Posts Tagged ‘Tree Felling Notches’

Arborwood Tree Service Inc. provides comprehensive safety and skills training to staff.

Friday, July 17th, 2015

Arborwood Tree Service Inc. is investing in comprehensive safety and skills training for their staff in 2015 and 2016 by hosting three weeks of training that will cover the topics of:

– Tree Dynamics & Integrated Risk Assessment

– Tree Biology & Care

– Hazard and Danger Tree Cutting & Falling

– Tree Climbing, Fall Protection & Work Positioning

– Tree Rope Access

– Emergency Readiness & High Angle Rescue

– Aerial Lift Operations & Fall Protection

– Aerial Lift Emergency Evacuation & Extrication

– Production Tree Removal & Rigging

– Arborist Technical Rigging

The training started with one week in May and will continue with weeks in November of this year and in April of 2016.  The program is being partially funded by the Canada – Ontario Job Grant Program.

Arboriculture Canada customizes training programs to specifically meet the job requirements and unique training needs of your staff.  Our training programs are facilitated by experts in both adult education methods, as well as experts in the skills areas of arboriculture being taught.  If you are interested in receiving funds for training your staff internally in arboriculture skills and safety from the Canada Job Grant programs available in every province of Canada, please inquire with Arboriculture Canada to receive the information for applications.

Arborwood Tree Service is dedicated to providing superior customer service. Their great reputation is built on professionalism and customer satisfaction.  This training will ensure that staff meets this expectation.  www.arborwood.ca 

 

The Key Notch

Tuesday, January 13th, 2015

In some cases, trees are hung or snagged because they have been uprooted.  In these situations determining where the loads are concentrated can be difficult, and often the root plate is a stronger force to be considered than the hung tree itself.  Gravity is always acting on mass and never takes a day off.

This uncertain circumstance presents challenges that must be considered when attempting to cut the tree free from obstacles.  The main focus of the cuts I have described in my past two articles (mis-match cut and controlled hinge release) has been to allow the cutter to be at a safe distance when the final cut is released and the tree falls and is cleared from its snagged position.  The use of rope and mechanical advantage allows cuts to be released in a controlled manner and the tree to be pulled from a safe working distance while trying to free it.  For safety’s sake always plan, prepare and use an escape route.  Avoid cutting and releasing a snagged tree while standing next to it by creating a barrier using distance and rope.  The further away you are from the snagged tree, the better (within reason), but a good rule of thumb is to be a distance away that is equal to the height of the snagged tree.

The key notch is a technique for freeing a hung or snagged tree that releases all holding wood while maintaining control until a pull force is applied.  It takes some time to cut and works well on trees that are hung and snagged where the compression and tension forces are very difficult to identify, such as with uprooted trees.

First evaluate and determine the zones most likely under compression and tension.  In the case of an uprooted tree, the compression and tension zones can be exactly opposite that of a tree in the same hung or snagged position that is not uprooted.  The techniques of the key notch will work the same for either situation.  This is why it works well for trees where it is difficult to determine how much force the root plate is applying.

The key notch is made by making five cuts into the trunk; the first three cuts utilize the bore cut technique, cutting through the trunk and forming a tongue and groove – or ‘key’.  The tongue and side of the groove should be of equal size or thickness.  This is determined by dividing the trunk diameter into three equal parts.  In order to properly form the key notch, it is necessary that the trunk be at least three times the diameter of your chainsaw bar width.

key notchBefore making the final two cuts, wedges are installed to prevent saw bind and pinch.  The wedges are placed under the tongue on both sides of the trunk and wedges can also be inserted into the sides of the key as well.  This requires several wedges, but a minimum of two will often work.  The fourth cut is made in the compression zone and the final cut should be placed in the area of the trunk that is determined to be under tension.  By releasing a load in tension the kerf should open and allow the key notch to be completed without any bar pinching.  KeyNotch with wedges1blog

KeyNotch with Mechanical Advantageblog

Using mechanical advantage to pull the the snagged tree free.

Once the cuts are completed the worker should retreat to a safe working distance and pull the snagged tree out of the key, using a pre-installed pull line.  Pulling the tree out of the key may require more force than one person can apply and that is where mechanical advantage is incorporated into the pull.

