Monday, January 25, 2021

Chain Saw Reference Material

Let me preface by stating that reading through this post and watching the linked videos is still no substitute for taking a proper chainsaw training & safety course from a certified trainer.  While I can offer some commentary and basic information in this post, you shouldn't consider this to be a proper substitute for proper hands-on training with a competent instructor.

If you're involved in forestry work, chances are high that you'll find it convenient to use a chain saw at some point.  Obviously, if you're working in the harvesting side of the industry, running a saw will probably be part of your daily routine, even in an industry dominated by heavy equipment.  However, even if you're doing tree planting, timber cruising work, surveying, or road building, it's always a good idea to have a saw in the truck for when you come across a tree that has fallen across the road.  If you're not employed in the forest industry, you may still find a chain saw to be very useful for work around your back yard or at a cottage.

Husqvarna and Stihl are probably the most well known pair of chainsaw brand.  Many people who use one or the other swear by the brand they use as being the best.  I don't subscribe to that notion.  Husky and Stihl are both great brands.  Personally, I own half a dozen Stihl saws, but I think Husqvarna also makes excellent saws and I've happily used Husqvarna equipment many times in the past.  Other common chain saw brands include Jonsered, Oregon, Homelite, Echo, Craftsman, Makita, Portland, Toro, and Milwaukee.  I also own a DeWalt electric arborist chain saw with a 12" bar, which I use for some small jobs.  A few years ago I would have laughed at the idea of owning an electric saw.  However, having tried out the DeWalt, I find that it's excellent for certain quick tasks around the yard, or for when I'm up in a tree.

Basic Safety
I'm going to work through five key areas (in point form) to share a bunch of safety tips:

