Chain Saw Selection and Basic Maintenance

[XJWoody]

I offer this thread as an examination of modern chain saws. I will limit its scope to gas-powered hand-held equipment, of the two-stroke persuasion. This is geared toward readers who may lack a broad knowledge of the subject, however it may be of some interest to more experienced users.

Chain saws currently available come in sizes ranging from tiny - 30cc, 1.7hp, 8#, to huge - 122cc, 8.6hp, 30#+. They are roughly split into two grades: Homeowner saws that cap out at around 60cc, and professional units that span the range.

Saws are designed for right hand operation. The operator grasps the front handlebar with their left hand, and the right hand operates the throttle and other controls adjacent to the rear handle. Some larger saws may have a wrap-around front handle, which allows a user to hold the saw from either side. These are often used in mountainous areas, where steep slopes affect the felling process. There are also ‘top-handle’ saws, which are designed for arborists for use while up in a tree, or from a lift bucket. Typically very compact and light, these specific-use saws have little application for normal woodcutting chores, and require the operator to be extra cautious during use.

In general terms, pro-grade equipment will offer better build quality, more robust controls, more advanced anti-vibration features, higher power to weight, longer service life, less complex maintenance & overhaul, and often have some interchangeability of parts. The homeowner-grade saws will typically be of lower initial cost, lower hp / #, and a little (or a lot) less quality. Each has its place, and users have their own requirements to evaluate while selecting a saw. A homeowner saw will last many years when used for its intended purposes (yard cleanup, moderate firewood cutting or light farm use.) If one needs to clear a large lot, or cut more than a couple cords of firewood per year, a professional-grade saw would be a better choice. With any small engine equipment, basic operator-level PMCS at the recommended frequency will extend the useful service life.

There are numerous manufacturers currently producing two-stroke equipment for the world & regional markets. I’ll be up front to say I own mostly Stihl, but have a couple Husqvarnas, and a small Dolmar saw. Stihl is the worldwide leader in sales and dealer coverage, with Husky, Echo, Dolmar and others bringing up the rear. Stihl and Husky (Husky's semi-twins are Jonsered, and their cousins are Poulan) have a manufacturing presence within the USA and Europe, Dolmar (and their twins sold by their parent company Makita) is made in Germany. Certain once-famous US brands (McCulloch and Homelite, specifically) are being made offshore, and are good examples of cheap Chi-com junk. Be mindful of which shore the stuff is coming from. I like to support local dealers of the major brands, who will support my purchases after the sale. Buying saws off the Internet will often provide limited warranty assistance, and possibly zero local dealer support. No matter which brand one decides upon, I suggest choosing a dealer like you would choose a spouse. They will be in it, with you, for the long haul.

Saws tend to be sold on “maximum guide bar size” and may be equipped with too much bar for the saw. This is where educated buyers can save themselves some aggravation or disappointment later on. Be honest in terms of requirements & expectations, and let that guide one towards a smart decision.

Guide bar lengths come in varying sizes ranging from 12” to 84”, with 14” to 24” being common. Selecting a suitable guide bar depends on the power of the saw, and the capability of the operator. One can cut roughly twice the bar length if an occasional need arises. Cutting softwoods such as pine and fir is easier on the apparatus than harder species like oak and hickory… this also is a factor in selecting and equipping a saw. Longer bars being used to their maximum potential require more horsepower to work efficiently.

As a basic guide, I offer this range:

30-40cc using a 14”-16” for wood -+10”
40-55cc using a 16-18” for wood -+ 16”
55-65cc using a 16-20” for wood -+ 20”
70-80cc using a 20-32” for production and or big trees
80cc and beyond is for really big timber or milling lumber. Folks shopping this range generally need little guidance, and the model selection is pretty limited.

The above is pretty conservative, and certainly not set in stone. It also shows my east-coast (flatlander with mostly hardwoods) bias towards shorter bars. Taller users may favor longer guide bars, as it lets them work without stooping over as much.

