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sexual_chocolate

Loose Bolts

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Head's up: we were climbing on a crag at the base of Icicle Buttress, and a friend pulled a bolt while falling on top-rope.

 

It was clipped as a directional on a steep route, so that tells you about the integrity of the bolt.

 

I then checked the anchor bolts, and one of them wiggled.

 

 

Anyways, head's up on bolts. They might not be as safe as you assume.

 

 

 

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Yeah, how about a heads up to the route itself... Then maybe we can check and replace those bolts and others put in by the same person in case a whole set is bad for some reason. Good to know on the crag though. Thanks.

 

As for "bolts" in general I don't think you should ever trust any single bolt. I mean you don't worry about it on lead but you should always use both bolts at anchor type situations or even back them up if the seem suspect. I've hand pulled a bolt on lead before. Just popped it back in and clipped it anyway :)

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Wow. Did the bolts look okay? What route was it?

 

yeah bolts looked great. pretty new and shiny, 3/8". only 2" or 2.5" in length though.

 

i think the route is referred to as "the beast", a project as far as i know. it's on the short overhanging road-facing wall left of a route called "spaghetti sauce".

 

the rock is somewhat decomposing and granular, so any bolt placed there should be epoxy-reinforced.

 

it does bring into question the integrity of hardware, all of which should be checked occasionally and any deficiencies pointed out in forums such as this.

 

there is at least one other bolt on the route besides the anchor bolt that also moves.

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the rock is somewhat decomposing and granular, so any bolt placed there should be epoxy-reinforced.

 

it does bring into question the integrity of hardware, all of which should be checked occasionally and any deficiencies pointed out in forums such as this.

 

I am a bit unsure what you mean by epoxy reinforced. I have always thought that bolts that work via some mechanical principle shouldn’t be epoxied because doing so can inhibit the mechanical action. That said if you use an epoxy suitable for a glue-in bolt what you are really doing is turning a mechanical device into a chemically bonded one which is probably ok just an inefficient use of dollars. If the wrong epoxy is used you might simply be creating a time bomb.

 

 

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the rock is somewhat decomposing and granular, so any bolt placed there should be epoxy-reinforced.

 

it does bring into question the integrity of hardware, all of which should be checked occasionally and any deficiencies pointed out in forums such as this.

 

I am a bit unsure what you mean by epoxy reinforced. I have always thought that bolts that work via some mechanical principle shouldn’t be epoxied because doing so can inhibit the mechanical action. That said if you use an epoxy suitable for a glue-in bolt what you are really doing is turning a mechanical device into a chemically bonded one which is probably ok just an inefficient use of dollars. If the wrong epoxy is used you might simply be creating a time bomb.

 

 

i'm not aware of the contra-indications with mech bolts and epoxy, and have never used the combo. seems to me if the wedge can be activated in the presence of epoxy, this approach would be superior to a simple epoxy bolt....

 

anyway, because of the rock issues at this crag, a one piece wedge bolt seems to be an unsafe approach.

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anyway, because of the rock issues at this crag, a one piece wedge bolt seems to be an unsafe approach.

 

Is this because of the rock issues, or because the bolt was placed incorrectly?

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anyway, because of the rock issues at this crag, a one piece wedge bolt seems to be an unsafe approach.

 

Is this because of the rock issues, or because the bolt was placed incorrectly?

 

my thought is that any purely mechanical bolt will slowly loosen because of the decomposing and granular nature of this particular crag.

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i'm not aware of the contra-indications with mech bolts and epoxy, and have never used the combo. seems to me if the wedge can be activated in the presence of epoxy, this approach would be superior to a simple epoxy bolt....

 

My hunch is that the choice of expoxy is critical. Ultimately every choice involves tradeoffs. What I find surprising is how little people actually know about what they are doing. (myself included) Overall things seem work out but there are always great leaps of faith being made.

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Is this the same whaa whaa bad rock factor that caused a perfectly protectable crack to be bolted over by Spaghtti Sauce?

 

It sounds to me more like maybe the holes were drilled with the wrong size bit (9mm bolt but 10mm hole), or that the holes were drilled too deep so that the wedges did not engage.

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I....or that the holes were drilled too deep so that the wedges did not engage.

 

Say what? If we are talking about any bolt that I have ever seen, one is supposed to drill the hole deep enough so that the bolt doesn't bottom out. Drilling deeper holes has been postulated to provide a pocket for water to collect and lever out the bolt whenit freezes, but many climbers using wedge anchors drill extra deep so there is room to tap the bolt in an bury it if you need to subsequently chop it.

 

I have never heard of anybody suggesting a hole was "too deep" for a reason like what you are describing.

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Sounds to Me like a case of someone not knowing what they where doing.

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the rock is somewhat decomposing and granular, so any bolt placed there should be epoxy-reinforced.

 

it does bring into question the integrity of hardware, all of which should be checked occasionally and any deficiencies pointed out in forums such as this.

 

I am a bit unsure what you mean by epoxy reinforced. I have always thought that bolts that work via some mechanical principle shouldn’t be epoxied because doing so can inhibit the mechanical action. That said if you use an epoxy suitable for a glue-in bolt what you are really doing is turning a mechanical device into a chemically bonded one which is probably ok just an inefficient use of dollars. If the wrong epoxy is used you might simply be creating a time bomb.

