An some everyday objects, time seems to pass without a trace. In half a century, a kitchen knife will probably still have the shape it is used in today, but the materials may be new then. We didn’t think there was much to improve on a chainsaw chain either. And then the Swabian company Stihl comes onto the market with a new tooth shape that is said to be better than the ones we have been used to for decades.
You have to know that a chainsaw does not eat a narrow groove through the wood like conventional hand saws, but planes out a relatively wide track using edged chisels arranged along the chain with a top and side cutting edge. Full chisel and half chisel chains are common today. The former have a sharp edge in the transition from the top to the side cutting edge, they are used where fast work progress in clean wood is important.
Semi-chisel chains have a rounded transition, they are less sensitive to dirt and have a slightly longer service life, but they also remove significantly less material, which is why they require less power and are regularly used on weaker chainsaws. Both are sharpened with a round file. This takes practice maintaining the correct angles, although the semi-chisel chain is a little easier to resharpen for the occasional user.
In contrast to these, the new Hexa chain from Stihl is sharpened with a hexagonal file, so the side cutting edge is not rounded on the inside but has an edge. Stihl promises a cutting performance that is up to ten percent higher than that of a full chisel chain and a slightly longer service life. The offer is primarily aimed at professionals who have no problems with sharpening, but the hexagonal file should also make it easier for less experienced users to resharpen.
The new Stihl Hexa chain is sharpened with a hex file.
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Image: manufacturer
Now one could argue that none of this is new, after all Stihl itself has edge grinding chains in its range for certain markets, the side and roof cutting edges of which can be resharpened with a normal flat file and the cutting performance of which some true miracles report. The board of trustees for forest work and forest technology considers it dangerous because it is supposed to quickly cut through the chainsaw trousers. According to other reports, it is neither better nor more dangerous, but everyone agrees that correct sharpening is extremely difficult. Stihl says that these are special chains that play no role on the European market (except for a small group of professionals in Switzerland). They are mainly used in the north-west of the USA for large-diameter softwood. The hexa chain is more like a round cut chain than an edge cut chain.
After a few days of hard work and several cubic meters of wood with this round edging chain, we can say: It’s true. The cutting performance of the Hexa chain is between 10 and 15 percent higher than that of a full chisel chain on the same wood, which in turn is almost 20 percent faster than a half chisel chain. Everything measured with the same saw, whereby the hexa chain and the full chisel can only exploit the advantage with a relatively high engine power. That’s why they are only available in 3/8 pitch with 1.6 drive link thickness. The service lives are difficult to compare in practical operation because of the non-homogeneous material to be cut. The Hexa chain feels like it lies somewhere between half and full chisel.
The hexa chain is more like a round cut chain than an edge cut chain.
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Image: manufacturer
It gets interesting when you sharpen it. The angular shape of the teeth gives the file some guidance, making it easier to maintain the angle than with a round file, but you still need practice. Two of the six edges are smooth, which prevents the bottom filing popular with beginners – pressing down there will remove material from the sawtooth, although it shouldn’t be.
The advantage is also the weakness, because a round file can always be turned a little while working, which extends its service life. You can’t do that with the special hexagonal file, and it costs significantly more at 9.90 euros RRP. Stihl has the hexa chain in its range at prices starting at 27.90 euros (for a bar length of 35 centimetres).
The hexa chain is unfamiliar to professionals, but it remains to be seen whether it will prevail in the forest. We think even the discerning amateur should give it a try.