4. 3D printing for repair#

Repairing objects by ourselves is something the modern society has inhibited for a long time. It is time to take back the right to repair.

Part of broken object are in majority electronic circuitry or plastic part. Here, these plastic part can be replaced (and improved) with 3D printed pieces. This 3D Printing for Repair Guide is a good introduction.

For this class, I worked with Moïra Vanderslagmolen.

Steps#

Here are the steps to repair an object with part replaceable by a 3d printed piece.

  • Analyse of the object
    • determine what piece has to be replaced/repaired
    • Mesuring and drawing the intact parts that are in direct contact. It allow to :
      • Ease the design process
      • Simpler access to measures
      • Make an assembly of all existing and functional part. It allows to design the piece with a visual result. This image shows all already existing component determining the design of the transparent case. Project mistik: a case for a joystick with microcontroller and gyroscope. All credit to myself.
    • How to reassemble (taking picture is a good idea).
  • Drawing the object on a CAD software.
    • Keeping in mind that 3D printers are slow.
    • Fragile part can be reinforced if the reinforcement part is not in the way of a mechanism.
    • If something has to fit inside another thing, estimating the gap of free space is complicated. The assembly of all the parts can help estimate the scale of the gap.
  • 3D printing
    • See this module for 3D printing
    • Try to make adjustments to the printed object before printing it again with design adjustments.

The original object#

A roommate of mine had a light with a broken foot. The object is made of 2 principal part: the top part and the foot.

At the end of documentation, there is a picture of the lamp.

Analyze of the broken part#

The foot is made of one thin piece of plastic. It is broken in half and maintained in place by adhesive.

Bottom part of the lamp with adhesive.

Repairing the foot would be too visible for that kind of object, so we made the choice to print the entirety of it. As it is thin, we can design it as to make it plastic and time impression efficient.

Breaking to repair#

We decided to keep the top part and de circuitry part.

  • The circuitry was inaccessible due to the plastic blocking it. We had to break the bottom part.
  • We forgot to take some measures before breaking it. Lesson learned, always double check (or make a drawing of the existing part).
  • Once we had prying open the foot, we gained access to measurable part for the circuitry.

Design of replacement part#

We separated the design of the foot in two part. The bottom part was made by Moïra and the bottom part by myself.

Bottom part of the foot#

Moïra made the bottom part on OpenSCAD. Alt text

// FILE : lamp_bottom.scad
// AUTHOR : Moïra Vanderslagmolen
// LICENSE : Creative Commons Attribution 4.0 [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/)

$fn = 360;
outer_circle_diameter = 1.65;
inner_circle_diameter = 0.5;

// The bottom part of the lamp
module pied(){
rotate_extrude(){
translate([1.5,0])
difference(){
square([5,9]);
translate([10.1,8]) circle(10);}}

// place to pass the little notch and bulb
translate([0,0,9])
linear_extrude(height=0.1){
difference(){
   circle(outer_circle_diameter);
   square([0.5,1.62], true);
   circle(inner_circle_diameter); }}}

difference(){
   pied();
   // Place to pass the cable of the lamp
   linear_extrude(height=1) {translate([0,4.5,0])square([1,9], true);}
     }
Description#
  • We can see the gap to let the cable pass through.
  • It is full except for a cylinder for the circuitry.
Printing#

The object is very study due to its design, so we can economize plastic without making it too fragile.

All parameters are at default exept:

  • infil: 5% (Gyroid)
  • generate support
  • pattern spacing: 4mm (print les support.)

view of the inside of the bottom part

As we can see, the inside is practically hollow. The printing time would have been longer if the object was hollow as more support would be needed. The other advantage is the fact that support is not part of the final product and has to be trowed out. So, by making the object non-hollow, the support plastic can be used to reinforce the object instead.

Upper part of the foot#

The upper part of the foot was made on Fusion 360.

Description#

Like the bottom part, I made the upper part non-hollow to maximise solidity and printing time. The model is made of a single ration and an extrusion. Here is the sketch of this rotation:

rotativ sketch

Printing#

Parameters:

  • infil: 5% (Gyroid)
  • generate support
  • pattern spacing: 3mm (print les support.)
Defect#

Maybe due to the low infill, there was not enough support resulting on some printing irregularitys.

Visible defect of 3D printing

We can also see vertical lines. These lines are due to the printer being not capable of doing a perfect circle.

Design problem#

The upper body of the foot don’t fit with the upper par of the lamp. I made some cut with a saw the help the plastic of the edge to bend. I also limed generously to reduce the diameter.

Final result#

Alt text

Files#

STL file upper body

STL file lower body

Licence#

Alt text

This work is under CC BY-SA license.

  • BY: credit must be given to the creator.
  • SA: Adaptations must be shared under the same terms.

More on the different CC licenses here.