Acute edge vs Obtuse edge

[Ben Dover]

If you put an edge on that really is too thin, a small micro bevel can often be all you need to prevent damage, rather than thickening the edge.

That is correct. While I generally shun micro bevels, if one gets a bit overly enthusiastic in thinning the edge, a micro bevel will "fix" the problem very quickly and easily.

 

[Joben]

Even for a machete used for chopping wood?

If a thin edge requires more frequent sharpening, it's only because the edge rolls or chips more easily. In any case, I've found a 20 degree edge to be more than satisfactory given that I can split hair with the resulting edge.

A harder steel can take a thinner edge, but I wouldn't whittle wood with such an edge. I suppose it depends on what you're doing with the knife. I know 15 degrees per side is fine on cardboard. I would only go for less with a decent kitchen knife.

You wouldn't whittle with an edge under 20 degrees? *cough* scandi grind *cough*

 

[HwangJino]

It really depends on the knife and what HRC and how it's used.

I sharpen my misono Swedish at about 8• per side, very acute, but extremely sharp.

It only sees soft food so chipping is not a problem, I sharpen 2-3 times a week.

I can get hair whittling edges but they never last in a professional kitchen. I need scary sharp but durable.

 

[Benuser]

It really depends on the knife and what HRC and how it's used.

I sharpen my misono Swedish at about 8• per side, very acute, but extremely sharp.

It only sees soft food so chipping is not a problem, I sharpen 2-3 times a week.

I can get hair whittling edges but they never last in a professional kitchen. I need scary sharp but durable.

With kitchen knives, the dulling factor is the board contact, rarely the food. You should notice a great increase of edge retention when you would have the left bevel of the Misono a few degrees less acute than the right one. Performance wise you won't notice a difference, excepted for the somewhat reduced steering.

 

[Magnaminous_G]

Several points were brought up. My humble opinion as follows:

1. Yes, there is a place even for 90 degree inclusive: A tanto point on a fighting knife, for example, benefits from that type of extreme obtuseness.
2. In my opinion, lower (more acute) angle is always better. It's the steel that tells you how low to go.

 

[HoosierQ]

ok so you put a 20°/side edge on an axe ? interresting. what kind of axe ?

Get a protractor and draw yourself a line and then a draw another line 40 degrees to the first one. Make it big enough to see. You will see that there is a lot of metal behind that edge.

 

[HoosierQ]

What I do is redo the edges of my knives to about 25 and then, depending on use, microbevel to either 30 or 40...usually 40. The exception is on scandi ground knives where I either leave them as is (zero grind) or put a quick 30 degree microbevel on there. Most scandis come at about 25 or so.

 

[kwackster]

My rule of thumb: as thin as possible, but thick enough.

 

[me2]

I've been running a couple of blades at quite low angles, about 7 - 12 degrees per side (dps). So far they have been fine. Neither are super steels by any stretch. One is a Parker Trapper at 7 dps. I have used it to cut heavy plastic (soda bottle caps and openings) and sheet aluminum (soda cans) without issue, at least until a lot of aluminum was cut. I've used a Cold Steel Scalper in Carbon V to do light yard work, kitchen work, including bone cutting, and various utility tasks, even batoning, with a 12 dps edge with a 15 dps Sharpmaker microbevel with no damage or excessive dulling, except that one time hitting a brick paver. The Sharpmaker was able to remove that damage.

 

[FortyTwoBlades]

My rule of thumb: as thin as possible, but thick enough.

Bingo. Make it as thin as will function for your range of uses, with a slight margin of error accounted for.

And regarding the earlier comment in the thread about edges thinner than 40 degrees on machetes for chopping wood, I keep ALL of my machetes at about a 30 degree included angle or even a little thinner and have never had any issues with denting or rolling unless I hit something I shouldn't, like a rock or a hidden old wire fence. Most steels can take a thinner edge angle than you might expect.