Author Topic: Rigging a Fixed Scaffold bar  (Read 1607 times)

Offline JWright

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Rigging a Fixed Scaffold bar
« on: August 03, 2020, 05:30:25 pm »
What knot would you use to rig to a fixed scaffold bar?
The kind of situation I am thinking is like at the top of Hillocks climbing shaft (if you know what that looks like)  :)

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Rigging a Fixed Scaffold bar
« on: August 03, 2020, 05:30:25 pm »
Warmbac

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Re: Rigging a Fixed Scaffold bar
« Reply #1 on: August 03, 2020, 05:41:07 pm »
Tie half a figure of eight put the none load end over the scaff bar and back thread the half tied knot.
If you leave enough of a tail in the rope you could do the same for a back up on the bar too.

Offline wellyjen

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Re: Rigging a Fixed Scaffold bar
« Reply #2 on: August 03, 2020, 05:43:58 pm »
I'd always have it backed up to something if at all possible. As much to provide a loop easy to clip in to protect people on approach than as safety thing if the scaff pole failed. Wrap a short sling round it enough times to get the knot at a satisfactory height. Depends what if anything there is for people to stand on in the shaft where that is. Then, krab in to the ends of the sling and knot in to that. You can tie the climbing rope directly round he scaff bar if it is removable, like at the top of Oxlow, or Eyam Dale House. Nice big radius around the tube. If the tube is fixed, this makes judging how much rope to leave to go to a backup tricky and leads to time wasted adjusting lengths. Slings are cheap, so take one with you. The sling wound round the tube will also keep it in position. There may be parts of the tube that if the suspension point slides along will give a rope rub lower down.
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Offline mikem

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Re: Rigging a Fixed Scaffold bar
« Reply #3 on: August 03, 2020, 05:52:52 pm »
Sling if you have one, otherwise clove hitch tied off with half hitches (or a few round turns if you can't remember the clove)

Online Brains

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Re: Rigging a Fixed Scaffold bar
« Reply #4 on: August 03, 2020, 06:54:46 pm »
Same method as T Pot

Offline cavemanmike

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Re: Rigging a Fixed Scaffold bar
« Reply #5 on: August 03, 2020, 06:56:17 pm »
Sling every time

Offline mikem

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Re: Rigging a Fixed Scaffold bar
« Reply #6 on: August 03, 2020, 09:30:54 pm »
If you don't want the retied figure of 8 to slip, you can use round turns or a clove hitch in the middle.

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Re: Rigging a Fixed Scaffold bar
« Reply #7 on: August 03, 2020, 10:15:27 pm »
I actually did manage to tie a re-threaded figure-9 one night when I was bored, so it is possible. But boring  :(

Offline Tseralo

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Re: Rigging a Fixed Scaffold bar
« Reply #8 on: August 03, 2020, 11:09:41 pm »
I prefer to tie a bowline with a long tail that I can backup to another thing or the same scaff bar if there isn't anything else IE JH. Some of our members seem to dislike this as its a bit more faff to remove when its blowing a gale and prefer a sling and crab. Personally I would rather reduce the amount of failure points in the system.

Offline mikem

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Re: Rigging a Fixed Scaffold bar
« Reply #9 on: August 04, 2020, 08:54:44 am »
If they are happier with a sling & krab, than that is better than them tying a bowline wrongly. The only place it is more of a risk is where someone else might comes along & remove it.

Offline paul

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Re: Rigging a Fixed Scaffold bar
« Reply #10 on: August 04, 2020, 12:30:32 pm »
Also a sling and krab makes the knot lower than tying directly into the scaffold bar making it more difficult to get on or off the rope in some cases. Why add more gear when you can tie he rope directly to the scaffold bar and use the tail to tie to a back-up or nearby anchor?
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Offline MarkS

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Re: Rigging a Fixed Scaffold bar
« Reply #11 on: August 04, 2020, 01:13:19 pm »
I prefer to tie a bowline with a long tail that I can backup to another thing or the same scaff bar if there isn't anything else

Is a backup really a backup if it is attached to the same thing? :-\

Offline Tseralo

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Re: Rigging a Fixed Scaffold bar
« Reply #12 on: August 04, 2020, 01:18:40 pm »
I prefer to tie a bowline with a long tail that I can backup to another thing or the same scaff bar if there isn't anything else

Is a backup really a backup if it is attached to the same thing? :-\
It’s the same reason we teach people to backup their fig 8 with a stopper in climbing.

In reality if the first knot is tied correctly it’s not needed but people talking to you, being a bit excited to get underground or just keen to get out of the wind can distract people. Sadly this has killed people climbing including a friend of a friend quite recently.

