How Can You Tell If Its A Convex

Blood_Grooves

Blood_Grooves

Joined
Oct 28, 2007
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well i read the barky's page and did the hard plastic marker test and my GW passed, dose that mean its a convex? it looks like it is with the naked eye, there is no bevel to be seen. and the light kind of "rolls" off of it. with all the clues i have found, i would have to say its a convex edge:confused::confused::confused:

EDIT: it also looks like the pics i have seen but mine has a coat so the edge looks like the otheres

SORRY I SPENT ALL MY MONEY ON THE KNIFE NOT A CAMERA...
 
Well, the hard marker test should tell you. It'll also look that way to the naked eye. Most of the time, the convexed edge will look considerably smoother from the polish and high grit sandpaper.

Did you convex it or did it come that way from a purchase?
 
i did it. the reason i am so sceptacal (bad spelling) is i did it mainly stropping it with my pants, cardboard, and a belt. but i did it for like 4 hours or more(didn't keep track) so i think if you spend enough time its possible:)

EDIT: no sandpaper!
 
That hard plastic bite test is to see if it's sharp, not convex. I would think four hours of stropping on your pants, carboard and belt would do little to make the edge profile into a convex.
 
resinguy said:
That hard plastic bite test is to see if it's sharp, not convex. I would think four hours of stropping on your pants, carboard and belt would do little to make the edge profile into a convex.
Click to expand...

Yeah, what he said. You'll need grittier material to strop on. Wet/dry sandpaper is cheap. Try it. :thumbup:
 
Yah no dice on that. I assumed you had followed the convexing procedure. It would take more than your pants, carboard and a belt, even if you used a polish.
 
I hold a business card or straight edge perpendicular to the edge to judge the level of convexity (spell checker choice).

Works for me.

If Mr. Clean spent 45 minutes with < 100 grit sandpaper, jeans aren't going to do it.
 
but what really makes a flat grind into a convex can someone explain whats going on when you reprofile a flat into a convex because what i think is going on is that your rounding of the corners on the flat grind and pushing that material further down the edge so it finishes rounding the sides of the edge, am i wrong?


i have only got one suggetion on how you actully check if its a convex. if you were to get a knife and didn't know the edge profile how would you check?
 
Basically your sanding the knife edge on a material that gives, hence the sharpening surface is not flat. The material is not pushed down, it's removed.
Another way to check for convexing is the take a marker and mark your edge. Try a flat sharpening style and if it removes all the marker at one angle, it's not convex.
 
Blood_Grooves said:
but what really makes a flat grind into a convex can someone explain whats going on when you reprofile a flat into a convex?

i have only got one suggetion on how you actully check if its a convex. if you were to get a knife and didn't know the edge profile how would you check?
Click to expand...

When you sharpen freehand you do not keep the same angle with every stroke on your abrasive (i.e. your pants/belt/etc). Because your angle changes a little bit each time, what would normally be a "flat" secondary bevel becomes rounded on the edges. In other words, the shoulder between the primary and secondary bevels gets worn down, and your secondary bevel is not straight.

Some convex grinds are so slightly convexed you may not be able to see it. In fact, some people have argued here on bladeforums that all edge bevels are convexed to some degree, as infinitesimal as that may be. So don't worry if you can't see a convex shape. If you can't see it, it's practically flat ground.

To check if a knife is convexed, the first thing you want to do is make sure you know the different kinds of grinds that people commonly use. This can be tough because some grinds have many names. Here are some sources for info about knife grinds:

http://en.wikipedia.org/wiki/Grind
http://www.knifeart.com/bladgeomfaqb.html

The "primary" grind on a Game Warden (GW) starts at the spine and is called a "full flat" grind. It is flat and not convex. The "secondary grind" on the GW is the small ~1/8" bit you see near the edge. I believe the secondary grind is also flat and not convex from the factory. These two grinds together on the GW would be what the Wikipedia link above would call #5, the double or compound bevel.

Some people also add what is called a "micro bevel" which can be very hard to see with your eyes. If you tilt your knife edge under a light you might see that the light reflects off the edge at a different angle than it reflects off the secondary grind. This could be because of a micro bevel, or it could be because your edge is convexed.

When you convex your GW's edge, you may find that the secondary grind starts getting rounded, and if you keep sharpening freehand it will happen and eventually it will be very pronounced.

(hopefully someone will correct me if I have any of this wrong)
 
Here's how your flat grind turns into a convex when you sharpen freehand:

2165275408_62fce80057_o.png
 
Mikeymoto has the right answer.

Ignoring the oddities like the Off Duty (which is hollow ground) the primary grind on almost every Busse but the HOGSJT is flat (either full or some degree of saber). Some come with traditional v-grind secondaries and some (e.g., the SJLE, ABALE, and UMFLE) come with a convex edge.

The HOGSJT and some HOFSH models have a full convex PRIMARY grind. You can sorta see the convex grind on the HOGSJTLE in this photo, compared with the full flat on the HOFSHLE:

hogsjtleandhofshle.jpg


This diagram may help some:

complexedgeshapediagram.jpg


Rick
 
well if what turns a flat into a convex is rounding the secondary bevel then i have made a convex...

the marker test i cant do right now i am at freinds house and dont have any kind of normal sharpening systems...:thumbdn:

I took some pics with my phone. they are not very clear but hopfully helpful.

http://i264.photobucket.com/albums/ii191/Blood_Grooves/cc.jpg

http://i264.photobucket.com/albums/ii191/Blood_Grooves/fd.jpg

http://i264.photobucket.com/albums/ii191/Blood_Grooves/nm.jpg

http://i264.photobucket.com/albums/ii191/Blood_Grooves/tn.jpg

http://i264.photobucket.com/albums/ii191/Blood_Grooves/hfhch.jpg
 
They're 115x113 pics, need to be a bit larger. Still I say that all that rubbing probably just smoothed a corner. But if it's sharp and you like it, who cares!
 
but isnt that all a convex is the corners rubbed smooth. a convex slices better because the coners or gone thus less friction.

I am a prefectionist i want to get it perfect:p
 
Blood_Grooves said:
but isnt that all a convex is the corners rubbed smooth. a convex slices better because the coners or gone thus less friction.

I am a prefectionist i want to get it perfect:p
Click to expand...


If you just rub the bevels(corners) off you will have a blade you have to sharpen often.

Convex is more rounded, like in the illistration above.

Also, convex will not slice better. Convex is used when you want a very tough edge.

I only like convex on chopper. If you really want convex on a small GW you will need to use sandpaper with a backing that gives, like a mousepad.
 
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