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Secret Boot Heel Grappling Hook Supplies 1. 8" of 1/8" steel tubing 2. 10' of 1/16m or 3/32 steel cable 3. 1/16 or 3/32 wire clamp...
Mark and cut the 1/8" steel tubing into two four-inch pieces.
I found that the easiest way to bend the tubing was to put the metal in a vise and heat it up as hot as I could. Then, I was able to bend it into a h...
Taking the hook and one of the old shoes, I traced out the hook pattern on to the heel of the shoe. After doing that, I put the shoe in my vice and d...
To store the cable, I decided to use an old sock and a piece of velcro. I sewed a band of velcro on to the sock so that it formed a little velcro lat...
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(1) Working Load Limits are for static (nonmoving) loads, not dynamic (moving) loads.
If a cable breaks at 120 lbf (pound-force), a 95-lbf person jerking the cable at a rate of 40 ft/sec^2 would break the cable. [Calculation: 120 lbf * 32 ft/sec^2 / 95 lbf = 40 ft/sec^2]
If a 95-lbf person were to swing on a 5-ft cable that breaks at 120 lbf, he would only have to swing 3 miles/hour (about walking speed) to break it. [Calculation: sqrt((120 lbf * 5 ft) / 32 ft/sec^2) ~ 4 ft/sec ~ 3 miles/hour]
(2) Lucky for you, working loads are usually given a safety factor of 5, meaning that your cable shouldn't break until you give it a 600-lbf load. This means you (being 95 lbf) would have to jerk the cable at a rate of 202 ft/sec^2 to break it. You would also break it if you were to swing at about 6 miles/hour with 5 ft of cable.
(3) Unfortunately for frisbeechampe1983's acquiantance, the combination of swinging and abrupt stopping when he hit the wall made a large enough acceleration for the load to exceed the cable's limit.
(4) Additional notes: (a) Make sure you know the difference between mass and weight. (b) The working load limit is determined by a load being uniformly applied in a straight line pull. You are not only changing the load by moving along the cable, but any additional movement on your part makes it risky. (c) The tensile properties of the cable are changed every time you go on and off just because the loads are changing.
Wait, I shouldn't give you any ideas.
The cable is very thin and you cannot hold it very well for a slow rappel... Probably another use. But GREAT idea
Here's my suggestion;
Produce a pile more equipment accessories that are wearable and usable in emergencies and get yourselves a brand name too for those devices and vids.
You've got talent, exploit it.
Robert.
Any thoughts?
If you are not concerned with retrieving your hook (Q-branch would give you another in any case), you could use a carabinder on your house keys and webbing (as noted above) for a belt that would likely pass casual inspection.
Well done instructable and great acting.
Cheers