Grinding em thin.

[stoffi]

Here you go:

http://brkca.com/convex.htm

 

[Noctis3880]

I said the same thing about a 24 grit belt when regrinding the machetes. After an hour of little progress, I switched to a new one and was done in 30 minutes. IME, cheap belts wear out fast. It's not that they cut slowly, they just stop cutting.

Not sure it had much to do with wearing fast so much as the belt was getting loaded up real fast, as my belt would have a metallic gleam on the high spots when I was grinding chips out of my coworker's machete. I personally would have preferred a nice low grit micromesh belt, though the lowest grit they have is 60MX which is equivalent to the P220 belt. As well, 1/2" x 12" belts are pretty limited as far as suppliers go, so beggers can't really be choosers.

Here you go:

http://brkca.com/convex.htm

Thanks, though that's not exactly the official Bark River site, which is why I couldn't find it. Also, there's a significant difference in the term of "lifting the handle" between sharpening on sandpaper and sharpening on a belt sander.

 

[stoffi]

Good luck

 

[Noctis3880]

Finished a few days ago but never got around to posting it. So I figure after I finished an 8 hour shift from midnight to 8 in the morning and sleep deprived would be as good a time as any:thumbup:.

Here's the knife in question:

Burned the tip a bit(which subsequently chipped off later on):

Finished!:

I've noticed that if you drag the very tip of the knife off the belt, it'll burn easily. But if you pull it off just shy of the tip, then it rarely even sparks. So that last 1/4" from the tip should be left for much finer belts(finer than P220). Another thing I noted was that my P220 belt seemed to leave much more coarse grind lines than my P80, which meant I was using a really worn out belt this whole time:grumpy:.

Not a bad first try. Didn't screw much up aside from the tip. I also just got in 5 Norton 40 grit ceramic belts and about 30 Zirconia Alumina 60 grit belts(messed up on the ordering there), so that ought to speed up and complicate future attempts. I've ordered a Kershaw Needs Work as the guinea pig knife, mostly because I figure edge retention is a step up from AUS-8 in the Cold Steel Mini Tuff.

Cutting ability did seem to be improved for the Mora, though it still split my apple in half when cutting a piece out. I figure because the grind is convex rather than full flat, it would be more beneficial on a wider leaf shape blade like a Spyderco. So I figure maybe the Spyderco Native would be a better choice than an S30V Leek.

 

[230grains]

I've done quite a few full convex grinds and also a few FFGs on knives. You HAVE to be patient or you will end up destroying the knife. The trick is to only use sharp belts. I started this saber ground swamprat with a 30 grit belt. Do not use cheap AO belts either,

Here is an already convexed NMFBM, I thinned out the entire grind.

 

[Noctis3880]

To be fair, the knives you're doing is in an entirely different league from what I have in mind. It does seem like heat generation goes up dramatically with increased pressure, and the grind becomes more convex than I would like. I certainly hope I don't have any "cheap" belts. It's weird, as I seem to recall the P80 being described as ceramic, but looking at the site now it says it's AO while the red P220 is ceramic oxide. I personally prefer silicon carbide myself, but the Micro-Mesh series only goes down to 60MX(P220 equivalent).

I bought 5 40 grit ceramic belts and about 30 60 grit zirconia alumina belts. I certainly hope neither was "cheap".

 

[Noctis3880]

Little update:
I wanted to break in my new belts and had my eye on my Lone Wolf "cheapie"(like $50 cheap).

Had a little compatibility issue when I had to shove the belt in and sparks went flying when I turned the machine on. Turns out the belt was a little more than twice as thick as my other belts. Like a good monkey, I went and brute forced a solution by holding it on until either the plastic or the abrasive was worn down:thumbup:.

The belt(which was 40 grit and not the 60 I had thought) worked great. It ate up the steel in a hurry and didn't seem to heat it up any more than my P80.

I did run into a little snag here:

Note to self:
Don't try to regrind a hollow ground blade:thumbdn:. I won't have anymore suitable candidates until the Needs Work gets in the mail. If that works out well I might give a try on a Spyderco Lum or Caly3 in ZDP. Though I might pass on regrinding the tip on those and just try to blend the grind lines in since harder steels would tend to leave me with a broken tip.

 

[Noctis3880]

Hmm, the needs work is hollow ground as well, so I won't get anywhere unless I severely thin out the spine as well:grumpy:.

 

[Noctis3880]

I'm on a roll!!! I felt like giving my Mora another go with a very light touch since it didn't feel thin enough. Turns out it wasn't necessary to use a featherlight touch since the belt is too thick to flex much.

I have to say though, my new belt is amazing. It eats up metal like crazy(I only noticed when I felt metallic dust all over my arms, chest, and legs). I only hope I didn't inhale too much dust before putting on that filtration mask I've been neglecting. Heat doesn't seem to be a problem so long as I don't mash the blade against the belt.

Overall I'm looking forward to using this bad boy at work tomorrow:thumbup:. Also have to wonder if there's a market for super thin ground folders. Wouldn't trust myself to regrind someone else's knife, but I wonder if people would buy knives that I bought and reground.

 

[Noctis3880]

The reground Mora cut my Braeburn apple without splitting it, which is an improvement. Didn't get to use it at work, so I'm not sure how it does slicing other things.

I still felt itchy, so I bought a couple of Queen Country Sodbusters to experiment on. If that goes well, I'll try an HK Soldats in N680 steel. Maybe even a JYD blem in CPM-D2. I get the feeling the Queens knives will be best for it though considering what can take advantage of the thin edge geometry and still doesn't cost a fortune.