Online Brains

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Re: Rigging a Fixed Scaffold bar
« Reply #13 on: August 04, 2020, 01:49:58 pm »
Re-threaded fig 8 with a tail to a backup stake, note how little gap is between the bar and usable rope for descent

Offline Fishes

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Re: Rigging a Fixed Scaffold bar
« Reply #14 on: August 04, 2020, 10:07:59 pm »
A wrapped sling or bowline. A rethreaded figure of 8 is good but can be a real pain in the ass to undo sometimes.

Offline nearlywhite

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Re: Rigging a Fixed Scaffold bar
« Reply #15 on: August 06, 2020, 08:33:15 am »
I actually did manage to tie a re-threaded figure-9 one night when I was bored, so it is possible. But boring  :(

I use them fairly often. And would use it in this situation

Rethreading a bunny ears when someone you don't like is derigging is more of a challenge.

Offline PeteHall

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Re: Rigging a Fixed Scaffold bar
« Reply #16 on: August 06, 2020, 10:53:28 am »
Rethreading a bunny ears when someone you don't like is derigging is more of a challenge.


As long as it's not your rope, otherwise they might be tempted to just cut it off  :lol:
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Re: Rigging a Fixed Scaffold bar
« Reply #17 on: August 06, 2020, 11:13:34 am »
Rethreading a bunny ears when someone you don't like is derigging is more of a challenge.


As long as it's not your rope, otherwise they might be tempted to just cut it off  :lol:

I recall a derigging trip down Oxlow with Rostam in my first year where I had to de-rig a re-threaded figure of eight bunny ears in new 9mm rope that had just been weighted by Rostam - it was DCC rope as well so not ours to cut! After 30-45 minutes I finally got it undone, and he then revealed to me that he hadn't brought any tackle bags.

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Offline nearlywhite

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Re: Rigging a Fixed Scaffold bar
« Reply #18 on: August 06, 2020, 03:32:06 pm »
I had to de-rig a re-threaded figure of eight bunny ears in new 9mm rope that had just been weighted by Rostam

it had been weighted by 6 other people... cheeky sod. Also for the record I had assumed the tackle sacks were hung up as they'd used them... nope they'd taken them out. I do think of that trip most times I'm on that hillside.

Online Fulk

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Re: Rigging a Fixed Scaffold bar
« Reply #19 on: August 06, 2020, 04:53:21 pm »
Fed up with struggling to untie recalcitrant knots, last year I bought a marlin spike – though admiitedly it wouldn't be much use for untying rethreaded knots underground.

Offline Bob Mehew

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Re: Rigging a Fixed Scaffold bar
« Reply #20 on: August 06, 2020, 07:27:04 pm »
This question did raise in my mind how one might quantify the difference between knots.  Work by Lyon Ltd indicates most knots have a similar level of reducing the strength of a rope, so the next step would be to look at the ease of tying and untying it after loading.  Any ideas on quantifying the difficulty of untying a loaded knot?

Online pwhole

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Re: Rigging a Fixed Scaffold bar
« Reply #21 on: August 06, 2020, 07:39:02 pm »
Measuring the swollen lump on the right thumb knuckle two days later is my usual method ;)

I must say I'm now almost fired up for trying that re-threaded Figure 9 again ;)

Offline Mike Hopley

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Re: Rigging a Fixed Scaffold bar
« Reply #22 on: August 06, 2020, 07:47:03 pm »
Any ideas on quantifying the difficulty of untying a loaded knot?

I suggest measuring it in swear words per minute per fresher.

...Is that a laden or unladen fresher?

Offline Tseralo

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Re: Rigging a Fixed Scaffold bar
« Reply #23 on: August 06, 2020, 07:49:39 pm »
This question did raise in my mind how one might quantify the difference between knots.  Work by Lyon Ltd indicates most knots have a similar level of reducing the strength of a rope, so the next step would be to look at the ease of tying and untying it after loading.  Any ideas on quantifying the difficulty of untying a loaded knot?
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Offline Mike Hopley

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Re: Rigging a Fixed Scaffold bar
« Reply #24 on: August 06, 2020, 07:55:57 pm »
Okay, serious answer:

Time taken for the same person to untie the knot. Repeat across different knots, and different rope diameters, and multiple people. Average results from all different people to get time for a given knot, at a given diameter.

Probably standardise the knot tightening, say 100kg, slow pull, for 5 minutes. You'd also need to decide whether any "tools" are allowed, like carabiner noses or spanners.

To get any meaningful results, you would need a lot of data. I expect you'd find that thin ropes drastically exaggerate the differences between knots.

In 8.5 mm or lower, I've stopped using figure-8 loops at single-bolt rebelays, as they are a bastard to untie. Bowline-on-the bight is a lot easier. Alpine Butterfly is easy, and Fusion is easy.

Maybe the sneaky way to get your data would be to turn it into a new competition at Hidden Earth!

 

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