  Use the Correct Saw
- Gasoline or electric?  There are advantages and disadvantages to both.  For forestry work, you're certainly going to want a gas engine.  However, although I always used to think that electric chain saws were a joke, I've been using one recently for certain small jobs around the house, and although I would never use one in the bush, I have a new respect for it.  Match your tool to the job that you're doing.
- Large CC (engine displacement size) and large weight, or small CC's and weight?  Smaller saws are frequently designed for more casual off-and-on work.  Larger saws are generally designed to be run hard for full days.
- Length of bar?  16" is standard for homeowner saws, although 12" or 14" is common for some arborist or electric saws.  Fallers in most parts of Canada use bars of 18" to 24".  Longer bars are available for areas with big wood.
- What is your experience level?  A smaller and lighter saw with a shorter bar is most appropriate for new users.
- What is your physical build and strength?  Even if you're an extremely strong and muscular faller, you shouldn't necessarily grab the biggest saw you can lift.  If you're cutting for very long, your arms will start to tire, and your safety risk becomes exponentially higher.
- What are you cutting?  Don't use a tiny casual-use yard saw for 24" trees.  Conversely, a large saw may not be appropriate for pecker poles or brush.
- How long will you be using the saw?  If you're cutting firewood for an hour, a light "homeowner" saw will be fine.  If you're using the saw for a few hours each day, a "farm and ranch" model may be best.  If you're running the saw for extended periods with high power requirements, you'll want one of the "professional" models.  Light homeowner saws are not intended to be run for hours at a time.
  Wear PPE
- Personal Protective Equipment is incredibly important.  I see lots of videos online with people cutting in jeans or shorts, or without safety glasses.  Having seen some of the ways that a saw can react unexpectedly, I know that it's just a matter of time until these people are seriously injured.  Using a chain saw without proper PPE is about as stupid as driving at high speed on a busy two-lane while texting on your phone without a seatbelt on.  Eventually, the odds are going to work against you.  I put on safety gear even to quickly cut a single tree that has fallen across a logging road.
- You need a hard hat for overhead protection.  Sometimes, when you're cutting a tree, a branch can shake loose and land on you.  Imagine a "small" sixty pound branch hitting you in the head from a 40-foot drop.  Make sure your hard hat is fitted properly.
- Eye protection is absolutely necessary.  Your hardhat should have a faller's shield as a first defense to protect you from larger projectiles, and you should wear goggles or safety glasses underneath the shield to protect your eyes from the wood chips that will constantly bounce up behind your shield.  How comfortable will you be trying to drive to the hospital with a large splinter embedded in one eye?
- Kevlar pants will keep you from losing a leg.  Kevlar is a type of material with long ballistic nylon fibers embedded within in.  If a running chain saw comes into contact, the material starts to cut, but then the fibers are supposed to bind up in the chain and sprocket of the saw (choking it and stopping the chain).  In practice, this doesn't happen instantly, so there's still a risk of a minor injury if you nick yourself.  But the injury would be a fraction of the severity compared to what would have happened if you were wearing jeans.  A sharp professional saw can cut though an unprotected human limb to the bone in less than a second.
- On the subject of pants, a lot of people wear chain saw chaps that fasten over your work pants, rather than full wrap-around pants.  I highly recommend against wearing chaps.  Although they protect the front of your legs, which is the most likely area to cut yourself, it's still possible to injure yourself on the sides of your legs.  Wrap-around pants are much safer.  I believe that WorkSafe has banned the use of chaps in many jurisdictions, for good reason.  Be aware that Kevlar doesn't work as well at stopping an electric chain saw motor, but it's still the best safety option.
- For footwear, leather work boots are not enough.  You need a pair of chain saw boots of some type, which feature Kevlar protection to keep you from cutting off your foot.  I always put Kevlar boots on, even for just a couple quick cuts in the back yard.  You can take it a bit further.  If you're working on uneven ground in the bush, you should strongly consider chain saw boots with "caulk" attachments.  Caulks are metal spikes which dig into the ground and give you extremely secure footing.  Do a google search on "viking black tusk caulks" to see one type.
