Splitting Firewood

by Khoke & Ida Livingston of Davis City, IA

When I was in fourth grade I can remember sitting through a science class where the teacher was explaining kinetic energy, the energy of motion. My nine year old brain was convinced it was the most boring way to spend time that I had yet discovered. Yet the laws of kinetic energy are at play when a splitting maul blasts apart dense hardwood rounds. The design of most hand tools harnesses and optimizes these laws to our benefit.

Kinetic energy is increased by mass and/or speed. So when you hit a piece of wood with a 3-1/2 lb splitting maul and your wood doesn’t split apart you can either hit it harder (swing with more speed), use a 5 lb maul (increase mass), or hit the wood repeatedly. This transfer of energy from you, through the speed of the handle and the mass of the maul head, will focus the energy at the cutting edge of the bit into the wood at the point of impact, and then that energy blasts the wood apart. The better a maul is designed the less energy it takes to accomplish the task. Bored yet? I will try to leave Mrs. Clum in her classroom and out of the woodshed.

Hand tools have been around much longer than mechanization. Each new generation of hand tools improved upon the last. Until the last two or three generations of tools, it seems anyway. In time past quality tools were recognized by the familiarity with them. Manufacturers competed with each other to provide the best quality and price for the tool savvy farmer.

As old hand tools phased out in light of power tools, the hard earned knowledge about those tools slipped gently away with their need. Now few know the difference by sight of a good axe handle that will last you for years and one that will break the fourth time you use it. Few recognize the working value difference between a $30 Walmart splitting maul and a $200 hand forged one. A five pound maul is a five pound maul, right? Or is there something to getting what you pay for?

These days with a low demand for quality hand tools, many manufacturers have cut corners in the name of profit and produced nice looking, poor quality tools. Expensive, good quality tools are often bought by people who can afford to buy them for the sake of having them but with little intention of regular use. The struggling farmer who would need it is the one who goes to the hardware store to buy a generic tool that works him half to death. Too often the only difference we really know is the price and never give quality a chance.

Khoke, like any practical young farmer, was the one with the cost efficient splitting maul. One fall day found him splitting a pile of wood for a neighbor. The older man stood by watching for a while and then came forward with another maul. He asked Khoke to try it. He had paid a pretty penny for it and wondered if, for its price, it would work any better than the other. By the end of the pile Khoke was sold and determined to buy one for himself. For the amount of wood he works with, it was certainly worth it. Now several years later Khoke has not one but several of the forged tools from the Swedish company Gransfors Bruk.

In our day and time one can generally expect to get what they pay for when it comes to new tools. Auctions and antique stores can be a good resource for finding inexpensive quality old tools. But even then it pays to know what you are looking at. A good tool used for the wrong job will still not work well.

One does not know the past life of an old tool. An axehead that survived a burned down shed or had a broken handle burned out of it will have lost the temper of the metal. It will need to be re-tempered or it will be a poor quality axe. But many excellent old tools can be collected and serve a long life of good use and still outlive the hands that use them today.

Many homes today are still heated with wood. For this, new splitting mauls and axes are among the tools still available today, even though hydraulic wood splitters have elbowed their way into popularity. But anyone who really knows how to swing a maul will find a hydraulic splitter tedious and slow. Sometimes the easiest way is not the fastest.

Splitting Axes and Mauls

A splitting maul has a heavier head than the splitting axe and it is designed to take on larger and more difficult wood. However when you are splitting kindling or a lot of small easy wood a maul’s extra weight works you harder than necessary and a splitting axe is much more efficient.

Your axe or maul will have a bit or cutting edge on one side of the head and a poll (flat end) on the other. In the center is the eye of the axehead where the handle fits. Technically a maul is designed to be hit on the poll end with a sledge hammer when necessary to drive it through the wood. This however is not advisable because it causes the poll to mushroom out over time from metal to metal impact and then will not effectively split the wood. The mushroomed edges would then need to be filed smooth to work well again, and to prevent pieces from flying off and hitting someone.

A splitting axe is lighter weight and thinner. It is used for splitting smaller wood. It is not designed to hammer the poll or to be used as a wedge. To do so can not only mushroom the poll but can also buckle or break the eye of the axehead.

Every bit of length, taper, angle, weight and sharpness contributes to how and for what the axe is used. The temper (hardness) of the metal must be hard enough to hold an edge and soft enough to file and not be brittle. A blunter maul with an abrupt taper blows the wood apart, or bounces off if it cannot penetrate. A sharp bit with a longer taper will cut in and penetrate easier before splitting the wood apart. If it doesn’t fully succeed one must pump the handle to loosen the head and hit it again. When the axehead is embedded in the wood do not try to push the handle sideways to try to dislodge the head, this can break the handle.

