Badgerado

Just got a couple new Stihl fs85 trimmers and noticed the new model has a different fuel cap, (thread is on the out instead of in) they're really hard to get on and off (it's got the feeling of being misthreaded), we thought they might loosen up over time but it's been 2 months now and they're even worse, if you don't tighten them up ridiculously hard they can leak (and yes I know not to force threads lol)

SHERRILLtree | BackBone Knotless Rigging Connector

This has a few more applications, I'm leaning towards the other system basically being instead of a carabiner.. Thanks for sharing, I'm always interested in new solutions

I personally drop or rig the tree depending on the situation, one thing I do use for larger or awkward cut and hold's is metre long rigging slings which not only allow me to avoid using snap cuts instead letting the branch tear and take the weight, it also allows me to keep a better grip than if I were holding the branch (espescially if it want's to twist), I can get more swing for tossing it aswell, and if the tree is smaller i can hand limbs directly to the groundy if need be.. keeps my arms away from the saw too (I know it's not standard practice to use the saw one handed)

I keep them bunched up in a rock climbers chalk bag.

I personally like the weight of steel biners, I even have them on my flipline's cause I find it easier to flip them round the tree..

I've been on sites where aluminium has been used for rigging and unless it's really lightweight stuff it makes me nervous..

If you do decide to use aluminium I'd say make sure you inspect it all the time and avoid side loading.

You can see, just about, that there is a large rigging ring set up to the right of the tree. A 2:1 was created (double whip tackle) to be hauled by the Smart Winch, into an adjacent tree. The splayed out branches were pre-rigged and cut to hang off the rigging ring so that the tree could be lowered into a much smaller drop zone than the initial size of the canopy.

Sweet, thanks for the reply, I only got shown that 'double whip tackle' technique last year, really cool how it works and now I know the name lol, I'm always keen to learn something new, there's so many ways you can work a tree.. Some techniques you learn and then wonder how you did it before that

And I'm glad it's not just me who can't see the logic in cutting out from the collar when lifting..

Thanks again for your reply Wooden Hand 😊

Okay so what I was actually meaning to ask is; what (if any) is the advantage of cutting a scarf away from the collar when lifting a branch vertically with GCRS?

Apologies for the confusing rambling post

I don't quite understand this last bit?

 

In reference to the rest...I don't have as much crane experience as the likes of some on here, but I don't personally think i'd use a gob on that cut, more likely a thick step cut leaving a ledge to keep it swinging back into the trunk.....but more likely would just attempt to balance the limb and have it lifted away from me

Sorry my diagram wasn't explained well, I'm talking about lifting that branch right up to vertical, imagine a house underneath and where balancing would still make it hard to lower into a small landing zone, GCRS is winching it up to a central anchor point.. (see below)

Balancing limbs is one way to do crane work but if not using spider legs etc.. The same thing can be achieved by lifting the limb straight up so the limb is balanced when it is released, obviously operator pulls it slightly away and up.. Advantage of this is that it is a quick setup and mainly no possibility of misjudging weight which can cause the branch to swing etc.. disadvantage is the time taken to winch it up.

Sorry about the confusion, the diagram was focused on the use of GCRS, just that I have used the similar technique with a crane.. (No scarf though)

(B) is explaining what I meant by altering the balance/weight distribution

Thanks for your reply Steve 😊

I'll leave my climbing line at the last cut come down and make the gob. The climbing line is easily retrieved by pulling the tail and I now only have one back cut to put in near both lines.

That's good procedure for both above, I'd say the scarfs angled cut would be the one where people cut their rope, you'd need to be a naf to cut them both on a back cut aye

Thanks for sharing Bumble B

I'd like to hear from people about the placement of the scarf when lifting a limb using a crane or GCRS.. I have attached a diagram showing the 3 methods I have seen used.

Personally I prefer to cut at the collar as the branch attachment has stronger wood (crossing fibres), also you are positioned closer to the trunk when cutting allowing for a faster 'escape' if the limb were to twist or break off whilst cutting.. When using a crane or if the limb will end vertically I often won't use a scarf, instead letting the holding wood tear off or cutting through to release.. The advantage of this in my opinion is more holding wood, and a smoother release when using a crane, the disadvantage is that you may still be cutting when the limb releases.. The hinge wood on a scarf can provide a 'ledge' which can stop the limb swinging back..