- Gloves are useful.  When limbing, you'll have to stop the saw frequently to pull brush out of the way.  Even if you think your hands are tough enough that you don't care about getting poked by splinters and sharp corners, you'll probably want to avoid getting pitch or resin all over your hands, since it's so sticky.
- Some people overlook hearing protection!  Your handhat should have mounts for ear muffs.  You can also wear earplugs underneath the muffs to really protect your ears in the long run.
- Don't forget a safety whistle, so you can catch the attention of someone working nearby.  Also, I usually wear a radio harness chest pack to carry my phone (screen toward chest).  It's less likely that you'll damage your phone there than in other pockets.
  Saw Maintenance
- At the start of each day, give your saw a careful examination before starting to work.
- Examine your chain carefully.  With the saw turned off and the chain brake disengaged, check that the links appear to be in good condition, that none of the teeth look broken or dangerous, and that the chain spins properly on the bar.
- Check your chain tension at the beginning of the day when the chain is "cold."  Your chain should be tight enough that as you "pull" it away from the center of the bar, it only comes out about a centimeter or so.  Any looser, and it is more likely to come off the saw.  Any tighter, and you're going to have more friction, plus your chain won't spin as fast and therefore your saw won't cut as well.  Chains expand once they heat up, so you may want to stop the saw after 10 minutes of use and re-check your tension.  Also, a new chain stretches quite a bit in the first hour or two of use, so you'll probably want to quickly check the tension every fifteen minutes or so after starting to use a new chain.
- Clean out the guide on your bar that the chain links travel though.  This should be whisked out once per day, or any time that you feel that your chain isn't spinning freely.  To check the chain for this, turn the saw off and put it down on the ground, then disengage the chain brake, and try spinning the chain by hand.
- Know how to sharpen your chain properly, and keep it sharp.  That's a complicated topic that is explained in dozens of online tutorials.
- Make sure your fuel is mixed properly.  Chain saws have two-stroke engines, so they need to use "mixed" fuel.  Typically, the ratio is 50 parts of gasoline to 1 part of "two-stroke oil" or "mix oil," so the ratio of oil is quite small.  However, the presence of mix oil is critical, as it lubricates the piston within the cylinder.  If your fuel mix is too rich (too much oil), your saw will chug and die because the spark plug is unhappy.  If your fuel mix is too light (not enough oil), your piston will heat up due to increased friction, and it will eventually start to expand and score the inside of your cylinder wall.  The piston might even seize within the cylinder, then you'll need a new saw.  Two-stroke oil is typically a dark bluish-green, so your mixed fuel will have a slight blue-green tinge to it.
- Make sure you have "chain oil" or "bar oil" in the oil reservoir.  This oil does not mix with the gasoline or lubricate the engine.  Instead, it lubricates the inside of the bar, so your chain spins more smoothly and there is less friction and less heating up.  Your chain oil and mix oil are completely different products, and should not be substituted for each other.  Chain oil typically comes in a couple different weights.  Light or winter-weight oil is fairly thin (low viscosity), and works well in the cold of winter.  Medium or heavy oil is fairly thick, and works well when the saw is quite hot in the summer.  Chain oil is frequently dyed red, partly to distinguish it from mix oil, and partly to make it easier to see as you're double checking the lubrication on the bar.  Some of the Stihl chain oils don't have that red dye, which I find somewhat annoying.  By the way, you can get vegetable-based bar oil, which is much better for the environment than traditional oil.
- Make sure that your chain oil is feeding properly.  Sawdust can build up and block the channels where oil flows out of the reservoir and onto the chain.
- Make sure your air filter is clean.  You should brush it off probably a few times during the course of a day of cutting.  Clean it out with soapy water at the end of the day then let it air dry for best performance.
-  Once you've done a complete examination of the saw, start it and let it run for thirty seconds or so.  Test that the chain brake works to stop the chain.  If it doesn't work, do not operate the saw until you get it fixed.  If you notice that the chain break stops working during the day, stop cutting and get your equipment fixed.
- Incidentally, once you start cutting, check your fuel level frequently.  You should probably never allow the fuel level to get below a third of a tank.  This is because you should never walk away from a partially cut tree.  It is the operator's responsibility to ensure that every time you start a new tree, you have enough fuel in the saw to complete that tree.

