Posts tagged #thin axe handles

Axe Handle Breakage, Designing For Resiliency, Weak Links and Stress Distribution

An axe head with a wooden handle has some inherent problems. The head and handle are made of very different materials that behave differently. Steel has a very high density compared to wood. Wood is much more flexible than steel and will dent and break more easily. When using an axe, these differences can cause problems, such as the wood being damaged by forceful contact with the hard unyielding metal head, or the relatively high density of the steel head behaving differently than the handle, thereby putting stresses on the weaker wood. Breakage just below the eye is a very common occurrence. This article and video are an attempt to explain some common reasons why axes frequently break near the eye, having to do with design, or perhaps lack of design in some cases. Breakage in the main body of the handle can of course also occur, but I’m not really dealing with that here. I’m pretty sure that the greater percentage of axe handle breakages are initiated right where the handle meets the bottom of the eye, or within the first few inches of handle, especially if the breakage is not due to wonky grain or other defects. Shear stresses seem to be particularly high in this part of the handle.

In this article, I will be assuming that we are dealing mostly with American axe head patterns, which tend to have thinner eyes than European and Scandinavian axes. Even though American axe styles migrated back to Europe (many axe patterns on that side of the pond are actually American or modified American patterns) the axe eye sizes largely remained bigger than American axe eyes. This is an important point when we look at overall handle design, because with any given axe head, the eye shape just is what it is, and the size and shape of the wood where it enters the eye is therefore pre-determined. Some of these problems are obviated by the use of tapered axe eyes, in which the handle feeds in from the top and fits by friction, but that is a separate subject also. The assumption here is that we are dealing with American style patterns that are wedged from the top. For whatever mix of cultural and practical reasons, these axes have pushed the limits of strength and resilience of the wood used in handles, by evolving toward a small eye.

Aside from the size of the axe eye being fixed, there are two other things that are pretty much givens as well.

One is that the section of handle just below the eye, lengthwise (poll to blade) is wider than the rest of the handle. If the whole handle was the same front to back dimension as the eye length, it would be unusable, so the body of the haft has to slim down soon after leaving the eye.

Predetermined factor number two is that we need a slight flair in handle thickness just below the eye at the back of the handle, as well as on both sides, so that the head seats firmly around the bottom as it is driven on. The front edge of the handle can come straight out of the eye if desired, with no rise, but the other three sides need at least some flair, though not very much. In my view, it is always unnecessary, and also a detriment, to come out of the front of the eye and then immediately outward, forming a shoulder. I see no reason to do that, and every reason not to. If the handle isn’t completely straight coming out of the front of the eye, the rise is best made as a gentle transition.

WE CAN CONSCIOUSLY WORK AROUND THESE FIXED PARAMETERS. IN OTHER WORDS, DESIGN AROUND THE THINGS WE CAN’T CHANGE.

Axe Handle Shock and Preventing Repetitive Stress Injury in Chopping

These are factors I know of that play a role in the amount of shock you absorb from your axe handle, such as chopping style, grip, handle rigidity, cutting ability and wood type. These are the kinds of things that can allow a person cut more, longer and in harder wood without incurring numb sore hands, tendonitis, etc. More text below.

Chopping with an axe is a high impact, high energy exercise. As choppers, we necessarily absorb some of that energy since we are holding the tool. There are a number of factors I know of which are important in the cause or prevention of repetitive stress injury or discomfort in chopping, most of them at least partially controllable.

The axe should not be gripped very hard while chopping except as necessary in specific situations. A hard grip unavoidably tires and stresses the hands, but it also creates a more efficient transfer of the energy from the vibrating axe handle back into the hands. The Style of chopping is also important and interrelated to grip. A heavy handed chopping style should be avoided. Don't think of chopping as pushing or forcing the axe through the wood, but rather as whipping or throwing the axe head into the wood using the handle. Pushing on the handle after the axe hits the wood adds little if any real power to the cut, but stresses the handle and the hands and probably sacrifices control to some extent. You can cut plenty deep if you build velocity in the axe head before it hits the wood. If the work is done before the axe hits the wood, then the grip is only to lightly control the axe after it strikes.

The handle of the axe, depending on it's thickness, density, inherent flexibility of the wood and probably other factors, will transmit more or less shock. Thin handles transmit considerably less shock than thick ones do and tuning your handle or thinning it down is probably mentioned by authors writing about axes more often than not. Older axes tend to have thinner handles than modern axes, and vintage axes, old photographs and older illustrations demonstrate this fact. There is a reason that axe handles have become thicker, which is that they aren't actually used very much. Most axes are now the equivalent of handbags for men, and are put to real use only infrequently for short periods of time.

If you cut into wood at an angle, usually around 45 degrees, it cuts more easily than if the cut is made at a right angle. When cutting at 90 degrees the axe stops suddenly and more of the energy embodied in the head is transferred to your hands rather than cutting into the wood. It's fine to cut at 90 degrees as needed, but generally a poor habit to get into on a regular basis. Most axe work is done with cuts around 45 degrees for a reason.

Another way to transfer a lot of the energy embodied in an axe head back up the handle and into your hands is to use an axe that is not cutting well for any number of reasons. The axe must cut well and easily or it will stop suddenly causing more vibration. Most axes as they come from the factory, nearly all in fact, require at least some reshaping to get them cutting well. In most cases, a significant amount of metal needs to be removed from the sides of the axe near the bit in order for it to be able to slide easily into the wood. It is often recommended to file the cheek of an axe in a fan shape, but that depends on the shape of the axe head to start with.

Finally, the wood plays a role. When chopping hard dry wood, less of the energy from each blow of the axe is dissipated in cutting, whereas when cutting soft and green woods, the energy is dissipated gradually as the axe sinks deeply into the cut. You may or may not be able to control what wood you end up cutting, but you can control other factors that cause or prevent the kind of handle shock and fatigue that might keep you from working or cause a longer term injury that will put you off of work for a while. The stuff mentioned here is important if a person want's to be able to use an axe under varied conditions, on varied woods, for longer periods of time, on consecutive days. What separates the men from the boys isn't being tough enough, young enough or dumb enough to tolerate a club of a handle or an axe that otherwise doesn't cut well, but to be wise enough to work smart and not hard. If you are going to sit at your computer trying to breath life into your flaccid member to some freaky internet porn, or work your thumbs out pushing buttons on your t.v., remote then I guess maybe none of it matters all that much. If you're going to dig, carry, lift, hammer, weed, process and otherwise use your hands, wrists and arms, you'll be able to do all of it more, and longer, day after day if you pay attention to these types of details.