Zt reprofiling angle

[Threethreethree]

Hey there

Yesterday i started to reprofile my 0200 which had a stupid thick edge angle and wasnt able to cut decently even sporting a tree topping arm hairs edge, i usually use sandpaper strips clamped to a very firm leather strop but due to the recurve i had to use a very narrow balsa piece which i glued a sandpaper strip on.
The sandpaper gets worn very quick this way due to the little surface and the knife being SO THICK behind the edge, adds a lot of frustration and made the process an awful experience.
I have to add that i really thinned the crap out of it with a wide 15 dps convex on the left side, right side is still bearing the factory edge and it is about three times smaller than the convex bevel i just put.
Prolly gonna break the burr and refine the edge when i'm done with the left side and use it as it is until dull before i start the right side.

What angle do you choose for heavy brick-bladed folders like that when reprofiling ? What is the purpose of such a knife with a 50+ inclusive edge ? How is ZT's 154 cm compared to Spyderco's and benchmade's ? ( had the the knife for a year or so yet i barely used it because of the tin snip geometry -no joke i whittled a few shavings from a chrome plated piece of zamak without significant damage-).

Jeez i'm glad it ain't s30v or worse.

 

[Obsessed with Edges]

Using a HARD backing under the sandpaper will greatly speed up the work; lower grit will obviously help as well (220; maybe even lower). Something like glass or stone underneath, with some adhesive used to firmly attach the paper, will make it perform much like stone (with glass, it'll even sound like a SiC stone). The larger the hard backing is, the better; abrasive surface area rules, for heavy grinding. For the recurve, consider using a hard cylinder under the paper, like a piece of pipe or hardwood dowel/broomstick/etc. A combination of small surface area and softish backing (like leather or even softish wood, like balsa) is nothing but a handicap, and greatly slows the working speed of sandpaper; edges won't finish very crisply either.

For the angle, since you're going to so much effort in the first place, I'd go as low as you're comfortable. 154CM will hold up well at anything down to at least 25° inclusive, and maybe lower. If you find, later on, that your thinner edge isn't as durable as you'd like, just add a microbevel at a somewhat wider angle to it. The wider micro will add some durability to the apex, and the thinner primary geometry behind it will still make the blade cut much more efficiently.

And you're right; be glad it's not S30V. Took me about 6 hours to re-profile a ZT-0350 in S30V using my Lansky set (tiny 4" x 1/2" hones), even with a supplemental diamond hone. If I were to undertake that project again, a large diamond bench hone and/or a diamond rod (for the recurve) would be a better choice.


David

 

[Threethreethree]

I broke the burr and microbeveled it at 40 for now as i want to play with the recurve and do some tests, the right side is much less borked than the left side was so it wont be as long and boring but it wont be symetrical unless i waste a lot of steel,as always this is going to be work in progress for a good time.
I might try a hard backing to do the grunt work though but i am worried to give up my semi soft backing for the finishing because i never managed to blend the shoulders and do a seamless transition the few times i tried beech wood.
Usually i use a larger strip of sandpaper on a hard leather epoxied on pine and use 240 then 600 sic paper with great success on vg10, s30 v, cpm m4 but this time i used 120 AO fabric roll to make up for the tiny weeny surface and i'm quite sure it's not only the reduced surface but also the abrasive which go dull quite faster and cut much less than what i was used to, but i cant get 120 grit sic here it seems.

 

[Jason B.]

If you don't have a stone then I would recommend getting one. Even the Home Depot norton stone would do. Having a stone will increase the cutting speed where it's needed most.

