What have you been printing.

The Shed

Are these instead of using servo controlled relays?

Friend of mine had used all the available Function Outputs on a decoder he was using, the decoder had two unused Servo Outputs, hence the idea of combining a Servo with a Micro Switch, activate the Servo, Servo arm moves and closes the Micro Switch, simple but effective ON - OFF switch.

The Shed

These are the items used, no doubt they could be sourced elsewhere, given the fluctuations in prices and the difficulty in sourcing from the Far East, opted for UK Sellers.

Not included is the cost of the PLA filament, some small nuts and bolts and bits of wire!

As a price comparison...Hmmm.... guess that's down to each individual.....

It does what it does, switches whatever alternative circuit ON or OFF.

Micro Switch £4.60 for 5 works out at £0.92 each.

MG90S Servo £2.99 each, discount available for multiples.

The price difference between a standard nylon/plastic geared Servo to a Metal Geared Servo is minimal, down to end user choice.
Last edited:


G Scale, 7/8th's, Electronics
5 Jun 2013
Tamworth, Staffs.
Did you print the shaft-coupler?

Such things do exist, but seem to be kept next to the Unicorn Horns..

Could you divulge the source, or print me a couple, please?


The Shed

Testing the theory....

Slight tweaks and reprinted the two mounting brackets, test program using a Arduino UNO R3, to establish upper and lower angles of the Servo in relation to the wiper on the Potentiometer.

Next stage, to attempt to design and print a coupler adapter between a 180 degree Servo to the Potentiometer, as the theory worked, splashed out a several pounds on some genuine Alpha and Bourns Potentiometers.

Plenty of time on my hands, extended shielding enforced until the end of March, hence have time to theorise!

Servo Potentiometer Testing with Arduino.png

Tinkercad Servo to Potentiometer.PNG
  • Like
Reactions: 1 user

The Shed

The coupling adapter for a 180 degree Servo, challenging but doable, just awaiting genuine potentiometers.

Servo 180 degree coupling.png

Whist awaiting parts for the above, designed and printed surrounds/ base plates for the LGB Track Cleaning Loco electronic adaptation for the Cleaning Motor.
Track Cleaner Relay Speed Controller.png .

Very much a work in progress, test prints to see how it a) looks and b) ease of assembly.
(Idea subject to change!)
Hp 0-1-2 Colour Light Signal.png
Last edited:
  • Like
Reactions: 1 user


British narrow gauge (esp. Southwold and W&LLR)
24 Oct 2009
  • Like
Reactions: 1 user


Master at annoying..
Staff member
GSC Moderator
24 Oct 2009
Scrap plastic wheels 20210222_160634.jpg and a re hash of a design..into metal wheels on a load...