Question about angles.

CrimsonTideShooter

CrimsonTideShooter

Joined
Oct 23, 2010
Messages
3,196
Ok I sharpened my izula on the edge pro to 30 degrees inclusive, and it widened the bevel a lot which doesn't really matter to me.

I was wondering though if there would be any issue if I wanted to start sharpening at 42 degrees inclusive? Can I just start sharpening at 42 degrees and the edge will eventually catch up with the bevel I set at 30?

Sorry if this is confusing.
 
Yes it will catch up with repeated sharpenings. The edge geometry will be a little funky in the mean time, but it should be fine.
 
You can do 42, but you'll be putting on a 2nd bevel. Think about how much metal you'll have to eat up to get a single bevel again.
 
THG said:
You can do 42, but you'll be putting on a 2nd bevel. Think about how much metal you'll have to eat up to get a single bevel again.
Click to expand...

I'm not going to try to remove stock until I have a solid 40 degree bevel. I'm fine with the 30, and I guess I'll just be putting a microbevel on it? Will it take years for the 40 to catch up to the 30?
 
Well, if you put a micro-bevel or a secondary bevel on it you probably won't notice much performance difference versus a plain V bevel, depending on what you use it for. However, if you put a new bevel on at 40 degrees and grind over the previous bevel entirely you're going to thicken the edge out a bit. This happens naturally over time anyway, but you'll basically be accelerating the process. It's not really a big deal, but you'll get better performance for longer if you leave the 30 degree bevel and use a 40 degree microbevel. I don't have much experience with microbevels, but you'll probably get about the same edge retention as a 40 degree V bevel and it will be much longer before you thicken the edge out.

No idea how long it will take to cover the whole 30 degree bevel though. Kind of depends on how much you use it, how frequently you touch it up, if you have to reprofile at some point anyway. If you're just worried about the cosmetics, you might as well bite the bullet and profile it back to 40 and thicken the edge--having a secondary bevel probably won't be that appealing either.

I would just stick with the microbevel since you've already got the 30 degree bevel. They make touch ups super quick and for the most part they don't really effect cutting ability.
 
When you went from 40 degrees to 30 degrees, you would have widened the edge (shoulder to shoulder distance) a bit, but you should have gained noticeably in cutting power. Acute edges out cut less acute edges, all other factors equal. I didn't catch why you were unhappy with the 30-degree edge. If it's not cutting as well, there is probably a flaw in the geometry of the new profile. I'd check that first.

But if you want to go back to the 40-degree edge, you won't thicken the edge, but you will shorten its edges a bit -- probably about 25 percent.

The only reason I can think of that you'd want to increase the edge angle is if the 30-degree edge is not durable -- it may be rolling or chipping.

If you simply start sharpening to 40 degrees, you'll initially put on a small microbevel that strengthens the edge a bit, without losing much in cutting power. If it still chips or rolls, you can redo the bevel, making it stronger still. As you continue to sharpen at 40 degrees, you will eventually get to a pure 40-degree angle.

But you may find that a 30-degree primary bevel with a light or heavy microbevel at 40 degrees will give you the best balance between cutting and durability.
 
I was unhappy with 30 degrees because I'm going to be using this knife hard. Whittling, possibly batoning and other similar bushcraft things. The edge thinned out too much when I went 30 inclusive so I wanted to thicken it up.


I just now went ahead and set the edge pro to 36 inclusive and took it from 120 all the way to the 3000 grit tape. Now it looks kind of funky with two different bevels but the edge is just a little more obtuse which I wanted. While I was doing this I guess I had a breakthrough with my EP and I formed a great burr and kept sharpening until I had my sharpest edge yet using the EP.

I'm happy with it now even though I know it will take a while for the 36 degree edge to catch up to the shoulders. I'll try and post pics of it tonight.
 
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