Now I try to explain how I think the arm component construction. All arm parts or items will be made from metal plates. This is an easy way to create strong and not too heavy items. The metal plate is an easily cuttable by laser, and easily weldable with AWI. By the way, a laser cutted metal component is more cheaper than a milled aluminium component, and the aluminium welding is more difficult than the standard metal welding.
First item of the arm-system is the boom.
This item will be made from 1,5 or 2mm thick plate. The sheet metal components will be cut by laser and after all components of the boom will welded with AWI.
All sheet metal components will be designed to easy assembly. It’s means, that I will plan holes, slots and ears for components like a puzzle. As I saw on the web this is a standard procedure.
The side elements of the boom will be made from thicker plate, maybe 2 or 2,5mm.
The inner elements – like the ribs- will be made from 1,5mm thick plate. However I have to use more thicker (maybe 3-4mm) plate for the main load-bearing elements. These plates will be contain the connecting points for the arm cylinder.
The side elements, inner element and ribs will be connected (welded) to each other, so this welded structure is a complex load-bearing structure by itself. With the outer cover sheets the boom will be a very strong component.
I think for the turning / fixing point I will welded a metal rod into the boom. After the welding I will machined the holes for the bronze sleeves. My idea is, that the contact point will be made from a cylindrical metal rod. To connecting with the house, I will use an 10 mm diameter bolt. To greasing the boom-bolt, I will have to build in a greasing knob. There will be a stepped hole inside the rod for the two sinter bronze sleeves. So, this will be the base point of the boom and here will be contacting with the house.
Here is a sketch:
