3 1/2 lb head on a 28" haft?

[Chignecto Woodsman]

I measured the handles on my university timbersports team axes and they were all between 28"-31". These are 5+ pound heads and they are anything but clunky

I've been having way too much fun since I joined the team!

I suppose there are regulations, and some of the lower weight classes probably prefer a 28". Technically swinging a 28" if you're 5'5" is about the same as swinging a 31" if you're 6'2". There's probably some scientific correlation based on armspan.

Yeah, if you can post anything you have learned from timbersports it could be very helpful.

 

[Bridger]

Did you ever use one of those 5 pound axes to limb a tree that was fallen in heavy brush? Have you ever fallen a real tree with one?

But it's cool that you're on the timbersports team. I bet that is a blast. Post some pics for us if you get the chance.

Unfortunately, I'm not able to take any of the axes home to play around with. We practice on cottonwood 10"x10"s. I definitely wouldn't be able to swing one all day doing regular work, but they sure do cut the big stuff quickly. 4 pounds is probably about my limit for use over a longer period of time like you would in a real world application. None of the other people on the team know how to hang an axe so I get to hang 3 of our practice and 1 of our competition heads over the rest of the semester. I'll be sure to take some pics to share and maybe a video of me test cutting with one.

As far as the handle length discussion goes, I'm 5'9" and I would struggle to land my top blows on the underhand with a handle longer than 32" without choking up on the handle or something. That's still plenty of length to reach the bottom of the log though and the shorter length seems to make the axe quite a bit more controllable.

 

[killa_concept]

"I think those are usually 32""

A post on arboristsite by Arden Cogar Jr. says the Tuatahi handles are 31". Not sure why I thought they were 28", I thought one of the other competitors said this. Oh well. You're right that it is best to go with what feels comfortable, and square_peg is correct about the balance issue. I find the 4 pound on a 31 doesn't feel quite as balanced as the 3.5 on a 30. A 3 on a 28 would probably make a really great size, especially if you're shorter.

I'd like to try one, but I really shouldn't buy any more axes.

True - generally with replacement handles, about 1" to 1.5" is lost if you're doing your hang properly (seating down close to the shoulder and sawing off the excess). 36" and 32" are popular handle lengths which works out to 35" and 31" respectively after hanging.

And I actually really love my 4lb Connecticut on a 31" - it's what I took camping with me this year. It's quickly becoming by favorite work axe. Not as much of a multi-tasker as my 3 lb, but boy howdy does it throw out chips:

 

[EngrSorenson]

I’m resurrecting this thread because I rehafted a 3 lb 10 oz head on a 28” haft and used it comfortably and safely for felling and bucking a 15” diameter spruce tree. Limbing was difficult because of the density of the branches, so I switched to a hatchet which was easier in this specific instance.

Just another guy’s two cents, but the “inexperienced users shouldn’t use short hafts” line doesn’t doesn’t make sense to me. Using any axe bears careful consideration, and I think the dangers are easily mitigated.

I’m 6’2 and i don’t think even a 32” haft would have made it significantly more safe. I just was always thinking about my swing, and the placement of my feet and position of my stance.

I found that bending my knees during the swing (while bucking) was key to eliminating risk. I would probably continue this practice with up to a 32” haft. I want to be sure the axe ends up in the dirt if I miss.

While felling I squared off with the tree in such a way that the head could in no way deflect into my foot or leg.

heavy heads are harder to redirect, and short hafts could put the axe head on undesirable paths, but I personally believe that careful risk assessment is always important and more significant than haft length.

the folks who recommend kneeling to prevent injuries with boys axes have a great idea for “idiot proofing” the process, but there’s other legitimate methods for using shorter hafts safely.

Energy is mass times speed, so when a user swings his light axe head much faster than he can his heavy head they will hit the target with the same energy.

Energy is actually 1/2*mass*velocity^2.
Momentum is mass*velocity.
It’s an important distinction; in energy equations, velocity counts significantly more.

A hatchet handle isn't long enough and the head isn't heavy enough to generate as much force as a 3.5 lb. axe head.

