Recommendations for sharpening convex magnacut

Edbriver

Edbriver

Joined
Jan 12, 2020
Messages
51
Hello everyone! Long-time lurker, just made an account, first time posting.

I bought a BRKT Bravo 1 LT in Magnacut last year. It's pretty good, but it hasn't been the gem that I'd hope it would be.

It seems okay, but honestly the steel doesn't seem that great. I don't think it's the Magnacut steel itself, but maybe the BRKT heat treat. I dunno.

I sharpened it up pretty good with increasing grits of sandpaper over thick leather pieces and ended with a green compound strop and got it decent, but it still seems like I can get it more out of it.

Does anyone have any tips for sharpening this knife/steel?
 
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Edbriver said:
It seems okay, but honestly the steel doesn't seem that great. I don't think it's Magnacut itself, but maybe BRKT heat treat. I dunno.
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Now there's a surprise......
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Use the search function, look for past posts concerning BRKT and its owner...
 
lol I didn't mean to open a can of worms.

Yeah, as a long-time lurker I should have done more research and listened to people's insight instead of just going after shiny things. I've learned my lesson.

It does seem fairly stainless. There's nothing that leads me to believe that it's NOT magnacut, but maybe just not a superb heat-treat. Not sure.

It just showed up only somewhat sharp and it's my first convex, so all I did at first was strop, having not sharpened a convex before.

Am I doing it right with the sandpaper and strop, or should I try something else? Like a diamond stone?
 
Having read about how great magnacut is, I thought I would be head over heels with it, but it doesn't seem to hold a great edge, and it's not as easy to sharpen as my other blades which includes another magnacut (hence the post).

I felt that it could just be a mental thing with the convex edge, but I can sharpen my axes/hatchets just fine (as well as my loads of V-edges), I should be able to sharpen this thing, but while I can put an almost shaving edge on a hatchet I can't get this knife quite saving sharp and I'm not sure why.
 
Have you tried sharpening with something that has more give than leather?
I use an old mousepad and it sharpens convex just fine.
 
I haven’t. I did think about doing that while I was sharpening it, but I couldn’t think of anything I have that’s somewhat foamy or has ‘give’ like a mouse pad.

I’ll see if I can find something later today if I have time and try it again.
 
Sharpening convex grinds with sandpaper is better done over a very firm backing under the sandpaper, like wood or something harder (glass or stone, for example). Anything with much give under the sandpaper will increase the likelihood of edge rounding as the sandpaper wraps itself over the apex under pressure. The sandpaper itself, over a hard backing, will provide enough give to follow the blade's convex grind above the edge, without so much rounding too close to the edge itself. Keep the held angle conservatively low so the sandpaper won't wrap itself around the apex, but instead only skims the 'cheeks' of the apex itself.

And for a steel with much vanadium carbide content, like Magnacut's 4% vanadium, it won't respond so well to green compound in stropping. That'll also tend to round over the apex, as the compound isn't nearly hard enough to thin & shape the carbides at the edge. Try diamond or cbn compound instead.
 
Obsessed with Edges said:
Sharpening convex grinds with sandpaper is better done over a very firm backing under the sandpaper, like wood or something harder (glass or stone, for example). Anything with much give under the sandpaper will increase the likelihood of edge rounding as the sandpaper wraps itself over the apex under pressure. The sandpaper itself, over a hard backing, will provide enough give to follow the blade's convex grind above the edge, without so much rounding too close to the edge itself. Keep the held angle conservatively low so the sandpaper won't wrap itself around the apex, but instead only skims the 'cheeks' of the apex itself.

And for a steel with much vanadium carbide content, like Magnacut's 4% vanadium, it won't respond so well to green compound in stropping. That'll also tend to round over the apex, as the compound isn't nearly hard enough to thin & shape the carbides at the edge. Try diamond or cbn compound instead.
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Thank you. This situation is making a lot more sense after reading your post. I’m gonna try this later today.
 
J. Doyle said:
But heat sure isn't. Most 1 x 42 grinders don't have a VFD so they're running wide open. It's really easy (probable/likely) to overheat the edge.
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Good point.

Plus hand sharpening is the bees knees. I haven’t touched my lansky in over a year, and that was just to reprofile a folder.
 
Update: nailed it. I took Obsessed With Edges advice from above.

I used the back side of my hardwood strop block with sandpaper. The hardness really does matter.

I started off behind the belly and slowly worked my way toward the edge. You can feel where the edge almost starts to catch, then I backed off a little and repeated, working my way down the blade. It’s something you just have to fiddle around with until you get the feel of it, then it’s super easy.

I went a little overkill with the sandpaper, but 800 - 1000 - 1500 - 2000 - 2500 - 3000 grit, got a semi mirror finish, and it’s now shaving sharp.
 
Edbriver said:
Update: nailed it. I took Obsessed With Edges advice from above.

I used the back side of my hardwood strop block with sandpaper. The hardness really does matter.

I started off behind the belly and slowly worked my way toward the edge. You can feel where the edge almost starts to catch, then I backed off a little and repeated, working my way down the blade. It’s something you just have to fiddle around with until you get the feel of it, then it’s super easy.

I went a little overkill with the sandpaper, but 800 - 1000 - 1500 - 2000 - 2500 - 3000 grit, got a semi mirror finish, and it’s now shaving sharp.
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That's exactly what I did, when I first started experimenting with convexing. I had a small strop block of oak (see below) with leather on one side, which I'd use with sandpaper over the leather to shape the shoulders of the convex behind the edge at a low held angle to avoid the edge itself. Then I'd flip it over and lay the sandpaper on the bare wood backside, when I was shaping & refining the edge itself. Really steps up the edge quality a notch.
onYcvaL.jpg

stId0PA.jpg
 
Obsessed with Edges said:
That's exactly what I did, when I first started experimenting with convexing. I had a small strop block of oak (see below) with leather on one side, which I'd use with sandpaper over the leather to shape the shoulders of the convex behind the edge at a low held angle to avoid the edge itself. Then I'd flip it over and lay the sandpaper on the bare wood backside, when I was shaping & refining the edge itself. Really steps up the edge quality a notch.
onYcvaL.jpg

stId0PA.jpg
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Yep, works really well. I leveled up my sharpening skills today.
 
bigmark408 said:
K, never had a heat issue 🙄
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🙄🙄🙄🙄🙄

This topic has been addressed ad nauseum, even in this very subforum.

I guess for those who don't wish to actually read the published research on the topic, there's not much hope for them.

But they should quit recommending blistering fast power sharpening to those new to sharpening.

You won't ever see or feel the damage to the edge fast/dry power sharpening is likely to cause. But you will likely notice it in performance.

I know, I know...........you've never had a problem and your results are just fine.....we've heard the line before.
 
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