I think we can probably all agree slow cutting and reading the wood is the key to any lifting..

If the limbs anchor point is lower and the butt is intended to swing back try to be on the other side of stem to the weight and not be hidden when it is being raised.

A useful technique to balance/distribute weight better is to drop the end of the limb on to itself before lifting the branch.

You could cross over your side strop which acts as a choker. and helps with stability on thin stems. I generally use a Hitchhiker so my line would be choked against the stem so no real worry about that flipping. I tie in above the rigging point because that's the way I was taught due to all the business that goes on below the block. If you are worried about the block slipping you could always cut a recess in the back of the stem.

Good call to extra wrap on thin stems

Again both lines above has disadvantage of increased hazard of cutting both lines.. And if seperated too much it creates a larger shockload..

Yeh agreed if set correctly it shouldn't slip but it's something to keep in mind, specially if your putting your line between block and sling (wouldn't have to move much) notch on the stem is usually my solution if I'm worried..

Rope guide then, gotcha.. Thought he was talking about a classic cambium saver (two rings)

First of all congrats on the X-rigging ring, great invention!

The THT is a very interesting piece of kit, can someone explain to me what the benefits of having adjustable friction like this over a block is, (does it reduce pressure on rigging point?) (could see using it with inexperienced groundy) was a bit concerned about how the rope runs on the inside too but I guess you'd just put both lines above..

Again congrats on the innovative thinking 😊

If i feel like doing everything "properly" I have lanyard just above the blocks whoopee sling, and a pulleysaver choked tight to the stem precisely under the whoopee sling.

That way when the blocks loaded its only the whoopee sling pinching the cambium saver, can still decent if needed whilst the riggings loaded and lanyard and life line are not at risk of getting cut at the same time

"Properly"? Can you clarify, you use a cambium saver when chogging off? Is it somehow chocked off to the stem? Also as mentioned above you should be aware of the rigging slipping down on smooth barked trees..

Interesting discussion. I think there are sure advantages to both methods.

 

Above- eliminate the danger of block slipping and taking your primary climbing line with it. Also prevent damage to climbing line from pinching/running rope etc.

Below- Minimise risk of cutting both lanyard and primary climbing line at once.. in order to leave enough of a space between lanyard and climb line this could increase shock load due to greater distance the work will fall.

 

In the situation of intense stem shake I agree with the above comment by wooden hand. Some possible ways of reducing the likelyhood of this occurring could include leaving lower branches to dampen vibrations, letting rigging rope run or simply cutting smaller sections.

 

I have heard of respected arborists putting the climbing line just below the sling and above where the block sits. I guess if you get your sling choked up tight to the stem this will minimise the risk of the rigging slipping down. However on a smooth barked tree I for one would not be willing to take the chance.

 

In my opinion this issue is not clear cut and worthy of debate. Having read the comments above it would seem like the current industry practise in the UK is to have both above? Are there any NPTC or LANTRA assessors here that could clarify? Thanks!

Thanks for your reply, a very comprehensive listing of advantages and disadvantages and while I don't think either way is right or wrong we should all remember that there are variations e.g. Smooth bark as mentioned, and be mindful of the disadvantages of the chosen technique..

Quite a well put together video, each to their own however definitely not a recommended practice so it's an odd job to have as the promo video. Perhaps it looks more efficient to customers and they weren't worried about what other arborists would say.. The tree is solid and the scarfs aren't terribly deep, but like someone else pointed out hidden defects could still make this potentially hazardous.. Wouldn't do it myself or lower for him but each to their own and the tree came down and everyone went home that day..

Great terror tale from Matty.. All actions have consequence

I was taught in college below years ago with the idea being on a violent snatch you could get flicked off the stem , in 20 years I've never burnt a rope or pinched one in a topping strop/rigging block so will Continue to do it this way although I did do it above in a nptc refresher last week when the examiner asked to see another snatch I knew immediately why. I also like the idea of my ropes being further away from the block whilst cutting.

The violent snatch was the same reason I was taught, but now it seems the concern has gone to the shockload of dropping if your lanyard fails (im assuming through the violent snatch or cutting through it) the latter being dangerous in my eyes as your climbing line sits at practically the same level (unless your cutting higher above your block which is more likely to cause a violent snatch lol). Not going back to school anytime soon but I'm always keen to stay up with the standards . Thanks for your post

The standard paractise ISNT either, theres a right and a wrong way. Below is wrong, and above is right, for fairly obvious reasons I would have thought.

