It amazes me when someone makes improvements to a job as old as splitting wood. Millions (billions?) of people have been doing it for thousands of years, and there's still room for improvement.

This is really a specialty tool. Normal axes were also used to fell trees, demolish wood structures, and occasionally personal defense.

I'm guess that it's less useful if you're chopping against the grain or if you want precision.

Chopping firewood takes up so much labor, that there have always been specialised tools, there is no such thing as a "normal axe" - an axe for felling trees is different than an axe for splitting firewood, there are differences in the shape, width and weight of the axe head and you wouldn't want use one for other if you're doing it more than once a year; and a carpenter would use a different type of axe(s) than those.

And that's not a modern invention, it goes back for centuries. I'd guess that even stone age flint tools have been specialized in similar ways.

True. It's also worth nothing that axes intended as weapons are also very specialized. Indeed, there are multiple types, depending on just how you want to kill people with your axe.

This isn't actually a new improvement, just a 'hardware' implementation of a really old technique. You can get the twisting action with any normal axe, even if you're a barefoot girl:

https://www.youtube.com/watch?v=7fWo0P0MdJM

... you just linked to some one's pornography didn't you.

That's how I felt when I saw a paper box a few years ago. It had a folded lip in the paper that makes the lid stay shut when you close it.

I think this is it: http://ecx.images-amazon.com/images/I/61AigOH-ptL._SY300_.jp...

you might like the history page. It's a great "man sits and thinks of how to improve simple task" story, even if a bit contrived.

http://www.vipukirves.fi/english/tale_of_vipukirves.htm

I found it entertaining, mostly for the interesting use of language.

"Once in a while he found new axes at the hardware store. They were proclaimed to give greater striking power and strength through added weight and a variety of shenanigans to the sides of the blade."

It looks interesting. I have to wonder if the sideways action of this ax is tough on the wrists? I know with a regular axe when you get a bad hit and the ax goes sideways, it's very unsatisfying - not to mention slightly jarring to the wrists and arms.

Try to relax just before impact.

I use a maul (about 5lb head) to split wood (mostly elm since a neighbor cut down dozens of elm trees in the attempt to stop Dutch Elm disease from propagating) and the best motion I know of is to lift it straight overhead with hands spread wide. Then accelerate it downward while sliding the hand closer to the blade down to the base. Focus on coming down in a line through the center of your body. At the moment of impact, both hands are close together and your grip is just tight enough to hold onto the maul, with arms and shoulders relaxed.

It substantially reduces stress on your body and you still maintain good control. Feels like a Kendo "shomen uchi" strike.

I'd have thought the rubber tire was easier on the axe if you miss.