 

 

i'm not aware of the contra-indications with mech bolts and epoxy, and have never used the combo. seems to me if the wedge can be activated in the presence of epoxy, this approach would be superior to a simple epoxy bolt....

 

anyway, because of the rock issues at this crag, a one piece wedge bolt seems to be an unsafe approach.

sexy chocolate...its not a good idea to mix the two...either rely on a mechanical bond (friction) or rely on a chemical bond. The epoxy WILL fuck up the mechanical bond....

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anyway, because of the rock issues at this crag, a one piece wedge bolt seems to be an unsafe approach.

 

Is this because of the rock issues, or because the bolt was placed incorrectly?

 

my thought is that any purely mechanical bolt will slowly loosen because of the decomposing and granular nature of this particular crag.

on shitty concrete, we have significantly OVERDRILLED the hole and used an epoxy bolt to keep the bond stresses between the wall holes and the epoxy plug as minimal as possible...you basically are "rebuilding" the local area with an epoxy grout....

 

freeze thaw will fuck you though...the advantage of a slip cone for mechanical bond is that its "adjustable" in the sense that the bolt can be retightened to account for slop in the system...one way to hedge this is to increase the length of embedment for either system...

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I....or that the holes were drilled too deep so that the wedges did not engage.

 

Say what? If we are talking about any bolt that I have ever seen, one is supposed to drill the hole deep enough so that the bolt doesn't bottom out. Drilling deeper holes has been postulated to provide a pocket for water to collect and lever out the bolt, but many climbers using wedge anchors drill extra deep so there is room to tap the bolt in an bury it if you need to subsequently chop it.

 

I have never heard of anybody suggesting a hole was "too deep" for a reason like what you are describing.

Matt,

There are bolts that require one to drive it with a hammer into the bottom of the hole for the shaft to expand. Some manufacturers of these expansion-style bolts are Hilti, Mammut, and Petzl.

 

Here's Petzl's version.

 

I have a kit made by Mammut that I bought in Italy, but I can't find a decent pic of the bolts that go with it. But the same principle applies: Drill the hole to the same depth as the bolt shaft/cutting unit is long, blow out/clean the hole, insert solid cone into cutting end of bolt, drive bolt home with hammer, place hanger over bolt, screw in Allen head stud to secure. Note that the Mammut style of expansion bolt is NOT the same as the more common Rawl/Powers/Hilti/Petzl expansion bolts that achieve fixation by tightening a threaded bolt, thereby drawing a tapered cone inside the sleeve toward the nut, hence expanding the sleeve against the walls of the hole as the nut is tightened. Clearly, those bolts should have a deeper hole.

 

The kit I have is a hand-drilling kit. The bolt and cutting unit are integral - the bolt is the drill bit. The stud threads into the bolt after you've embedded it, and the stud secures the hanger. It does nothing toward increasing the expansion/holding power of the bolt. The hammering of the bolt into the rock after placing the solid truncated cone in the drilling end is what expands the bolt into the hole. If you drill the hole too deep, this expansion will not take place. Kurt Hicks used my kit to place a needed bolt on a FA at Lightning Dome two years ago. He needed a short lesson on how it worked, but he got 'er done. You could PM him for more info, if you care.

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Matt, if you drill an 8 inch deep hole and put a 2 inch long bolt in it, do you think the extra 6 inches of dead air space reduces or increases stability vs. a hole with no airspace?

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Dru, what mechanism for "stability reduction" are you proposing? I am having a hard time imagining a lot of physical scenarios where it might really matter, aside from the aforementioned case of water freeze/thaw. Are you implying that the back of the cavity is somehow load bearing? I.E. that the tensile strength of the back of the cavity some how has a non-negligible effect compared to the compressive strength of the rock around the expansion collar.

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When you place an expansion bolt, the wedge/cone is forced into the bolt somewhat by the sides of the hole, but the back of the hole also has an effect. A bolt that has dead space behind doesn't have the wedge forced as tightly into the sleeve and hence is weaker.

 

Put another way - if the bolt, like matt suggests, can be tapped deeper into the hole by hammer blows - it can also be pulled OUT by the same forces. If the bolt is snug against the back wall of the ole and can't be tapped further in, it also has the wedge deeper into the sleeve and is more solid as a result.

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Thanks, Sobo. Those Petzl long life bolts are pretty spendy, no? Have you ever seen them used?

 

I've seen those "self driling" bolts at PMS or some other local shop in years past, but never tried 'em. If you were just carrying a couple of them for a possible bail out option, I can see the utility in not carrying the drill. What is your opinion of them?

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I only trust bolts I have placed, and they are 3 or 5 piece anchors.

 

Wedge anchors are for construction, and anyone too cheap to get the decent bolts should stick to trad or clipping other peoples bolts! :battlecage: :battlecage:

 

Why on earth anyone would waste energy/drill power drilling a hole 6 inches deeper than the bolt is long is just as much of an idiot as the person above, and should follow the same advise.

 

There. Cleaned that mess right up! :poke:

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there's a Petzl Longlife on midway direct direct

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It's hard to botch a wedgebolt placement in hard rock, as placing one is as simple as drilling a hole deeper than the bolt is long (you can't drill the hole too deep), blowing the hole our, tapping the bolt in, and tightening it down.

 

ASCA Page

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