 

 

 

 

 

Its a total no brainer hehe....

;-)

Hmm must've changed since I went to arb school in NZ 9 years ago, thanks for the update reasons that might seem obvious are countered by other arguments (see Matty f's reply) lot's of standards in the industry change or are different in different countries, thanks for your contribution

Ha ha

 

A handful of posts in and you go on the offensive against one of the forums senior and respected contributors.

 

Take a chill pill dude, you might not like the answer you get but what you get is what you get

I wasn't on an offensive, or trying to be offensive in any way, But I will be more careful with my responses in the future, obviously there's some sensitive people on here that take offense very easily..

Above, it's a no brainier .

Why bother responding then? If you read the post I was asking for people to discuss pros and cons and industry standards not just say "yeh same here" OP is a dumass, not really very productive dude. Would've been interested to hear from you as to why it's a no brainer.

I place both above the block, once you have a piece hanging from the block you could feasibly damage your climb line through friction from the rigging line. Or the rigging line could pinch your climb line to the tree making any further movement impossible. Place the block low enough to ensure you aren't in danger of your tie ins coming off, but high enough so as to minimise the drop of the piece.

Interesting, I can certainly see your point

I realise the standard practice is varied for this, but when snatching down pieces I put my lanyard above the block and my climbing line choked off at about knee height.. (If the block slips that much then you've tied it wrong or the piece is far too large and should have snapped your rope) I understand it is now taught to have both lines above the block (to reduce any drop you would get if your lanyard either flips off or is cut) I think this is more of a climber preference but would like to get some different views on pros and cons.. And esp. Industry standards, I believe they are currently changing it in the U.S. where choking off the climbing line wasn't in good practice before.

the first thing all trainee climbers should learn is how to dismantle a tree with just a single rope for rigging, that includes vertical sections

 

it's the best way to understand how friction is the most important part of the rigging system

LOL and a three strand prussik loop to climb on

there's no great science to where you tie the half hitch despite what you read in this thread

 

basically you place it high enough to stop it rolling off the butt-end of the timber as the section inverts and is caught by the rigging

 

the relative distances between the block, cut and half hitch is not as important as some people think, the 3 critical positions will nearly always fall within safe parameters mainly due to the work position of the climber ie the climber is not going to tie the block 6ft below the cut or tie the half hitch 6ft above the cut because to do so would be very time consuming and pretty damn stupid. The main thing is you tie the half hitch and running bowline well so they dont fail when the timber is rigged.

 

on the science being discussed in this thread, someone could research then write up a 40,000 word thesis on half hitch placement when rigging down a tree trunk. This research however would not be able to give a definative answer on the optimum position of the half hitch because we're working with non uniform objects, large organic structures of infinite variety and structural strength.

 

 

 

 

 

.

Thanks for your reply,

I understand what your saying with worker positioning but if you cut an extra foot above the block you would be adding an extra 2ft of shockloading, safety factors in my mind are to be adhered to i.e. Guestimating weights in your rigging system, 10:1 is used to give a little bit of leeway but if you start shockloading ropes past that then the life of that rope is reduced dramatically (stress turns into strain)

Also your right about variations due to natures different forms and weights, cuts etc.. Some of those are really only able to be judged or guessed by experience/intuition, but I think the more we understand the basic physics involved the better we can be at understanding our rigging systems

Its quite sad that our industry training falls flat at the first hurdle, one of our industries veterans and i were talking about this just the other day. Training courses teaching people this, actually quite basic, level of understanding are few and far between with cs 41 falling WAAAAY short. Even when 10's of thousands of pounds are spent on producing & peer reviewing rr668 you have people on AT disagreeing with its findings, sigh. I really feel for the students and professionals that come on AT to help further their understanding having to try and decipher who's posts are correct.

 

Id love to post a load of green-screen annotated photos from my training literature to help illustrate and explain these forces. A great amount of time and resources that went into producing them and my clients have paid accordingly to benefit from them and would quite rightly feel pretty miffed if I plastered the original literature up here for all to access for free.

 

Hopefully the new guide to good rigging practice will illustrate the theory well enough for all 'on the ground' to understand that the forces DO NOT increase relative to the attachment point unless that attachment point causes the centroid to fall further.

