as it is, has a lot of human element involved. You might think you're using the 30° setting, but human error could easily be several degrees off. It takes practice, concentration, and muscle memory. Some people might never get skilled at it. There's nothing wrong with that. Not everybody plays guitar like Jeff Beck either. The Sharpmaker might be the Guitar Hero of sharpeners. It's definitely the best compromise between affordability and usability. But it does take skill to be a pro with it. I'm nowhere near a pro myself. Will you get mirror polished edges with the Sharpmaker? Most probably not. Does it cost as much as an Edge Pro, which can give you mirror edges? No. Should you be able to get a very good edge with a Sharpmaker? Probably. Probably good enough to shave armhairs with the included fine rods. Personally, I don't care for the ultra fine rods. I can't get as good a result from them as I do with the fine rods. Probably because I'm not a Jeff Beck at sharpening.

Reprofiling on a Sharpmaker, even with the diamond rods, can take a long, long time. Stick with it, or reprofile with something like and Edge Pro and do your touch-ups with a Sharpmaker.
 
I was looking at the Edge Pro's, they make that bevel look awesome and I'm sure they're scary sharp. If I would get one, is it easier to reprofile with it? Am I going to have another huge learning curve? If I can't get the Sharpmaker to do what I want, I might pick up an Edge Pro. Which one should I get? I'd like to be able to handle pretty much all steel, I do have a ZDP-189 blade, a few S30V, etc. edit: also just realized how expensive they are... :) Probably won't buy one any time soon.

Also, how do I know when it's reprofiled if I'm using the Sharpmaker?
 
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Bump... mainly looking to know when a S30V knife is re-profiled if I'm using the Sharpmaker with diamond rods?
 
The edge has a new profile when the Sharpie is gone. It's not rocket science. Just hold it perfectly straight up and down and keep at it until the Sharpie is gone. Don't push too hard, just enough pressure to keep the edge hitting the stones at a nice, constant pressure. With the Diamond stones, it will take hours.

I worked on my 710 (D2) over the course of an entire weekend. I did a little here, and a little there. I would get up and leave it alone when I got tired or started getting sloppy and come back later. I did this for hours. Even with a system like the Edge Pro or the Wicked Edge, you have to learn how to use it and it still takes some time to re-profile. There's no such thing as a free lunch!

If all of this is too much, just send it off to one of the forum members to have it done. Then you can just keep it maintained with the Sharpmaker.
 
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