What throughbolt?

[pwhole]

For me the strength of the fixings isn't the issue, but the permanence of the throughbolts. As they stress the rock when installed, that stress can never be removed again, and so that area can't realistically be used again either. Screws don't stress it, and I've even re-used a clean screwhole a year later with a different screw with no issues. Once the final route has been determined, then throughbolts are fine for installation, but it seems daft to write off whole sections of rock (and the resultant dangerous rusty stubs) just for the ease of hammering them in, especially if bolting downwards. There are probably twenty or so screws still in the shaft at Longcliffe from all the various routes we've rigged, but they're all fine, none have rusted, and they can be removed eventually with no damage to the cave. Apart from one throughbolt that I didn't install. And now it's there for ever - in the wrong place! I used stainless throughbolts to hang a water-barrel from as that's essentially a permanent feature for now, but they can be incorporated into a rope route at some point if it ever comes out.

I have done bolt-climbs with screws, and whilst the distance reached might not be quite so great as a with a throughbolt, it still works. Cleaning the holes out first is essential though, and that can also be a bit trickier going upwards, but I find a long bit of flexible 7mm hose is great for blowing it out.

 

[SamT]

Re Strength...  What rob said.

Its always struck me that cavers are utterly utterly obsessed beyond belief with the strength of anchors.  Way beyond a point that's reasonable.  Its as though they're utterly convinced that on every trip, they'll be taking factor 2 falls on a single bolt that will for definite, snap in two like a crisp, sending them hurtling to their death.

If the history of caving was littered with past heroes, dead and buried from anchor failure, then I could understand this.  But it doesn't happen, it never really has.  I'm sure there are maybe some unfortunate souls out there, but I can't, off the top of my head, think of a fatality from bolt/anchor failure.

Snapped ropes, yes, hang ups, yes, etc etc.

So why the obsession.

We're pretty bloody amazing it now.  We've got incredible standards, especially compared to the climbing world, which arguably uses many many more bolts.

Back to the original topic, couple of thoughts.

All trade/tourist routes began their life as exploratory routes, so bare that in mind when exploring.

For me
- 8mm thrubolts, over drilled for bolt climbing.
-down rigging.  I've tended to use 8mm thrubolts in the past, but the screws make so much more sense.

I'm not so convinced that 8mm through bolts "stress" the rock as much as is made out, and thus I don't think great areas of rock are rendered unusable.

/2p

 

[Joel Corrigan]

Poor Ari: he was just asking a simple question!  We kind of screwed up in the Dachstein but I guess that hindsight is a wonderful thing.  For many years, the standard routine was to find a promising cave, push it for two, three or even four years before it beat us into submission & we ran away in defeat.  Our policy was to use the cheapest thru-bolts we could afford (generally from Screwfix) as we knew with utter certainty that nobody would ever return.  With the discovery of WUG, though, this all changed & we realised that decent rock was at a premium so replacing the initial wank anchors with decent stainless wasn't always feasible.  If I could go back in time I'd insist that the project only used stainless right from the word go as we still find ourselves re-investigating abandoned sites to check for snowmelt etc...  And now we have a situation whereby one of our previous discoveries (Burnies Pot) could become the key to a higher entrance (some of our keen youngsters intercepted it from another cave & have been using the original rigging) and it fills me with dread as rescue from that place would be brutal.  If only we'd used stainless   

Few other thoughts: back in 2014 Tony Seddon & I spent a week or so in the Vercors doing the French cave rescue training course with the SSF & they disliked thru-bolts with a passion & only used Spits.  The trainers weren't too keen about going into too much detail in English as they favoured the Spanish & French speakers so we missed out on some of the detail but they certainly have plenty of reason to dislike thru-bolts.  Concrete screws weren't really popular at the time so we never had that discussion, but from my point of view I can't stand them (concrete screws, not necessarily the French!).  I find them to be time-consuming to install & remove, way too awkward to use for serious climbs, don't sit in a hanger whilst racked on your harness, holes often need boring out in hard rock, and it's quite easy to damage the flutes which means they're not necessarily that reusable.  For the UK I can certainly see their place but I don't get how deep Alpine projects like them as speed is of the essence.  And Andrew: we were only using the Fischer ones because we got a deal & not because they were necessarily better than others. 

Top of my hate list, though, are those daft anchors that require a setting tool (I think the Oxford lot use them in the Picos?).  Ian Holmes told me about a few that popped out because they hadn't been installed properly & although that can technically happen with any anchor it's less likely with others. 

 

[pwhole]

It seems like the Petzl push-buttons are the way forward for genuinely eco-friendly exploratory bolting combined with ease of installation (and removal), but I'm trying to guess how many you'd need for a full-on expo - and how much extra sponsorship would be required! It's a shame they're so expensive as I would love to use something like that. Maybe we could have a chat at the club about buying a set of ten, which would probably cover local bolting trips OK, but I can imagine the conversation might be fraught, considering it would be the ballpark of one of our annual services bills.

