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slacklinejoe
Nov 22, 2010, 10:43 PM
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Am I missing a point here? If a glue in is left unnecessarily high and loaded excessively, of course it'll bend (and then break).
Many fresh 3/8" bolts have snapped under slackline loads, hence the reason we use multiple 1/2" bolts (usually 3+ on each end) for highlines.
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majid_sabet
Nov 22, 2010, 11:47 PM
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qwert wrote: [majid] [image]http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=5364;[/image] [/majid] qwert
pretty high forces but interesting so who makes this bolts and how do you fix it ? screw-in or glue-on ?
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majid_sabet
Nov 22, 2010, 11:49 PM
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slacklinejoe wrote: Am I missing a point here? If a glue in is left unnecessarily high and loaded excessively, of course it'll bend (and then break). Many fresh 3/8" bolts have snapped under slackline loads, hence the reason we use multiple 1/2" bolts (usually 3+ on each end) for highlines.
Joe
you mentioned you broke 3/8" under load so did you just use one bolt or multiple and what type ? SS or galvi ? any photos you can share !!.
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slacklinejoe
Nov 23, 2010, 12:06 AM
Post #5 of 6
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Sorry, no pics that I can remember. Lost Arrow Spire is missing one that snapped. I think some friends blew a bolt in StackRock Arkansas (wasn't equalized well so their fault) and I even blew one in my garage for my indoor A-frames.
It's important to note that failures are usually in line with rated strengths. Certain types of lines just produce that much force.
Biners break all the time too, hell there's probably a dozen or more posts here with photos of that. Granted a lot of these were tri-loaded and so forth.
Harsh jumps on a short semi-static line with nearly zero give tends to be the gear breakers from my experience.
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USnavy
Jan 24, 2011, 7:27 AM
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qwert wrote: [majid] [image]http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=5364;[/image] [/majid] qwert
For starters, that bolt was installed incorrectly. I hate when unqualified people install these bolts. Doesn’t anyone read the tutorial on Fixe's website?! You have to chisel out a channel for the bottom of those bolts to sit in. Doing so will increase their shear strength. Also, placing a bolt 2" from the edge of the rock is pretty stupid. Three words, critical edge distance. The critical edge distance of a 3/8" x 3.5" bolt like the one pictured above is about 5" in 4 kPSI concrete. A quick refrence check with Simpson shows that placing a 3/8” x 3.5” bolt 2” from the edge of normal weigh concrete (probably 4kPSI) gives a load reduction adjustment factor of only .37. In other worlds, if the ultimate mechanical breaking strength of a 3/8” bolt is expressed as x, than placing that bolt 2” from the edge of your material would give you a shear pullout strength of .37x, which is pretty damn low.
Now granted that rock probably has a compressive strength of 10 kPSI, but that’s not the point, it’s not wise to place bolts that close to the edge of your material, especially when you don’t even install them correctly in the first place.
This is how you install those bolts: http://www.fixeusa.com/guide_14a-gluein.htm
(This post was edited by USnavy on Jan 24, 2011, 7:45 AM)
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