Spinning through bolts

[Becka]

Over the summer I saw directly or heard about a dozen or so through bolts that span when people were trying to derig them. This meant that the hanger couldn't be removed as the through bolt just rotated in its hole rather than the nut unscrewing to allow the hanger to come off.

Spinning bolts happened to different people using different drills, different rock and with varying levels of rigging expertise and gorilla tendencies and there was no obvious common factor for the failures.

I've heard many suggestions about what could be going wrong. They include:
- insufficient torque so the bolt wasn't ever set (cone mechanism didn't engage)
- wobbly drilling making a too- large hole
- not blowing dust from the hole
- not drilling deep enough / not over-drilling
- galling between the stainless nut and stainless thread of the through bolt
- hitting the nut rather than the end of the bolt and damaging the threads of the through bolt

Any ideas about which of these are more plausible? Or is it more likely a combination of them?

How can spinning bolts be removed?

Are they unsafe to use?

 

[Space Doubt Caver]

Over the summer I saw directly or heard about a dozen or so through bolts that span when people were trying to derig them. This meant that the hanger couldn't be removed as the through bolt just rotated in its hole rather than the nut unscrewing to allow the hanger to come off.

Spinning bolts happened to different people using different drills, different rock and with varying levels of rigging expertise and gorilla tendencies and there was no obvious common factor for the failures.

I've heard many suggestions about what could be going wrong. They include:
- insufficient torque so the bolt wasn't ever set (cone mechanism didn't engage)
- wobbly drilling making a too- large hole
- not blowing dust from the hole
- not drilling deep enough / not over-drilling
- galling between the stainless nut and stainless thread of the through bolt
- hitting the nut rather than the end of the bolt and damaging the threads of the through bolt

Any ideas about which of these are more plausible? Or is it more likely a combination of them?

How can spinning bolts be removed?

Are they unsafe to use?

I wouldn't use a spinning bolt, if it's spinning, and not releasing the hangar it's a catastrophic failure of the bolt, if it's in the north the CNCC might cover it,
and for the south i think it's the CSCC both of them probably look into replacing and re-bolting and inspection
Sometimes local caving clubs do it, most places are starting to use the P-bolts these days

 

[Space Doubt Caver]

If it's in the north here is where to report it: https://cncc.org.uk/caving/report/?rt=anchor&cid=0

If it's in the south here is where to report it: https://cscc.org.uk/wiki/about/contact_us

Or you could contact your local caving club,

It's really good you found it, hopefully it can be removed/replaced ect... so no accidents happen 🫶😇

 

[rsch]

How can spinning bolts be removed?

In my experience, through-bolts appear to be set fine when installed and it only becomes apparent they are spinning when it comes to derigging.

To derig and retrieve the hanger from a spinning through-bolt, I have found it a repeatably successful technique to have a big fatso (hello, my name is...) clipped in with a short cowstail directly to the hanger so that their weight causes the hanger to to bear down on the through-bolt - this loading can often provide enough extra friction to prevent the bolt spinning for long enough to start loosening the nut.

That's a technique that allows you to retrieve your hanger and complete that part of the derigging.

Where you might think that leaves you with re-using that same through-bolt in the future is a different question but once you have retrieved your hanger, it is an option (if you have time and enthusiasm...) to put the nut back on and wind it back in and see if a bit more torque helps the sleeve expand a touch more and stop the spinning. Again, I have found that to work.

 

[andrewmcleod]

What brand of bolts?

I think a small fraction of installed 8mm through bolts just spin on installation; I would consider them 'failed' and hammer them into the wall (I generally over drill) if I can get the nut off. It's a pain if you can't, because you lose the hanger plate.

I also think through bolts don't like being repeatedly loaded and unloaded by being screwed and unscrewed (unlike spits, for example). I wouldn't want to use them where I was repeatedly removing and replacing the hanger plate; however, I know some do get used like this (in mines?) so mileage may vary.

Hitting the nut and damaging the threads is definitely one way of knackering the bolts and somewhat common I think (with newer bolters).

Someone got a bolt spinning (and actually bent the bolt) trying to hammer it into a hole this year - not sure if they'd under drilled the hole or just failed to hammer straight or something.

I've seen a bolt spin because it was put in really hollow rock (that badly failed the hammer test and should never have been placed there).

Forgetting your hammer and using a chisel to hammer in your bolts is apparently another good way to end up with spinning bolts (not me!).

I am reasonably confident that bolts that aren't blown out don't bite quite as nicely.

We are using Fischer FAZ II stainless bolts (got some ridiculous deals on eBay; about 250 for £100 ish) and FBN II non-stainless for prospecting.

