Beginners guide to rigging.......

[DrewB]

a good friend dropped a very big piece of oak into a rigging line and snapped the rope. we roughly calculated the load at the anchor (using a forces calculator) to be 56t. the big impact block and 22mm dead eye took it but the rope snapped over the block. wonder what would of happened with the dyneema sling?

[DrewB]

ill try and get the link to the calculator...

[slack ma girdle]

It should be standard practice to let all rigged pieces run as far as possible with gradual and gentle breaking. I expect my groundies to stop the piece just before it hits the ground where possible.

I do not like nasty shaking in the tree, and it reduces the excess loading on my equipment.

 

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Check ALL the simple things first.

[Ewan Murray]

Scary thing when the line snaps, had the rigging block flip up infront if me almost hitting me in the face then i watched this log roll down the customers front garden.

 

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[tuttle]

a good friend dropped a very big piece of oak into a rigging line and snapped the rope. we roughly calculated the load at the anchor (using a forces calculator) to be 56t. the big impact block and 22mm dead eye took it but the rope snapped over the block. wonder what would of happened with the dyneema sling?

 

is that a x10 calc? maybe the rope was flawed in someway.

 

The dyneema is rated at 12.5T minus the whoopie set at 40%, so at best you'd want 8 slings to hold that up:001_rolleyes:

[Paul Smith]

For each meter that a log is allowed to free fall multiply its original weight by 3+1.

 

E.g 1m free fall with 4ft x12 inch diameter beech. Shock load of- 80kg x3 = 240kg + 80kg shock load 320kg

 

2m free fall of 4ft x12 inch diameter beech. 80kg x 6 = 480kg +80kg= 550kg

[DrewB]

It was something like a 1000kg piece with 12m of rope in the system and the tie point being 30cm above the block. Like i said, I'll try find the link

[Tommy_B]

Scary thing when the line snaps, had the rigging block flip up infront if me almost hitting me in the face then i watched this log roll down the customers front garden.

 

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How big a piece were you taking?

[Ewan Murray]

Only about a 3 or 4 meter section about 50 or 60 cm wide.

 

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[DrewB]

Fall factor and impact force calculator

 

I know its not accurate but does show how forces rapidly add up if you stop falling objects