Handles

The handle of your axe or maul needs as much attention as its head. If you must replace the handle of an axe or maul, do not throw it in a fire to burn the handle out, tempting as it may be. Those temperatures can ruin the temper of the metal. Instead, drill several holes into the wood and then clamp it in a vise and pound or chisel it out.

It is generally accepted that wooden axe handles are made from American Hickory. Hickory absorbs shock and will flex. This wood developed its superior handle reputation in the age where handle makers worked with the grain of the wood to optimize its strength. These days manufacturers just carve out handles from wood blanks regardless of grainlines and a true handle is hit or miss.

A handle should be made from the sapwood and not the heartwood of the tree. The sapwood is a lighter color and absorbs shock better than the more brittle heartwood. The handle is not simply just straight and round but has been shaped to more of an oval. The flatter sides line up with the flat sides of the maul or axe head. Ideally you want very straight grainlines that run from the eye of the handle all the way to the grip end.

To split a piece of wood, you are using your strength to swing the weight of the maul and hit the wood. The shock of impact (we are talking about kinetic energy again) drives that energy through the wood and splits it. It also sends some of that energy back up the handle. If you ever try using a metal handle on a maul you will feel the energy travel up the handle and vibrate the daylights out of your hands. If your wood handle grainlines are perpendicular to your axe bit, as your handle flexes it can crack or split your handle. However, if your grainlines are straight and in line or parallel to your axe bit, then when you hit that block of wood, the energy traveling up the handle would have to tear the grain fibers where it flexes because there is no cross grain to split. A handle like this absorbs shock very well and should last quite a long time.

When making your own handles it is better to split your axe handle blank than to cut it out with a saw. When you split a short log into axe handle blanks it doesn’t cut across grainlines like a saw will. When your handle has grainlines that come out of the side of the handle and don’t go all the way from the axe grip end to the eye, this can create a weak place for the handle to split.

Knots are also best avoided. Knots distort the grainlines. As the grainlines curve to go around the knot they reach out farther than the edges of the handle. These cut grainlines are then where the handle is most likely to break.

An exception to the no-knot rule was made by Khoke’s cousin, Zach Miller. Zach is a longbow maker. Using a bowmaking technique, he split the wood and followed the grainlines down a length of wood and around a small knot, never cutting a grainline. Doing this he made a perfectly sound handle that will last for years.

My father was a timber cutter for much of his life. More than once he has split out or broken the handle of a maul deep in the woods and a long way from the house or new handle. In this case he would cut a straight branch or sapling, shave one end down to fit the eye of the maul head, pound it in and continue working. This got him by until he could put a good handle in.

Mauls with fiberglass handles have become popular in recent years as an alternative to crummy wood handles that split out. Fiberglass handles flex and have a decent life span. Unfortunately they have more of a disposable design. The trouble is the impact shock from regular use will dislodge the epoxy that secures the head to the handle over time. Often maul heads with a fiberglass handle are made with a smaller eye. This makes replacing a fiberglass handle with a wooden one more difficult. Since you don’t replace a fiberglass handle with another fiberglass handle, when the handle wears out of these mauls they are often just thrown away if a wooden handle isn’t modified to fit it.

If you have a homemade handle, or any handle for that matter, that is loose in the tool it serves, this can be dangerous should it fly off while in swing. Just pound a couple nails into the eye of your axe handle and this will compress the wood and tighten the head.

Splitting Technique

Most straight grain wood is relatively easy to split. That is, if you can hit the same mark twice. One reason why Khoke splits our wood and I don’t. Obviously, this could be corrected by the practice I have not yet given it.

Most rounds are simply quartered. When a tree has twisted as it grew, or the wood has knots, the grain is disrupted and then more difficult to split. Knots are branches or former branches that the grain of the tree has swallowed as it grew out. This creates a pocket of wood grain that deviates from the course of the grain that circles the trunk of the tree. Loved by some wood workers and hated by others, knots are a pill for the wood splitter.

Knots can sometimes be isolated and split around. Large knots that dominate the round you are trying to split can take longer to split than to saw in half with a board saw. And you don’t want to do that. These are great holding wood if you have a stove door large enough to fit the chunk whole.

When splitting wood that is very difficult, such as Elm, split it a few inches in from one side. Then work your way around the chunk knocking off the outer edge. This works with the grainlines as well as splitting off manageable sized chunks. Wood splits easier within the grainlines than it does trying to cross them.

Similarly, extra large rounds are best split by knocking off a chunk several inches thick from either side and then splitting the center in half or thirds. From here these pieces are manageable to split down further.

The bark of the tree can give you clues as to how the wood will split. These lines can tell you where the knots are and if the tree twisted as it grew.

