Some designs work

I was thinking about the treeMOTION after what I wrote the other day about colour coding.

I am always amazed by the number of treeMOTIONs I see when I am at a tree care event. It would appear that back when we were working on the harness design we got certain things right. Of course, when you are involved in such a project, you believe in what you are doing – or else you would have to ask yourself the question why exactly you were doing it – , yet ultimately it is the market and the end user that do the final validation of a concept.

Having said that, back in 2008 when we launched the harness, I would have never thought it would stand the test of time so well. Looking at it today, it remains a highly functional, well-adapted piece of kit that does what it is supposed to do really well. Admittedly not for every shape and size of body, but still a surprising number of people buy into the design philosophy behind the treeMOTION.

The other thing I was expecting was for it to be copied wholesale in a matter of a couple of years. Here again, that has not been the case. Maybe certain aspects were taken on board by other manufacturers, but that is a normal process where the way pieces of equipment are designed co-evolves in sync – until someone comes along and does something radically different.

The philosophy behind the features that make the treeMOTION distinctively different have proven to be well suited to tree work: the load distribution, easy customization, the front hardware configuration, replaceable wear parts or the colour coding.

As I said above, ultimately it is the people out there using the harness for their daily work who validate a concept, so I would like to take the opportunity to send out a big thank you to everybody who over the years has climbed a treeMOTION.

First workshop day in Japan

A decidedly fraught journey to Japan yesterday left me feeling rather shaky prior to the first workshop day with KEM Japan today.

Once we got started, however, everything came together: the group was really motivated, switched on and keen, Takashi Osaka as usual did a fantastic job of translating and Paul Poynter mucked in too and helped seeing the thing moving. The Forest Park in Satiama is stunning, calming and moving – all at the same time.

One of the things I like here is that it is such an easy place to be respectful and p0lite in, as everyone else is too. Apart from that, lots of things about Japan remind me of Switzerland… it is also a society where many people are sharing little space together, hence a high degree of cooperation and oranisation. Yet it is decidedly not Switzerland.

Tomorrow we travel onwards to Nagano, I am excited as I have never been to the west coast – well, or that direction at least.

 

Making it intuitive

I have been renewing all our company’s rigging gear and have been thinking the past few days about how we make things intuitive and encourage good configuration decisions.

Colour coding is one obvious possibility that springs to mind.

After having just finished James Garvey’s The Persuaders, a highly recommended read, which will leave you rather worried and more than a little paranoid in regards to which choices are truly yours, I realize that the use of colour to indicate good or bad practice can represent a powerful nudge.

EN 1492-2, the European standard for round slings foresees a colour coding scheme for round slings that corresponds with minimum breaking strengths.

This makes a lot of sense, as it creates a high degree of clarity for the end user, removing the ambiguity resulting from lost, damaged or removed labels.

We used colour coding for the treeMOTION – admittedly not exactly at a rocket science level – green for go (i.e. PPE attachment points) – red for no (non-PPE, gear storage points).

DMM used the EN 1492-2 colour coding for the sheaves on their Impact Blocks… green on the IMB-S indicating the 200kN MBS, yellow on the IBM-L indicating its chunky 300kN MBS.

This would appear to me to be one appropriate means to introduce checks and balances into the harsh environment (for gear) that we work in at an intuitive level, by doing so encouraging good choices.

I suppose alternatively we could also start popping Post Its on everything… not sure that concept will fly, though. It would look funny, mind you…

Heading off to Japan

All packed up, ready to take off to Japan tomorrow to do a couple of workshops and events with KEM Japan. I missed going last year, so I am really happy that this all came together. A bit thank you to KEM for making this trip possible.

I will put up some pics as we go along, this time we will be in Saitama and Nagano. Looking forwards to spending a bit of time with old friends and meeting new folk.

Why am I banging on about balancers anyway?

Why have I spent the past few day relentlessly banging on about balancers, you may ask yourselves. Fair question.

