Once upon a time the CNCC decided to do something about the increasingly dodgy M8 bolts in its caves. After much bullshit an agreement was reached to use DMM eco-hangers (popularly known as 'P' hangers), glued in with resin.
The pros of 'P' hangers are:
The cons of the system are:
It is necessary to place the bolts with battery drills, as the holes required are 18 mm diameter, 80 mm deep - epic by hand. After hearing about this at the BCRA conference the Wook thought that it seemed like a good idea to help by volunteering to bolt our 'Adopted' cave, Tatham Wife Hole. This proved to be somewhat harder than anticipated.
Early in 1992, there was a demonstration session in Yordas cave, where Les Sykes (CNCC secretary) showed how to install the hangers - size and depth of hole, glue gun use, dust removal, ensuring glue mixing, period of setting, time before first use, time between hole injections. Anyone placing bolts should have been to one of these demos, as the process is not simple, and getting it wrong could be fatal. It is consequently an insurance requirement. Tony manfully went along to this all alone.
The hangers are not cheap at £2.70 each, and the glue costs £9.95 a tube (about 6 holes per tube). Thus Tatty would cost nearly £100 to kit out, never mind buying drill bits and any other required gear. The club agreed to stump up the dosh, but negotiations up north meant that the Sports Council would, in fact, cover the cost of the materials, and the CNCC provided a kit containing drill, bits, batteries, glue gun, hole cleaner, et al.
Contact with the CNCC was made in May, and some glue was bought on our behalf. The glue has a limited period for safe use of 6 months so this had to be completed by November - no big deal.
The first time I actually got to see the hangers in action was at the Cavers' Fair in the Forest of Dean (July 1992), where there was a theory session with Owen Clarke (the NCA's equipment officer), and some Hilti representatives. It became clear here that the Hilti people weren't at all sure how well their resin (designed for use in concrete) would perform in limestone. After the theory we went and placed some hangers in some bits of rock that had been procured. They were done as 'worst case' tests to see what happens to hangers placed in:
After having a few hours to set they were pulled out with DMM's hydraulic test rig. This showed that all the hangers still managed about a ton. The bits of rock were probably too small as they all split, although this allowed examination of the holes, and the scoring which gave indications about the mode of failure. Another good feature of the failures was that even when a hanger 'failed' it was still extremely stiff in its hole, and a great deal of effort was required to pull it further out. - So, perhaps a little disappointing in comparison to the expected ideal of 4 tons, but certainly adequate.
Meanwhile not much bolting was getting done. To be precise:
1) 12th September 1992:
Tony, Jeremy, MarkF & Christine set off for Yorks armed with instructions on how to get to Les Sykes' house to collect the glue, hangers, and bolting kit. They decided that they couldn't be bothered to go via Skelmersdale and instead planned to have a reconnaissance trip to work out the hanger positioning. Unfortunately the fatal suggestion of a pint in the Hill was taken up, so no one felt like going caving, although they did manage to walk to the entrance, and go down the first climb in dry grots. Strike 1.
2) 24th October 1992 (Yorks I)
Time was already running out for our glue, and we hadn't even got hold of it yet! Wook and Sam went to another Yordas training session and collected the goodies from Les. Unfortunately Wook left the drill in Cambridge, and the CNCC's was being used by someone else - strike 2. Fortunately our glue turned out to be dated May, so we still had a bit of time - easy peasy.
3) 21st November 1992 (Yorks II)
Now we're getting somewhere - ha ha.
On Saturday, we collected the drill bit from the new resting place of the CNCC kit - Bernies - and bought some crayons & tippex to mark the hanger positions. The weather was pretty foul, but two teams, one to rig and the other to pontificate, got together. (Respectively, Fran, Gill, Anthony, Glen and Pete(notL), and Wook, Andy and MarkF). Whilst team rig got changed and set off in the freezing rain, team B went off to get Andy's helmet, which had accidentally gone to Kingsdale. On our return we found team A cowering in the Hill bogs, having jacked in the face of adversity - strike 3.