  Safe Operation
- Know the different types of cuts used to safely fall a tree.  Make a plan for your tree before you start to cut.
- Plan two escape routes from every tree.  Your two escape routes should each be away from the intended direction of fall.  Ideally, each should be 45 degrees off the axis extending directly backward from the tree's direction of fall.  Use your saw to cut out any brush that could trip you up as you walk away via your escape routes, and take a minute to pick up and move any larger obstacles, such as branches or pieces of logs.  For reference, your escape paths aren't just a precaution.  You will always use one of your two escape routes to walk away as soon as you see that your tree is starting to fall.
- Before starting to cut a piece of wood on the ground (whether clearing or bucking), assess for tension and compression.  Any piece of wood that is under tension and compression will probably require two cuts, one on each side.  By understanding the tension and compression, you will know whether the top or bottom must be cut first.
- Make sure you're in a good stance, with your feet spread apart and body standing in a comfortable position, before you throttle up.  If you feel that you are not well braced when cutting, stop the saw and re-position your feet and body.
- If you're about to shift position or move, get in the habit of engaging the chain brake before even lifting a foot.  It is much easier to trip while moving than while standing still.  If your chain is stopped and you engage the brake before you move, you're at a much lower risk level of falling onto your saw.  As strange as this sounds, it can be pretty easy to fall and land on your saw, especially when you're wearing heavy protective gear with restricted visibility.  You will frequently find yourself shifting position on uneven terrain which has significant trip hazards.  It is especially easy to lose your footing while limbing a downed tree.
- Understand the physics of the saw's reactions to cutting with different parts of the bar.  The saw will react differently when cutting with the top of the bar, versus the underside of the bar, versus the lower tip.  Be aware that if the upper tip of your bar comes into contact with anything while the chain is running, you're liable to experience "kickback" - another incredibly dangerous hazard.  Please learn about kickback, and always be aware of where the tip of your bar is.  Never cut something that is "out of sight."
- Always hold the saw in such a manner that if you experience unexpected kickback, the saw will spin in an arc that won't hit you.  Hold the saw off to the side of your body.  If you can see the bar perfectly "edge on" while cutting, your position or stance or saw placement is very dangerous.
- Always hold the saw in such a manner that when you fall, your left forearm will automatically hit and engage the chain brake.
- When limbing a tree on the ground, work your way from the butt to the top along the "left" side of the tree.  This is the inherently safest position due to the "right hand" design of all chain saws.  Incidentally, there is no such thing as a "left-handed" version of a chain saw.  You'll always find that the cutting bar is on the right side of the saw.  If you're left-handed, your safest bet is to learn to hold and operate the saw the same way that a right-handed person does.
- Never cut above shoulder height.  For the first few months you're learning to use the saw, do not cut above waist height.
- If you're tired or the saw feels heavy, do not cut above waist height.
- Never cut two trees at a time (even on the ground), or two branches at a time.
- Never cut while standing on a ladder or unstable platform.  When people are cutting branches above shoulder height, the only safe option is to bring in the correct equipment (a special type of saw called a pole saw).
- Watch out for "spring poles," which are small trees that are bent over but not broken.  These are under tension and can easily surprise a faller.
- Deciduous trees (especially alder) are more prone to barber chair than conifers.  In many cases, deciduous trees are the most dangerous types of trees to fall (other than compromised trees and danger trees).
  Hazard Checks
- Before approaching a tree that you intend to fall, scan for hazards.  In particular, look carefully at the tree, scanning for problems such as a dead top, dead branches or widow-makers.  If you're working near civilization, consider the potential for nearby lines and wires.
- Look for rot.  You may see visible signs, such as cracks or cavities.  You may see missing bark, and stem wood that is especially dry.  Conks or similar types of fungal growth on the trunk of a standing tree are a sign of likely rot within.
- Look at the trees around your target tree, and look for branch entanglement with other trees.  Never start to cut an entangled tree unless you are highly experienced and know the appropriate methods to control the hazard.
- Look for other danger trees in the area that could fall onto your tree as you're working.
- Look at your footing.  If there is brush and vegetation, clear it away.  If there are loose rocks, you'll need to assess whether your footing will be sufficiently secure.
- Assess the tree for lean.  It is easiest to cut a tree the direction that it naturally wants to fall.  Although there are ways to make a tree fall in the opposite direction from the natural lean, this only works for slight leans, and this type of a situation is significantly more dangerous.  Unless you have a lot of experience, don't try to cut against the natural lean.  Unless you have a lot of experience, don't try to swing trees as you're falling them.  If the tree isn't going to fall in the direction that you want, and you don't have the option of using ropes or heavy machinery to assist you, don't touch the tree in the first place.  Walk away.
- Look at the slope.  Cutting on a slope is significantly more dangerous than cutting on flat ground.  You will want to cut the tree so it falls down-slope, for safety.  Cutting a tree uphill is dangerous, as the tree can roll or slide or bounce back at you as it is falling, or after it hits the ground.  Never stand downslope or below a tree that you're cutting.  Always finish your work from the uphill side.
- Know your species.  Some species are especially prone to barber-chair, which is extremely dangerous.  I know of people who have been killed by trees that barber-chaired on them.  Aspens and poplars can be risky.  Alders are especially dangerous.  If you don't know how to cut this type of tree safely, leave it to an expert, since a specialized falling approach is required.
- Check the wind.  Don't work in heavy winds.  Don't fall trees into wind, since a gust can pick up your tree and bring it over backwards.