It is my intention in writing these articles and sharing techniques, to add tools and techniques to the mental toolboxes of workers who use chainsaws to cut trees that are hung and snagged during or after storm events.  I realize that there are many different tools and techniques and I always encourage workers to stick with ones that have worked well for you.  I also equally encourage everyone to always keep an open mind and give new techniques a chance and a try.  See if they work for you, and when they do you have another tool for the toolbox!

Success Chainsaw Train the Trainer Event!

Monday, October 27th, 2014

Last week near Caroline, AB – a successful week of Chainsaw Train the Trainer.  Here is a re-cap!

https://vimeo.com/110079520

Group Photo 2014 Caroline, AB

Arboriculture Canada is a National Awarding Body (NAB) with the ABA (Awarding Body Association) International.

Tuesday, June 3rd, 2014

We are proud to announce that we have been accepted as members of the ABA International body.  Arboriculture Canada is now a National Awarding Body (NAB).  We would like to introduce the ABA to our customers in Canada, and especially the candidates who have successfully achieved qualification status (chainsaw) through our testing process in the past years.   (other domains to come)

This article will introduce you to the ABA International, and tell you what credentialing through the ABA can do for you.    http://www.aba-skills.com/about.php

Who is the ABA?

ABA International (Awarding Body Association) was founded in 2012 in response to a demand for international recognition of qualifications gained at state or national levels. The trans-national mobility of qualified people facilitated by a voluntary partnership of national awarding bodies is a core principle of ABA.

ABA is managed on a minimum administrative basis in a cost effective manner. A simplified organisational structure provides each member country equal representation within the association.

National awarding bodies (NAB) are subject to an International accreditation and vetting process. Core to quality assurance and uniformity of the qualifications is the principle of trans-national supervision. In support of this principle ABA continuously develops, updates and enhances International qualifications skills standards & matrices.

Partner agreements include general procedures for cooperation; transfer of qualification credits; national awarding body responsibilities; certification endorsement etc.

Further, ABA endeavours to promote the mutual recognition of its member’s qualifications world-wide therefore reducing or removing potential barriers to employment and mobility.

The ABA’s Mission:

To facilitate, accredit, develop, support and promote the recognition of individuals national skills qualifications and certifications between partner countries worldwide

THE ABA’s Mission Objectives:

Establishing & setting certification standards: undertake a continuous review & improvement process to ensure they remain consistent and rigorous Quality assurance of the certification: ensure validation of content, currency, delivery and review methods are consistently maintained and comparible

ABA has the following key roles:

  • Qualification development: maintaining a support network with international educational advisors
  • National Awarding Body support: ensuring good practice is maintained, encouraged, developed and facilitating communication
  • National Awarding Body external inspections & vetting process: facilitating trans-national observations of training & assessment practices and awarding body audits
  • Promoting the principle of continuous improvement: facilitating exchange opportunities between National Awarding Body instructors, assessors and educational advisors

Why Get ABA Certification?

National skills certification demonstrates that you have achieved a recognised standard within your skills or chosen occupational sector. In addition, the ABA International ‘stamp of approval’ on your certification provides the following benefits:

  • Enhanced mobility: instant participating partner country recognition no need to re-take already proven training or skills tests to work abroad (saving time & money)
  • Enhanced employability: demonstrates your competency at an international level to current or potential future employers(helping to break-down barriers)
  • Enhanced credibility: demonstrates proof of your skills verified to rigorous national and international standards (high quality)

Are you an Arboriculture Canada Qualified Technician in a Chainsaw Domain?

Arboriculture Canada has been given equivalency for chainsaw qualification with the ABA in the following chainsaw training domains.  If you have taken a chainsaw qualification test and successfully become a Qualified Technician in one of these domains in the last five years (since January, 2010), you will be receiving an email inviting you to register yourself for the ABA Certification.  The only thing required to receive this ABA Certification is a $12 processing fee and you will then be registered with the ABA Registry (which is an online registrar).  You will immediately be registered as an ABA Certified Candidate internationally.

