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3D printed electric car contactor cover

Problem

The prototype version of the Luka EV electric car has a contactor between the battery and the controllers. It has a pair of always-powered contacts that are attracting casual touch. Some sort of a cover is desired.

Solution

Design

The cover was designed in OpenSCAD, around the contactor body. The body is composed of two cylinders of slightly different diameter, and the space with contacts. Original design contained pads to squeeze the contactor body using a bolt between the pads. They were omitted from the final design.


Rendered cover

Rendered cover

Printing problems

The cover is fairly large. Due to lack of familiarity with printing and configuration, the printout tended to lift from the bed in a rather bad way. It was decided to attempt to salvage the printout, trade perfection for filament. A stick of hot glue was heated with a torch and the glue dripped on the edges where the printout was lifting. While not perfect, the result was good enough to finish the print. The first couple layers were ugly but the printout worked.

The bed was found to be rotating as the head was colliding with the lifting printout edges. It was secured with a drop of hot glue.

Stringing was encountered, apparently due to overly high nozzle temperature.


Printing, salvaging with hot glue

Printing, salvaging with hot glue

Printing, salvaging with hot glue

Hot-glue securing of bed

Printing

Printing

Fresh printout

Fresh printout

Fresh printout

Fresh printout

Fresh printout

Fresh printout, bottom side before glue removal

Some unintended postprocessing was performed. During the elasticity test, one of the mounting pads broke off along the printing plane, which in retrospect is unsurprising. The part was then dropped, which cleanly broke off the other pad, at exactly the same point.


After breaking off the pads

The "edited" workpiece was then further processed with dremel; warts and strings and shifted edges were ground off and the inner side of the clamp part was narrowed a little to facilitate snapping on to the contactor body.

Installation

The modified cover fitted just perfectly. It was secured in place with a zip tie.


Contactor, exposed

Contactor, exposed

Cover fitted

Cover fitted

Cover fitted

Contactor, cables attached

Contactor, cables attached

Cover attached

Cover attached

Cover attached

Cover attached

Cover secured with a ziptie

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