BWM bevel angle

C

Cadman2008

Joined
Apr 20, 2010
Messages
111
Finally need to sharpen my BWM, and my sharpening system of choice is a Lansky. Using it for mainly green wood chopping duties.

Would you guys recommend 30 degrees / side, 25 or 20? I am not putting a secondary bevel or anything like that on it, just a straight \/ edge. I realize I should test it and see, but I am going to get a local professional to put a nice, symmetrical edge on it, because the hours required to do it with the little 3" stones on the lansky would be excessive.

Any opinions?
 
I take it the only way to fly nowadays is convexing?

Surely you haven't ALL convexed your choppers!
 
If I chop with it, it is convexed.

Even if I use a V edge, I don't know the exact angles... I use what works, if it doesn't I change the angle.

Can't be much more help than that. I know there are some guys here that get serious about exact angles, or at least there used to be.
 
Skrapmetal said:
If I chop with it, it is convexed.

Even if I use a V edge, I don't know the exact angles... I use what works, if it doesn't I change the angle.

Can't be much more help than that. I know there are some guys here that get serious about exact angles, or at least there used to be.
Click to expand...

Yeah, I was waiting for LVC to contribute but he must be busy these days :) so I guess I'll give my opinions, albeit probably misguided ones.
On a chopper, even an INFI one, I would go with an obtuse angle, like 30. But that's only because when I get to use my knives I'm usually far from home and don't have the access to good equipment for honing and sharpening. If you do, more acute would probably be fine.
 
I prefer a fine edge myself. On smaller blades of INFI or sr101 i reduce the shoulder almost to nothing, with a sharp file, then convex whatever is missing coating. I do this for future ease of sharpening; usually it takes me less than a minute on a steel(an antique nearly smooth one )to make air bleed. The tiny chips i sometimes get in the sr101have no effect on performance. The tiny dings in the busses get pushed back into place by going backward on the steel.
Even choppers get reduced in this manner but to a lesser extent.
 
Convexing is typically ideal on a chopper, but I enjoy using my edge pro for some impressive v-edges.

Without a secondary bevel 30* will maintain the closest to factory edge toughness but 25* will perform just a bit better.

A 20* back-bevel followed by 30* on the edge for strength is very impressive.

Or if you are thinking of having a pro do it, the shop can do it for the cost of shipping both ways with pretty fast turnaround, which results in a really sharp edge guaranteed by the factory. ;)
 
AZTimT said:
Convexing is typically ideal on a chopper, but I enjoy using my edge pro for some impressive v-edges.

Without a secondary bevel 30* will maintain the closest to factory edge toughness but 25* will perform just a bit better.

A 20* back-bevel followed by 30* on the edge for strength is very impressive.

Or if you are thinking of having a pro do it, the shop can do it for the cost of shipping both ways with pretty fast turnaround, which results in a really sharp edge guaranteed by the factory. ;)
Click to expand...


Hehe I WOULD send it back to Busse, but I live in West Australia, which is about a 25k mile round trip for it. Pricey on postage and without it for weeks. Hopefully I can find a talented machinist here that can do a nice, precise edge without overheating it.

Judging from the replies, I think I might wimp out and go 30 degree. 25 would be more awesome, but the original factory edge was great, and if it's at 30 at least it's an easy sharpen for me with the lansky.

Thanks for the help guys, will go looking for a good professional in my area now :)
 
When I first started sharpening I also got a Lansky system ... then a number of other systems ... so I started with using V edges and found that the research Spyderco had put into determining the optimum edge angles before releasing their Spyderco Sharpmaker was more or less spot on for most uses. They suggest a 20 degree either side or 40 degee "inclusive" ( both are the same but confusion begins to creep into these threads when people don't distinguish clearly from inclusive or either side ) for the primary bevel and then reducing the shoulder on the edge with a 15 degree or 30 degree inclusive back bevel. This gives an edge which has worked well for me ... to the point where I practised a great deal on a belt sander to replicate this style of edge in a convex bevel ... and this is now how I sharpen all my knives for "chopping".

Things to note when going this route by getting a professional to re-profile the edge is that by buying a Spyderco sharpmaker you can easily top up the edge yourself ... and the Spyderco system is not expensive and is easy to carry in the field.

To get the Lansky to work properly do not rely on the pre-drilled holes which give angle figures. These don't work because the thickness of the spine and the depth of the blade always vary. You need to measure the distance from the edge to the clamp and then the middle of the spine to the hole ... then use trigonometry by working out the inverse tangent to determine the angle of the stone to the edge. This method works excellently ... but remember the need to move the clamp along the spine on a long bladed knife ... which then means you get "patches" of edges which are not seemless ... so for this reason I like the Spyderco system which enables a single accurate "draw" along the edge to give a consistant edge either side.
 
PeterPHWS said:
To get the Lansky to work properly do not rely on the pre-drilled holes which give angle figures. These don't work because the thickness of the spine and the depth of the blade always vary. You need to measure the distance from the edge to the clamp and then the middle of the spine to the hole ... then use trigonometry by working out the inverse tangent to determine the angle of the stone to the edge. This method works excellently ... but remember the need to move the clamp along the spine on a long bladed knife ... which then means you get "patches" of edges which are not seemless ...
Click to expand...

...Crap. Didn't think of that.

Thanks Peter, must think on that for a bit.
 
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