Experimenting with the 3D printed lamp holder prototype

PROTOTYPE ARRIVED TODAY

I had Xometry.com whip off a single lamp holder for me, allowing me to test its fit and functionality before I ordered 164 of the final versions. This site offered a relatively quick turnaround, although at a higher per unit price that other fabs would charge. I would tweak the design, if needed at all, then order from a more cost efficient vendor. I also want the final product to be in white nylon, whereas the prototype only had a black nylon option.

Bulb fits between two upper wings

Opening in bottom for two position header

View of top which will fit into honeycomb cell

BUILDING A LAMP USING THE HOUSING

The process of building a lamp starts with the insertion of a two position header strip through the bottom of the holder. The strip must have round pins in order to fit in the round sockets I put on my PCB. I can use a breadboard as an anchor for the strip (and the holder above it) for the next step.

Header inserted into the holder

I then took a 2114 lamp, which has wire terminals, and placed the leads around the header strip upper pins. When the bulb is situated properly inside the two protective side wings, with the leads wrapped on the pins, I can carefully solder the bulb in place. 

Bulb in place but wires not soldered to pins yet

TESTING FIT OF THE CONSTRUCTED LAMP IN HOLDER

I then plugged the test lamp into the PCB in various positions, some with absolutely perpendicular sockets and some where the socket is tilting to the side. That would give me a sense for how sensitive the system will be to tilt, since the holder ends have to find the cell and slide into the round hole inside the cell of the honeycomb matrix. 

Final check was sliding the holder into the cell just to see whether it might hang up on an edge, requiring more curvature of the part, or if it aligns itself automatically upon insertion. 

Holder in place and bulb lighting 

Placed behind the honeycomb matrix and the lamp illuminated

OBSERVATIONS AFTER THE TESTS

While unsoldering a bulb from the header strip prior to re-using it in the holder, the plastic of the strip got soft and the pins bent sideways slightly. This left the pins at an unexpected angle, tilting in the direction of the longer edge of the holder. I was only expecting alignment issues when the sockets on the PCB were not perpendicular, leaning the holder in the direction of the short edge. 

The pins on the header strip only project out of the holder base a relatively small amount, less than I imagined. This reduces the space available to coil the wire leads and to get the soldering tip in place. I believe it is workable as it is. If I were to make a relief cut on the sides, there would be less bracing for the header strip which would aggravate any leaning tendency. 

I decided that I should straighten the sockets on the PCB as much as feasible, just to improve alignment, but don't find them critical. The holder slides easily into the opening of the honeycomb but does NOT slide into the hole. That causes the completed assembly to stand back a bit from the honeycomb, but eases the alignment requirements substantially. I think this will do just fine.

With that determined, it was time to place the volume order through 3D Hubs which knocked the price down to $0.91 per holder delivered. I expect them to arrive no later than April 21 at which point I will install all the headers and bulbs to finish the project.