Rubber ring on bolt

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Justin
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Rubber ring on bolt

Postby Justin » Mon Jun 02, 2014 5:33 pm

Out of interest...

I spotted a Fixe bolt with a rubber ring around it - the (fixed) rubber ring is seemingly there to stop water seeping down to the 'mechanical' (bottom) part of the bolt.

Engineers out there: Is this a good idea/necessary? I ask because all (25 or so) of the bolts that I've broken off have broken at that point just below the thread (i.e. a few mm's inside the hole)?
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bolt_with_rubber_washer.jpg
Fixe climbing bolt with rubber ring
bolt_with_rubber_washer.jpg (196.05 KiB) Viewed 1364 times
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Brussel
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Re: Rubber ring on bolt

Postby Brussel » Mon Jun 02, 2014 7:25 pm

I guess it may keep water out assuming the surface of the rock is smooth and there is no gap for water ingress. I'd be concerned though about it keeping water IN the hole. In my experience that is more than often what happens with things meant to keep water out :)

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XMod
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Re: Rubber ring on bolt

Postby XMod » Tue Jun 03, 2014 12:48 am

Its an O-ring seal so I presume its for waterproofing, I would think though, that our rock can be somewhat porous and absorb moisture, it would all depend on the piece of rock itself, The O-ring might be an excellent idea in compact granite (not ours).

All the old bolts that are snapping are of a poor design, narrowing to only 6mm in diameter underneath the sleeve which is close to thread. The 316 rolled bolts we are using now will not exhibit the same failure, their sleeves are of very thin material and the taper underneath the sleeve is less than a millimetre off the bolt diameter, also the sleeve is located far from the thread (and deep in the rock).

So the O-ring may help with extending the lifetime of the sleeve, but only if the piece of rock its placed in is waterproof itself. Probably a good idea for smooth, compact, metamorphosed or highly quartzitic sandstone but probably a bad idea for porous rock such as Orange Plasma wall at Rocklands?

Brussel
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Re: Rubber ring on bolt

Postby Brussel » Tue Jun 03, 2014 7:08 am

although the rock being porous would also allow water in the hole to drain away?

No matter which I cannot think it makes a huge difference.

Go with glue in anchors...I feel safer on them anyhow :)

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Re: Rubber ring on bolt

Postby Old Smelly » Tue Jun 03, 2014 9:56 am

Justin the mechanics of the break are very similar to an ice screw in that it will fail in shear (across its diameter) at the thinnest part where the load comes onto it (the first place where the rock surrounds the steel of the bolt) - sort of like if you snap off a stick that is sticking out the ground the easiest place to do it is right where it sticks out the ground - the change in cross section causes a stress raiser.

So climbing bolts that die from normal use will break at the point where they are supported in the rock. Ironically having threads there makes things slightly worse - reducing the cross section and making their own stress raisers. Glued in anchors see the same forces but do not have the change in cross section associated with the threads so they will be better off.

O ring - funny idea- no perceived advantage.
Really, its not that bad...I think it's my shoes...

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Justin
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Re: Rubber ring on bolt

Postby Justin » Tue Jun 03, 2014 10:55 am

Thanks all for the comments.

Just looking at the pic again (+ the new one below)... when you start to hammer the bolt into the hole, the rubber ring could potentially come loose and slide up to the entrance of the hole (the rubber ring being wider than the bolt). Without using too much force I did try to roll the rubber ring with my hand but it was quite secure on the bolt - so perhaps it would stay in place!?

If the thread is hammered into the hole (which is often the case) then moisture will get around the rubber ring via the thread.
So nice idea, but seemingly no advantage? With a potential disadvantage of trapping water in the hole?

On the Fixe website, they do mention the rubber washer (ring) but don't give any details for it being there.
Also interesting is that they recommend using 12mm bolts for marine environments.
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fixe_bolt_with_rubber_washer.jpg
Fixe climbing bolt rubber washer
fixe_bolt_with_rubber_washer.jpg (75.51 KiB) Viewed 1206 times
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mikej
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Re: Rubber ring on bolt

Postby mikej » Tue Jun 03, 2014 11:39 am

Ask on SuperTopo. A couple of those guys will know I'm sure.

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Justin
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Re: Rubber ring on bolt

Postby Justin » Tue Jun 03, 2014 11:46 am

I just mailed Fixe, will wait and see what they say.
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Re: Rubber ring on bolt

Postby Xenomorph » Tue Jun 03, 2014 2:28 pm

Heya Justin,
BTW what are the lengths of those bolts?

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Justin
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Re: Rubber ring on bolt

Postby Justin » Tue Jun 03, 2014 3:42 pm

Xenomorph wrote:what are the lengths of those bolts?


90mm (the one in the photo above)

They also have a 12mm x 110mm 304 SS bolt listed on their site.
The 'Marine' bolt is a 12mm x 90mm 316 SS (although the pic of the bolt on their website does not look it) - http://www.fixehardware.com/shop/anchor ... edge-bolt/
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Justin
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Re: Rubber ring on bolt

Postby Justin » Tue Jun 03, 2014 3:56 pm

Just looking on the Fixe website again and found the video below on anchor installations.

I took a screen shot of the rubber 'washer' that they refer to. I assume that the rubber 'ring' is something else.

Attachments
fixe_rubber_washer_bolt_01.jpg
Rubber washer on climbing bolt
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Re: Rubber ring on bolt

Postby XMod » Tue Jun 03, 2014 6:02 pm

Look at the '6.99' pic, see where the bolt goes under the sleeve how much thinner it is? That is the same design as the old bolts that keep breaking. Our new spec of either Hilti HASR or Fisher bolts is MUCH better, better design and quality manufactured. DONT use anything else PLEASE.


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