With the rough design in mind I designed all the joint components in Solidworks for 3D printing.
In total there are 6 joint pieces per side; two at the base, two at the top, and two small nubs that will connect the reflector (not shown above). The two joint pieces at the base are pretty straight forward, the only important feature in this was to make the inner piece, which fits inside the copper tube, hollow so that the LED wires could be run internally. The top two joint pieces are the most complex of this design. The outer (left) piece has a large hole in the bottom so that it can be fixed to to the copper tube. The majority of this piece is hollow aside from the core which supports the axial screw. The hollow cavity is for extra slack in the wires so the connecting piece can rotate without tugging on them. The inner (right) piece is the crux of this joint system.
a) Hole for axial screw and bolt. b) slot for aluminum bar with a notch for the led wires. c) Hole for locking screw to fix aluminum bar in place. d) Slots to allow reflector to move from front to back. e) Mounting hole for telescoping bar.
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The bottom reflector nub attaches to both ends of a brass bar and slots into the inner-top joint. The top nub also attaches to both ends of a brass bar which connect to the top of the telescoping bars.
The most difficult part of this was determining tolerances since I had not yet made anything that joined to other parts (of various materials). Additionally, I found that the 3D printed PLA changes over time, depending on the shape and the way it was extruded, it can shrink, expand and even warp if under stress over a long period of time.
The only way to resolve this was by trial and error. Parts were designed to fit snugly however I quickly realized I needed at least 0.1″ extra clearance to get ‘snug’ fits.
Joints aside, I also needed to get together the non plastic parts that would fill in everything in between. I sourced 2″ #6-32 machine screws + nuts, 1/2″ wood screws, a 1/4″aluminum bar, 2 1/8″ brass rods, a piece of 3/4″ diameter copper pipe (meant for plumbing) and a 8′ plank of 1×3, all from Home Depot. All the metal components were cut to size and polished with steel wool to achieve a very nice shine. The wood was cut to length, however I found despite being very careful to pick one that was straight, after cutting it it turned out to be very warped.
Additionally I picked up a sheet of poster board from the dollar store which would become my reflector and a set of bunny ears (telescoping TV antennas) which was the single worst purchase I’ve ever made. I don’t think I’ve been scammed worse than for the bunny ears which cost me ~$10 for 2 pieces of telescoping metal, a plastic shell and a copper wire that was screwed to the bottom of each ‘ear’ that went out to the TV. I had no idea these things were that simple and it certainly was worth much much less than $10.
With all the joints printed, it was a simple matter to assemble everything together. It really is amazing to be able to develop a concept in my mind and make it into a reality. However, like any other prototyping process, design flaws may not be realized until after the thing has been built.
Two of the major issues I found with my design are weight distribution and using screws in rotational joints. Looking back at the design, I had imagined that the majority of the lamp would be fairly light, but having used metal bars, pipes and rods with a light cedar base, the lamp is very top heavy. This was further compounded with the fact that the rotational joints had fixed slots for the nuts, meaning the joints would loosen every time it was moved. Even if the top heavy lamp managed to stay upright, there was a good chance the reflector section would just spin downwards since the joints would not be tight enough for friction to hold it’s position.
In the mean time, I’ve left the lamp mostly upright, which is still usable. Now that it’s been tested, I have a better idea of what I want to do and the design requirements for revision 2. Ah, the life of prototyping.