Sharpening chainsaw chains is only a part of general chainsaw maintenance.
Possibly no other piece of power equipment is more used, more coveted, more debated, more feared, and more crucial to managing costs on the homestead than the chainsaw. Granted, each homestead is different, and maybe a tractor-mounted auger saves you thousands in labor costs every year, or maybe your haying equipment is responsible for an entire family’s livelihood. But to the average small property owner, choosing the right chainsaw and learning to maintain it and keep yourself safe while out in the grove is a critical step to warmth during winter, affordable fence posts all year long, and managing your wooded acres in a variety of ways.
Purchasing a chainsaw usually happens when you find yourself without one just one too many times, so knowing what you’ll be cutting is, of course, the first step in determining what chainsaw will best suit you. For most users, this means knowing trunk diameters and the species of wood they are likely to cut the most. If your use is varied and unpredictable, multiple saws and chains may suit your needs best. For a common two-saw setup, remember short saws are best for limbing, while long saws are best for felling large trees and cutting logs.
Manufacturers and professionals mostly agree that a bar-to-tree ratio of 1-to-2 can be safe. That is, an 18-inch bar is sufficient to cut through a 36-inch diameter trunk, depending on the skill of the user. To do this properly, the operator needs to gain practice plunge cutting appropriately (starting with the bottom quarter of the saw’s tip) and then working through half the trunk at a time. However, if you’ll be constantly cutting 3-foot diameter trunks, you will want to consider a larger bar and engine. Oftentimes, the bar length that you want will dictate to a certain degree the engine size, but don’t overdo it for more power and work with unnecessary weight when you don’t need it. Likewise, a chainsaw won’t last long when constantly used at its maximum workload. Consider your intended use for the saw and talk to your local dealer.
Operating the saw correctly also will extend its life. Squaring your stance before cutting keeps kerfs straight and chains spinning freely. Too often, users saw back and forth, or erratically rock the bar. No matter the cut, a firm, stationary grip is mandatory, and a solid stance — try adopting a boxer’s stance — is a must. If you need to move the saw around while cutting, bury it up to the dogs (the jagged teeth at the base of the bar), and rely on them for leverage. Regardless of how strong you are, you can’t get more leverage than the dogs. Fatigue from using too large a saw and overhandling are both pretty common, so choose the right machine and let it do the work for you.
A good chainsaw owner knows chains, and there’s no better place to start the discussion than with pitch and gauge. Pitch is the spacing between rivets, measured either as fractions of an inch (1/4) or in thousandths of an inch (.404), with numbers increasing along with chain size. Gauge corresponds to the width of the drive teeth. Sizing is in thousandths of an inch (i.e., .063). Compatibility is the main concern with pitch and gauge, secondary to overall performance. Always write down and store these sizes — your saw’s drive sprocket and bar will thank you.
Consumer saws come with round-toothed chains, which are less prone to kickback and vibration. Professionals, however, make use of the square-tooth, or chisel, chain. While rounded teeth scoop wood out of a cut, a chisel or square tooth chips the wood away, severing the wood fiber quicker. People do not agree which tooth profile is better, but the point is moot: Each serves a specific purpose, and they both do their jobs accordingly. Round-toothed chains are best suited for limbing, brush-clearing, stumping, and cutting through frozen or dirt- and mud-covered wood and hardwoods. Additionally, because they require more effort from the engine on big cuts, they are best used on shorter bars. Square-toothed chains, though, will best please the user when placed on a long bar (24-plus inches) used for felling softwoods.
Cutting teeth come in different spacings: full-complement, half-skip and full-skip. A full-complement chain has the maximum number of teeth possible. A half-skip chain adds an extra spacer (non-toothed link) between pairs of cutting teeth, and a full-skip chain adds two spacers, resulting in about 33 percent fewer cutting teeth than a full-complement chain. Consumer saws come with full-complement, round-toothed chains. A full-complement chain is safe, practical, and good for cutting debris and brush, and even felling small-diameter trees of all sorts. Because they have so many teeth, they cut smoothly and cleanly, and respond predictably to user input.
The very benefits of a full-complement chain, though, are also its shortcomings. Cuts are smooth and clean because they are relatively slow, thanks to the close-set teeth pulling more debris out of the cut. But this also means that there is heavier strain on the engine. A half-skip chain installed on a longer bar will make a rougher cut, but will cut quickly and easily through denser woods and be a boon if you have to tackle a large-diameter trunk. Believe it or not, half-skip is not a popular choice for chain replacement. This is likely due to owners simply replacing full-complement chains and professionals preferring full-skip, with neither wanting to experiment with the middle choice.
