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deuce4
climber
Hobart, Australia
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Topic Author's Reply - Mar 21, 2017 - 11:40am PT
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Nice rig! And nice partner! I think that was soon after we had climbed the Zodiac? Great photo!
(Those things weighed about 20kg, didn't they?). Back to our roots!
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John Mac
Trad climber
Breckenridge, CO
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Mar 21, 2017 - 01:30pm PT
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A young Lydia... first woman to climb the big E without O2.
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'Pass the Pitons' Pete
Big Wall climber
like Ontario, Canada, eh?
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Mar 21, 2017 - 11:16pm PT
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Interesting point about the six-point suspension having the see-saw fulcrum point in the middle cuz of the two middle straps. Never thought of that but it makes intuitive sense.
Don't you make those buckles too low! I would far rather stand up to adjust the straps, than to sacrifice any "adjustability" for asymmetric hangs, especially when there are four lovely daisy clips in each strap for me to hang my stuff off of!
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deuce4
climber
Hobart, Australia
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Topic Author's Reply - Mar 22, 2017 - 07:47pm PT
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Down to 16 left at the Kickstarter discount!
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duncan
climber
London, UK
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Mar 24, 2017 - 03:10am PT
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THAT Lydia, a very nice partner who wasn't a punter at all, but neither of us had done many walls and we imagined ourselves first team to do the route who were not the usual Yosemite suspects.
That ledge was a heavy old thing, the D4 looks sweet!
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deuce4
climber
Hobart, Australia
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Topic Author's Reply - Mar 24, 2017 - 11:15pm PT
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Updated setup video here:
[Click to View YouTube Video]
NOTE: Steve Pearce of the The Tree Projects has found it easier to set up the end tubes first (making two big U's), then the long tubes. Initial testing on the ground confirms this, is likely another benefit of the unique D4 design (this wouldn't be possible with the block corners, as the corners would offer too much flex when setting up and would probably fall out of the joint, but the U's in this case are completely rigid and ready to accept the middle poles on the long side.) It is more important to ensure that the long tubes are all fully inserted with this method, but of course, getting to know any ledge by practicing, and ensuring that all joints are fully inserted is essential no matter what method of set-up--this is clear and easy with the D4 because the joints offer an audible "click" when fully inserted, and can easily be checked by pulling tubes slightly apart then letting them snap back for the "click", thanks to the shockcord.
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'Pass the Pitons' Pete
Big Wall climber
like Ontario, Canada, eh?
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Mar 25, 2017 - 11:08am PT
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All right then, buddy - let's see a video of Setup Method 2.
This is somewhat counter-intuitive to me, which makes it very interesting.
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deuce4
climber
Hobart, Australia
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Topic Author's Reply - Mar 25, 2017 - 03:26pm PT
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Here is the complete Kickstarter information as of March 26 (with 4 updates), as PDF (which has clickable links) and images, to openly document the ongoing design process of the current reinvention of the portaledge:
PDF: D4 Portaledge Kickstarter
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Woody the Beaver
Trad climber
Soldier, Idaho
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Mar 26, 2017 - 08:19am PT
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This thread is huge fun! How can I have lived this long without a portaledge?
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Moof
Big Wall climber
Orygun
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Mar 26, 2017 - 01:16pm PT
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Duece,
Early on you implied something other than 6061-t6. I have never been able to find small suppliers for 7075 tubing, did you get better luck, or figure something else out?
I'm looking to make a corner block ledge for personal use with your hybrid pole design for kicks (got to do something with all my corner blocks...).
Thanks!
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deuce4
climber
Hobart, Australia
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Topic Author's Reply - Mar 27, 2017 - 10:22am PT
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No, just using 6061-t6, really the ideal material for portaledges. 7075 would indeed be stronger, but not necessarily more rigid as hopefully explained in this thread. But the 6061-t6 is strong enough, and provides the rigidity with my redesign of the frame for the larger "full-size" ledge platform (reminds me, to have a party soon to load up one of my prototypes with six or seven people, then everyone jump up and down until something breaks--the obligatory "Everyman' test!).
As mentioned, i am playing with carbon fiber, but the frame itself is really only about 1/3 of the total portaledge weight, and though carbon would indeed lighten the ledge a couple pounds, the cost is still way too much. I also really don't think the carbon would be as durable in a big wall setting, but still, would like to make one or two for that key expedition to Jannu!
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Moof
Big Wall climber
Orygun
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Mar 27, 2017 - 03:06pm PT
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Thanks for the clarification John.
I overthought my carbon frame for sure, and threw away a large portion of my weight savings on excessive reinforcement. What is hard to discern until you start shelling out $100's for carbon tubes is that most of the poles are made almost entirely of unidirectional fibers with just a single outer layer of woven fabric mostly for aesthetics. Crush resistance is not great as a result, and I feared a sharp nubbin creating the start of failure. I also feared the corners crushing the ends if things torqued funny under load. I think your new invention is the clear way to go.
Using CF as the internal double butting on the sides probably is where the most bang for the buck of stiffness and weight savings, but would add absolutely zero to the look of your design. CF sadly has poorly controlled OD, and the ID tends to be right at size, so it becomes necessary to either sand the CF, or machine down the aluminum to make joints with acceptable clearance. I am really curious to see what you come up with, your string of recent ideas is innovating where I have dumbly assumed things were pretty well rung out.
