[video=youtube;IlS7LlTBDro]https://www.youtube.com/watch?v=IlS7LlTBDro[/video]
[video=youtube;1xxf5_0djvE]https://www.youtube.com/watch?v=1xxf5_0djvE[/video]
Great videos :thumbup:
...The concave cheeks are designed to induce max wedging in the shortest possible distance to prevent binding by splitting the wood, penetration is not a positive attributefor a splitting maul beyond the first inch or so. The wedging/splitting action should begin while the tool still has plenty of inertia.
Note: the sides are concave to induce max wedging force over the shortest distance, concave being opposite of convex....
Have you taken basic physics? You do understand the concept of mechanical advantage, yes? Note
where the concavity flairs out on those splitting axes. Is it within the first inch?
NO, categorically NO, it is WELL BACK from the edge. WHY?? Because the goal is to
maximize penetration first through increased mechanical advantage from the thinner edge (lower bevel angle) that does NOT significantly reduce the tools inertia, and
THEN, only after the grain is separating and the blade is sunk deep enough to eliminate the likelihood of a bounce-out, then BLAST the round apart through that quick increase in thickness.
If you put the thick wedge up front, you have a significant loss of mechanical advantage, like using a slug instead of a slimmer bullet, that results in all that inertia being lost almost
immediately to
impact, to crushing the material instead of splitting through it as intended, there is increased risk of a "glancing blow" as well as
binding due to the increased resistance of the wood against such a lack of mechanical advantage in the blade - the thicker the wedge, the greater the resistance to splitting. The
ideal geometry is to get 2-3 inches of steel embedded into the round before flaring it apart in order to beat the strength of the round trying to keep the gap closed.
The only reason for a convex edge up front is to provide more strength (thickness) against the edge being bent/deflected inside the round and resulting in failure of the blade.
And for the other felling axes ... the convex region at the last few inches of the business end are clearly convex shaped. There isn't a shoulder to be seen anywhere, nor a flat side. The edge then slopes in to reduce weight at the cheeks and flares again to accommodate the eye with a decent amount of space for handle strength. In normal use, the cheeks only bury when splitting with your felling axe, a job it doesn't perform as well as a maul, but it does work. If they make contact at all when felling its going to be on one side of the cut only, and trailing behind the convex warhead. The concavity in this instance is a byproduct of weight reduction.
The concavity increases
clearance on each side of the head. Weight-reduction is the bi-product. You
want the weight to increase the force of the swing, to aid the inertia. You want the thin edge (and I DO see flat sides with rounded shoulders) to maximize penetration (mechanical advantage) with just sufficient thickness to prevent edge-flex and failure, and you want concave cheeks to prevent the wood on either side from from slowing you down - clearance to prevent binding and also glancing of the blade off the side. When felling, at least the trees that I'm familiar with, the trunk is usually thicker than the height of the entire blade.
Finally, regarding flat-sided splitting mauls, you've seen how those work, haven't you? It isn't a one-man job, the maul has a polished poll for a reason - it takes a second main SLAMMING that poll with a
sledge hammer to push that wedge through the round - the inertia comes from the
second man with the hammer, the first man with the maul just gets the thing to sit just inside the face of the round.
EDIT to add: try as I might, i couldn't find a video of the two-man splitting teams. As a scout, the Amish trained us to split large oak rounds this way. The mauls are just wedges on top of a long stick. The stick makes it easier and safer for one person (usually the younger/weaker) to hold the wedge in place while the other strikes it with the sledge, then pick up the wedge and place it on the next log without even having to bend over. The maul was reserved for large rounds and two-person teams. If rounds were smaller (<14" diameter) or only one person was present, an axe was used instead. Lifting that maul for a swing was a mad chore, not recommended for splitting... But I do see a lot of youtube videos of folks doing that way, so perhaps I'm wrong, though it seems odd given the design of the handle (straight and round) and the massive weight behind such obtuse geometry that presents a very deliberate pounding surface on the back end... Maybe folk forgot what it was for? *shrug*
Cut stuff with a variety of profile strategies and see for yourself. You might find something different from me but I doubt it.
For me there is a nice dividend to reshaping some tools to an arched configuration as it reduces mass and drag behind the edge. It cuts deeper, there's no real downside, it isn't less efficient at the expense of durability etc.
I live in the woods in WI, I heat with oak that i cut and split myself, I HAVE tried various profile strategies, I also understand the physics behind which work better than others for different scenarios. What you describe in the second sentence is, again, cutting a "relief bevel". You can do it convex and leave more meat at the shoulder, you can do it flat and leave less, or you can do it concave and
really thin out behind that edge, but YES it increases mechanical advantage = cutting depth and efficiency. Just keep in mind that there is such a thing as "too thin", and the best way to avoid that is by going convex :thumbup:
.I sharpen and touch up convex blades on sharpmaker too with great results.When secondary edge gets larger ,than I reprofile whole blade ......Belt sander is great for this.
