O1 edge holding, Scandi grind, Bushcraft

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MachSchnell
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Postby MachSchnell » Tue Oct 02, 2012 1:06 pm

I managed to get some "rolls", but more like a slight bend on the edge of my bushcraft. :( Not from abuse, batoning, or severe twisting though, but I was whittling on a limb of some local hardwood for a walking stick. Not sure what caused the edge to bend, but now I'm thinking of converting to a full convex/scandi grind or sending it in for sharpening service. I'm really thinking of putting a high polish convex on it with the myriad of progressively finer belts I have for my grinder.

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Postby Cliff Stamp » Tue Oct 02, 2012 5:09 pm

What is a full convex/scandi grind exactly?

MachSchnell
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Postby MachSchnell » Tue Oct 02, 2012 8:47 pm

Cliff Stamp wrote:What is a full convex/scandi grind exactly?
Haha, I guess just turning the flat part of the grind into a convex, but then it really isn't a scandi any anymore than is it?
Technicalities aside, it'll be like one of bark river bushcraft knives. So I guess it's called a convex scandi grind?

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Postby Cliff Stamp » Wed Oct 03, 2012 1:44 pm

Before you steepen the edge angle, you may just want to sharpen out the damage and see if it happens again, it could just be weakened metal at the edge which can happen for any number of reasons in manufacturing.

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Postby MachSchnell » Wed Oct 03, 2012 5:35 pm

I would aim to keep it close to the current set edge or go a little lower, but mainly just polish it to slight convex. Of the blades that I convexed they always end up with a more acute edge angle than what they initially start with.

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Postby Cliff Stamp » Wed Oct 03, 2012 6:13 pm

In order to lower the edge angle on any bevel you have to raise its height. On a single bevel flat grind that is going to take some work given the existing bevel width. You have a fair amount of patience to do that with stones.

I don't see though why you would think that would help the issue of durability if the existing edge angle is already too small and it is rippling. If you reduce the angle further it is likely only to get worse. The common solution to that is a small secondary bevel.

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Postby MachSchnell » Wed Oct 03, 2012 6:37 pm

Cliff Stamp wrote:In order to lower the edge angle on any bevel you have to raise its height. On a single bevel flat grind that is going to take some work given the existing bevel width. You have a fair amount of patience to do that with stones.

I don't see though why you would think that would help the issue of durability if the existing edge angle is already too small and it is rippling. If you reduce the angle further it is likely only to get worse. The common solution to that is a small secondary bevel.
MachSchnell wrote:I'm really thinking of putting a high polish convex on it with the myriad of progressively finer belts I have for my grinder.
I'm thinking that a finer polish with the hamaguri grind it should glide through material requiring far less force, and hopefully reduce edge problems. Since this is mainly a wood knife it will benefit from a mirror edge.

It also came with a small secondary bevel. But I think what might have caused the bent edge could have been the wood being cut, it was what I believe to be a Hornbeam-which is an Ironwood.

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Blerv
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Postby Blerv » Wed Oct 03, 2012 7:31 pm

It's possible the edge damage is simply a result of the wood or technique (or a combo). Wouldn't it be easier to keep the edge as sharp as possible and just micro bevel when it wears down a bit? While more acute its going to repair quick and cut easier.

Total guessing though. I'm a sharpening newb.
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Postby MarcusH » Thu Oct 04, 2012 9:13 am

dbcad wrote:Made the mistake of putting a microbevel on the Bushcraft in the past. I remedied that and put the original scandi back on a couple of months ago.
Oh yes, a microbevel on a scandi grind is really terrible.
After two years of use my Bushcraft needed a complete regrind, but it looks like almost new.

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Postby DCDesigns » Thu Oct 04, 2012 11:03 am

I love my bushcraft blank! Next you should get a Puukko! The s30v and scandi are a great combo for a super slicer! Its great for all sorts of outdoor tasks!

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Postby Cliff Stamp » Thu Oct 04, 2012 7:05 pm

MarcusH wrote:Oh yes, a microbevel on a scandi grind is really terrible.
Why would a microbevel be terrible, it would be the most efficient way to sharpen and is the most optimized (i.e. minimal) cross section for a given durability requirement.

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Cheddarnut
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Postby Cheddarnut » Fri Oct 05, 2012 2:22 am

Cliff, what about a microbevel on a zero grind? Im thinking id like to pick up the nilakka when it comes out, but dont think im commited enough to grind the entire blade to sharpen.
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The Mastiff
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Postby The Mastiff » Fri Oct 05, 2012 8:08 am

1095 gets a horrible name as it is used in some extremely cheap knives and thus often gets extremely cheap performance. Have you used any carbon steel from a decent ABS guy, or any custom maker who is sensible with it. Ideally try it at the max torsional peak which is about 65-67 HRC for a fairly unique experience in a cutting tool. There are no large carbides, the edge forms exceptionally sharp almost trivially, no significant burr formation, very hard, resists rolling very well, but yet no alloy carbide so it works readily even with basic stones.


Cliff, I had a custom smallish tanto in 1095 run at rc 65. It was a very different steel than the 1095 production knives I've had/have with very basic hardening jobs with rc's down as low as rc 54. One was advertised as rc 54-58 which is quite a variance.

At rc 65 it was pretty stubborn on the stones. I had a custom O-1 knife at rc 64-65 too, and I know it's not the steel's fault what kind of care it recieves.

Still, I prefer O-1 over 1095 and when the option exists I will pick it for folder or fixed blade. It's one of my favorites.

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Postby kbuzbee » Fri Oct 05, 2012 8:41 am

The Mastiff wrote:Still, I prefer O-1 over 1095 and when the option exists I will pick it for folder or fixed blade. It's one of my favorites.
An O-1 Chap would make my "buy" list. Or a Native 5....

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Postby Cliff Stamp » Fri Oct 05, 2012 3:25 pm

Cheddarnut wrote:Cliff, what about a microbevel on a zero grind?
I don't see why you would not want to multi-bevel aside from the enjoyment of actually sharpening. There is little advantage of putting enough work into the entire bevel as needs to be put into the apex to sharpen. I would take care to work the entire bevel on occasion because the edge will thicken quite rapidly compared to a full flat grind. I normally flatten the primary with a 1000 until the edge apexes and then finish on a 3000/8000 at a slightly elevated angle.
The Mastiff wrote: At rc 65 it was pretty stubborn on the stones.
As you start to pass 60 the stones stop having much of a machining ability and move to pure abrasion. For those steels I like at least silicon carbide stones to grind efficiently.


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