Gas station without pumps

2019 September 17

Spacers for electric outlet box

Filed under: Uncategorized — gasstationwithoutpumps @ 12:34
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Yesterday I printed some functional (rather than decorative) parts. The problem I was addressing was one that had been bothering me in a low-key way for several years—an electrical outlet in the living room that was wobbly. The problem started when I had the front wall insulated. Because the wall is self-formed concrete, sheets of foam insulation were added on the inside of the wall, sheet rock put over the insulation, and then a skim coat of plaster added to match the original texturing of the walls. The outlet box for the electrical outlet was now rather deeply recessed in the wall, and the carpenters move the outlet forward by using longer screws.

Unfortunately the spacers they used to hold the outlet in the new position were not real spacers, but plastic wall anchors, which did not hold the outlet firmly in the right place—they were relying on the strength of the plastic wall plate to hold the outlet forward. This was never very secure, and this summer the wall plate broke while plugging in an extension cord, so I decided to print some properly sized spacers to hold the outlet securely in place.

I turned off the power and measured the spacing needed with the depth gauge of my calipers, as well as measuring the room available for the spacer. I printed two spacers that were 13mm long and replaced the outlet, only to find out that outlet was still too deep in the wall for the new cover plate to be screwed to the outlet. I tried measuring how much further out the outlet needed to be (estimated at 9mm) and printed a pair of 22mm long spacers.

These are the 13mm and 22mm spacers that ended up being extra. The ears on the spacer are not necessary—I put them on to match the outlet, to make alignment easer, as the hole was initially not centered vertically. I later changed the design so that the hole was centered, so the orientation is now irrelevant and a simple rectangular spacer would suffice. The parts are printed with 0.14mm layers in Hatchbox Gold PLA, with 25% infill.

On the first attempt to print a pair of 22mm spacers, one printed fine, but the other ended up with a long trail of tangled spaghetti after printing halfway just fine. Reprinting just one 22mm spacer failed again, this time with a blobby mess. The problem, however, was clear—the print had gotten detached from the baseplate and was moved around by the printhead. Using some hairspray on the bed increased the adhesion enough that it printed fine, without needing to add a brim.

These two prints were supposed to be 22mm spacers. The one on the right was printed at the same time as one of the successful prints, and the one on the left was an attempt to reprint just one spacer. For both, the failure was insufficient adhesion to the glass bed—I fixed the problem by using hairspray to increase the adhesion.

When I put the 22mm spacers in place, the outlet stuck out too far (my measuring skills clearly need some improvement). The outlet stuck out much more on the bottom than on the top, so I put on the cover plate and measured the clearance from the wall on both the top and the bottom. I decided that I could use the smaller 13mm spacer on top, but I would need an 18mm spacer on the bottom. After printing an 18mm spacer, I assembled the outlet once more, and everything fit perfectly, with the cover plate flush against the wall as desired.

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