Spacecraft . square pyramid jig

Posted on by dkoa
4 pcs 1in angle bar chamfer cut and welded to form square inverted pyramid with sturdy base, metal off-cuts.
4 pcs 1in angle bar chamfer cut and welded to form square inverted pyramid with sturdy base, metal off-cuts.
square pyramids made with 4 pcs. iron rod with single weld bead at tip should be self-supporting.
square pyramids made with 4 pcs. iron rod with single weld bead at tip should be self-supporting.
pre-cut all iron rods to identical length using metal cutter, saw or angle grinder.
pre-cut all iron rods to identical length using metal cutter, saw or angle grinder.
16 pyramids required to fabricate one semi-octet truss.
16 pyramids required to fabricate one semi-octet truss.

Spacecraft . 2d truss jig

Posted on by dkoa

Mild steel angle bar is liable to twist or bend before the truss is triangulated; to ensure that each octet truss you make is straight (±1 mm) use a straight and square metal jig with wood board forming welding bed (will burn over time, flip over before replacing). Use clamps to secure 2d truss frame to jig, and push metal against wood plate of jig with a nonconductive pipe or wood stick.

Welding: Tack weld first throughout to assemble octet truss, then complete full weld once all metal elements are held in contact. Usually a small amount of grinding required to clear sharp edges. Apply hardener coat to seal and spray 3-6 coats of automotive paint. Paint damage possible (e.g. scratches) during transport and assembly; paint touch-up work may be done after assembly.

use clamps to secure 2d truss frame to jig, and a nonconductive stick (preferably wood) to push metal against wood plate of jig.

2d truss jig spacer2d truss jig side viewweld flat bar ladder into 2d truss frame5 weld sides to 2d truss frameuse clamps to secure 2d truss frame to jig, and a nonconductive stick (preferably wood) to push metal against wood plate of jig.5 weld safety first6 weld pyramid chain into 2d ladder truss7 weld invert pyramid to angle bar at vertices8 semi-octet trusses should stack interlock9 7 1.5in semi-octet trusses welded, load to paint

finished octet trusses sprayed and loaded in truck bed
finished octet trusses sprayed and loaded in truck bed

Octet truss drill template

Posted on by dkoa

Use a template for drilling holes in octet truss, to ensure that all holes are the same and identically located. Print on paper first,then trace or laminate onto cardboard and punch hole centers per template guides. Provided octet truss welding work is standard, dimensional tolerance of ±1 mm is achievable. Square face bolted connection is 20×20 cm, with holes of sufficient tolerance for no. 17 bolts. Drill templates are here in PDF: octet truss face joint, octet truss face joint -alt (print to A4 size sheet).

octet truss face joint20140910_124607-MOTION copy 220140910_124650-MOTION copy 220140910_124644_15198270395_o20140910_151612_15013174610_o

Spacecraft . octet truss fabrication process

Posted on by dkoa

Fabrication of a semi-octet truss using 1 or 1-1/2 inch mild steel angle bar requires use of several jigs: 2d truss jig, square pyramid jig, and spacers for setting flat bar and holding string line to gauge top angle bar when welding. Each truss comprises 16 square pyramids of 4 pcs 10 or 12 mm by 16.85 cm iron rods welded to a linear array of 19.6 cm flat bar straps set in a 1 or 1-1/2 inch ms angle bar frame 20 cm wide by 282.5 cm long.

Welding: Tack weld first throughout to assemble octet truss, then complete full weld once all metal elements are held in contact. Usually a small amount of grinding required to clear sharp edges. Apply hardener coat to seal and spray 3-6 coats of automotive paint. Paint damage possible (e.g. scratches) during transport and assembly; paint touch-up work may be done after assembly.

2 weld octet truss 1-MOTION

3 weld octet truss 2-MOTION

4 weld octet truss 3-MOTION

amp_octet truss_template

To assembly a semi-octet truss, you will need: 2d truss jig and square pyramid jig.

amp_octet truss_template2 amp_octet truss_template3 amp_octet truss_template4 amp_octet truss_template5 amp_octet truss_template6 amp_octet truss_template7 amp_octet truss_template8 amp_octet truss_template9 amp_octet truss_template10 amp_octet truss_template11 amp_octet truss_template12 amp_octet truss_template13

Spacecraft . box truss assembly

Posted on by dkoa


deck_box_truss-1 deck_box_truss-2 deck_box_truss-3 deck_box_truss-4

deck_box_truss-0

tack weld outer frame of 2d truss in jig then use spacer to precisely set out 1in flat bar lengths.
tack weld outer frame of 2d truss in jig then use spacer to precisely set out 1in flat bar lengths.
tack weld 1in flat bar lengths either side to 2d truss frame.
tack weld 1in flat bar lengths either side to 2d truss frame.

on flat and level ground surface, weld pair of 2d trusses together with 1-1/2in angle bar at top and bottom corners.on flat and level ground surface, weld pair of 2d trusses together with 1-1/2in angle bar at top and bottom corners.

Finally, weld diagonal struts for cross-bracing.
Finally, weld diagonal struts for cross-bracing.

5 box truss floor raft