A full-skip chain is overkill for casual chainsaw users. The full-skip is for big cuts. Thanks to having fewer teeth, there is less drag when embedded in a tree, and the engine will run smooth and fast. Because it has fewer teeth, however, cutting smaller diameter limbs or branches is less stable, therefore prone to kickback or snagging.
It stands to reason that the more teeth a chain has, the less wear per tooth occurs while cutting. A full-complement chain will stay sharper than a skipped chain simply due to the lightened load per tooth. This is part of the reason discrepancies exist between claims of tooth-profile durability.
Bars will last a long time, often outlasting both chain and motor. For even more adaptability, consider adding multiple bar lengths to your kit. As a general (if unstated) rule, one engine can reasonably power three different bar lengths: the stock size, one size shorter and one size longer. Putting too much strain on a saw’s engine will absolutely ruin it. The exception comes when running full-skip chain, which allows even longer bars due to reduced drag. Adding bars and sprockets is a cheap, simple alternative to buying three different saws.
Like pitch and gauge, the drive sprocket must also match the new bar and chain, and both must be maintained regularly. By regularly inspecting and lubricating the drive and bar sprockets (with bar lubricant only), and by flipping the bar occasionally, you can dramatically prolong bar life. Keeping written logs of pitch, gauge, and sprocket size as they correspond to bar length becomes crucial at this point in saw ownership.
Plenty of tools exist to sharpen a chain at home, but you really only need a file, good lighting and time. You can secure the chain in a vice, sharpen directly on the saw, or even secure the saw and bar using a vice.
Round teeth take a question-mark shape due to the rounded side plates, and most chains specify what size round file to use. Looking at the top of the chain, you’ll notice the cutting portion of the tooth is formed at a 35-degree angle, and your goal while sharpening is to maintain this angle, or to reclaim it if it’s been offset for some reason.
The underside of the top plate is also cut at a specific angle (the undercut). To maintain proper undercut, the top of a round file needs to protrude over the top plate just slightly (about 1/8 inch). While sharpening, one hand maintains the 35-degree angle, while the other maintains the file height. Maintaining the undercut makes for smoother cuts.
A couple of firm strokes (away from you) and the tooth should be done. Cutting teeth need not be a uniform height, so resist the temptation to take them all down to match the lowest one.
Square chains, which have a “7” shape, require a bit more patience. Three-cornered and double-beveled files are best suited for square-tooth chains. Align the corner of your file with the corner of the cutter. Proper positioning here squares everything else — top plate angle, undercut and corner. The cutter tooth should be your jig, and if the file moves within the jig, even slightly, all your angles will be off. It is important to go slow and firm when sharpening a square cutter. Clean the gullets, too, by filing them up to the corner.
Rakers determine how much wood enters the gullet, and since the top plate is angled, the cutter height will decrease with each sharpening. You have to adjust the raker height to keep your saw cutting properly. While this is something that can be done freehand, best results occur when using raker-specific gauges and filing tools. Low raker heights are ideal for softwoods and limbing (.035-.050), while high rakers perform better in hardwoods and large cuts (.020 to .030).
Replacing broken or damaged teeth, or kinked sections of chain, requires only a few tools and spare links and teeth. After first filing off the rounded head, knock the rivet through with a narrow punch, or place in a chain break to back the pin out of its hole. Completely remove the pin, install the new tooth, section, driver or link with the correct side facing up, and finish with a new pin. If done with a hammer, you’ll need to form a rounded rivet head with a ball-peen. If the chain is stiff, the rivet is too tight, but it will loosen with use.
Keeping a close eye on the condition of your chainsaw is an important safety step that cannot be overstated. Bent bars, dull or chipped teeth, and loose chains can all result in tragic accidents, so it is of utmost importance that, at the very least, we swap out dull chains when we’re feeling too lazy to sharpen them.
It’s easy to put the saw up on a shelf when not in use and not think about it until we need it again (which some are likely to do for years). Aside from general maintenance, like changing plugs and filters, engine maintenance isn’t a task that’s suited for the average do-it-yourselfer. I always encourage friends and colleagues to have their equipment professionally serviced if it isn’t running correctly.
Likewise, advanced cutting techniques are important skills to master even for just the occasional user. However, this is a subject that could (and does) fill entire books. Still, it’s important to master the lowly thru-cut, bore cut and hinge cuts first. The average commercial chainsaw will indeed suit most average users. If you find yourself limited by constant sharpening or slow cutting speeds, the information in this guide should serve as reference for low-cost solutions. Often, all we need to get the most out of a chainsaw are wider chain options or new skills, and not necessarily a new saw.
Joseph Love is from Tennessee but has lived and worked all over the southeast. He has felled trees in Kentucky, North Carolina and Tennessee to clean up storm damage, build hiking trails, or clear lots for personal use.