Falling a Tree
There are a lot of different ways to fall a tree, and in this section I'll try to describe the basics of how to do it safely.
The traditional approach is to start by cutting out a piece of the tree in the direction that you want the tree to fall, then to cut it from behind.  The front cut is generally two or more distinct cuts that remove a piece or pieces from the side of the tree in the direction in which you want the tree to fall.  The part that is removed is called the face or notch.  After you've cut out your notch, the tree should not fall down yet!  If so, you've done it incorrectly.  The notch generally only goes to a depth of one-quarter to one-third the diameter of the tree.
Once you've made a notch, your back-cut is a single horizontal cut which is typically intended to be aimed at a point approximately 1 to 2 inches above the deepest part of your notch.  Your back-cut is the cut that causes the tree to start falling.

When done properly, you will end up with an uncut band of tree trunk between the notch and the deepest part of your back-cut.  This strip of holding wood is called the hinge.  Ideally, your hinge is of equal depth on both sides.  Here's a graphic to illustrate some of these concepts:

I don't particularly like this graphic for a couple reasons.  First, it says that the notch is about one-fifth of the diameter of the truck.  However, that label is not correct.  You can confirm visually that the depth of the notch in this illustration is about one-third the diameter of the tree.  That makes sense.  I'll clarify that there are occasionally times when a very shallow (and tall) notch of 20% of the diameter makes sense, and there are times when a very deep notch (>40%) makes sense.  But those are for special situations which we're not going to explore here.  Another thing that I dislike about this graphic is that it looks like the back-cut is sloping downward slightly, which should not be necessary.
Wedges can (and should) be used as a precaution to keep your back-cut open, so the trunk doesn't settle back and close on the bar of your saw.  This shouldn't happen in the first place if you are cutting properly, but sometimes a tree will surprise you.  Wedges are also used to force a tree over if you've completed your notch and back-cut, but the tree is still standing.  Wedges are easier to use in larger trees than in smaller trees, since there may not be room to put a wedge into the back-cut of a smaller tree without the tip hitting the bar/chain of your saw.  Instead of going into detail about the use of wedges here, I'll save that for the video tutorials you can find further below.  Just remember that it is always smart to carry an axe and several plastic wedges while falling.  Also, never wedge a dead or rotten tree.

Your notch can be one of three types:  Humbolt, Conventional, or Open-Faced.
The Humbolt notch should be open to an angle of about 45 degrees, with the top of the notch extending horizontally into the truck, and the bottom coming up into the trunk at that 45 degree angle.

The Conventional notch is the opposite of a Humbolt, ie. the bottom of the notch is cut horizontal into the trunk, and the top is angled down into the trunk at a 45 degree angle.

The Open-Faced notch is sort of a combination of both Humbolt and Conventional.  You may also hear it referred to as a V notch or Swing notch.  This notch extends into the tree both "down from above" and "up from below," with the two cuts meeting perfectly.  The total width of this notch is frequently up to 90 degrees, although some fallers will cut it slightly narrower (say 70 degrees).  Take a look at this graphic to get a better understanding:

If you look carefully at these three examples, you'll notice that the back-cut is always horizontal.  You'll also notice that the back-cut does not always aim at a point exactly an inch above the deepest part of your notch.  The back-cut on a Humbolt notch should aim to stop on the other side of the hinge at a point which is an inch above the deepest point of the notch.  The back-cut on a Conventional should be slightly more than that, perhaps closer to 2 inches above the deepest part of the notch.  It is only the Open-Faced notch which gets a back-cut that is basically aimed at the back of the notch.
The upper and lower face of your notch should meet perfectly along the entire back of the notch.  If either cut goes too far on either side, the overcut is called a Dutchman.  A Dutchman destabilizes your hinge, and reduces or eliminates the ability of the hinge to control the direction of fall.  This is very dangerous.  If you create a Dutchman, you'll need to make your notch larger to clean it out and eliminate the Dutchman.  But you don't want to make your notch too deep, which is also dangerous.  If you're starting to think that falling a tree safely requires a lot of skill, you're correct.

I want to really emphasize something here, once again.  You should NEVER allow your saw to sever the hinge.  If your back-cut goes too deep and cuts the hinge, the upper part of your tree is no longer attached to the stump.  This is an incredibly dangerous situation.  Instead of falling in a controlled manner with the hinge dictating the direction of fall, your tree will go wherever gravity takes it.  And that isn't always where you want it to go.

