How to Pick the Perfect Log Splitter
Rather than wearing yourself out with an ax, you can split more wood with much less effort using a log splitter.
Log splitters work by focusing a great amount of pressure against a small surface area to split logs apart. But how do you know how much pressure you need?
The amount of pressure a log splitter can apply is measured in tonnage. Choosing the right log splitter tonnage will depend upon a few factors:
- The size of the log measured across, or its diameter
- Whether the wood is green or seasoned
- The density of the wood, or its hardness
Start with this handy chart to get a basic idea of how much force you’ll need from your wood splitter. Then, read on to learn more!
How Large Are Your Logs?
Here’s something you might not have known about wood: some of the most important cells inside a living tree are long and fiber-like, and they run up and down the length of a tree’s trunk or branches. When we look at cut wood, we see this arrangement as the wood’s grain.
Log splitters work by applying pressure that splits wood along the grain, instead of cutting the grains short. Splitting along the grain is easier; cutting grains short requires specialized cutting tools like chainsaws.
The thicker a log is, the more wood there is to force apart on either side of the grain. Logs that are larger in diameter need more pressure to split.
That’s why a 4-ton log splitter will work well for 6″ branches, but a 24″ tree trunk will require at least the force of a 20-ton splitter.
Green-Wood vs. Seasoned Wood
Green logs are freshly cut logs. They still contain much of the moisture that they held while they were part of a living tree. They’ll look slightly green or yellow in color.
As wood ages, the moisture inside of it slowly evaporates, making it more brittle. As a result, older firewood splits and burns much more easily. This process is known by several names:
- Aging wood
- Curing wood
- Seasoning wood
Properly seasoned wood, which is wood that has had at least six months to dry, will look closer to brown than greenwood.
Freshly fallen wood is very moist and difficult to cut, so it takes more tonnage (or a little more time aging) to split through it effectively.
Professionals recommend waiting until your wood is cured to split it. If you plan on splitting green wood, you’ll need either a more powerful log splitter or some old-fashioned, inexpensive patience.
Wood Hardness and Density
Simply knowing how thick your logs are and whether or not they’re seasoned can go a long way in helping you choose the right amount of tonnage in a log splitter.
However, if you want to dive even deeper, you can also consider the kind of wood you plan to split and its hardness.
Remember those long, fibrous cells mentioned earlier? It turns out that different kinds of trees have more space in between those fibers:
- Hardwoods are dense woods that have little space between fibers
- Softwoods are lighter woods with lots of space between fibers
Woods like oak and hickory are considered hardwoods, while pine and other cone-bearing trees produce softwoods. Looking up the Janka hardness value of the types of wood you plan to split can help you figure out if you need a splitter that uses more force.
What Is the Janka Hardness Test?
Talking about lignin and moisture content helps only so much. The Janka scale describes the hardness and density of different kinds of wood in a way that’s easier for people with firewood to split to understand: with numbers.
Gabriel Janka, an Austrian researcher who worked at the U.S. Department of Agriculture, developed his lumber test and rating scale in 1906. The test was simple but standardized. It measured how much force it took to embed a steel ball 0.444” (11.28 mm) in diameter halfway into a plank of wood at least 2” by 2” by 6” in size.
The denser the wood, the more pressure it took to embed the ball.
Researchers have noted that the direction of the wood grain affects results. Embedding the ball into the plank’s smooth surface perpendicular to the wood grain is known as a test of side hardness. In contrast, pressing the ball into either end of the plank is known as a test of end hardness.
Although the steps for testing wood hardness are standardized, the way of reporting the results is not. Today, the United States measures pressure in the Janka hardness test in pounds-force. Sweden, however, uses kilograms-force, while Australia uses a unit called the newton.
In the U.S., the Janka rating goes from 0 to 4000 pounds-force. The lower the number, the softer the wood.
That’s the number you need to know when choosing your log splitter.
How Do I Use the Janka Scale?
A quick Internet search for “Janka scale” will get you a list of trees growing commonly in the U.S. along with a Janka rating for each tree’s lumber, like this:
That’s helpful for understanding which woods are denser and more difficult to split, or softer and easier to gouge and scratch. But those numbers don’t translate easily into log splitter tonnage.
Remember, the right log splitter tonnage depends on two factors:
- The wood’s hardness on the Janka scale
- The diameter of the log being split
A chart that assesses both of those factors would be a helpful, useful way to interpret the Janka hardness test.
One important point you might realize after studying this chart: if you have a large log, but it’s cut from a softer wood, you might not need as high a tonnage or as powerful a log splitter as you think.
On the other hand, a small piece of a dense hardwood might require a little more power to split.
You’ll see a lot of variety in the diameter of the logs you split from one type of tree to the next. While the trunks of red maple trees tend to be 18″ to 30″ across at maturity, for example, the trunks of ponderosa pines can grow over 48″ in diameter.
However, some of your logs might actually be smaller branches from those larger softwood trees, which a less powerful log splitter can easily handle.
Also, the grain of the wood can affect how easily it splits. Often, woods that have a straight grain (like red oak) are easier to split than woods with a spiral grain (like sweetgum). You might even notice some variety within a species because of this; for example, some people find red oak easier to split than white oak.
All of that variety might make it seem difficult to choose the right log splitter. Based on this chart, though, it’s easy to get ideas of which splitters are best for certain kinds of logs. For example:
- A small log splitter (like a 7-ton) for a 6″ pine log
- A mid-sized log splitter (like a 22-ton) for a 12″ maple log
- A large log splitter (like a 37-ton) for a 36″ oak log
A Tool that Fits the Firewood
It’s always helpful to plan ahead. Take a look at the trees on your property. If you think you might be splitting larger logs in the future than you are now, it’s better to buy the more power splitter ahead of time than to be stuck with the wrong tool.
That being said, no one wants to spend more money than they have to, even on the necessary equipment. Choosing the most powerful log splitter to split nothing more than small pieces of softwood will only burn through your cash.
However, choosing a smaller, less powerful splitter when hardwoods are common in your area will have you burning through your time as you wait for your splitter to get the job done.
The best way to get warm is to sit by a toasty fire. The Janka hardness scale can help you make sure that you have the right log splitter to split all the firewood you need.
Once you have an idea of how much tonnage you need from your splitter, you can choose the style of log splitter that will provide it!