The Convex Grind Blues

[wildcat33]

I've got a couple Bark River knives that Im thinking about re-profiling to a straight grind edge.

I've got the leather blocks loaded with sharpening compound and I'm pretty decent at the sharpening method for the convex grind edges, however I've found that even with A2 steel it can be extremely difficult to get an edge back on a knife after hunting season. With S35VN, for me its impossible to sharpen with the green and black compounds. I have much better results sharpening flat ground edges with a Lansky system and Ive been looking to upgrade that to a Apex Edge Pro or Wicked Edge.

So you knifeheads out there: is this pure evil to put a flat grind on a convex blade?? You convex grinders out there; have you had the same issues?

 

[Shraggs]

Omg no! I’d hate to see that. I’ll shoot my phone number maybe I can help.

I remember long ago I had accumulated 16 bark rivers and was not able to sharpen them. I called the owner and he invited me up. I spent the day there and was taught by him and his son how to sharpen them.

John

 

[Ehiggins]

I use an old mouse pad and progressive grits of automotive sand paper (400,800,1000,2000) then move onto the black, then green compound on leather. Depending on how long it's been since the last sharpening you can get away with starting somewhere in the middle of those grits and working through the green compound.

 

[Lawnboi]

How I normally go about sharpening depends on how dull the blade is.

A strop does it if it's not too dull, however I haven't had much luck with the simple green, white and black compounds with some of the tougher steels. However strops impregnated with diamond cbn have done well.

If it's more dull, I break out the sandpaper. I do as said above. Go to the automotive section and pick up an assorted pack.

If I need to remove chips, or the knife is really dull, or I want to reprofile the edge, I use a stone. Fallkniven makes an awesome 2 sided stone.

On top of that, it's been my experience that most of my bark river knives needed some edge reprofiling to obtain an edge that lasted and I could easily touch up at home. Not saying bark river makes a bad knife, but iv had more than a few that needed some real work on the edge.

I am also familiar with the edge a wicked edge will put on a knife. IMO these are a pain. There is no field sharpening for the most part, at least it won't get it close to what the WE will get it. On top of that you need to remember your angle, hope you get it right when it comes to resharpening. I just think it's more work than is needed. Where as grabbing a stone, some sandpaper and a couple strops is much easier, and if done right is the edge I prefer.


Keep up on stropping and for the most part that really is all you should need for a knife used mainly for cutting meat.

 

[wildcat33]

Ive got some wet/dry sandpaper - sounds like i just need to go after it with a coarser grit. I found that the black really wasn't doing anything for me.

For sharpening with the black and green compound, Ive got a 2x4 with thick leather on both sides. I heat the leather up with a heat gun and rub in the compound. It seems like the compound really only lasts 8-10 strokes before i need to re-apply, which is time consuming. I'll try the sand paper tonight and get back to you all.

 

[Shraggs]

Dull knives are too far gone for strop. As they cut less is when you strop. Black will sharpen, equivilant to 3-4000 sand paper.

Key to leather is hold angle - should be half what edge angle is. Ie if 20 then Hold at 10 no more than 12. You are sharpening the whole curved convex edge that way. If you hold at 20 you will round the edge and dull the knife.

Some like it - not really recommended by bark river is using a mouse pad too soft and makes the convex edge to curved unless you can keep all pressure off even the weight of the knife.

Sand paper works,but if on mouse pad with abrasive grit you can really round an edge. Put sandpaper on top of the leather and secure. Leather is enough to give convex edge using sandpaper.

If knife is really dull use ceramic stick brown medium grit at 20 degree in my example her until you get a burr. Then sand paper to re set curved portion of convex. Then leather.

Green is waste of time. Black. Then a few stokes on white to polish a touch.

Hunting knife best 22-25 in my experience with Bark rivers.

 

[arborist1969]

I've got a couple Bark River knives that Im thinking about re-profiling to a straight grind edge.

I've got the leather blocks loaded with sharpening compound and I'm pretty decent at the sharpening method for the convex grind edges, however I've found that even with A2 steel it can be extremely difficult to get an edge back on a knife after hunting season. With S35VN, for me its impossible to sharpen with the green and black compounds. I have much better results sharpening flat ground edges with a Lansky system and Ive been looking to upgrade that to a Apex Edge Pro or Wicked Edge.

