Bolts at the mine

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Bolts at the mine

Post by DavidRob » Tue Apr 28, 2009 7:42 am

Question -

I was climbing at the mine recently and noticed that some of the nuts holding down the hangers on the bolts were loose (I had to tighten them with my hands). I have heard that that this is ok and the reason they're not tight is because applying too much torque to the bolt is not a good idea....

but if somewoen has taken a fall on a loose hanger doesnt that predispose that bolt to failure? or am I just being over cautious??

Thanks a lot!!

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Re: Bolts at the mine

Post by Justin » Tue Apr 28, 2009 8:35 am

If a hanger is very loose I would think that their is a chance of the hanger becoming damaged (from being levered), however no damage would occur to the bolt.
The big overhang route at Legoland has a spinning bolt (it can't be tightened any further) and it appears to be fine and un-bent.

If the nut on the bolt is only finger tight - I don't think there would be any increased risk of the bolt/hanger failing as long as there is thread above the nut (the thread keeps the nut on, which keeps the hanger there, which keeps your quickdraw attached to the rock, which keeps your rope in place, which keeps you from hitting the deck :cyclopsan
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Re: Bolts at the mine

Post by XMod » Tue Apr 28, 2009 10:30 am

Nuts do tend to loosen as the bolt settles in the hole and rock crystals underneath the hanger become crushed. Vibrations from falling and lowering also speed the nut on its way. Its not great if the hanger is flopping around loose as this may damage the thread of the bolt making retightening of the nut and later hanger replacement problematic. It is highly unlikely however that you will come flying off the crag provided there is still some thread above the nut.

Carrying a #17 spanner with you is a good habit to get into, offroad motorcycle shops may stock the variety with an aliminium shaft and steel driver head - ultra trick and lightweight! Just dont crank down hard on the nut when tightening, all you want to achieve is to stabilise the hanger and it does not take much torque (force) to do this. The bolt itself will have seated itself long ago and does not need massive torque to stay in place. Justin that spinning hanger needs some stainless steel washers placed under the nut to stop the spinning as the thread is most likely becoming damaged, you may need penetrating oil to loosen the nut if it has been cranked into the end of the thread. In fact if its been cranked too far it may not come off at all (a pity), add stainless steel washers in this scenarion before someone cranks the nut too far. Double check that the bolt is not migrating out of the hole (checked over time), this is an indication of soft rock and if this is the case the bolt should be replced with a glue in.

Consider putting Threadlock on the thread of loose bolts which will stop the loosening yet allow the nut to be removed if required, spring washers also help but be careful that the spring steel is compatible with the steels of the bolt and main washer or nut (check with a reputable bolt supplier if you decide to use these). Incompatible steels can lead to hugely speeding up corrosion of the parts - not cool! Another possibility is to use Nylock nuts which can only be turned with a spanner, again these need to be of compatible steel and are expensive. I much prefer Threadlock. Good quality 316 bolt studs will far oulast hangers (which cannot be made from the same quality alloys) and should be taken care of. If the thread gets damaged this limits the life of the bolt.

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