Need some Tips: Convex Sharpening

C Bryant

C Bryant

Joined
Jul 12, 2008
Messages
3,143
I have a couple of passarounds that will be headed my way at some point and I want to be able to send them off with a decent edge after I have had my fun with them. Not to mention keeping nice edges on the convexed blades I own. I'm not spectacular at sharpening to begin with, so a convex it even tougher for me.

So the other day I tried my first convex sharpening, and it did not go well. I started with a knife that did not need sharpening but I figured it could not hurt.....well it did.

I used the mousepad and sandpaper method becuase it looks easy, material not hard to get, and very simple to get the hang of (I hope). I followed the instructions from knivesshipfree (Part 4, Sharpening with Mousepad & Sandpaper). As per the instructions I used 2000 grit wet/dry sandpaper and a soft mousepad. I did the best I could to mimic the motion of sharpening, I even used a sharpie do mark the edge and see how I was doing. It seemed like I was doing ok, but it turns out that I really ended up dulling the blade. I tried not to roll the edge over, but I think I did. I can run my finger up and down the blade with moderate pressure and it does not even bit a little bit, feels very smooth.

So I'm asking you guys for help. Can you give me some pointers on this method? I would prefer to sharpen by hand, not beltsanders at the moment so it can be done anywhere w/o the need of electricity. Any ideas what I may have been doing wrong? I am curious if using water on the paper like a wet stone would make a difference?

Any help is appreciated.
 
I won't be of much help in this type of sharpening, but I do enjoy sharpening by hand through the use of arkansas stones and systems.

I use diamond systems to reprofile my knife edges and then polish up by hand on my arkansas stones.

Now I've heard to act like you're slicing as the proper direction, and I've also seen people do it in a forward direction (tip first) and moving inwards to the handle. Kind of confusing :o Hopefully someone familiar with this method will step in and help :p
 
richard j said:
what are you stropping your blade with?
Click to expand...

Howdy, Richard. I should emailed you this question.

Well, I did not get to stropping because the edge ceased to really function. I did not think stropping would do any good yet. I would be using a piece of leather. I don't have compound at the moment.
 
ive actually decided that convex is the easiest way to sharpen. i bought this kit. actually just the replacement kit for 14 bucks from jre.

http://www.jreindustries.com/EMS.htm

it works great.

if i need to reprofile i take the knife a few swipes on my coarse diamond stone. i do this to establish an edge. basically as close to 0 as i can get. just thin it out and then work my way up the grits. Im new to convex but am ocd when it comes to a sharp blade so this is what works for me. hope this makes a little sense pm if you have questions. ive gotten into the homebrew tonight so my apologies in advance..

oh and i dont use a mouse pad i stack the paper on top of each other in order from small to large. i dont use the emery pads unless i absolutely need them. i think the lowest is 220 and go from there. it creates a nice padded surface to use. i have created some nice razor sharp blades. I have also sent a few of my blades to siguy to reproflie and sharpen. If the knife comes sharp and to your liking the 14 dollar kit works great to maintain the edge it comes in a little plastic bag that i throw in my day/ edc pack that goes everywhere with me.

edit: i just reread your original post. i had some of the same issues when i started. 2000 grit is great for a nice mirror finish but i think that the most important are around 400 and 600. This is were your edge get sharp. Also for me i try to keep track of how many times i swipe each side but i go by feel now. you can actually feel when the paper is no longer really getting a good bite on the blade. this is when i move up to the next higher grit. hope this helps.
 
Last edited:
You may be pressing too hard and knocking the edge into the grit.
 
Sorry buddy I could show how I do it but find it hard to explain it !

The best explaination for the mouse-mat/wet n dry method that I use is that it's like buttering toast, right top corner to left bottom corner then left top to right bottom.You need to apply very little pressure.
 
once you work up a burr you have to remove it in order to get a good sharp edge. how you remove the burr has a lot to do with how sharp the edge is when you're finished.
 
Two simple items for convex edges, diamond sharpeners and a strop. Either rods or paddle type, flat or oval. I use coarse, fine and super fine diamond abrasives then strop on a leather belt. Eze-Lap and DMT.
Scott
 
Sounds like you are using too much pressure. Try like pitdog said, buttering toast.

You might also try a slightly lower angle, so that you are removing the marker from higher up the blade. On thinly ground convex blades (like many of the BRKTs) you want to remove a wide swath of marker from the edge to roughly maintain the same angle. With thicker ground convex, or those with a bevel at the edge, you want to remove metal along the whole bevel, not just the very edge.
 
kiahs said:
You may be pressing too hard and knocking the edge into the grit.
Click to expand...

I guess this is the case too. I always have found that mousepads are too soft for my taste. I prefer something like a hunk of the old military closed cell foam sleeping pads. Still enough "give" for a convex edge, but not so much that you easily roll the edge off.

B
 
Shoot - when reprofiling - I start with 360.

Siguy has answered a question I have had for some time - and tells me what I need to do to a knife that is sharp - but not quite 'right'.

TF
 
I learned with tools like Scott mentioned above. I'm still learning, too; far, far, far from an expert. Sometimes it can take A LOT of time and effort that way when reprofiling to get to convex, but using those tools really teaches you the in's and out's of the profile like Siguy speaks of.

The wife and kids got me a very small "el cheapo" tabletop 1 inch belt and disc combo sander from Harbor Freight for Christmas http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=34951. I then went to Lee Valley and ordered different grit belts and some leather honing belts that I can load up with compound. http://www.leevalley.com/wood/page.aspx?c=2&cat=1,43072&p=48040

I've practiced over the past few months with it and man does it save time to reprofile or repair! I still get that final nice edge with a little more work with a pad, some leather and some compound on a table top. Plus, it is what I use to maintain the edge, not the machine. Still, I don't think I would have learned to use the machine very well without all that time spend with the hand tools. You have a lot more control with hand tools when learning. Plus you can toast a blade with machines if you aren't careful. I played with some very cheap knives before stepping up to things I didn't want to ruin.
 
Last edited:
I'm a long way from being a sharpening guru but I've had better luck with emery baords I picked up in the nail care isle of CVS. They come in various grits, are portable and only cost a few bucks. I find it easier to get a consistant angle than with a mouse pad. YMMV

Frank
 
i'll give you a call tomorrow afternoon and get you fixed up c. if not send it to me and i'll make it scream.
 
Last edited:
I prefer a flat/scandi grind myself.With that said,any convex ground knives I have I send in to richardj.I usually get them back in less than a week.You can't go wrong sending them in to Rich.He's a helluva guy & will give you advice on how to touch up the edges so you won't have to send them out anymore.
 
You must log in or register to reply here.
Back
Top