One follow up on the now obsolete corner blocks. The A5 design always had the short end poles plug into the corner blocks that were permanently affixed to the the side poles rather than the other way around. I have always been perplexed by this choice. What is the wisdom of that choice? What bad stuff happens if the corner blocks were instead affixed to the end poles?
Thanks again!
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deuce4
climber
Hobart, Australia
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Topic Author's Reply - Mar 27, 2017 - 04:35pm PT
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Good point Moof. Might just be another carryover of the "old" way of doing things which was never really been re-thought (it does amaze me more and more, as I develop this new design, that the "old" way has been the status quo for the past 20 years with the main manufacturers, as everytime I actually use or make a new one, new and better ways pop up naturally!)
Anyhow, probably the reason I made it a right angle corner is that the original ledges were made before we invented the bed tensioner concept. So with a tight bed with no other adjustability in the tension, it was easier to lever the corners onto the end tubes, rather than the other way around. I think I did make a round cross section corner at one point that I think set up the alternate way you describe, but didn't like the way the end tube fit into the perpendicular hole drilled into the side of the round cross section corner piece. Not sure if that is clear, never mind, I can try to find my old sketches perhaps, but in any case, with bed tensioning, perhaps the corners fixed on the end tubes and fitting on the long tubes would be a better way to go.
Cheers
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cadl
Trad climber
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Mar 27, 2017 - 06:41pm PT
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John, any issues for the triangle fabric suspension points if the anchor is off-center? For example if the belay is in a dihedral and the anchor bolts are less than 3 feet from the dihedral corner, the straps will be shorter on one side to compensate for the off-center anchor. Seems like this would create stress points on the triangle fabric attach points.
Thanks for your latest project and continuing contributions to the "state of the art"! Much appreciate by many.
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jeff constine
Trad climber
Ao Namao
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Mar 27, 2017 - 06:55pm PT
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Spreader bars have uses!
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deuce4
climber
Hobart, Australia
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Topic Author's Reply - Mar 27, 2017 - 07:08pm PT
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Hi Cael
The way I have designed the four/eight point suspension is that a majority of the load is on the webbing connections (2 per fin) rather than the fabric, and they equalize somewhat when, as you say, there is an off-center loading taking place. Due to the greater stretch of the fabric, the fabric simply creases to adjust in such as case. The benefit of the fabric is that is does actually take part of the load in a more distributed way.
It was indeed mostly theory for me, too, until I actually tried it on actual rock with off center loadings, plus I have played with it in my gym with most extreme off-center loadings, and the equalising concept does seem to redistribute forces as conceived in this type of situation.
If there are any engineers out there, I actually wouldn't mind a second opinion on the statics analysis. Here's a start (as all good things begin on the back of an envelope, or extra white space in a paper in this case...):
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Moof
Big Wall climber
Orygun
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Mar 30, 2017 - 03:48pm PT
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I'll bite on the 4/8 point suspension. Still working on the math a little, but I'll start with a few assumptions necessary to get started.
1) I assuming that A and B are fixed locations so as to distribute the load over the frame/bed kind of evenly.
2) Further I am assuming that ideally the tension on each of the 8 points is desired to be balanced (force on the bed at A and B equal). Having just a loop guarantees this due to the quick link acting as a pulley for this kind of analysis. This basically means you have to solve for the resulting angles rather than choose them, since things auto equalize. Should I NOT assume the real world pulley action and solve per your picture? I'll keep going with the pulley action for now.
3) The free variable is then the length of the strap connecting A and B. If it is very long you get 8 straps with zero force multiplication, but that is dumb. Make the strap short and there is huge force multiplication. So a good engineer needs to set some target to trade off excess stress trying to rip apart the bed and extra weight from having 8 full length straps. I am choosing a 20% force increase to back calculate the strap length and resulting angles, and will play with this when I have the math figured out..
I am further only going to look at the outside straps where the force is the highest, and assuming a 4' wide ledge body and 5' distance from the anchor down to the bed elevation to be able to calculate all this. I am going to put A 1' from the end pole and B 1' from that (3' in between B to B for a 7' ledge). Reasonable? I am probably missing an obvious simplification as to what I should be solving for, but I am an EE and my statics/physics has about 23 years of rust on it.
Green paper to follow...
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deuce4
climber
Hobart, Australia
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Topic Author's Reply - Mar 30, 2017 - 04:42pm PT
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Moof, you are on the right track, but in addition to stability, I designed the fins to support more of the middle as well. I can send you the specs I created, but would be interested to see what angles you determine first.
Yes, you can assume that the load is distributed equally between each of the two straps in each fin--though of course the fabric does take some of the load in a distributed way (for the better), I ignored this in my analysis. But real-world testing showed this to be largely the case--also when the ledge is set up in a corner, the load does shift a bit so the ledge is better optimally supported by the eight main points of connection--you will start to see how once you do some engineering statics, as the angles change.
Cool, looking forward to seeing what you come up with.
Bottom line, I tested them on a real wall, and the idea works!
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