How to Split Wood
Editor's note: This article was written and sent to us by Anne and David, two visitors to woodheat.org. We appreciate their contribution and hope you enjoy it. In addition to the excellent advice offered here, we would mention the importance of good gloves and steel-toed boots for serious wood splitters. If you use wedges and sledge hammer, safety glasses should also be worn.
Cut firewood logs into "rounds" of reasonable length. The longer the round for any given diameter and condition, the more difficult it will be to split. If you are just starting or are having difficulty splitting, cut logs into short (twelve-inch) lengths. Increase length later as your ability increases. If you have any choice in the matter, avoid wood that is terribly knotty or set it aside "until later".
Use a "wood splitter's maul" rather than an ax. The maul is basically a wedge with a handle. The advantage of the wedge shape over the ax is that the wedge, with its more abrupt slope, is less inclined to stick in the wood than the gentler slope of the ax head. The steep slope of the maul also increases outward pressure on the wood.
Save the wedges and sledge for really tough wood. Wood that splits easily or with moderate difficulty can be split faster with a maul which avoids the necessity of "setting" the wedge and striking it repeatedly. Keep a couple of wedges on hand for really gnarly wood.
Use a six-pound maul rather than the eight or ten-pound models. A lighter maul can be swung much FASTER. Velocity is more important than mass in producing results. Perhaps this is related to the laws of physics, which state that energy is proportional to the SQUARE of velocity, but only DIRECTLY proportional to mass. Thus, the maul head should be traveling as fast as possible when it strikes the wood. It takes a very strong person to properly accelerate a large maul.
Position yourself slightly uphill from the round to be split if at all possible. This employs weight and leverage to maximize effectiveness of the blow. Place rounds on reasonably hard ground to prevent the force of your blow from being absorbed by soft ground below. Striking a round that is too high or one that is on soft ground decreases the energy delivered to the wood by the maul head.
Study the round to be split for existing cracks or other signs of weakness and align yourself with these as your target. Look down the exterior of the round to avoid splitting through any obvious obstructions such as large knots or twisted grain.
The most effective blow is delivered near the edge of the round, NOT the center. By hitting near the edge (bark), the maul strikes at 90 degrees to growth rings where they are wide and vulnerable. Look and listen for the beginnings of a split. Strike the split with the next and subsequent blows and watch it progress across the round. After the split is well started, strike the far side along the split. Repeat with increasing aggression as necessary.
Make the best blow you can EACH time. Never make a half-effort, even if it becomes necessary to rest between swings. Light blows seldom split wood and almost always discourage and tire you for no gain.
Learn to strike within a quarter-inch of your intended spot. This is accurate enough for effective wood splitting and is not too difficult to achieve with practice and focus. Hold the maul with the same grip each swing because any slight difference in position of the handle in your hands will produce a large change at the striking edge of the maul.
Swing with authority
Stand with feet shoulder width apart facing the round. Measure your distance by placing the maul where you wish to strike with arms fully extended, then step back a third or half step. This will encourage you to lean forward a little as you complete the swing and it will add power. Hold the maul horizontally near waist level, elbows comfortably bent, one hand at the base of the handle, palm facing toward you, the other hand at the neck, thumb next to the maul head, palm facing away from you. Switch hands if that is more comfortable for you. As a challenge, you can learn to use either grip equally well.
Flex your knees and bend slightly at the waist. Abruptly raise the maul overhead, extending arms high, straightening back and knees, and rising up on toes to gain maximum potential energy. During this up swing, allow the hand next the maul head to slide down the handle to meet the hand holding the butt of the handle. When your hands are directly overhead, the maul head will be at some angle behind the vertical line of your body.
With no delay, begin a very forceful downswing. Concentrate your vision on the point of intended impact. Bend at the waist and bend your knees to involve all of your body in the swing. At the very last instant before the maul head strikes the wood, pull it back toward you very slightly using your abdominal muscles and legs not your arms. This seems to increase accuracy and accelerate the head to make the blow much more effective. Also, if you can learn to "snap your wrists" downward at the last instant you further accelerate the maul.
DO NOT allow your vision to wander from the striking point during the swing. Focus your attention on striking all the way through the piece to the very BOTTOM. This is the same approach used in the martial arts. Strike toward where you want the blow to finish. Visualize the maul head penetrating the piece completely and visualize the split pieces falling away. KNOW that the wood will not resist the blow. Anticipate success.
There are those who split well using different tools and techniques. We respect them and encourage them to describe their methods to help others to learn. Here are some tips we've discovered.
- Firewood cut too long for its intended use is a constant source of irritation.
- Branching sections ("Y" pieces) can be split effectively in most species. Cut "Ys" as close as possible on the small ends then split with the "Y" down.
- Fiberglass handles can be pleasant to use and they are nearly indestructible.
- NEVER strike long (overstrike) which is an embarrassingly amateur way to break a maul handle.
- Six pound mauls use the same handles as a standard sledgehammer instead of the much more expensive special handles for heavier mauls.
The heat output (Btu content) of wood is proportional to its density (weight per unit volume) when air-dried. A cord (128 cubic feet or 4x4x8 feet) of dense hardwood weighs considerably more than a cord of softwood and thus has considerably more total heating potential. This is not to say that one should avoid lighter wood; in fact, it often makes excellent firewood. Because more bulk is required to do the same job, however, light wood should cost less in money or effort.
Some species of wood tend to have straight grain that splits well (red oak). Others have entangled fibers and can be very difficult to split (elm). Some wood splits easiest when green (live oak) and some split much easier when dry and brittle (some pines).
Stack firewood where air and sun can dry it thoroughly by the time you will burn it. Twenty-percent moisture content is supposedly ideal. "Dry" is good enough. You can burn wood that is not dry but there is some loss of heating potential through evaporation of moisture. In a pinch make a hot fire of any dry wood available and add the unseasoned wood.
Size and strength are not as important in effective wood splitting as determination and technique. We regularly split wood together. Anne is 34 years old, 130 pounds and relatively new to splitting. David is 61 years of age, 200 pounds and has decades of experience splitting wood. The only concession made for the difference in size and strength is that Anne's rounds are cut two-thirds as long (proportionate to our weight difference).
We thoroughly enjoy splitting firewood - a rare art and skill in this technological age. Our intent here is to present ideas that might refine or accelerate the learning process for someone and make wood splitting more enjoyable and effective for them.
By Anne and David