Arboriculture Canada Chainsaw Qualification Programs and ABA Equivalencies:

Arboriculture Canada Qualification ABA Qualification
Chainsaw Safety & Cutting Techniques (Chainsaw Operator Technician) Chainsaw Level 1:  Chainsaw Maintenance & Cross-cutting Techniques
Technical Tree Falling & Cutting (Tree Faller Technician) Chainsaw Level 1:  Chainsaw Maintenance & Cross-Cutting Techniques andChainsaw Level 2:  Basic Tree Felling Techniques
Hazard & Danger Tree Cutting & Falling (Hazardous Tree Falling Technician)  (provided you have received the Tree Faller Technician) Chainsaw Level 3:  Advanced Tree Felling Techniques andChainsaw Level 4:  Windblown & Damaged Tree Felling Techniques.

For any candidates who have taken customized tests with Arboriculture Canada through your organization or company in the chainsaw domain, please contact Nancy to inquire which equivalency is applicable to your test.

Arboriculture Canada is choosing to endorse and support the goals and aims of the ABA, as we believe that the intentions align nicely with our corporate vision and the recognition of ABA qualifications around the world will serve to improve the safety of working arborists and chainsaw operators.

Controlled Hinge Release – releasing lodged or hung up trees.

Sunday, May 8th, 2011

In my last article I shared a technique for safely releasing lodged or hung up trees.  I am going to expand on this concept in this article.

One disadvantage of the mis-match cut is that in some cases, the vertical wood fibre lamination may release before the saw operator is at a safe distance away.  It is a rare occurrence, but it can happen and is an example of why alternative techniques are always good to have in the mental toolbox.

The controlled hinge release is another technique for releasing hung or snagged trees that can offer some additional control when cutting these types of trees.

Controlled hinge release techniques at work.

The controlled release hinge technique is employs the use of a notch and also requires the hinge to be established using a bore cut.  The notch and hinge are set before the final back cut is made and optimizes safety by using a mis-matched back cut and a pull line to release the tree when the operator is ready and clear of the danger zone.

An open face notch is cut in the opposite side of where the pull line is installed. This way when the tree is pulled, the notch closes and the tree hinges towards the pull line. The placement of the notch should not only consider the pull line direction but also the side that best facilitates the dislodging of the snag or hung tree.

Preparing to by-pass the strap.

The bore cut establishes the hinge which should be made thinner than normal when dealing with a standing tree.  Instead of the standard 10% to 7% of diameter, a maximum of 5% to 3% should be used. This is due to the lack of bending moment that exists in hung or snagged tree scenarios.  A limitation of this method is that it is best suited for large enough diameter tree where there is enough wood behind the hinge to allow for the bore cut to be made and in situations where the butt of the tree is not attached to the roots or dug into the ground.

First attach a pull line to the tree and install any mechanical advantage needed to pull the tree. Once the notch and hinge are cut, you will have the small portion of wood left uncut at the back of the tree – commonly called the ‘strap’.  The final step is to place a by-pass or mis-match cut just below the bore cut and cut far enough so that this kerf passes the kerf above, creating a mis-matched strap. This will hold or control the release of the tree until a load is applied to the pull line.

The strap releases and the tree will fold or ’walk’ in the direction of the pull line when the tree is pulled.  Often this action is enough to dislodge the hung tree or snag.  If it does not, the line is moved up and the technique is repeated. The repeated cuts move the snag or hung tree in a lateral direction, encouraging it to dislodge and keeping the snag from becoming more vertical where it is likely to fall unpredictably when it dislodges. The controlled release hinge maximizes cutter control and safety.

Bore cutting the back cut of the controlled hinge release.
Safe working distance.
Using mechanical advantage to dislodge a snag.

An article is no substitute for hands on training and this article is intended to stimulate thought.  I trust my description along with the photo’s can help you to understand this very effective technique for freeing hung or snagged trees.

Too often a variation of this technique is used with a conventional back-cut, where the notch is cut in the upper side of the snag and the hinge is formed with the cutter standing right beside the tree and a very quick and abrupt jump is made in an attempt to escape as the tree releases and hinges.  Control is not part of this technique and can result in the cutter being struck or pinned by the butt of the tree.  This technique also moves the tree closer to the snagged or hung obstacle, causing the tree after frequent attempts to become more and more vertical resulting in a very large and dangerous drop zone.