 

[Obsessed with Edges]

I broke the burr and microbeveled it at 40 for now as i want to play with the recurve and do some tests, the right side is much less borked than the left side was so it wont be as long and boring but it wont be symetrical unless i waste a lot of steel,as always this is going to be work in progress for a good time.
I might try a hard backing to do the grunt work though but i am worried to give up my semi soft backing for the finishing because i never managed to blend the shoulders and do a seamless transition the few times i tried beech wood.
Usually i use a larger strip of sandpaper on a hard leather epoxied on pine and use 240 then 600 sic paper with great success on vg10, s30 v, cpm m4 but this time i used 120 AO fabric roll to make up for the tiny weeny surface and i'm quite sure it's not only the reduced surface but also the abrasive which go dull quite faster and cut much less than what i was used to, but i cant get 120 grit sic here it seems.

It's MUCH easier to first focus on thinning the overall grind first, using whatever means works best for that; and THEN it becomes much easier to gradually shape it to convex, using whichever methods you're most comfortable with. Most of my edges end up convexed, because my favorite methods eventually make them so. On thickly-ground blades that I've done, I've first focused on re-bevelling to a fairly acute V-bevel (30° or less), sometimes using a guided setup like a DMT Aligner; this ensures the 'foundation' of the work will be as symmetrical as I can make it. Once the edge grind is thinned and symmetrical, it's a lot easier to gradually introduce the convex to the shoulders of the V-bevel, and it can be done over time using your favorite maintenance methods, like sandpaper over leather, or even stropping on a firm backing with smartly-chosen compounds can do it pretty fast, with some steels. The advantage in first thinning to a crisply-apexed & acute V-bevel is, you'll still have a great-working slicing edge from the beginning, and you'll not have to worry as much about finishing the convex before your knife is once again useful to you. The convex will come, but you don't have to feel as pressured to do it all at once.

Jason B's suggestion of finding an inexpensive SiC stone isn't a bad idea. Don't know if you have access to a Home Depot in Belgium, but they carry what's called a Norton 'Economy' bench stone (6"), which is available in the U.S. for about $7 or so. There are equivalents from Ace Hardware for roughly the same price. BUT, if you still can't find a stone, I'd still recommend using as hard a backing as possible for your SiC wet/dry sandpaper (sounds like your AO 120 isn't working well, so I'd put that aside for now). Even your 240-grit SiC paper will work much better with a hard backing.


David

 

[Threethreethree]

In fact i do own a Duosharp coarse/ fine polka dotted but it sees seldom use, i'm just not comfortable with it and i would be worried stripping out the diamonds when grunting the recurve on the corner.
I'm really fine with my method usually but the combination of lopsided edge angle, thick grind and recurve was too much and i ended up angry yet i didnt put THAT much time to do it.
I wanna try a norton SIC stone once though.

 

[Obsessed with Edges]

In fact i do own a Duosharp coarse/ fine polka dotted but it sees seldom use, i'm just not comfortable with it and i would be worried stripping out the diamonds when grunting the recurve on the corner.
I'm really fine with my method usually but the combination of lopsided edge angle, thick grind and recurve was too much and i ended up angry yet i didnt put THAT much time to do it.
I wanna try a norton SIC stone once though.

In your specific circumstances (recurve + 154CM + available SiC sandpaper), I'll repeat the suggestion to try the paper affixed to a cylindrical hard surface. A section of pipe or a large-diameter dowel would be perfect for it. 154CM doesn't present much of an obstacle to SiC sandpaper, and a 'stropping' stroke along the length of the cylinder would work well. This would present much less of a worry as compared to trying to grind the recurve on the corner/edge of a flat hone (though it can be done). You can get as aggressive as you want with the sandpaper (a wide-ish cylinder will distribute pressure), and not worry about damaging it or the blade's edge, as could easily happen with too much pressure on the edge of a hard, flat hone.


David

 

[Threethreethree]

Gonna try some exotic hardwood right now, i'll slightly round the edges to make it a light curve glue a bit of sandpaper then go to town as i got a huge dent to remove on my rajah 2.

I tried the 0200 today, i had a thick trunked dead bush to remove, shred and pack it up, the wood wasnt already dried yet but it was rather hard and required considerable force to get trough even when cutting the small limbs, the edge held up fine but it didnt shaved after at all.