 

[mikem]

I don't think removing dust is such an issue with through bolts as it is with sleeve bolts, provided the hole is deep enough that the dust doesn't prevent the bolt being fully inserted. Soft rock / calcite, however, will compress away from the gripping area, so that is another possible failure mechanism.

Through bolts aren't designed for repeated undoing, I suspect that turning them the wrong way will grind out the surrounding rock, as the pressure has come off the wedge, reducing the grip (they only have a small surface contact compared to the size of the bolt), so you've effectively turned it into a drill ! If space allows then knocking them further in will work, but the same thing will happen again.

Provided they aren't vertically inserted into the roof (& even then you'll struggle to pull them out) they'll still be safe to use (as long as it's not the rock around them splitting that has caused the failure), as the load downwards on a horizontal bolt also causes leverage to jam the end against the side of hole (this is reason that rsch's suggested removal method works) & also why you shouldn't hang on resin bolts before they set (movement opens up more space).

 

[MarkS]

We had this issue to quite a significant degree in Montenegro in 2016 with bolts that had been placed 2 years prior. However, these weren't stainless and we put it down to corrosion binding the nut to the bolt meaning that when we went to loosen the nut the whole lot rotated. I've seen it/experienced it a few times elsewhere, but only very occasionally.

My 2p worth (based on assumptions and anecdotal evidence!)

- insufficient torque
could definitely cause it. Should be easily rectifiable by tightening to re-engage the sleeve (weighted if needed).
- wobbly drilling making a too- large hole
I'd be surprised - on installing the bolt wouldn't tighten without the sleeve engaging.
- not blowing dust from the hole
I've never blown dust from a throughbolt hole and rarely had the issue, but having said that a clean hole is probably better...
- not drilling deep enough / not over-drilling
I think this should only really affect how far out the bolt sticks from the wall.
- galling between the stainless nut and stainless thread of the through bolt
Possibly, but I have no idea how likely this is for a stainless bolt that is just being done up once and maybe tightened a few times.
- hitting the nut rather than the end of the bolt and damaging the threads of the through bolt
I think this is definitely the cause if the bolt only starts spinning when the nut is nearly off, but it shouldn't be the cause in other cases (although it's a pet hate!)

For removal, I go with rsch's method (and whilst being a fatso might be beneficial, I think anyone's full body weight should generally be enough).

I'd not tend to use a bolt that spins, but it should be able to be re-set by tightening it (under load if necessary). I'd use it then.

 

[mikem]

If the end has expanded then it's not going to fit through the rest of the drill hole unless the hole is too big in first place or again rock has fractured. Having said that I wouldn't use it if you could easily pull it part way out of the rock

 

[pwhole]

Wasn't there a thread 'somewhere' (maybe not on here) about deliberately spinning a throughbolt with a drill to cut the rock out enough with the cone to then pull it out? I'm sure I've read that somewhere recently.

 

[Benfool]

Wasn't there a thread 'somewhere' (maybe not on here) about deliberately spinning a throughbolt with a drill to cut the rock out enough with the cone to then pull it out? I'm sure I've read that somewhere recently.

I think the idea is to tap the bolt in a little to release the cone from the sleave, then spin the cone inside the sleave to create a groove. Then when you pull the bolt out the sleave doesn't engage properly as it hits this groove and the bolt "should" come out easier.

B

 

[pwhole]

Aha! I don't think this is the one I saw, but it seems to be the same principle - thanks

 

[mikem]

Meanwhile, also in the US:

5-piece bolt removal tip:

Find rock climbing routes, photos, and guides for every state, along with experiences and advice from fellow climbers.

www.mountainproject.com

 

[nobrotson]

Apparently this was also a pretty common issue in Peru this year with the same bolts CUCC were using Becka. So I'm inclined to say it could be a technical fault with the Raumer hangfix batch...

 

[mikem]

Next question is whether it's a particular size (3 lengths of both 8mm & 10mm available, raumer have 12mm as well - the longer ones have 2 collars), plus new (flanged nut) or old (classic nut & washer) versions?

Blurb from inglesport website:
"The expanding collar is a new design and has greatly improved on the previous version.

The design phase focused on creating a technology which ensures expansion on an increased number of surfaces. Once placed, these anchors provide a safe, reliable and long lasting fixing.

Attention: On particularly soft rocks (such as sandstone) all expansion bolts – including our own – are not recommended due to the unreliable nature of the supporting material.

In these circumstances we recommend the use of fixed resin anchors (epoxy glue resin) or Multi-Monti screw anchors.

Very popular ior exploration and sport caving rigging."