It is a known fact that 90% of all tree cutting accidents occur within 5 feet of where the final cut is made, within 15 seconds of the tree beginning to fall or hinge. This is called the 5-15-90 rule. It stands to reason that if the tree can be released at a distance greater than five feet and before falling or hinging action begins that the likelihood of being injured is reduced by 90%. It is with this thought in mind that the controlled release hinge is utilized.

In my next article I plan to share another technique which is well suited for scenarios where an uprooted tree is hung or snagged, or where the butt of a snagged or hung tree is dug deep into the ground.

Dwayne Neustaeter

Back-Cuts, Hinges & Control (Article 6)

Monday, August 2nd, 2010
 

This is the last in a series where I have been discussing a sequenced planning method to tree felling.  When read in sequence, the articles combine to describe an effective tree felling planning process. It has been my intention to encourage readers to think about many aspects when felling trees – with the focus being on tree faller safety.

It is important to remember that some tree felling techniques developed from years of trial and error and in field practice and in all cases deserve our respect and acknowledgement. It is difficult to produce conclusive scientific data that verifies certain aspects of tree felling techniques, due to the many variables that are at work when dealing with living organisms such as trees.

Remember that new tools cannot get into a toolbox when the lid is closed.  An open mind is like an open toolbox and new tools when tried and proven are a wise addition.

In most cases, the back-cut is the final step when felling a tree.  The back-cut removes the wood left preventing the notch from closing, it also forms the hinge wood. The hinge wood is the wood left uncut behind the notch and is what provides control and guidance to a felled tree. It is important to understand that the hinge can only offer control as long as it can work; when the hinge fails, control is lost.

Cutting & Forming the Hinge
 

Traditional Back Cuts

A crosscut saw was the tool of choice and for generations back-cuts were cut by hand with a crosscut saw, cutting from the back of the tree towards the notch.  The modern chainsaw and tooth design offers us alternatives to this traditional method. The notch selected should be considered when deciding where to place the back-cut. Traditionally it has been recommended to raise back-cuts above the apex of the notch.  This technique (called the stepped back-cut) forms a step or back stop and minimizes a tree from sliding backwards off the stump causing great risk to the faller. It is important to raise back-cuts whenever felling a tree with a small notch opening such as 45 degrees or less. In these cases, the hinge will have to break when the face notch closes. After all a notch with a 45 degree or less notch aperture will have to break the hinge and as a result will lose control when the tree in most cases is only half way to the ground. A limitation of a small notch aperture is that it forces hinge failure before the tree reaches the ground, thus causing loss of control and gravity takes over before the tree is on the ground. If limb tying or felling obstacles are present that could snag the falling tree a stepped back-cut is also advisable regardless of notch opening.

Open Face Notch

Tree Felling Notches (Article 5)

Monday, August 2nd, 2010

Many times when workers discuss tree felling notches, the conversation ends up being about what kind of notches are used and what they are called.  Typically your hear about a common notch, a Humboldt notch, an open notch, and less frequently a v-notch, or swing notch. It is important to give techniques names because it helps identify one from another; however, it can also cause some problems. Typically when you learn a notching technique you identify the notch with a name and the learner connects the sequence of cuts and angles to that specific notch. This is typical basic training, however, I believe it is equally important to include an educational component that explains the ‘why’ behind the ‘how’. This leaves a worker with an understanding and the ability to make wise choices in order to achieve specific results.

Education is understanding how something works; training is knowing how to perform a technique that works. I find in many cases individuals who have been falling trees for a long time were never educated about the origins or reason why the technique was developed and simply repeat the same traditions, not giving thought to what the notch is, what the notch does and how it can be cut to enhance and achieve desired results. The fact is we learn so much about falling trees and cutting notches by doing and we tend to follow what we saw from those that cut before us.

