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General Climbing Discussion

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Only a Climber......

certifi

7-Feb-2008
7:25:00 PM

i just put up a Hammock on my City view balconey :) , i employed all of my climber savy and came up
with a bomber anchor! i figured that only other climbers would be able to appreciate this. cost me $40 for
the Hammock and i had everything else lying around/rack. hope you like.

PS mods, awefuly sorry for the huge pictures. will scale them down and re-post

kieranl

7-Feb-2008
7:38:24 PM

Interesting forces on the middle link in the chain. I'm guessing the bolts are glue-in but the diagonally bent RP hanger will gradually flare out under load. Probably not a significant factor unless you are talking 5-10 years.
Do you own the place BTW.


sliamese

7-Feb-2008
8:02:34 PM

is my memory right thinking 120 degrees puts 150% of the load on the anchors? maybe a longer piece of chain would be better! but awesome job! i need to something like that for my own hammock!!


cruze

7-Feb-2008
8:18:17 PM

The use of small diameter biners (and wiregate biners) with bolt plates is a no-no. I would recommend backing that rig up with a sling around the venetians.

certifi

7-Feb-2008
8:21:18 PM

Yes i own the place.
Yes the Bolts are ss 10mm x 100mm glued into solid concrete bricks with chemset
Yes i am aware that 120 ish degree puts roughly 150% load on each anchor, BUT i had to find a happy
medium between scrapping the ground when sitting on it and load on the anchors. Which im no to
concerned about seeing as i have 90~kilos spread between four equal load points. Also the load
direction was an important factor that i took into consideration. But again load is on four points so im
not worried. Well the hanger gets rotated and i change the one i use each time, as i take it down after
use.
I checked before hand wether the bricks were solid/hollow/vented and also wether the wall was
cavity/veneer etc.
If you do this dont skip on things. I did about a weeks worth of theory and practicle research as well as
testing before i started.
Got any Q's pm me.

certifi

7-Feb-2008
8:33:21 PM

"The use of small diameter biners (and wiregate biners) with bolt plates is a no-no. I would recommend
backing that rig up with a sling around the venetians."

rolling on floor laughing *does action*

i checked and even the 8mm didnt come out.

kieranl

7-Feb-2008
8:36:02 PM

Fair enough. But a better soluton might be to have two quick-links into the support loop of the hammock rather than one, and have each link clipped into a single chain link which is in turn clipped into a hanger quick link. That would reduce your forces quite a lot.

certifi

7-Feb-2008
8:45:11 PM

Fair point. But i think i should be fine as is, plus i wanted to make it out of existing gear, and your
solution would bring money into the equation.
also it would lower the height of the hammock (i can only just get the yellow pages under me as is) for
only a little less load.


matt

7-Feb-2008
10:27:53 PM

hmmmm so much thought went into this....

i got two dyno bolts from bunnings, some shitty chain links and two 'bunnings biners' and drilled away into my appartment buildings concrete supports.

No i don't own the place.
No i'm not alowed to drill into the concrete.
No i didn't seak any advice.
No it hasn't fallen down.
Yes i've had two drunken people swinging around in it jumping around stressing it etc.
No my dyno bolts haven't shifted.

here's my dyno bolt:

and the view with a drink...

cheers and enjoy the pleasures of a hammock...

certifi

7-Feb-2008
11:33:06 PM

BAHAHAHAHA @matt

love what you just said then

mate it was more than just about the hammock, it was a project. all men need there projects


gordoste

8-Feb-2008
11:43:51 AM

On 7/02/2008 matt wrote:
>Yes i've had two drunken people swinging around in it jumping around stressing it etc.

good to see you've put it through the "love test"

Ronny

8-Feb-2008
2:20:46 PM

... or someone who knows climbers.

I once visited my dad's house and he proudly showd me how he'd used bolt plates and spectra cord to tie down his washing machine that otherwise would vibrate itself across his laundry. I suggested that, given the likely force put on the bolt plates by the wayward washing machine, maybe it was slightly "over engineered".

J


Sabu

8-Feb-2008
11:07:10 PM

On 8/02/2008 Ronny wrote:
>slightly "over engineered".
NEVER!!!


evanbb

9-Feb-2008
6:33:10 AM

On 8/02/2008 Sabu wrote:
>On 8/02/2008 Ronny wrote:
>>slightly "over engineered".
>NEVER!!!

I tend to agree, what does 'over engineered' mean? It's just an increased margin of safety.


Eduardo Slabofvic

9-Feb-2008
4:29:56 PM

On 9/02/2008 evanbb wrote:
>I tend to agree, what does 'over engineered' mean? It's just an increased
>margin of safety.

......but more often a strategy to avoid litigation.

hero

9-Feb-2008
11:46:21 PM

When my daughter was young her car seat was attached with rp brackets, biners and slings. A guy in a garage suggested it wasn't safe. It was rated much higher than the official fitting which we didn't have.

lacto

11-Feb-2008
9:45:55 PM

Assuming that acouple from the "biggest losers ie 300 kg " were in the hammock , 300 kg is approximately 3 kN load on the system . if the hammock strings were at 30 degrees to the horizontal then the load in each string would be 3 kN , and equally the load on each bolt would be 3kN , that is 4 loads of 3 kN would support the two people .
loads within the system to be carried by the chain or krab is 3kn divided by 2 or 1.5 kN Mild steel has a strength of 340 mPa so the area required to carry 1.5kN is 4.4 sq mm or 2.4 mm diameter chain or crab
actual chain size
4mm area 12.56 sqmm os safety factor of 5.2
5mm 19.6 8.1
6 mm 28.2 11.7

vey few things built have safety factor in excess of 2 The steel work is not the problem but the capacity of the bolt anchors would more likely to be the weak link . Throw a normal person in the hammock and the safety factors are enormous and the consequenses of a fall a few cm to the floor. get a life enjoy the hammock it is safe

certifi

13-Feb-2008
8:35:47 PM

i wasnt posting it to check it was safe. nor did i use the anchors i did because i thought they would fail.
as i have no information about the brick work wich is why i wanted to reduce potential load on bricks.


matt

13-Feb-2008
10:46:40 PM

nah you did it so you can swing in the hammock and drink beer and get sea sick... i do if it swings too much...

certifi

14-Feb-2008
7:19:52 PM

thats not even the best part. if you need to open your beer, one of the rp bolt brackets does the job
nicely.. :)

There are 21 messages in this topic.