Forces on Hammock stand guylines/stakes...

**Nest** · 10-10-2007, 17:04

umm... huh?

**warbonnetguy** · 10-10-2007, 17:22

Originally Posted by Rapt

If you intend to hang lower down you'll have to do a pure bending analysis also. Perhaps a choice for the subject of another thread.

But this should get you started...

i was thinking about being able to adjust the guyline attachment point as i adjust the hammock attachment height. that way both points are always the same height, and i can avoid this force while still allowing for adjustable height.

**Rapt** · 10-11-2007, 06:38

Yes, that would solve the issues with bending and keep the pole (column) in pure compression.

FWIW bending analysis is easy (at least as easy as buckling). But it is another thing and would result in needing a stiffer (and therefore heavier) pole.

**ZDP-189** · 10-11-2007, 23:33

The more I think about this the more I appreciate the Bat hammock offering lay-flat comfort and a single attachment point and no side load.

**warbonnetguy** · 10-13-2007, 00:04

i've been looking at alum tubing, some places are pretty pricey, i did find one interesting place though, they make tube for ham radio antennas, which are designed so that each size fits perfectly into the next size up.their prices seem good too. they have 2 kinds of alum though. 6061 extruded, and 6063 drawn. doesn't say which is stronger, or what the difference between extruded and drawn is.

if i go with the drawn, the wall thickness is only .058", which is a bit smaller than 1/16". i'm wondering if this might be too thin. the outside diameter would be 2" or 2 1/8". if i switch to the extruded, the wall thickness would jump all the way up to 1/8", which seems a bit large, and i would still have to use a .058" wall piece for an insert unless i get the insert from somewhere else.

here is the link:http://www.texastowers.com/aluminum.htm

**warbonnetguy** · 10-13-2007, 00:45

this place http://www.globaltecheng.com/alutubi...ID=15039389521
has .083" wall thickness, and is cheap, but tubes don't fit together. rapt sent me a link where you could make your own carbon fiber composite tubes, but i'm hesitant to try this. here's the link:http://www.aerosleeves.com/

**warbonnetguy** · 10-15-2007, 07:30

i think i'm going with the .058 wall thickness and the 2.125 tube dia. how long should i make the insert pieces?

**Rapt** · 10-15-2007, 07:47

I think your tubing choice should be fine. (about .4 lbs per foot)

This partly depends on how much clearance there is (or how tightly the insert fits). Tighter means better alignment and stress distribution, but harder to put together and take apart... And more prone to dirt gumming things up.

Looser is easier, but also weaker. ]

The fixed side can be shorter since it'll be tight and permanent. The taking apart side is where the most length should be. I'd say use a similar length/diameter ratio as tent poles do for their inserts... (probably you can get away with a bit less since you're not bending them in arches.)

Or you can start long and keep cutting it down and then when it fails you know the minimum length.... So then you make them longer than that... Of course that means making at least one extra pole.

**warbonnetguy** · 10-15-2007, 17:22

well, i want to make it light within reason, but i'm not taking it backpacking or anything, so an extra few ounces doesn't really matter here. the way my easton poles are, the ratio of insert diameter to length sticking out, the part of the insert sticking out would be 11". this seems excessive. i was thinking around 4"-6"(sticking out), do you think that would be pushing it? i ordered enough insert tube to make (4) 18" inserts, so i will have enough to make them longer.

do they sell a home anodizing kit somewhere too?

i was thinking just paint, but having them anodized would look good. how does one anodize by the way?

Originally Posted by Rapt

I'd say use a similar length/diameter ratio as tent poles do for their inserts... (probably you can get away with a bit less since you're not bending them in arches.)

Or you can start long and keep cutting it down and then when it fails you know the minimum length.... So then you make them longer than that... Of course that means making at least one extra pole.

**Cannibal** · 10-15-2007, 17:28

Originally Posted by warbonnetguy

how does one anodize by the way?

Current increases the oxidation of the metal, creating a barrier to corrosion. Or something like that.

Basically, set it in a liquid solvent and run a small current thru for a while. I did this in High School (eons ago) and it was pretty basic. Google it and I bet you find detailed instructions.