A powerful example of this is the common notch.  The common notch is typically cut with a 45 degree opening.  Why a 45 degree opening?  The explanation of why lies in history. The modern day chainsaw has only been in use realistically since the 1950’s, which means for many years prior the tools available for cutting notches were different. The tools most commonly used in North America since the arrival of the white man was the crosscut saw and axe. In order to cut a notch in a tree with a crosscut saw and an axe, the first cut is sawn perpendicular to the grain of the tree with the crosscut saw. Next, an axe chips the wood out using downward angled strikes; it is interesting to observe that an axe chips out wood best at a 45-degree angle to the wood grain. It is reasonable to deduce that the 45-degree common notch is a result of the limitations of the tools available at the time. Many cut the same notch today as it was done hundreds of year ago. Some consider that this notch was technically developed yet history suggests otherwise, the 45-degree notch is largely the result of tradition and older equipment limitations.

What is a notch and what does it do? A notch is an opening made into a tree trunk by making two angled cuts into the trunk with the intention being that the notch starts the tree falling in the desired direction of the fall and dictates how long the hinge can work and when it will have to break. From a mechanical point of view this notch in the tree changes the gravitational load forces on the remaining wood fibre, and the wood fibre left behind the notch is referred to as hinge wood.  I will discuss hinge wood and tree falling control further in my next article.

Therefore rather than focusing on what a notch is named or called, let us look at what we want the notch to do for us when falling trees. Whenever I ask students if they would like to learn techniques that would improve safety and control of falling trees they all raise their hands or nod their heads in agreement. I must say that I am speaking in this article about notches that specifically focus on maximizing safety and control. The notching technique I am speaking of in this article is not a typical production falling notching technique. The technique has many technical considerations that are necessary to allow other important aspects of the tree falling process to work better and longer, such as the hinge. This notching technique is not based on tradition and equipment limitations as it requires fallers to think and plan and not simply follow a cookie cutter routine.                                             

In order to improve safety and control when falling trees it is important to aim notches in the desired direction of fall and ensure that the completed notch opening or aperture should be of sufficient degrees to allow the hinge to provide control all the way to the ground. It is also important that the two cuts made to form the notch meet evenly and have no by-pass as this can encourage premature hinge failure. 

The following simple three-step notching plan can help anyone achieve consistent and repeatable notching results.

Step 1

Determine the angle formed by the trunk and the ground level; this angle should be the same as the angle or aperture of your notch opening. This will ensure that your hinge has every opportunity to work all the way to the ground giving a greater degree of control. Trees grow nearly perpendicular to level ground so often an opening of 70 to 90 degrees is common. However, trees growing on heavy slopes will always try to grow parallel to the force of gravity, this plant response is called geotropism, and in some cases the angle created by the trunk and the ground level is well over 100 degrees or well under 45 degrees.

Open Face Notch

Step 2

Stand beside the tree and behind your saw, with your chainsaw positioned to begin cutting the top cut of the notch aiming the sights in the direction you want to fall the tree. The felling sights are raised ridges, indentations or black lines and are located on the top and both sides of the saw body on most professional model chainsaws. Wherever these sights are pointing when cutting the notch should indicate the direction the tree should start to fall. (NOTE: many factors dictate where a tree will fall and an aimed notch does not guarantee the tree will fall in that direction.)

Line up your felling sights

Step 3

Make the top cut first, and then the bottom cut of the notch. By doing this you can use the kerf created as a window to know when to stop cutting when making the final cut in order to avoid by-pass or mismatching. It is important to have even alignment where the top and bottom cut meet.

Make your top cut first

Following these three simple steps can improve your safety and control when felling trees.  As often is the case with working with trees, chainsaws and gravity, there is no substitute for hands on practice, coaching, training and education. I always encourage people to attend hands on courses and attend seminars – after all education is a journey. It is my intention to stimulate thought with this article and get fallers to think about why they make the particular notches they make, where the techniques originated and why it developed. I have never seen one tree the same as another so why should we use a notching technique that is the same for every tree. In most cases it makes sense that techniques evolve that are similar and have common trends and that is a good thing.  Just remember that repetitive complacency is a silent killer. Avoid mindless routine, challenge yourself daily to think through your work and make adjustments regularly even though they may seem minor. This engages your mind and stimulates learning.

In closing I want to tell you the name of this notching technique; it is called ‘the open face notch’, I think the name in this case says a lot, ‘open face, open mind’.

In my next article I will explain how the back-cut and hinge work together with the notch.