You should leave at least 10% of the diameter of the tree for your hinge, or "holding wood."  Here's a graphic from Husqvarna illustrating this concept:

Different types of notches have different pros and cons.  An Open-Faced cut may be the safest and most commonly used cut for beginners.  In certain types of situations, it is the safest cut even for an experienced faller.  However, among professionals, the Humbolt is viewed by many of my friends as the safest cut.  This is not to say that the Conventional notch should always be avoided.  I'd estimate that when I'm cutting, I probably use the Humbolt notch on about 95% of the trees, the Conventional notch on about 5% of the trees, and the Open-Faced notch very rarely, perhaps only one or two trees out of a thousand.

A Humbolt (or Open-Faced) notch does a better job of letting the butt of the falling tree slide down the stump as it starts to fall, so the butt hits the ground before the top of the tree.  In my personal opinion, this is safer and causes less damage to the tree.  With a conventional cut, the butt is held in the air by the stump as the tree is falling, so the top part of the tree hits the ground before the butt.  On a high stump, this may be slightly less safe, and may cause more damage to the tree when it impacts the ground.  Of course, you should always use one of your escape routes to quickly walk away from the tree as it starts to fall, so you should never have to worry if the butt kicks back toward you as the tree lands.

When cutting commercial timber, a Humbolt gives you a few extra inches of prime usable wood at the butt of your largest piece, unless the Humbolt forced you to cut higher on the trunk.  You often lose a few inches of commercial wood when you use a Conventional notch.  I'm almost never cutting for commercial value, therefore, I don't avoid using Conventional notches based upon economic reasons.  A professional logger would more likely be motivated to avoid Conventional notches.

There are other types of specialty notches and falling techniques, such as gap-faced notches, and cutting slits or sub-notches from one side of a larger notch to affect tension and swing a tree slightly as it falls.  There are also techniques for falling trees that are leaning in the wrong direction, although this is only possible to a somewhat small extent, unless you want to bring in ropes or other equipment.

Until you've had proper training and months of cutting experience, you should stick to the basic three notches.

Video Resources

Here are a few basic chainsaw use & maintenance videos from Husquavarna.  If you own a different brand of saw, they are still worth watching:

Here's a basic chainsaw use & maintenance video from Stihl.  Again, this is worth watching even if you don't own a Stihl:

The US Agricultural Safety & Health Centers has a pair of good basic safety videos:

 Here are the links to WorkSafeBC's entire series of faller safety videos.  They're quite good, and I watch the entire series again every winter as a reminder about safety, because I spend a lot of time cutting each year.  I'll list these seventeen videos as links rather than as embedded videos, to save bandwidth for people reading through this post:

01 - Introduction (5:57)
02 - Stretching (8:18)
03 - Saw Maintenance (11:49)
04 - Using the Saw (6:01)
05 - Site Assessment (2:10)
06 - Preparing to Fall (3:41)
07 - Thick Bark (1:22)
08 - Undercuts (21:23)
09 - Wedging (10:55)
10 - Falling Small Trees (20:28)
11 - Slope (5:57)
12 - Heavy Lean (9:51)
13 - Falling Hazards (37:43)
14 - Winter Falling (13:37)
15 - Limbing (7:47)
16 - Kickbacks (2:04)
17 - Bucking (17:32)

The guys in this next video are entertaining, and they share some good information.  I find that they didn't always explain the entire rationale for what they were doing before they went ahead and started cutting, but if you already know the basics, you'll probably learn a few things from this video.  The only thing that really bothers me about this video is that some of the operators are not using chain saw pants, safety glasses, or hard hats with face shields.

That's all for now.  If you're just about to start working with an instructor, I'd recommend that you watch the videos in this post and then re-read all my safety comments before you begin your training.  However, even though reading and watching videos is an excellent way to start learning, there's no substitute for one-on-one instruction with a qualified, certified instructor.  Training courses with certified instructors don't come cheap, but they're a hell of a lot cheaper than cutting off a limb or allowing a tree to flatten you.  I go through and re-watch all of these videos at the start of each winter to help remind myself about best practices & techniques, and I typically spend 80-100 days cutting each winter.

Good luck, and be safe.