Author Topic: Blacknor Hole bolts  (Read 1715 times)

Offline Keris82

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Blacknor Hole bolts
« on: February 18, 2019, 11:49:14 am »
We visited Portland this weekend and abseiled off the cliff in to Blacknor hole. 2 of the P bolts at the top are loose so please take care and make sure you have enough backup just in case!  :o

Offline Simon Wilson

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Re: Blacknor Hole bolts
« Reply #1 on: February 18, 2019, 12:59:13 pm »
Resin anchors coming loose is a serious problem that some people persist in trying to play down.

I might be assuming wrongly that you're talking about resin anchors not bolts.

Something new was installed around 2015. Maybe they are actually bolts.

I visited the cave recently and found that new bolts had been installed at the top of the cliff; old P hangers lower down still in place. Need to replace old raw bolt in Sandy Hole entrance.

Offline Keris82

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Re: Blacknor Hole bolts
« Reply #2 on: February 18, 2019, 01:18:06 pm »
You are probably right. I'm not sure what the correct terminology is but wanted to warn people either way

Offline Simon Wilson

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Re: Blacknor Hole bolts
« Reply #3 on: February 18, 2019, 01:38:14 pm »
You are probably right. I'm not sure what the correct terminology is but wanted to warn people either way

Thanks for reporting the loose anchors. Hopefully they will get replaced using a better type of resin.

The reason why I'm pedantic about the terminolgy is that I remove bolts and try to discourage the use of any type of bolt. If I talk about bolts I do mean actual bolts with threads.

https://en.wikipedia.org/wiki/Bolt_(fastener)

Offline andrewmc

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Re: Blacknor Hole bolts
« Reply #4 on: February 18, 2019, 01:39:11 pm »
Why does it seem to happen to cavers but not climbers?

Generally in Portland, the resin anchors last longer than the rock...
c.f. the intro image for the Dorset Bolt Fund:
https://dorsetboltfund.co.uk/

(PS no doubt the name of the Dorset Bolt Fund will annoy Simon :P )

Offline Simon Wilson

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Re: Blacknor Hole bolts
« Reply #5 on: February 18, 2019, 01:46:25 pm »
Why does it seem to happen to cavers but not climbers?

Generally in Portland, the resin anchors last longer than the rock...
c.f. the intro image for the Dorset Bolt Fund:
https://dorsetboltfund.co.uk/

Does it not happen to climbers? The reason why it continues to happen in caving is that cavers carried on using the same out-dated resin and didn't try to find out why anchors were coming loose.

Resin technology has moved on in the past 26 years.

Titan Climbing are now using epoxy resin.

http://www.titanclimbing.com/Titan%20climbing%20products%20-%20Epoxy%20resin.html
« Last Edit: February 18, 2019, 02:02:23 pm by Simon Wilson »

Offline Simon Wilson

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Re: Blacknor Hole bolts
« Reply #6 on: February 18, 2019, 01:50:29 pm »

(PS no doubt the name of the Dorset Bolt Fund will annoy Simon :P )

 :lol: It doesn't annoy me at all. It's quite handy when people refer to resin anchors as bolts because it flags up that they aren't engineers.

Online tim.rose2

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Re: Blacknor Hole bolts
« Reply #7 on: February 18, 2019, 06:18:12 pm »
A couple of us had a look at these over the weekend.  The 'bolts' are indeed resin anchors.  Not certain of make as I'm no expert but would guess at Fixe
P Anchors.  Unfortunately they were install incorrectly with the bolt head being proud of the surface rather than the welded part set down into a groove.  Apologies if I've explained that poorly.  I've used them a few times recently and they were solid so it's within the last couple of weeks they've worked loose.  They only move a couple of mm but clearly that's not how things should be.  I believe the current bolts were installed by a local climber who also does a bit of caving on the island.

On the whole the local climbers (who taught me how to install bolts) use home made staples from 8mm 316 stainless bonded with Fischer 410 C vinylester resin.

 

Offline andrewmc

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Re: Blacknor Hole bolts
« Reply #8 on: February 19, 2019, 07:39:25 am »
Unfortunately they were install incorrectly with the bolt head being proud of the surface rather than the welded part set down into a groove.

I guess since neither U-staples (are people really still making and using them?) nor the BP anchors now generally being installed (at least by the bolt fund) need to be recessed (the twisted leg makes this unnecessary, according to the manufacturer) Portland climbers would never normally need to recess an anchor head.

 

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