DIY $50 portaledge frame--a simplest and strongest DIY frame.
This frame inspired by the need to create easy DIY activist "sits" for aerial activists, namely in the threatened Tarkine Rainforest in Tasmania.
The standard tubing for a lightweight portaledge frame is 6061-T6 Aluminum Tubing.
The A5 Alpine Double design used 6061-T6 tubing, with a 1.125" Outside Diameter, and 0.058" wall thickness, and was engineered for a compact 40" x 75" two-person portaledge frame (the ledge Xaver and I used on Great Trango for 18 days and nights was this size). Metolius and the BD Cliff Cabana ("A5 block-corner designs") also use this size, but it is not the right outside diameter tube for these larger frames, so those companies had to add a "spreader bar" stiffener, a sign of patched design. Over the years, I have helped dozens of homebuilders (including small manufacturers like Runout Customs) make their own A5 design portaledge, but I no longer recommend the "block corner" frame design, as was introduced with the first A5 portaledge in 1987. The better design is to use strong, curved tube corners, using the appropriate radius thin-wall bending tool. This makes for a more rigid (less flexy) ledge frame, and is easier to build.
If you cannot get 6061-T6 (or better yet, 2024-T3), you can use local sourced 6000 series aluminum if you beef up the wall thickness to about 1/8" (twice as thick as the tubing mentioned above). For example, below is aluminum you can buy at a number of supply shops locally in Hobart, Tasmania (6060-T5 is softer and weaker than 6061-T6).
USING LOWER GRADE ALUMINUM TUBING (I.e.6060-T5): (up the thickness to 3mm)
There are a myriad of tools used to bend tubing. Some people have made their own tube benders.
(NOTE: NOT PIPE BENDERS, pipe is a different category of hollow rounds. Pipe benders are not suitable for thin wall tube bending). The most affordable option getting a tool that allows fine control and with the correct bending radius is a tool currently found on eBay for less than $120USD.
Below, just my initial notes in calculating general size. I actually made a tapered ledge by varying the angles of the two "double-bend" ends, so the ledge has a delta shape, allowing bed tensioners on only one side of the ledge. See videos.
VIDEOS (frame, bed, suspension):
Sewing a portaledge bed:
Super simple suspension:
It all starts with the frame.
See this document for a primer on frame strength, deflection, and weight: https://www.deuce4.net/web/GoodByeSpreaderBars.pdf
First the tube size--what tube available?
Ideal tubing for one-person ledge is 1.25"OD, 0.058" wall thickness, and 1" OD, 0.065" wall thickness Aircraft Seamless 6061-T6 tube.
Ideal tubing for two-person ledge is 1.375"OD, 0.058"wall thickness, and 1.125"OD, 0.058" wall thickness tube, with some of the 1.125" reinforced with 1" tube.
many larger order suppliers--check the Thomas Register listings for "6061-T6 Seamless Tubing"
I have found excellent quality 2024-T3 tubing from AliBaba suppliers who have stocklists of metric size tube. But AliBaba suppliers can be hit or miss. You need to request samples prior to getting a big batch. It's possible to find a good supplier of China tubing, which at its best is as good or better than USA seamless aircraft tubing from Alcoa, but be aware of import costs (Australia is quite reasonable).
For metric D4 designs, 5mm of OD tube difference works well with D4 joiners. For example 35mm*1.5mm tube and 30mm tube make for a good combination with the D4 joiner system. In this case, the 30mm might be 1.5mm wall thickness, or 2.0mm wall thickness, depending on design.
Post questions and comments and local supply on bigwallsforum.com, specify what kind of tubing (material, outside diameter, wall thickness, etc) that you can get in your country. Ideally at least 6061-T6 or stronger--HOWEVER, you can use weaker 6000 alloy, but you need to get larger and thicker tubes (heavier). Let me know if you need help with the strength and deflection calculations for a specific size. You can compare with a proven design for a particular size ledge.
I use the Bramley bender for most of my work: Note radius of bends chart.