A forked tree develops scar tissue in the crotch or V of the tree. The branches of the fork interrupt each other’s normal growth pattern where they meet. They develop a gnarly scar tissue as they are forced to grow together as the tree enlarges. Splitting into the crotch tends to have the grain too disrupted to be able to split it. It’s like splitting into a knot. Khoke takes a split off the outer sides of the forks and then flips it over to take on the V from the bottom side.

Splitting wood requires good hand-eye coordination. Much like hitting a nail with a hammer. The best splitting results happen when in your mind’s eye you calculate the arc of your swing to end not at the point of impact but rather to carry through and end at the bottom of the wood block. This subconscious shift is the difference between the person who can drive in a 16 penny nail with three strikes and the person needing ten (Ida).

It is always helpful to have a nice big chopping block. A big round with too many knots to split makes a great chopping block. This helps keep your maul from being dulled too much from hitting dirt. Generally dirt isn’t as big a problem as the rocks in it. Soft ground may cushion the impact a little making your wood harder to split. The energy passes through the wood and into the ground instead of popping the wood apart.

Some wood has its seat belt on, so splitting through gnarly or other less-than-ideal wood can require a good sharp maul. The sharp edge cuts the cross grain fibers and the angle of the maul forces the wood apart. Pump the handle to loosen the head and hit it as many times as necessary.

Another popular way to split difficult wood is to sink the maul into the round area and then flip the maul and swing the wood and maul together bringing the poll down on the chipping block. This adds the weight of the wood to the swing and helps to split it. Be careful that the wood does not dislodge from the maul as you are swinging it over your head.

Wood and Splitting Ease

Not all wood splits equally. Far from it. You have wood like walnut that is generally very easy to split, with the occasional tree out to make a liar of me. And then you have Elm who is famously difficult to split yet who have random members who defy their reputation.

Some wood is worth the work, if you are going to do it, and some wood is such poor quality firewood it is not worth the extra effort.

Oak and Locus run middle of the road with splitting ease but are some of the best firewood to have. Osage Orange is a good firewood that is easy to split if it doesn’t have too many knots. Elm is good firewood but a bear to split. Hickory is a favorite of Khoke’s, good wood and easy to split unless you happen to get an obstinate one. Walnut, Cherry and Hackberry are also good wood that splits well, usually.

Beech, Sweet Gum and Sycamore are hard to split and very poor burning wood. Particularly Sweet Gum and Sycamore. Sycamore is a very wet wood and supposedly the only wood that doesn’t float. When it does dry out though it is very dry and burns up quickly. The same goes with Tuliptree Poplar and Sweet Gum; these burn better if you don’t cure them too long. If too dry, they burn up too fast. But they are wood that does split decently.

Some of the worst wood to split is Black Gum and Pine. Both are poor quality wood. Pine boards are easy to split sure, but pine rounds are riddled with knots and the trunk wood grain is so soft it absorbs the shock. This swallows the maul without splitting the wood.

Black Gum is generally considered unsplitable. Its grain is knit instead of straight and virtually impossible to split. With one memorable exception. One of my brothers in his mid-teens happened to have the strength to match his stubbornness. Curious about the process it takes to split White Oak for basketry, he cut one down and set to split it. The trouble is, at a certain age a young Black Gum and a young White Oak tree can look similar. At least to the untrained eye. My father came home to find a six foot length of Black Gum, several inches in diameter, split in half and laying in the driveway. The wood was completely ribboned. Dumbfounded, my father would not have believed it possible, yet there it lay. Between a mistaken identity with wood and my brother’s determination that if someone else could split it, he could too, the Black Gum was conquered.

Elm is difficult to split too, or it can be. At least it is a good quality firewood. Pine burns too fast, too hot, and Black Gum just doesn’t burn well. Black Gum has few virtues as it isn’t good lumber either and the tree tends to hollow with age. In the old days they used to carve wagon hubs out of Black Gum as the wood could really take a beating and not split. They had to be replaced regularly because the wood rots easily however. They used to also make mallets from Black Gum and in the time before people could afford to buy metal wedges they cut wooden wedges out of it too. This wood can take a beating like no other.

Khoke has had quite a bit of success splitting Elm when it is green in subzero weather. The frozen wood is more brittle and pops apart easier. Some Elm has fibers more brittle when dry and some is absolutely unsplitable when dry. But if you take this and let it weather for a year or two and “rot” just a little, the fibers break down and become brittle again. This however compromises the quality of the wood.

Back to Kinetic Energy

I am not sure that understanding kinetic energy is all that much more practical now than when I was introduced to it 25 years ago. Understanding the concept simply defines what we already know intuitively. If a hammer doesn’t pound it in, get a sledge. Yet a whim of interest is caught in my mind at the idea that somehow the toast I ate for breakfast was converted to energy that flowed out my arm, down the handle to the maul head and laid a chunk of wood in halves.

Be aware of what you teach your children. It might stick around a while and have another audience in a couple decades.