How to make a Solder Feeder (Mk I)


Step-by-Step Instructions

The Solder Feeder feeds solder wire down a brake cable, using a servo motor (modified to give 360 degree rotation). I realised after making it, that this was similar to a MIG welder or even some 3D Printers – but the interesting part is that the switch operates by a circuit being made between the solder wire and the winding of the brake cable. See diagram.

This tutorial is a useful introduction to how to work quickly with thin plastic (ABS) sheet, in a way that does not involve heavy-machinery. Arguably this could have designed in CAD, but with new mechanisms such as modifying the servo motor to feed the wire, this is hard to estimate virtually – and getting it right beforehand in a quick prototype could save time and money later. Often being able to make a quick prototype can open discussions in groups (and silence doubters!) when trying a new idea.

This version of the Solder Feeder will be revised in time to incorporate new ideas that I realised when making this one – and also those kind and helpful suggestions from my post on Instructables. As I was fortunate to be awarded a 3D Printer by Instructables – I hope to do another version in CAD, that can be printed.



A quick overview of the main parts of the tutorial.

Parts and Tools

Great new tools include Proxxon’s Mini Drill, a Zona Saw and the Verstip Soldering Iron.




Roughing out the dimensions of components can save a lot of time later.



Box Assembly

Please check out the Plastic Techniques tutorials if you are new to this, here.



Box Sanding

Some useful techniques using Wet&Dry Paper.



Box Finishing

I opted to sand the exterior for a matt finish as well.



Servo Modification

How to make a Servo Motor Run 360 degrees.



Roller System

Created from a ball-bearing and rubber innertube.



Roller Testing

This really is done best with a test-rig like this. CAD would be far too tricky to guess!



Brake Cable

Fixing the switch to the brake cable.



Cable and Servo Mount

Mounting it to the main assembly. Some useful Multimeter tricks too.



Cutting Through Box

How to make a square hole, safely.



Wiring Switch

For feeding the wire on teh first run.



Heat Shrink

A ‘pro’ tip to stop wires short-circuiting.



Circuit Test

Keep on testing as you go!



Brass Inserts

A really cool way to make your two haves of your box screw together professionally.



Sunk Screw Fixtures

Easire than you think – and all in sheet plastic!



Sugru Grips & Handle

Sanded-down Sugru for a stable product.



In Action

Good luck – hope you find ways to persnalise your own soldering experience for the better!