Reign of the chain
Many chainsaw operators take their chains for granted, assuming designs have not changed much over the years. The reality, writes John Power, is that chains are extremely complex products that are subject to continual research and development.
Chainsaw chains are a moving feast of technological marvels – think of different kinds of high-strength metals and compatible metal plating, cutters that have to chew through woods of different grades and ages, edges that must stay sharp for lengthy periods, as well as safe and consistent performance within huge temperature ranges – and it is clear that the ‘humble chain’ is arguably the most sophisticated component of a chainsaw.
Far from being rudimentary and generic products, chains are the finely tuned mechanical hearts of complicated cutting systems, and a great deal of research and development is devoted to improvements in chain sharpness, safety, cutting speed and efficiency.
One of the world’s top chain brands is Oregon, which has extensive product lines available in Australia through its distributor Briggs & Stratton (B&S).
Sydney-based Geoff Peters, B&S’s Product Development Manager – Oregon, is a lifelong chain specialist with international experience in product development and training. Before joining B&S a year ago, Mr Peters spent 37 years with Oregon, and he continues to be involved in Oregon’s technical services group.
Mr Peters says Oregon, which invented the modern chainsaw chain more than 70 years ago, is “forever upgrading the product line – they make over 200 different types of saw chain, and there’s an Oregon chain to suit every chainsaw on the planet.”
According to Mr Peters, saw chains have never been more important than they are today, principally because modern chainsaws are lighter and faster than older machines, and possess lower torque levels. These characteristics mean modern chains must perform a larger share of the tool’s overall workload, whereas older machines might have relied on higher torque levels or greater horsepower to supplement the action of the chain.
“The modern chain really needs to be perfect to get the best results,” he said.
Today’s chains might have the appearance of older-style chains – i.e. pitch sizes1 have remained the same, the most popular being 1/4”, 3/8” low profile (LP), 0.325”, 3/8” standard profile, and 0.404” – but the similarities are only skin deep. Beneath the surface is a range of contemporary improvements, including superior base metals and chrome plating materials, dramatically sharper edges, and design enhancements that allow cutters to chew through different kinds of green and dry wood faster while ejecting chips more reliably and rapidly.
Mr Peters says the greatest improvement in chain technology in recent years can be seen in Oregon’s PowerCut 70-Series EXL range of chains, featuring an entirely new level of sharpness achieved with a new multi-axis grinding process.
Released in Australia last year, the EXL range is “completely different to anything that’s ever been on the market in terms of the way it’s been ground in the factory,” Mr Peters explained.
“This new chain comes out of the factory with a razor-sharp edge and it’s ready to go to work straight away. What Oregon developed is CBN (cubic boron nitride) technology; it’s a new material for sharpening cutters. Not only did they develop the material to sharpen it with, but they also developed the procedure to sharpen it, and it’s given an absolutely superb out-of-box sharpness.”
Mr Peters said the EXL chain, made with Oregon’s own OSC01 steel rather than industry-standard NS801 steel, contains an industrial chrome plating applied and sharpened prior to assembly. The result is a cutter that is 11 per cent sharper than previous models, delivering an equally faster cut. Crucially, Mr Peters says the EXL cutter design accepts easy hand sharpening using a regular file – a major prerequisite for easy, long-term chain maintenance.
Keep it sharp
Indeed, keeping chains sharp through hand file touch-ups in the field, combined with professional grinding at a dealership, is a particular passion for Mr Peters, who swears by a lesson he learned as a young man at his father’s sawmill: give chains a quick file (just a few strokes, or several minutes’ work, in total) every time the chainsaw fuel tank is filled.
“When I was working for my dad he said to me one day, ‘You don’t sharpen a saw chain,’ and I looked at him and asked what he meant, and he said, ‘You keep it sharp.’”
Mr Peters says that while modern chains are vastly superior to predecessor technologies, traditional care and maintenance routines still apply, including occasional trips to a dealership for a professional sharpening.
As far as chain sharpening at a dealership is concerned, Mr Peters says common bench-mounted grinders, whether manual or hydraulically assisted, work well with modern chains. A proficient operator should be able to sharpen six or seven 20” chains in an hour. More expensive automatic grinders may be appropriate for larger dealerships.
Given the importance of chain sharpening, Mr Peters says dealers are sometimes guilty of underestimating the value of the service, thereby risking the reputation of their businesses. Furthermore, he believes dealers should always offer full sharpening and maintenance packs (including file, personal protective equipment, plus chain oil) with every chainsaw sold, not only to boost sales, but also to equip the operator with a complete bundle of necessary accessories.
Right product for the job
Mr Peters says another vital piece of advice is always choose the right product for the job at hand.
Chainsaw chains come is a variety of different sizes and capacities, including full-chisel or semi-chisel2, low or regular profile, as well as different lengths and sizes to suit guide bars up to 24” or more.
As a rule of thumb, modern chainsaws should be selected based on the minimum requirements of the job – “Bigger is not always best when it comes to guide bar length selection,” Mr Peters said, adding that “a longer bar can be hazardous to the operator. The bar length should be the minimum length to do the job effectively; a shorter bar will give better balance to the saw, less maintenance and is also safer.
“I’ve often advised operators to come down from 0.404” to the lighter 3/8” chain in an application where, in the past, they might have used a 0.404”, simply to get more chain speed and more efficient cutting,” he said. These days 3/8” chains are the most popular size worldwide.
Similarly, Mr Peters believes a semi-chisel chain, “which essentially is more forgiving in abrasive cutting conditions than the faster full-chisel, is often considered a better all-round chain for cutting firewood.”
Dealers and operators have different opinions about which chain is better for hard or softer wood – Oregon does not make chains specifically for either, as the cutting performance in either condition is determined by the way the chain is sharpened. Hardwood requires less kerf width to clear the chips, and for most operators a semi-chisel chain will perform better in dry hardwood conditions. This may vary depending on the skill level and experience of the operator.
Oil and tension
Always keep chains lubricated, Mr Peters says. Even the latest chains, which function at approximately 22 revolutions of the guide bar per second at full power, need effective oiling to remain in good order. Oils can be thinned with diesel to overcome dirty or gritty conditions.
Chain tension is also critical for safe and efficient operation. In general, Mr Peters says chains are “almost always” too loose. “The measure is you need to hold the guide bar nose up while you’re making the adjustment, and to test it by gripping the chain on the top of the bar and the bottom of the bar and pulling it forward.” The chain should take some effort to move.
In conclusion, Mr Peters says the following four pointers are the keys to avoiding most problems with chainsaw operation:
- Sharpen the chain and set the depth gauges correctly.
- Correctly tension the chain.
- Keep the chain lubricated.
- 4. Cut wood only, not dirt or ash rubbish.
- The pitch of a chain refers to the distance between links, as defined by the distance between three rivets, multiplied by 0.5.
- A semi-chisel chain that features round-cornered cutters, will cut slower than the sharper-edged full chisel but will generally retain their edge longer in more abrasive conditions, and as a result are more suitable for general firewood cutting conditions in Australian hardwood.