The Different Types/Styles Of Chainsaw Chain & Their Uses
I am often asked by newcomers to chainsaws about the difference between Semi-chisel and Full chisel chain, or what is Ripping Chain and Do I Need It?
Now ignoring Ripping chain for a minute, the short answer, for the average consumer who only uses the saw once in a while for general garden tidying, tree pruning and a little weekend firewood, is that there is no need to worry about whether you buy semi or full chisel chain.. Indeed the small consumer saws bought from garden centres, mail order catalogues and such like, are as often as not fitted with Low profile 3/8" chain, which is virtually always only available as a semi-chisel anyway, so they have no choice! But for the more discerning saw owner I will try to shed some light on the mysteries of chain styles and types.
Before considering chain types it is important to understand WOOD.
There are two types of wood, Hardwood and Softwood. Now the terms have absolutely nothing to do with whether a wood is soft or hard, nor it's density. It all has to do with pores and fibrosity.
Hardwoods are technically and scientifically non-monocot angiosperm trees (there, bet you wish you'd had never asked !). In short in Northern Europe these are virtually all broadleaf deciduous trees (that is they lose their leaves in Autumn). Tropical hardwoods on the other hand are largely evergreens. Some hardwoods are actually quite soft, the most extreme example being Balsa wood.
So what defines a hardwood ?
Hardwood trees when examined under the microscope have a porous structure these pores act as natural gaps in the fibre of the tree, making them easier to cut through. The sorts of hardwoods you will likely encounter in your garden include oak, beech, ash, cherry, and a couple of hardwoods that are evergreens namely boxwood and holly. In firewood terms hardwoods make the best logs, burn better,spark less etc. Hardwoods are best cut with a Full chisel Chain.
Now European softwoods (which generally come from evergreen or coniferous trees) are devoid of the pores found in hardwoods (the pores transport water throughout the tree, think veins if you like). Typical softwoods are fir, pine, larch and spruce. The wood is more fibrous, lacking the natural gaps in the structure created by the pores in hardwood. This fibrous nature dulls chains much more quickly than hardwoods, for this reason Semi-chisel chain is the weapon of choice for softwood cutting.
Now the commercial woodlands managed by the likes of The Forestry Commission are mostly softwoods, since that is the easier type to work into finished products like furniture. It also grows faster and is easier to manage. This is the reason many .404" pitch chains used on largest commercial saws are semi-chisel.
Semi chisel chain
Conventional wisdom has it that semi-chisel chain keeps it's edge for longer than full chisel chain. This is the reason it is selected for cutting in softwood stands. The rounded shoulder profile of semi-chisel is also more tolerant of sharpening errors. In my experience however, I find little difference in length of time it stays sharp compared to the full chisel, but then we are cutting mostly hardwoods. How long should my chain stay sharp for ? Well how long is a piece of string ? If you are a carpenter on a building site cutting brand new timber joists to length it may stay razer sharp for many hours of use. If your Joe average cutting up old railway sleepers you might get 30 seconds or 3 hours ! Dirty, dusty conditions, hitting nails, stones on ground or embedded in trees, shotgun pellets and bullets etc will all result in a blunt chain. Some days I get by for hours without a file, next day I get 2 cuts before it's filing time. Softwoods will dull any chain faster than hardwoods.
Full chisel Chain
Cuts faster in all types of wood than semi-chisel, that's a fact. Needs more careful sharpening to keep it cutting straight, has a square shoulder profile (not to be confused with square ground cutter which is a different animal entirely,though they are full chisel). Theoretically dulls faster, especially in softwoods. For general purpose use I recommend Full chisel they just cut faster.
This is special purpose chain, with shallow angle cutters (typically 10 degree angle, whereas conventional chain is 25-35 degrees). Only used for chainsaw mills, making planks etc. Gives a smooth finish to the cut timber due to cutter angles. Ripping chain is ALWAYS semi-chisel, since cutting with the grain along the tree trunk, effectively makes all wood fibrous like softwood. you are never cutting across the pores (veins) so do not get the natural breaks in fibre caused by cutting across the pores.Now if speed of cut rather than quality of finish (fence posts, roof joists etc) is your aim, then full chisel normal chain will do the job fine, and cut faster. For real speed use a skip chain.....
This type of chain needs a saw of at least 60cc to work well, the bigger the better. Unlike standard chain this type has two blank links between the cutters. It therefore has half the number of cutters (takes half as long to sharpen as a result). Each cutter is able to take a bigger bite of wood before the next cutter snips off the chip and takes over cutting. This stuff cuts very fast, and is the most efficient cutting chain type. That big bite of course puts more strain on the saw, hence the need for plenty of power. the larger gap between cutters means less clogging of chain and more efficient clearance of waste. Will rip well enough and fast, but leaves spirals and rough finish on timber. This is stuff I use on my saws on bars 20"and above. there also exists semi-skip chain, this has alternating single link then double link gaps between cutters, rarely found on sale in UK.
Square Ground Chain
A Full chisel chain type for professional use. Whereas most chains are round ground and sharpen with a round file, these sharpen with a type of flat file or more usually a triangular file. Very fast cutting, but a a pain to sharpen for the amateur. Obviously if you have a bench grinder for sharpening then these are no problem. Not commonly sold on EBay UK as not really a consumer chain. Best left to the Pros unless you have a grinder.