Angus

I like climbing with as many tricks in my bag as possible, because I like being groundie when a climber isn't limited to one style.

The compass bearings of the three highpoints are fixed, and as you've correctly pointed out, the vertical angles will be ever changing. We only need to address this change at the point of cut - so we have a device that is sat on each rope and tells us the inside angle. These three angles + the weight of the log we are cutting are fed into the program which then specifies what the exact tensions need to be. I'm hoping to release the program at the same time I release the video of the system in action. When I wrote the program I did write a test GUI for the calculation class. There are a few boxes which pop up with horizontal forces, vertical forces etc. but this will eventually be integrated into a 3D model of the parameters entered. With this ability you'll be able to specify limits on your anchors. This will be particularly helpful for ground anchors. Thats what the class tester looks like, I don't think you could even call the application in alpha stage at the moment. If you use Google Sketchup (free), you can take a look the Trivect 3D model I gave the example earlier that you've got one high point, but no opposing highpoint(s), Trivect would allow you to have two ground points. In the picture, the ropes run down to the ground at -34o and -30o, our highpoint is 60o to the point of attachment on the log. The two ground points are separated by just 25o. Our log is going to weight 600kg when we cut it. We can see that that tensions of each line are quite high compared to the load. There are still a few bugs, and there are certain conditions that make the program do back-flips. I've added a few constraints to the basic formula to help the program stick within reality.

Thats the thing - when I asked him about it, he said ArborAge was the only one he knew of. The journal of arboriculture didn't accept it... I completely understand, and as I said above, lowering with two ropes isn't something new. I guess I am trying to address this fixation with using two GRCS's... The job we derived opposing pendulums for was about control and efficiency. We keep talking about how the GRCS could've been used, but I can't seem to get an acknowledgement that it doesn't improve both control and efficiency. If there is a disagreement with that, then there's a fundamental misunderstanding as to why one would use opposing pendulums. On that note, the job we've created the triple point lowering system we need the same level of control and efficiency - but we can't find two opposing highpoints... But we can find three! I'll do a second post with a picture.

Removing the dynometer would defeat the whole purpose of the system... You probably could do what you suggested, but there are plenty of other systems that have an equivalent level of control of your suggestion but would allow a much faster work rate. Reg has an excellent example of a dynamic system for lowering timber sections using his twin rope lowering device. [ame=http://www.youtube.com/watch?v=aiqK8z_4GyM]YouTube - Video for Angus[/ame] Opposing pendulums is for absolute and complete control where everything must be as static as possible.

I still get a buzz out of chatting to people on the other side of the world! In southern parts of Australia, things that bite are not as prolific as they are up north. We do come across snakes and bitey insects fairly often during a week, but working up in the tropics is where most of the nastys are.

I feel your pain. During the fire cleanup we had someone break into one of our excavators on a weekend and steal over 20 cubic meters of split firewood that was supposed to go back to the community. Bastards. Up on Mt Dandenong, the competition for good wood will actually have residents physically fighting over who gets wood. Before you've even finished the job, they'll be backing everything from lawn mowers to bobcats up to the job to make sure they get it first.

Who would I be to pass judgement - I'm still on my climbing learner plates! I can only speak for my small pond, but there does seem to be a growing tendency amongst climbers coming from arboriculture courses to overcomplicate simple jobs with advanced rigging and access techniques. That could be a whole other thread... Practical and academic pursuits meet in an unusual mix in the tree industry. So far as I can tell, there has always been a need for professional tree workers which can safely adapt a variety of techniques to remove tree's in a safe manner. The rigging we're talking about addresses a very specific set of job conditions, where absolute control is the highest priority. I think we must have some sort of scottish roots with names like Angus, Keely, Allister and Lachlan! Irish too... (Don't judge me for it)

I'd always wondered how he seemed to get so much helmet cam footage without tape changes....

Yes is the short answer. We need new techniques and tools to work in some of our sites, and that is a motivator for developing them. This motivation applies to our whole industry! The tools available to tree workers has been snow-balling for the last few years. The effort required to develop a triple point lowering system hasn't been required by us until now. Since creating this system, I can see the day-to-day benefits it may give us. The preconditions are a lot more flexible than opposing pendulums, and it will be interesting to see how the system fairs in the real world.

I've gotta do something about the helmet cam situation. The footage from that looks great, and regardless of discount - now I know where to get the camera from! I don't know what camera Reg uses, but it comes up well too. AA batteries is probably the best thing they could do for the product... No more running out of power 2 hours from the nearest 240v wall plug!