Sunday arrived with more shoddy weather, even wetter but not as cold. Determined this time, I persuaded Andy that a walk in the pouring rain would be more fun than doing nothing so we trogged miles up Inglebugger from the Hill in the fog and horizontal rain. The idea was that we would be able to check out the cave in extra-wet conditions (if we could get in) and relate this to the rigging. In fact we trailed about in the fog for hours, and failed to find the sodding hole. - strike 4
4) 7th February 1993 (Yorks III)
Saturday saw us toddling up to Bernies to collect the bolting kit - but it wasn't there, someone else having taken it to do Notts. Bugger. It was decided to go and have-a-look with DaveF and agree on some rigging (quite a lot like Elliot's, oddly enough). It is difficult to arrange entirely satisfactory rigs for ladders, SRT and rescue, which have conflicting requirements, with a sensible number of hangers, but we had some ideas, and we bottomed the cave just to show it who's boss. We decided that the crayons 'n' tippex idea was daft, and memory would have to suffice.
On Sunday, we were foiled again; still no gear in Bernie's. Strike 5.
5) 12th March 1993 (Yorks IV)
With the time on the glue running out I decided to buy a bit in Cambridge so we weren't dependent on the CNCC's being available, and completed the kit with a bottle brush and waterproof paper. Of course, the gear was there this time, (I got up earlier) so we had absolutely everything. In a fit of optimism Me, AndyA, and Spencer trailed up the hill with drill, battery, rope and enough goodies to drill and glue the entire cave. (I had now discovered that the walk is massively improved by starting from the road near the Quarry, rather than from the Hill (1.5km instead of 6)). We finally got going and managed half a hole before the drill died. Aaaaaarrgghhhh! Examination showed that one of the fuses had gone. Replacement with a spanner simply blew the other fuse, and it seemed that the drill had gone short circuit - Bugger, Bugger, Bugger. A desultory trip to show Spencer the cave ensued, although we thought up some more imaginative rigging plans this time. Unfortunately the transport was such that we had to walk all the way back to the caravans with that bloody battery. Strike 6
I had now realised that only one of the glue tubes lasted till May, the other three were only good till the end of March - sigh. A slightly embarrassing phone call to Les produced some more (to be left at Bernies), and an admonishment for nicking the bolting kit - one is supposed to book it in advance.
6) 1st May 1993 (Yorks V)
At Last - SUCCESS. The new glue was collected as promised. This time we only took drilling gear, not gluing stuff too - much more realistic. Me, DaveG, and NickP went down and merrily drilled the holes for the climb and pitches 1, 2 & 3 (14 holes). We then realised that not taking a rope for the 4th pitch (because we didn't intend to go down it) mean't that we couldn't drill the 4th without risking falling down it (and we would be jolly late home) so we called it a day. The only thing I forgot was the small drill bit used for roughening the holes for improved glue keying so no gluing could be done without more drilling first. But that could be done on Sunday.
Sunday came, and Sam was the only one who could be persuaded to go, and as we were camping and had missed the pub the night before we had been unable to recharge the battery. I had no idea if there was any juice in the baby battery so we had to take both of them, as either could go flat at any moment. Along with the gluing gear, drill, hangers, shit & rope this was a heavy load for two. However we finished off the climb and the 1st two pitches, working around the hordes of Reading Uni. CC who were wandering around. We discovered that gluing is amazingly mucky, with resin going all over the place if you don't take some care, and also a plastic bag. We did, of course, not need Small Paul, the fat bastard lumping battery, and had a hard time staggering out with multiple light failure (Sam's blew up in his face, and I found him trying to fettle his carbide in total darkness). Strike 7, but getting closer.
7) l5th May 1993 (Yorks IV)
With four people the gear loading was much more sensible (Wook, Sam, Lummat & Seb). This was the first time we had the cave to ourselves, showing just how popular it is (I reckon it gets two trips every weekend, except when the weather is too shit, so probably 50-80 trips a year - no wonder the bolts wear out). A long trip saw the drilling and bolting completed to the end, and we discovered that two of the hangers placed on the 2nd pitch a fortnight before were slightly loose. One of these had been knocked whilst setting by a Reading Novice, the other had persisted in sliding back out of its hole for 20 minutes after insertion, so it would seem that disturbing them whilst setting is not good for the adhesion.
So it only took a year!
Now that the job has been done, the next thing is to get hold of some test gear and see how strong the new hangers really are, especially the loose ones (which are quite sufficient to hold people up). There are also a couple of spots where another hanger might well be required to call the job truly complete.
Thanks to all those who did (or tried to do) their bit, and if anyone else feels like doing some bolting: pick a cave closer to the road.