Non-convex axe grind?

[fishy1]

I was just wondering why axes always have convex grinds? I've seen a few diagrams of how this means the edge is only in contact with the wood at the start of the cut, but surely you would get the same effect with a scandi or secondary bevel? Plus it would make sharpening easier. I have an old axe I might try regrinding to see what happens (lots of filing) unless someone can tell me why this is such a bad idea?

 

[British Red]

Actuallly no, you don't get the same effect (you can draw the shapes yourself and see). The cutting edge remains in contact with the wood right through the cut. Its a good thing on a shaping axe for example - less useful on a splitter though as it blunts much faster

Red

 

[C_Claycomb]

At the start of a split, but not only at the start of a cut. The convex edge gives a thinner section for any given edge geometry when compared to a Scandi type single bevel. This means that you will have less binding and more efficient cutting. A flat with a flat secondary bevel will either have the same disadvantage of the scandi, or will have less metal in the head, making it weaker and a poorer splitting tool.

I know that progress only happens when people look at the world around them and imagine ways of making things better, but in this case I reckon there is good reason that the axe is ground the way it is. People have been using axes for thousands of years and I can't help but think that if a flat or Scandi bevel would be an improvement for general work, it would have had more of an effect on the tool's evolution. Instead, except for specialist purposes, axes have settled on a convex profile.

If you want it to cut better, just file it to a thinner conves shape. What is hard about sharpening a convex anyway? It isn't like you have to maintain a fixed angle Again, generations of forresters have managed just fine with a file and a puck, so it can't be that tricky.

 

[perpetualelevator]

My Gerber/Fiskars axe came with a flat grind. It was actually a flat sabre-ish main grind with a secondary hollow grind. I never used it as is, though, and flattened the secondary bevel and convexed the transition between the two. Don't know why it came like that, as a hollow grind just seems like a bad idea for an axe.

It's still a very different shape from a standard axe, but I haven't gotten a chance to use it yet.

 

[fishy1]

Why then, if convex grinds edges only make contact at the start of the cut, do felling axes have convex grinds? Surely it would be more effective to have the sharp cutting edge in contact with the wood at all times when cutting through the grain?

 

[British Red]

A falling axe has a far narrower profie - not the bevel but the entire profile. The role then of the convex shoulder is to roll the severed fibres out of the way and keep the cutting edge in contact with the grain. On my sharpest limbing, falling and cross grain axes, the profile angle is as narrow as many a knife so the convexing is miniscule.

If you want to flat grind your axe, go ahead. I wouldn't but maybe you will find an answer that generations have missed. Ultimately, a conves grind is more robust for impact cuts (through or cross grain) an angled grind (scandy, zero ground or flat with secondary bevel) is better at slicing, draw or planing cuts. However, feel free to try it. I have.

Red

 

[fishy1]

Red, your posts releated to sharps are always excellent.