Ax Head Geometry

[thunderstick]

Personally I think the Gransfors tomahawk design is better suited to the smaller axes carried by the woodsman, trekker, or camper rather than for what loggers or homesteaders would have used for large volume felling, splitting, hewing. I think our American history would show they typically used the Tomahawk/Hudson Bay design for a woodsman's axe and a Dayton or Jersey pattern for a working axe.

 

[Briarbrow]

yup. the hudson bay, or specifically my norlund,as i aint seen 'em all, has no swell and is handy. I like the swedish version even better for the lugs

Personally I think the Gransfors tomahawk design is better suited to the smaller axes carried by the woodsman, trekker, or camper rather than for what loggers or homesteaders would have used for large volume felling, splitting, hewing. I think our American history would show they typically used the Tomahawk/Hudson Bay design for a woodsman's axe and a Dayton or Jersey pattern for a working axe.

 

[rg598]

Hi Guys.

I'm not sure I understand the purpose of reprofiling. To be honest I would feel alot better about it if the "half moon" bevel was prevalent on forum axes. I hardly ever see it. rg, it's not really a matter of following a pattern in a book. It happens naturally by filing a swelled center at a consistent bevel.

Of course. I was trying to explain what I meant by the “crescent” sharpening pattern. In two of the pictures I put up above, that was not possible without ruining the overall geometry of the axe. Changing the bevel will alter the sticking point, but there are other considerations that will alter binding as well. Peter has pointed out one of them here. I was trying to point out another. That is why people re-profile axes.

 

[Briarbrow]

RG this is how confusing it is for me. What you have just said as I read and understand it. You cannot file a consistent angled bevel on the ax without ruining its overall geometry.

I see forum axes all the time with a swell, and a even width bevel (or approximately even width. ) Maybe i need the Ax Book and get up to speed, as it is with my current level of understanding, the width of the bevel, and the radius of the edge are the two main factors controlling the depth of cut w/o binding. Throwing a chip being largely governed by the relationship of one cut to the previous cut, the nature of the wood along with the angles of those cuts.

The swell is putting meat behind the edge and inertia in the most beneficial area, driving the edge deeper. Extra metal on the perimeters of the head as in a true wedge is not really helping as much. Being evenly distributed as it is; it is mass, true. With a swel,l that same equivalent mass is focused to a more direct effect.

That may be completely wrong. I dont need to be right but I would like to understand axe geometry.

hollowing and reprofiling the cheeks seems to have nothing to do with chopping felling of notching. Unless y'alls axes are cutting that deep 1/2 way up the bit

 

[rg598]

RG this is how confusing it is for me. What you have just said as I read and understand it. You cannot file a consistent angled bevel on the ax without ruining its overall geometry.

I see forum axes all the time with a swell, and a even width bevel (or approximately even width. ) Maybe i need the Ax Book and get up to speed, as it is with my current level of understanding, the width of the bevel, and the radius of the edge are the two main factors controlling the depth of cut w/o binding. Throwing a chip being largely governed by the relationship of one cut to the previous cut, the nature of the wood along with the angles of those cuts.

The swell is putting meat behind the edge and inertia in the most beneficial area, driving the edge deeper. Extra metal on the perimeters of the head as in a true wedge is not really helping as much. Being evenly distributed as it is; it is mass, true. With a swel,l that same equivalent mass is focused to a more direct effect.

That may be completely wrong. I dont need to be right but I would like to understand axe geometry.

hollowing and reprofiling the cheeks seems to have nothing to do with chopping felling of notching. Unless y'alls axes are cutting that deep 1/2 way up the bit

Unfortunately, there is more to axe head geometry and efficient chopping than that. For example, the convexed cheeks reduce binding, but they are not in the optimal spot behind the blade to throw chips. For that you would most likely want the thickest part of the bit about 3/4 from the heel. It is also possible to have convexed cheeks and fail to provide for reduction of the cheeks behind the bit, which will increase binding (as you see in some of the above examples). It is possible for an axe to get all these things right without ruining the others, but many miss the mark.

There are a lot of good free books out there on the subject. Just like with anything else, they don't all agree on all the issues. I personally disagree with some of the statements that are presented as "facts" in the Ax Book so I can't offer it as a great source on all these issues, but I know people say it's a good read. Here is a thread with some good free books: http://www.bladeforums.com/forums/showthread.php/846115-A-Good-Axe-Manual

http://woodtrekker.blogspot.com/

 

[wnease]

great and thoughtful thread!

 

[cckw]

I haven't had time to read steve's whole article, but every time I see the title I think of this so am just going to mention it to clear my head.

I was fixing the edge on a head and discovered a pretty subtle but complex contour to it. to make it not bind the thicker part was near the top of the bit (furthest from the users hands) it wasn't noticeable until I was sharpening, then I started examining it overall, and it was clear that there was a lot of subtle variation in this head and it all seemed to be on purpose once you think about it... but most people will never think about it

 

[BRab]

What I like about this thread is that it shows how much more complex axe designs are than most people realize. We don't all agree on what makes an axe better, but at least we can better understand how small variations can affect performance.

 

[M3mphis]

What's weird to me is that racing axes don't seem to use the same geometry types that working axes do, and yet they obviously cut like nobody's business. Maybe it has more to do with the nice, clean wood they use????