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“The parts provided are used to make the system that raises and lowers Luke’s lightsaber in its housing inside R2-D2’s head. It’s based on a electric motor geared to a long rack, with a pair of limit switches to control where the lightsaber stops and starts.”

We know this is going to another long issue because, again, they skipped the ‘Understanding Robotics’ section of the magazine. I don’t mind this as it means we have a lot more to do!

I took the photos for this issue (and the next three issues) with my new Canon 90D DSLR. However, after a long micro focus adjustment session, I neglected to turn RAW format back on. So, I apologize if these images seem to be of less quality than usual!



Materials: All of the non-electrical parts are plastic in this issue.


  • Building The Galaxy – Racing to the Finish
  • Droid Directory – E-XD Series Infiltrator Droids
  • Build R2-D2: Model Instructions


Lightsaber Ejection Mechanism

Step 1

Align the Base Plate to the Rack as shown:

Steps 2-3

Plug the tab of the Base Plate into the slot of the Rack and secure the parts together with one (1) 2.3×6 mm black screw, as shown:

Steps 4-5

Unwrap and straighten the leads of the Drive Motor:

Step 6

Feed the plug end of the Drive Motor leads through the large hole in the Motor Housing Left Half from this side:

Steps 7-8

Slide with wire all the way through, and press the Drive Motor itself into place until it is firmly seated. It only fits one way:

Steps 9-10

Fit the cross-shaped socket of the Drive Gear over the motor shaft. It should fit all the way down into the recess:

Steps 11-12

Unwrap the Limit Switches cable, straighten it out, and take note of the colored leads to the two switches (yellow and black):

Steps 13-14

Line up the hole of the switch with the BLACK leads with this pin/hole on the housing, and press it down over the pin, as shown:

Steps 15-16

Line up the hole of the switch with the YELLOW leads with this pin/hole on the housing, and press it down over the pin, as shown:

Steps 17-18

Fit the Rack into the housing as far left as possible and mesh its teeth with the Drive Gear, as shown:

Steps 19-21

Fit the Motor Housing Right Half over this assembly, taking care not to dislodge any of the parts you just fitted. Drive one (1) 2.3×6 mm black screw through this fixing hole (nearest the yellow cable) from the side of the Motor Housing Right Half:

Steps 22-23

Fasten two (2) 2.3×6 mm black screws through the other two holes of the Motor Housing Right Half, all from the same side:

Installing the Ejector

Steps 1-3

Fit the Base Plate of the ejector mechanism into the open end of the Lightsaber Tube we completed back in Issue 35. Slide the two lugs on the ejector mechanism up between the mounting points (arrows below) on the tube:

Steps 4-5

Drive one (1) 2.3×18 mm black screw through the lower mounting hole and tighten.

Make sure this screw goes in from the correct side, as shown:

Steps 6-7

Drive one (1) 2.3x 12mm black screw through the upper mounting hole (on the same side) and tighten:

Steps 8-12

Align the Lightsaber Tube Cap from Issue 35 with the end of the tube and secure with two (2) 2.3×6 mm black screws:


This entire assembly feels delicate, so take care storing it until we test the mechanism in Issue 53. The lightsaber itself will be built soon in Issue 41. I am really loving this build so far!

Next Up

 Issue 38 – Left Leg Outer Plate, Right Leg Plugs

2 thoughts on “ISSUE 37”

  1. Need help.
    One of the switches is broken and I need replacement. Did someone know which type it is and where I can buy one ?

    1. I do not know the exact switch type you are talking about, but it might have a model number molded into it and you can search online for a similar part?

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