It is by far not as though this is the only rigging technique we use, on the contrary, it is but one such method in a broad range of techniques we may chose to employ on a daily basis. Yet I found the process of selecting one specific configuration out of this palette and really thinking it through thoroughly highly interesting. It allowed me to gain a number of insights I was not expecting, apart from a better understanding of the ones I was expecting. So for instance I was surprised by how a relatively small change in weight at the outer extremity of the limb makes a really significant difference to the location of the centre of gravity, as this is not something you usually measure and are therefore unable to quantify.

An interesting aspect of using balancers is that this technique gives you instant feedback whether you got it right – or not. If you are snatching sections of stem into a block below the mass, the only feedback you get when you get it wrong is failure of a rigging element. With balancers you get a more incremental feedback, if you have judged the centre of gravity correctly, the limb will hang in position nicely, however, if have misjudged it, it will tip or roll over. This feedback allows for a higher degree of verification and an improved learning effect. It is not as though this were not possible with other techniques if your senses are tuned to the feedback you are getting, rather it is simply that in this case the feedback is very apparent.

So there you go: Balancers are without a doubt a handy item to add to your toolbox, that depending upon the situation, may be the perfect technique to use, not only in a static fashion, but also in a dynamically when you need to hold a limb in orientation and simultaneously move it away from an obstacle or hazard in a controlled, rapid manner.

For a more complete review of rigging configurations I would once more refer you to the HSE/FC rigging research document, a sadly under-referenced and under-recognised body of research that in my opinion to this day remains the definitive benchmark when discussing any form of rigging in arboriculture.

Balancers 4/4

And finally…

Using the balancer techniques may not be as easy as drawing by numbers, but once one has understood certain basic principles it is not as complicated as all that.

And that, as they say, was that.

Originally, I was going to do a scratch and sniff contribution to the reader, I love the idea of using good smells to indicate good configurations and malodorous whiffs the bad, but in the end I ran out of steam. So next best was drawing by numbers. Now, what I want you all to do is to get an Edding or a Sharpie and join the dots on your computer screen… then: BIIIIG SURPRISE when you see what comes out in the end!

(Please don’t forget to send me a selfie of yourself and your computer screen so that I can check whether you got it right)

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Balancers 3/4

Moving on… let’s have a think about other ways you might use a balancer:

(Comic man says) OK, I get it: balancers are static, have an overhead anchor point and are held in position.

In principle yes, but you could differentiate further. Up to now we have discussed static balancers, yet this is not the only way they can be used, balancers can also be used in a dynamic fashion, for example to move a limb such as in the image top right away from the building.

The yellow boxes discuss the angle of attachment to the limb: for the most efficient bending moment acting on the limb, for instance when lifting it, the line shall be attached at a right angle in relation to the axis of the limb, this allows for the most efficient lifting. Applying this to dynamic balancers, the length of the yellow spider leg needs to be considered so as not to decrease the high part of the balancer and by doing so making the pull towards the rigging anchor point less efficient.

During the move from left to right the limb moves through three distinct phases: during phase one, the two  upper spider legs are acting like a pulling line. In phase two the rig is acting as a rigging system, preventing the limb falling to the ground – and finally, in phase three, the rig ends its movement in equilibrium and is now acting as a balancer (obviously, for this kind of rigging you need some form of winch integrated into your lowering device).

What is important in this kind of rigging is that the entire movement needs to be anticipated to guarantee sufficient space and so that the limb does not get hung up. The orientation and size of cuts needs to be adapted to the required movement. And finally, the team’s level of competence and experience shall correspond to the level of complexity of the techniques being employed to perform the work.

Check back tomorrow for the final installation of the balancer saga…

Balancers 2/4

Moving on from yesterday’s post, here is the second part of the balancer spiel… again, translation below (by the end of this you are all going to be fluent in German).

(Comic man says) In theory, of course, you could hold a piece in balance by attaching it to one point exactly at the centre of gravity.