 

[andrewmcleod]

It seems like the Petzl push-buttons are the way forward for genuinely eco-friendly exploratory bolting combined with ease of installation (and removal), but I'm trying to guess how many you'd need for a full-on expo - and how much extra sponsorship would be required! It's a shame they're so expensive as I would love to use something like that. Maybe we could have a chat at the club about buying a set of ten, which would probably cover local bolting trips OK, but I can imagine the conversation might be fraught, considering it would be the ballpark of one of our annual services bills.

I can see them being great for aid climbing, but I wouldn't want to leave them in a cave even overnight (at least not in a damp cave wall) as I'd be worried about corrosion...

 

[Subpopulus Hibernia]

Concrete screws weren't really popular at the time so we never had that discussion, but from my point of view I can't stand them (concrete screws, not necessarily the French!).  I find them to be time-consuming to install & remove, way too awkward to use for serious climbs, don't sit in a hanger whilst racked on your harness, holes often need boring out in hard rock, and it's quite easy to damage the flutes which means they're not necessarily that reusable.  For the UK I can certainly see their place but I don't get how deep Alpine projects like them as speed is of the essence. 

I've used concrete screws quite a lot, especially since they're very suited to the terrible cherty friable rock we have in much of Ireland as they don't stress the rock all that much. I just use a small scrap of of inner tube with a hole in the middle on the screw like a washer so it holds the screw in the hangar. And sure, the odd one will get the teeth fouled up, but when you can re-use the other ones four or five times then that's not really an issue. The best thing is how eco-friendly they are, you don't don't have to go through the faff of over-drilling an 8mm hole and then banging them in and mudding over the hole.

Never really noticed that they were particularly slow to place - though I know some Aussie cavers who use a mini-impact drill to drive them home when bolt-climbing. A ratchet spanner will do more or less the same thing though.

I know they're pretty much all that's used in Australia - all exploration (in Tassie at least) is done with concrete screws which can be drilled out and replaced with resin bolts if needed. Australian cave rescue use them as well for rescue practices.

For Alpine projects I can imagine that a big saving would be the extended battery life they give - you can drill a lot more 6mm holes vs overdrilled 8mm holes.

 

[Fjell]

In a spirit of idle curiosity, the rugby being over, I had a look at what Hilti have to offer these days for the truly paranoid.

They sell the 8mm HST-HCR in 1.4529 material, which is class V. So pretty swish and likely not going rusty that easily. They will sell you a box of 50 for about a grand incl VAT. A snip.

It must be a bugger to machine with all that unobtanium in it, so worth every penny no doubt.

https://www.hilti.co.uk/c/CLS_FASTENER_7135/CLS_WEDGE_ANCHORS_7135/r1117?CHA_GLOBAL_ANC_SIZE=M8&CHD_ANCHOR_LENGTH=115%20mm&combo_content=6c085b69675be789f65f8dd20e8a0a77&salespackquantity=50%20pc&itemCode=387258

 

[pwhole]

Hahahah. Good grief. But no doubt it's a lovely abseil

 

[Steve Clark]

The Hilti pricing will vary greatly depending on account status and how things are bundled.

The 8mm HST-HCR-75mm lists at ?650+VAT / 50pc on our account. I've never (obviously!) bought some, but I expect it would be considerably cheaper if we spoke to the rep.

We buy a lot of their HUS-6 6mm self-cutting concrete screws for work. If we are not logged-in, 100pc of of 160mm HUS-6 is 146+VAT. Our account lists them at 30+VAT.

On the bundling, the smaller HUS-6 anchors can be bought bundled with 'free' 6mm TE-CX bits (the good ones), and are 10+VAT a box. That's cheaper than the bit by itself.

Edit : The A4 stainless version of the 'ultimate' HST3 is the HST3-R. They are about 3.50 each with no discount. The 'premium' HST2 in A4 is 2.00+VAT and carbon steel 70p.

 

[PeteHall]

I've always been amused by the pricing at Hilti.

Even as a very occasional customer I always manage to negotiate a considerable discount on the list prices. Makes you wonder why they bother with the overinflated price in the first place.

Either wat the products are second to none and I never buy anything else for drill bits. As for through bolts, I was fortunate enough to inherit a large box of M8 galvanised and a handful of M8, M10 and M12 stainless Hilti anchors from a former employer (they actually owed me a lot more than that, but such is life), which I am still working my wat through 

 

[Fjell]

I did once pay about a million quid a pop for lumps of inconel-sheathed carbon steel.

We were offered something very close to 1.4529 in the solid, but I rejected it as insufficiently corrosion resistant in the environment and temp. I would likely be standing near it when it was put under load, and I?m worth it.....

