Turn-Signal Mount Clip

Turn-Signal Mount Clip

In the early Spring of 2012, I was driving with a friend to Fazzio’s (an industrial surplus place in New Jersey, which is The Promised Land to Swarthmore engineers and which I can’t recommend highly enough), when he yelped that the headlight was dangling out of the front of the car. Upon stopping, we discovered that indeed, a small plastic clip on the turn signal housing had broken off, allowing the housing to vibrate out of the car (a ’99 Volvo S80), where it was left hanging by its wires.

Instead of purchasing a new light housing (to the tune of 70-something dollars), I elected to try and print out a new clip using the 3D printer my friend Andy Bastian was putting together. Of course, it took me nearly 6 months to get around to actually starting the project, by which time the Engineering Department had already purchased a uPrint 3D printer. I modeled both the right- and left-hand clips in SolidWorks, and printed a few copies of both (I had broken the clip on the other turn signal housing while trying to remove it to get dimensions off of it – clearly, the plastic in the housing does not age well).

Although printing went quite well, installation was not quite as easy, with my first few gluing attempts failing. I ultimately found the following procedure to work well:

  1. Clearly indicate where on the turn signal housing the clip needs to go (I marked the locations of the edges with a permanent marker).
  2. Flatten (if needed) and roughen the attachment surface of the turn signal housing. Roughen the attachment surface of the clip.
  3. Using Testor’s Model Glue (or any plastic glue that will meld ABS), glue the two parts together. Allow to cure fully (I’d do 24 hours minimum).
  4. Completely coat all corners between the two parts with epoxy formulated for plastics (I used Loctite Plastic Epoxy). Allow this to cure for a long, long time – I allowed 48 hours. I’m pretty sure that most of my previous failed attempts were due to insufficient curing.
  5. Install!
As of this writing, both turn signals have driven 2,500+ miles without any indication of the bond unadhering – fingers crossed that things continue this way!

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