The “one handed” aspect is a big limiting factor, but also a hatchet is limited both in swing radius and head mass , like you say. A hatchet is safer than a full size axe generally because of the fact that it’s easier to accelerate/decelerate- like swinging a twig instead of a baseball bat.

You might not be able to swing a heavier head as fast as a lighter one but it still delivers more energy, assuming you have the muscle to put into it.

Right, so assuming the torque (rotational force) is the same in both case, a longer haft generates more momentum than a heavier head.

this might be counter intuitive, but the rotational nature of the swing is what leads to this conclusion.

—————————————
Conclusion:

The trick to understanding axe optimization is realizing that momentum is what cuts the wood. The person merely accelerates the axe, and does not continue pushing the axe into the wood upon impact.

To that end, assuming a horizontal swing for simplicity, the equations bear out that a longer handle (higher linear velocity for a given rotational velocity) provides more momentum than a heavier head in this rotational dynamics problem.

practical limitations in longer handles include decreasing accuracy and resisting gravitational torque.

Swinging vertically uses gravity to aid the swing, and as such changes the game a bit- now a heavier head will accelerate more merely by virtue of having more mass. The user lifts the axe to gain potential energy, not in an arc, but straight up, which changes the dynamics in a way I haven’t fully considered. The height of the potential energy is proportional to the length of the handle, which further complicates the analysis. I’ll have to work this out and get back to this.

At the very least I can say that, for swings unaided by gravity, haft length (velocity) is a better contributor to momentum than head weight.

 

[rwdenney]

Something everyone already knows, I'm sure, but as an engineer who hasn't specifically thought through axe motion yet, the dynamics are interesting to me.

As with a golf club or a baseball bat, the left hand (which stays at the knob) acts as a hinge, and the right hand rotates the axe around that anchor. As the right hand slides down the handle, it applies acceleration with mechanical advantage--the hand is covering greater distance than rotation. Velocity comes from the resulting turnover--not how fast both arms move towards the target, but how fast the right hand passes up the left in the rotation. Remember those coffee-table trinkets from 40 years ago, where you accelerated a steel ball between two steel rods? That's the effect--the handle surfs on the motion of the right hand around the left hand, and the head accelerates faster as the hands get closer together. That significantly increases velocity at the head, as mentioned above. A heavier head is harder to accelerate through the rotation--it's heavier. But if the person is only trying to effect that acceleration with the right arm, or with both arms moving in the same direction at the same speed, they will get less velocity and a sore arm and shoulder. At some point, the left hand has to stop or even pull back to cause that whipping action that increases head velocity. Gravity helps, and I find that I'm never really using an axe against gravity. Even notching a standing tree, most of the blows are on a downward diagonal, which goes through a lot more wood than the horizontal bottom of the notch, and the horizontal swings are only for clearing chips. Contrast that with bucking a big log, where we make a symmetrical V.

Maximizing axe-head speed is as much a matter of technique as power. Look at those old Forest Service safety videos--those guys never look like they are working that hard, but they are taking huge chips. They are using technique to get the most out of every swing.

But a longer handle simply magnifies any error in hand position, which means less control. That's the downside, and that's also a demand on technique.

I see old catalogs where axe heads for timber-cutting professionals back in the deeps of time ranged up to 7 or 8 pounds. They used a 36" handle for those heavy heads. They would probably laugh at this conversation--for them a 3.5-pound head would be a lightweight appropriate for a boy's axe. I doubt we would have persuaded them that a lighter head would go faster and therefore cut more deeply on any given handle. Even in the not-so-distant past, the Plumb Dreadnaughts (for pros) could be had a pound or two heavier than the All-Americans (for non-pros).

Rick "who likes shorter and lighter axes when limbing and trimming, or when really needing accuracy, or when choking up one-handed" Denney

 

[FLINT77]

I've got a 3 1/2, two 4s and a 5lb head all on 27-28" straight handles, and two 3lb heads on 26-27" curved handles and have no problem with any of them. I prefer handles in the 28-32" range. Longer than that is just unwieldy.