This is true – only, not every structure has an attachment point available at the centre of gravity. In such an instance we use multiple spider leg balancers to hold a limb in its orientation.

The example in the illustration uses Blake’s Hitches at the high point to attach the spider legs (the attachment point is positioned over the centre of gravity) and two secured clove hitches to tie onto the structure, the third leg is secured via a webbing sling, a karabiner and a Prusik, making the length of the leg easily adjustable.

Where the centre of gravity lies is decided by many factors, such as species, density of the wood, time of year or the shape and structure. As a tendency though in branching structures the centre of gravity will often lie considerably further forwards than one might assume. The reason for this being the weight of the water in the periphery of the canopy, i.e. the end of the limb.

Hence, if you assume that the centre of gravity is roughly in the middle of the limb, as you have the weight of the wood on one side vs. the weight of the foliage on the other, this will often result in a rotating, tipping motion once the limb is cut, as in actual fact the attachment point lies too far back in relation to the centre of gravity.

The treemagineers balancer drip feed continues tomorrow…

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Balancers 1/4

At Climbers’ Forum I did a piece on the thought process regarding the attachment of limbs in balance. For the reader accompanying the event I did a infographic-style comic, see below… in German. Initially I thought I would translate it, but ran out of steam, so for translation below the image.

Just Rig A Balancer – That can’t be that hard (or can it?)

Reasons for keeping and rigging limbs in balance

  • No sudden changes in orientation of the mass that could result in shock-loading of anchor points
  • No sudden movement of the limb that could endanger the person in the canopy
  • As the piece is held in position, steps backwards are possible should initial plan A not work out

(Comic man says) OK, I get that, but how exactly do I do achieve all this?

There are various ways to establish a balancer

Fixed, made-for-purpose two-point balancer (in the example here using karabiners and a Prusik). OR… multiple-point spider leg balancer. This version allows you to rig as many spider leg elements as required. The long eye splice allows installation via Prusik, attachment to limb via a secured clove hitch to prevent roll out.

(Comic man says) Huh? Karabiners? In rigging? I thought that was a no-go.

In this specific application, with an anchor point above the mass, no dynamic component and forces acting in a defined direction on the connectors, using karabiners can make sense (the two boxes contrasting static overhead rigging vs. dynamic rigging with anchor point below the mass).

When rigging a limb the angle between the legs of the balancer is important. The more open this is, the more accurately the attachment point of the spider legs has to be positioned over the centre of gravity, therefore a wide angle increases the loads on the attachment points of the balancer and makes the rig less stable. Decrease the angle between the legs, however, and you have more tolerance regarding placement over the centre of gravity. There is a sweet spot between this angle and the amount of space available between the attachment point and the rigging anchor point required to perform the movement you have planned.

(Comic man says) Right, I get that now. So when do I use this technique?

Horizontal limbs with suitable anchor points above lend themselves to this technique, which can be combined with load transfer techniques. The use of balancers shall be incorporated into the rigging strategy adapted specifically to the requirements of each tree.

There you go… more tomorrow.

 

Looking back

This weekend I started looking back over the last few days, sorting through the many impressions and thoughts that accumulate around such an intense period. This will take some time…

I was really glad that, for me at least, the balancer presentation worked out well. This was a new format using some interesting elements to illustrate the thought process behind rigging limbs in equilibrium. It was quite ambitious to fit it all into 45 minutes, but in the end I stripped the content down quite a bit in order to make it more user-friendly, with the help of Vicki, Puk and Chris it all ran smoothly.

One of the things I always enjoy about working on new formats is how it brings with it realisations you were not expecting – the same was true here. It reminded me of working with Andreas Detter on vector forces, since then during rigging operations I imagine vector force arrows acting on the anchor points in the tree. Likewise, I suspect that after the balancer demo I will envisage centre of gravity symbols all over the place.

Thanks to Oscar McBurney for the photos and video footage.