 

Length of active & semi-active rope, recovery time between sections, holding power of the hinge, absorption properties of the rope & anchor, wind resistance of the section etc are all factors but the most basic to understand and most important to quantify is the distance of the fall (that means distance of the CENTROID'S fall) we can reduce this in a number of ways:

 

1 tie the impact block as high (close to the cut) as possible

2 place the attachment point no higher than the centroid

3 cut shorter sections

4 take as much slack out of the system as possible without significantly loading the rope/s (never pre tension lines that will then be dynamically loaded as the split second in which they become unloaded does not allow the rope sufficient time to recover!!!)

 

as we work down the stem everything starts to work against us, the active rope is less, the sections become wider making it harder to reduce them in length for fear of the AP slipping off and we have less distance to 'let it run'

 

A few years ago i was discussing with Chris Cowell the potential for 'more dynamic' ropes (more dynamic ropes than we currently use in arb) to absorb the forces when snatching, he scowled and said he believed that instead of looking for bigger, stronger/ more dynamic ropes to solve this problem we should look to other solutions, crash matts, cranes, air bags maybe? that way we can eliminate the need to 'torture' (as he put it) our ropes & rigging systems. It was a welcome angle but occasionally rope is the only/ most practical solution and with a good understanding of the physics we can rig more productively, safely.

 

The age old rule of thumb of original mass x distance of fall (OF CENTROID) in ft + the original mass was found in rr668 to be pretty bob on as field calculations go, this is the start point, until we understand this we're fish out of water and when we do get it we're in the water but not yet swimming.

 

if you've read this far then thanks for taking the time to read my poorly constructed, rushed response (typed rapidly whilst i should be working) better get back to some paid work now, peace out xxx

Thanks for the in-depth reply Mike Interesting like you say that such a fundamental of our work can have different teachings throughout the industry.. I certainly wasn't trying to mislead anyone here on Arbtalk, I guess I'm wrong, still trying to work out why it felt so different though, he was definitely tying it below the centroid.. Anyway thanks for your time to respond to my thread

By the time we get on to dynamic rigging there are many layers of interaction.

 

1. Length of section - As has been stated, the centre of gravity determines the incoming force.

 

2. Rope type and length within the system - let us assume in your drawing that you are decelerating the cut section and stopping before ground impact. We have a broad spectrum of rope choice from fully steel like static to rock climbing dynamic. Most arborists in England use a polyester/polyester double braid though a more stretchy polyester/nylon is becoming known. In fact choice of sling type determines peak loading too. The cut section can depart the stem at different angles depending on the type of cut and wood type. Ordinarily it will project outwards keeping the rope at least moderately taught as it does so. Ground rigger interaction begins here. Do we choose to begin running the rope immediately or pausing? The outcome begins to be determined.

3. Position of half hitch - This is always the point in contention. The placement of it determines the final hanging position of the cut section, butt tie hangs vertically, balance point tie hangs horizontally and all angles in-between. Each angle will have a different peak load. I agree with Mike and Pete that lowering the half hitch toward the cut DOES NOT decrease peak loading. As long as it is tied beneath the centre of gravity the cut section falls EXACTLY THE SAME DISTANCE. The half hitch should never be allowed to slip of the bottom of the cut section.

 

4. Position of the block - The block should be tied as close to the cut as possible. This is where climbers misunderstand half hitch placement. It is the block placement that determines extra kinetic increase.

As an aside, climbing line and lanyard should be tied, with one choking the stem, above the block and sling.

 

5. Dynamic movement at the anchor points - different cuts will influence the play of hinge released induced dynamic movement, so to will the decision of the ground rigger. And of course lets look at the tree in question. A 2M wide 15M tall beech tree will react differently to a 30cm wide 20 M tall red pine.

 

6. Energy transference - Where do you want to move energy to? I think relaying on the trunk to dissipate energy as the cut section impacts it is highly suspect, hazardous even, I do not recommend it.

Thanks for the reply Wooden Hand, good call to point out how close to the block the cut is made..

I will be starting another thread regarding what you say about having both climbing line and lanyard above the block, In my mind it is ideal to have your lanyard (steel core) above the block and your chocked off climbing line nearer to your knees, allowing for downward movement of the topping strop is neccesary but so is distance between your lines in case of cutting or the possibility of flicking your line off (I know climbing line is chocked but still) hopefully you can follow that thread and give me your views on that