 

[pwhole]

I used the same 8mm Hilti bit for over a year and drilled many, many holes - I lost count, but probably a couple of hundred, and I only retired it as I thought I probably should - I had several new ones! I think it was about double the cost of a normal bit, but probably about ten times the lifespan

 

[David Rose]

I was with a team that started using concrete screws in Huautla in 2018, re-rigging the early pitches of Agua de Carrizo which, back in the day, ie in 1978, was rigged the old-fashioned American way, that is, by tying a length of Bluewater or PMI to a natural belay, then abseiling down. After a couple of trips we started to notice that several screws on the first two pitches - 35 and 110 metres, with multiple rebelays - were just pulling out. The rock, it seemed, was too soft, or in some places, too brittle. Bloody terrifying. We binned the lot.

 

[andrewmcleod]

I was with a team that started using concrete screws in Huautla in 2018, re-rigging the early pitches of Agua de Carrizo which, back in the day, ie in 1978, was rigged the old-fashioned American way, that is, by tying a length of Bluewater or PMI to a natural belay, then abseiling down. After a couple of trips we started to notice that several screws on the first two pitches - 35 and 110 metres, with multiple rebelays - were just pulling out. The rock, it seemed, was too soft, or in some places, too brittle. Bloody terrifying. We binned the lot.

Did you have more success with through-bolts? Generally screws are supposed to be _better_ in weak rock, as the load is more distributed, but I can also imagine that (like so many things in life) 'it depends'.

 

[Joel Corrigan]

Years ago in the state of Guerrero in Mexico we were searching for & exploring caves but a lot of these places had previously been discovered by a lone American who spent years in the area.  We kept seeing old Spits in the walls but chose to install our own anchors (can't remember what we were using but could have been Spits too).  If I remember correctly, someone met this guy at a congress & during a discussion he apparently exclaimed: "oh, so that's what those cones are for: I just threw them away as I never thought they had a purpose".  So the dude had been self-drilling Spits for years in some fairly remote locations & had just tapped the bare Spit into the hole without using the cone.  For those that haven't done any bolting using these gizmos before, it's kind of like using a condom with a hole in the end: from a distance it looks the same but it hugely increases the adventure whilst drastically reducing the safety!!     

 

[Fjell]

The preload in stud bolts exceeds any likely shock load (even in 8mm) and you can happily keep using a spanner to check it as often as you like. If you used 10mm bolts, I would think the preload exceeds the nominal 22kn used for climbing standards.

What are you going to do with screws - keep rotating it in the rock until you break something? Wait.....

 

[Steve Clark]

I used the same 8mm Hilti bit for over a year and drilled many, many holes - I lost count, but probably a couple of hundred, and I only retired it as I thought I probably should - I had several new ones! I think it was about double the cost of a normal bit, but probably about ten times the lifespan

TE-CX are by far the best drill bits available.

For the gear nerds - They have a tiny wear indicator depression on the side of one the flutes near the tip. This is quite easy to see when they are new. The idea is that if this depression is still visible, the bit will be drilling a large enough hole to accept anchors ok. It also serves as evidence for their guarantee. If the tip wears out or fails whilst the indicator is still visible, then there is a problem with the bit and they will replace it.

https://images.homedepot-static.com/productImages/027c42c7-415a-4c5a-bc08-8d215b51885d/svn/hilti-masonry-drill-bits-2206616-c3_600.jpg

 

[Pitlamp]

Apart from one throughbolt that I didn't install. And now it's there for ever - in the wrong place!

pwhole's remark above interested me - and prompted me to ask a question which may be viewed as a slight digression (for which I apologise in advance).

I have a need to remove a particular Throughbolt, so I've been wondering on how this might be done. I know that overtightening the nut causes the a Throughhbolt to start creeping out of the hole but removal in this way is not possible because the thread is not continuous to the bottom of the bolt. I'm wondering about using a few larger nuts to act as spacers so that the unwanted Throughbolt can be extracted fully using its own thread.

Do folks reckon this will work? Also, would this compromise the safe re-use of the same hole with a future replacement Throughbolt (if it results in wear to the sides of the hole during extraction)?

(The consensus might also help pwhole solve the problem he mentioned above.)

 

[Fishes]

I've managed to remove and replace spits on a number of occasions but for a throughbolt I would use a diamond core drill and replace it with a resin fix anchor.

 

[Fjell]

Apart from one throughbolt that I didn't install. And now it's there for ever - in the wrong place!

pwhole's remark above interested me - and prompted me to ask a question which may be viewed as a slight digression (for which I apologise in advance).

I have a need to remove a particular Throughbolt, so I've been wondering on how this might be done. I know that overtightening the nut causes the a Throughhbolt to start creeping out of the hole but removal in this way is not possible because the thread is not continuous to the bottom of the bolt. I'm wondering about using a few larger nuts to act as spacers so that the unwanted Throughbolt can be extracted fully using its own thread.

Do folks reckon this will work? Also, would this compromise the safe re-use of the same hole with a future replacement Throughbolt (if it results in wear to the sides of the hole during extraction)?

(The consensus might also help pwhole solve the problem he mentioned above.)

With a decent sized spanner or breaker bar and socket (more doable in 13mm) it will either come out or snap. If it snaps, hammer it back in until it is flush. Maybe leave it alone after that either way unless you are desperate, otherwise maybe drill it out to the next size up?