So you knifeheads out there: is this pure evil to put a flat grind on a convex blade?? You convex grinders out there; have you had the same issues?

The ken onion work sharp with the belt grinder attachment will solve all of your issues, its so easy


Sent from my iPhone using Tapatalk

 

[Beendare]

^ agreed. if you want to maintain the convex edge....use the belt type sharpeners.

i prefer a flat edge and have reprofiled a couple of the super steel knives with convex edge knives to a flat beveled edge. Its easy with the diamond stones n my Gatco. For a hunting/meat processing knife, I think the flat bevel cuts better...and if you give it a little micro bevel the edge stays sharp for a long time.

 

[wildcat33]

I started in with 320 grit. From looking at the edge under a loop I’m making a good start. I need to hit the store and get some more sand paper to fill the gap between 320 and 2000.

Still tough to tell if I’m putting a consistent angle on it. Also, I can’t tell if a burr is developing or not. Might be that I’m using a pretty coarse sand paper yet.

 

[Shraggs]

With 320 grit, the burr will be more than obvious. You will feel it. And see it with naked eye. If you can't see it feel it then you do NOT have a burr. Keep sending. That's how dull your knife is.

A burr is the foundation for any sharp knife. Convex or v grind alike. Two edges meet, where they meet will be so thin that the steel rolls over in the direction of the last stokes you made. On a dull knife, if you are consistent hold angle and no burr, you have a ways to go! Trust.

Also, go 5 or 6 strokes per side before flipping knife. Don't alternate every stoke. Just easier to see and feel a burr.

Once you have a burr - your knife is now sharp!

The rest of the process of moving to finer grits accomplishes two things. Refining edge of rough grooves AND reduces size of the burr. The burr should stay with you the whole process but get smaller. Once you get to 1000 grit you'll need light to see burr. After 2000 a knife is usable for sure but leather will eliminate the burr and remove and grooves from sand paper or stones.

Think of leather as a chefs steel before making a meal - they don't sharpen but align and refine the burr on v edges.

 

[Shraggs]

Btw. I love belt sanders have several as I sharpen knives for many many friends every season.

Caution cause they can eat a knife up. I like the Ken onion version - but I like the $99 attachment better. When using the unit as is, some knives are heavy and will defect belt a lot, rounding edge too much. So if you think it's set at 20 degrees but have full belt deflection it might be more like 23. The attachment is a horizontal sanding technique as the belt is vertical. I like this cause I can set the tension of the belt very tight and all the weight of the knife is in my hand so I get at most 1 degree of deflection. You can avoid too much belt deflection with std Ken onion version if you or mindful of no weight or force in the belt. Speed of belt and grit should do all the work. Not a 5 oz knife. I also grind on setting one. And setting 5 when I get to the 12000 grit polishing belt. They sell a nether belt too I also use at setting 5 and barely touch the blade when polishing.

The super steels (3v, s35vn, cpm154, etc) are so hard even for this class of hobby belt sander that they can still round an edge before sharpening. On those steels I will still use ceramic or stone or water stone or sand paper on a hard surface at my desired angle to get a burr first.

Then move to belt sander and progressive grits.

I started this with hand techniques, I guess because as hunters processing game in the field means we may need to be able to sharpen in the field.

For what it's worth ....

John

 

[wildcat33]

I went out and picked up some 400, 600, 800, 1000, 2000, and 3000 wet/dry sandpaper and just worked down the line. Was able to get my A2 fox river workably sharp. Nice polish to the edge, pretty sharp but not laser sharp. Ive got some work to do to figure out a better leather strop system for finishing off with the black and green compounds. I made a strop myself using leather scraps and a 2x4, however the leather doens't have a totally uniform surface and is "shiny". Need to source some "raw" leather without too much nap.

Thanks all for the help. I wont be putting flattening out my convex grinds after all.

 

[Shraggs]

Thumbs up!

Go to Tandy leather or anywhere they sell,leather. Look for something no thicker than 1/8”. Soft not one hard side either, and preferable rough on one side. Smooth side glued down and rough side up. If rough is not uniform than use sand paper to rough it up. I like my black side to be noticeable maybe a 1/32” ish. Use 80 grit general sand paper and your stokes to make it even looking like shag carpet. For white I like half as short and 150 grit will work.

Or you can call Jason or Paul or Mary at DLT trading and order a high quality strop.

John