Chains come in several sizes, as well as different cutter shapes, widths & arrangements. One must match the bar groove width (gauge), chain drive link pitch and width (gauge), drive sprocket pitch, bar nose sprocket pitch, and number of drive links (bar length) together. If mismatched, these parts may not even fit up, but if they do, they will not play well together. Most bars will have the pertinent data stamped upon it, normally on the end closest to the powerhead. Some guide bars lack a sprocket-nose tip. These can be used for any pitch chain, as long as the gauge –and drive sprocket- is compatible. Note that Stihl has different bar stud patterns and oil passage journals than the Husky family and Dolmar. Unmodified, off the shelf guide bars are brand-specific.

3/8” Picco Micro or 3/8” LP (both .365” nominal pitch) low profile is found on the smallest saws.
.325” pitch comes in two gauges, NK (narrow kerf) and .063” (Stihl mid-size)
3/8” pitch has three gauges, .050” (common to any brand) .058” (Husky/Jred specific) and .063” (Stihl, typically PNW region)
Large saws may have a .404” pitch, .063” gauge.

Common cutter shapes & uses include round chisel for clean wood. Round semi-chisel is less aggressive, but tends to stay sharp longer in dirty or dead wood. Square-ground chisel chain is very aggressive in clean wood, but has a more involved process to sharpen. No woodcutting chain will tolerate contact with the ground, rocks, or other debris. My policy is such that if I even think I over-cut and nicked Mother Earth, I stop, inspect, and re-sharpen. Often, the thrown wood chips will tell on a dull chain. Sharp chains cut nice big flakes, similar in appearance to oatmeal, while dull chains tend to make powdery dust. A chain installed backwards will also cut (sort of) but makes dust and smoke as it hammers through the wood. A small saw with sharp teeth would potentially out cut a much larger saw with dull cutters.

Chains will stretch over time, and tension is adjusted via a screw on the sprocket cover adjacent to the bar nuts (sometimes this screw will be found on the front of the saw, beside the bar.) The drill is pretty simple: Unlock the chain brake, loosen the bar nuts, turn the screw to increase or decrease tension, and retighten the nuts. I apply some upward pressure to the bar as I am setting tension, to simulate the forces on the bottom edge of the bar as it contacts the wood. A chain that has proper tension will travel freely (by hand) in the guide bar groove, with a little resistance. At the center point of the bar, one should be able to pull the chain away to expose about ½ of a drive tooth. A chain that is too loose will sag away from the bar, and one that is too tight will be very difficult to turn by hand. Some modern saws have "tool-less" chain tension devices. That feature may appear handy until one pinches (sticks) their saw. What would be a minor hassle to remove the sprocket cover and free the saw head can become an impossible nightmare, and a job for a second saw, axe etc… With the older style manual adjuster, one can free the saw head, install a spare bar/chain, and liberate the stuck bar. Should one get the bar stuck, avoid wrenching & wrestling with it. This could bend the bar, damage the chain, or wreck the saw. A light-duty cutter (or one who never-ever gets their saw pinched) may be well served with a tool-less adjuster, but I prefer to stick with the non-complex manual apparatus.

Along the sharp chains track, I’ll mention that “yard trees” (or fence line trees) can often contain embedded debris like wire, bullets, nails, lag bolts, abandoned chain saw bars, etc, that can wreak havoc on your chain and could cause personal injury to self or a bystander. Often these hazards present with no advance warning, so really all one can do is be aware of the potential.

Shorter guide bars usually have chain with alternating cutting teeth every link. Longer bars and chains come with this same cutting tooth arrangement, but are often found with a “skip tooth” or “semi-skip” arrangement. These have blank links in the mix. This allows wood chips to be more effectively cleared from the cut, although taking longer to saw through. The skip and semi-skip arrangement is usually found on saws with guide bars that are over 24” length.

Some chains are equipped with carbide-tipped cutter teeth. These are intended for fire/rescue services, or for cutting extremely dirty wood like cross-ties, power poles, stumps, roots etc. It is expensive, must be sharpened with a diamond wheel, and presents an extra hazard from shrapnel if part of a tooth detaches.

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