Convex?

Mouse pad and sandpaper, Ooooor 3M drywall sanding pad, and sandpaper, very nice because it secures the paper, aaaaand has a handle. Also worksharp tool and knife sharpener is a thing of beauty, BUT stay away from the tip of your good knives until you get the hang of it, it WILL let you round the crap out of the tips until you figure it out.
 
Something to keep in mind is that as you remove the shoulder between the primary grind and the edge, you are almost inevitably going to change the angle of the edge. I think that is something that a lot of people don't realize as they are convexing a knife. For instance, if I start off with a knife with a 20° angle on each side for the edge (40° inclusive) then as I remove that shoulder, unless I am absolutely meticulous in my methods, the point is going to come back some as well, and that angle will increase.

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There we have a 20° angle on each side on the edge.

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There we have the end result in red of what "convexing" will do, and if you look closely enough you can see that the angle has increase dramatically. This is where the sharpie trick (coating the entirety of your edge with sharpie marker) comes in so handy, because you will need to hold the blade a much steeper angle than you originally did to sharpen it, and the sharpie will show you exactly how much you are missing or whether or not you are even getting to the edge. Use a magnifying glass and make sure you are getting to that edge, other wise you will find yourself in the same boat I have been in numerous times with a knife that just doesn't seem to get very sharp.
 
I notice something about my 2 this week. It still has the factory edge and I have been using this edge since I got it...I have not sharpened it.

I've been using the crap out of the knife though and, it seems I have one edge (angle) that is deeper than the other. Looking at the tip from the top of the knife it looks like instead of a 20 degree and 20 degree, I've got a 20 and a 15 (or worse). Would using Derek's method of convexing, fix this? Or do I need to take it somewhere and get it re-done? reground? re-profiled?

I'll upload a pic as soon as I can.
 
I learned a ton from this averageiowaguy video with a Jerry Fisk master class:

[video=youtube_share;DzBSjQFWyhM]http://youtu.be/DzBSjQFWyhM[/video]
 
I just bought a HF 1x30" belt sander with 150, 240, 400, 15micron, 9micron, leather belt w/ black compound, leather belt with green compound. Now both my Beckers are convexed, slicing through paper like butter and shaving with ease.
 
i convexed a endura very sloppily on mousepad and sandpaper and its easily the sharpest knife i have touch ups are so simple you could close your eyes and do it
 
tgreen812 said:
Any tips on convexing the blade on my 14 and 2?
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don't bother...

convex is overrated IMHO, except for thick chopping implements.... like an axe... as thick as the 2 is... it might work for you if you want to hack stuff up....convex is not sharper.. it is stronger...

YMMV

Doc
 
Doc_Savage said:
don't bother...

convex is overrated IMHO, except for thick chopping implements.... like an axe... as thick as the 2 is... it might work for you if you want to hack stuff up....convex is not sharper.. it is stronger...

YMMV

Doc
Click to expand...

Yeah, I'll agree. Convex just isn't for me. I find the knife loses its "sliceyness".
A lot of guys Around here love a convexed edge. I just can't warm up to it.
 
I won't argue the sharper thing or sliceyness, that really is determined by far more than just convex vs v-grind, but I personally find it easier to maintain as to me it seems more forgiving during the touch up phase. I used a v-grind on everything growing up, and did very well, but it took time and I found that once I got the hang of the convexing down it goes much quicker, with less work, and easier to attain results. That is all freehand though, so using a system like the thing Moose is always showing off, that would alleviate that tremendously. Again though, that is just personal preference, and that is going to vary by individual.
 
I keep hearing about this mousepad method. Anyone care to give further insight? I'm thinking about trying it in regard to my 17 and 11. If I did, would it be impossile to sharpen the knives in a standard stone or spyderco sharpmaker if I needed to?
 
I was about to ask the same thing. I use a Lansky diamond setup for sharpening...does changing the edge to convex make those types of sharpening setups unusable?
 
The idea behind it is that you use a mousepad as a backer for your wet/dry sandpaper so that there is some give behind the sharpening surface. If you are trying to get your knife to convex, it is a very time consuming process doing it that way (typically shown as stropping the knife on the surface in much the same way you would if it was a leather strop).
 
I've convexed most of my knives including my BK16. I started out using an old mousepad and sandpaper and a "Fine" grit foam sanding block. I used the sanding block first then moved to 400, 800, and 1000 grit sandpaper on the mouse pad. I then finish it off with a leather pad.
I put my sandpaper on the backside of the mouse pad because it's grippy (which holds the sand paper in place) and has the most give (the top side is hard plastic).
I've got best results by holding the knife nearly flat against the sanding surface. This really thins out the edge, some might say too thin, but this edge is on my EDC Benchmade and I haven't had a problem yet. It took some trial and error to figure out what worked for me so I suggest trying it out on a blade you don't care about.
I used the picture above to make up a diagram that I think shows how the mousepad method works.
The foam allows the sand paper to curve around the blade. The trick is finding the right angle and the right pressure. You don't need much pressure at all to get the right curve under the blade. If you put too much pressure the convex can get steep and round off the edge. As mentioned above, some marker ink on the edge can help you see when you start getting to the edge. If you hit the edge too fast you're probably at too steep of an angle or using too much pressure.
 

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Grizzly,
I believe that you can still use those types of sharpeners to put a micro bevel on a convexed edge, provided that it isn't a really steep convex.

I've kinda noticed that there's a big difference in my convex and the first convex. I was going for sharpness and thus went for a really thinned out convexed edge. When I first did my BM knife I was blown away. The first task I put it to was cutting the bottoms off a pair of jeans for my fiancee (she got some jeans from a friend that were a couple inches too long) I was able to cut a perfectly straight edge through two layers of demin without the meterial stretching. Like butta!
I put a similar edge on my BK16 and used it camping to cut and baton small wood without geting any damage to the edge.
 
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I'll leave the guys to their discussion..I have convexed some of my blades and I used a work sharp knife and tool sharpener. I agree the becker blades do hold an edge for a long time and since I convexed my bk2 I have not sharpened it and have split a crap load of wood and it still shaves hair. One draw back I see is if your not able to sharpen by hand or with strops then this edge might not be the best choice if you plan on spending any amount of time in the woods as if your not careful you can easily dull your blade...either way it's fun screwing around with differnet sharpening techniques and learning things.
 
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