04 December 2008

Advanced Hex Placements

Advanced Hex Placements

Advanced Hex Placements image

The following techniques are for those ‘RP O’ situations where anything is better then nothing. I’ve used all three techniques several times and they do work – just don’t expect them to work all the time.


You will often find yourself in a situation where you have a parallel crack but have no cam to fill it, especially if the crack is wide. One technique that can work is to use the hex sideways in such a way that the force is only applied on one side, and so create a far more effective twisting action then normally achieved. Once set give the nut some very strong jerks to lock it in place, and extend it. The strength of such a placement is dependant on how much metal is in contact with the rock, and what the effect of metal distortion will have in these areas (i.e. if the nut is just in contact and you lob onto the cammed nut, it may blow if the metal distorts enough for the cramming angle to be lost).


Another technique in the ‘RP’ category is stacking large hexs when you find a crack which is two wide to take anything else. To do this take your largest nut and find a nut that fits snugly into it. Push this in a far as you can and hopefully this stack will span the crack. Once placed pull down hard on just one of the hexs (not both), making them twist and lock together. The alloy bodies of large hexs aren’t designed for this kind of loading, so again don’t expect much strength. A variation on this is to stack the hex with a standard nut, and works well when you have a hex that’s just a bit too small.

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