Chockstone Forum

      Sponsored By
      ROCK
   HARDWARE

Chockstone Photography

Australian Landscape Prints

Chockstone Forum - Accidents & Injuries

Report Accidents and Injuries

Topic Date User

The 9-Feb-2009 At 3:50:16 PM devlin66

Message

On 9/02/2009 nmonteith wrote:
>80mm is not shallow. It's actually as deep as many ring bolts in the Bluies.
>The problems lies in the diameter of the hole and the grip of the expansion
>cone on the hole sides.

My point being that I think 80mm is not deep enough for real long term durability (20+ years) for frequently loaded bolts. With the compressive strength being so variable in sandstone I think that 80mm is too shallow and 120-150mm would be a better depth. I know that means slightly more cost but a far better installtion in my opinion.

>>Even with
>>the utmost care in placement these bolts the margin of failure is just
>>not high enough and the bolting not 'best practice'. :-)
>
>I reserve judgment until someone (me?) tries to test them from scratch.
>I'm not making a call either way at this moment. There is plenty of secondary
>evidence and theories that they won't work - but no one has actually tried
>it. I'll have a crack tonight on some Sydney choss if i can find an 8mm
>bit at home. I'm only discussing it because all things bolting interest
>me - and if I (and others) can learn more about how they work then we'll
>all be better educated when making bolting decisions in the future.

Sometimes I think we are trying to reinvent the wheel. I know that climbing anchors are unique in their installation but industry have many years of application experience. You will find that in soft sandstone and of the forces we are talking they would specifiy much longer anchors and advise against using mechanical where possible. I would still be interested to see what your testing comes up with though.

As much as I believe we should be responsible for our own action and descisions, if you are going to bolt with the intent that other people can use what is placed, then it has to be absolutely bomb proof. It's just conceited and ignorant to do otherwise. :-)