Dad still talks about his 2002 ISA adventures with you rb! In regards to the GRCS, you've summed it up quite concisely rb, but this isn't the first time we've been asked about using a lowering/winching device instead of two separate devices - So I'll have a crack at going through it... I actually gave Graeme a shout about this GRCS thing... he's down at the holiday house, having a fair crack at the prawn population. Damn him. Graeme acknowledged that the GRCS, had it been invented (not that capstan winches are a new thing...), could have been manipulated and adapted the the job. However it would be an inappropriate use of tools available, and the advantages trivial. I've shortened down a few of the key points he had. In Australia, the GRCS is a $4000 lowering device. For one. The 3/4ton winches were $700. For both. The GRCS is NOT an inline friction device, and is not designed to be loaded sideways. At some point before you lower, you must remove the dyno from the system. 1. If you are using a GRCS correctly - your rope will be above you, rather than sideways to a pulley (see top-view diagram in the article). 2. If you are using the GRCS as a winch - you'll need to transfer to another mechanism in order to drop the tension enough to remove the dyno. Add more money for another "mechanism" + the fact that the dual purpose device has now become a single purpose device. The steps required in this system to: 1. Attach Dyno 2. Tension 3. Lower Are not decreased by the use of a GRCS, in fact they are increased. Worse still, the device that ideally tensions AND lowers can only do one function, at ten times the price! FWIW, we used 'goldtails' as our friction device. Perhaps if I've misunderstood the application of the GRCS that was being proposed? Do you remember which publication it was? We've just got another job in the same place, but this time we have no practical highpoints that are within ~180o of each other. (a critical precondition to opposing pendulums.) As part of the solution we've taken opposing pendulums to the next level. A few weeks ago I derived the formula for a triple point lowering system. I've written and tested the formula AND program, and we're now eagerly waiting to test it out on the job. The applications of the triple point lowering system are very exciting - far beyond this one job. For example, any job where there are is at least ONE high point can use the program. (The other two can be on the ground, to a car, etc.) This would give crane level accuracy for significantly less cost. The highpoints can be at any angle from each other. The formula can tell you how much tension is on each line, and each highpoint. I've written the program as a graphical windows application, but I'll probably code it for a mobile phone fairly soon. We'll hopefully have a video of the system in action some time in 2010.

In Brisbane the palms are like weeds - 'Palm Slayer' Eric Frei at TreeWorld would have a few idea's on handling the buggers of things... I hope to never come across one - they sound nightmarish!

So, so true. We've had a lot of oversea's workers come and work with us as part of their travels. Most of them have been fantastic, but the thing that annoys me the most is people talking themselves up, and then being incapable of doing the walking. Just be honest about your abilities and a good safe work ethic - you'll have a job!

Darn good quality video for a helmet camera - Can you get more batteries for it?

Fantastic video Mark and Rocco! Looking forward to the next one.

Out of interest, how would that work?

This device looks sick! If you have a moment sometime, I loved to know more. If there is some broucher or something that answers my questions, don't hesitate in redirecting me! Could you run 19mm tri-braid on the double drum Reg? If not, what is the largest rope you've run on it? Do you find its bend radius satisfactory? In a situation where a branch gets hung up on the way down, what stops a stiffer rope from rolling off the end of the drum? Is there a front catch? (I may need to clarify that more...) Can the device it be side-loaded? Or does it need to be placed below the lowering point/re-direct? Is the tension arm hard on ropes? Is the tension mechanism similar to an ascender? How is the drum attached to the back of the device? What is this rated to? What length are the drums? Do the drums handle heat well, or can you place ice packs inside them? What is the surface of the drum like? Where can I find more photos? Thanks, keep up the great work!

Hi Reg, Congratulations on an amazing job - You've got some incredible videos, and this one is no exception! The quality of your rigging, and the variety of techniques you have at your disposal is mind boggling. Please keep them coming, and keep up the high standard of work you do. I have many questions! In the speedline setup, how were you retrieving the line after each piece was lowered? I've got to read up on your twin-rope lowering device, but how hard is it for one person to lower both ropes at the same rate? Can wraps be safely dropped from one or both drums while loaded? How and where are you storing the sheer volume of footage you are gathering? Your helmet cam footage must pile up by the end of the day. Who manages your cameras on the ground? Do these cameras film constantly? Are you editing the videos yourself? (Good clean edits), what are you editing the videos in? Thanks again

The link the the youtube version... [ame]http://au.youtube.com/watch?v=Y6hEfav9ZwI[/ame]

Hey Rob! It was great finally meeting you I've youtubed all the videos, and will eventually be removing old links. Here are the new ones. [ame]http://au.youtube.com/watch?v=gFyVJFIohkI[/ame] [ame]http://au.youtube.com/watch?v=3v8DIF02bDo[/ame]

Depends greatly what part of the world your in as to what saw is cheap and has easily available parts. Talk to your local shop and see firstly what they sell the most of (this will be an indication of what second hand saws and parts will be around). If it's not business critical, you may be able to afford waiting on shipping etc, in which case have a look around at what parts you expect to replace and the respective costs. Hopefully that helps.

Yep Stihl 044, Climbing saw to ground saw to learner saw. new in 1987, stihl working.

Reg without quoting your entire message, I couldn't agree anymore with your comments in post #40. Well said. Proper risk assessments which in turn justifies safe solutions to complex problems, is what rule book makers should be concerning themselves with. Too often the focus seems to be on doing things only by methods in the rule book. You appear to be a smooth and methodical problem solver, an admirable attribute for a climber. Congratulations and great work to yourself and crew. Regards Angus

Cheers. No problem Steve, it's only fair, particularly given the amount of traffic that the site receives from Arbtalk redirects.

Don't look at the site too hard lol... it's a bit of a cluster at the moment. In the process of all kinds of modifications. "Scotty" the winch was one of the early model winches, there are quite a few newer models which can ascend faster. Having been beamed by Scotty a few times, I am acutely aware that you can only really ascend as fast as you can negotiate limbs, bark and other anti-ascent obstacles. In short, aside for going up the skyscrapers, a faster winch in the arboriculture sense would be mostly pointless.