And now for something completely different!
April 6, 2009
** Update **
I delivered the gun to KJ precision engineering for testing. It has been named "Soldestroyer" by my former boss.
I spent a month working in an engineering shop recently. One job I did there was soldering the circuit boards for emergency phones. All soldering is done by hand and the boards are held in a frame so that you solder at least 8 boards in a hit. You go through a lot of solder, the rolls are too heavy to hold and leaving them on the bench and spooling off a meter or two of solder can still be a pain, especially when it gets caught up in the frame. That is why I decided to build a solder gun. At any rate it was a fun project for a rainy weekend.
Basically it has a small light roll of solder and feeds it out when you squeeze the trigger. The mini reel hold enough solder for about 4 hours worth and is removable for easy reloading with a cordless drill. The feed mechanism is almost identical to that of a MIG welder but a lot smaller.
The rollers are tensioned with a spring from a wooden peg and are cutdown fishtank hose joiners with silicone rubber hose for traction. They are driven by a minature servo that had fried it'scircuit board. I removed the circuitry and converted to continuous rotation so it is basically a motor and gearbox.
The circuitry is basically a picaxe 08M reading the pot and generating a PWM output. This may seem like overkill but the 08M makes callibration easy and the circuitry cost is about the same as if I used a 555 timer or some other dedicated circuit. The PWM output give good torque at the lower speeds.
The trigger mounts directly on the pot with a peg spring to make it return. It does not turn the pot very much so I have to make full use of the 08M's 10bit analog input.
The body is made entirly out of polymorph. The handle started as a flat sheet and was "folded" like you would fold cardboard using the techniques demonstrated in my walkthrough on polymorph. I then heated areas that I wanted to shape to fit my hand one at a time. By wetting my hand to prevent the hot plastic sticking to me and gripping the handle I slowly developed my hand grip. Starting with the thumb, then fingers and finally the trigger.
The gooseneck consist of a small long spring that guides the solder and some packing wire that allow you to bend the gooseneck to an angle that suits you. This is all encased in spiral wrap for a neat finish.
It's not pretty but it is comfortable to hold and works great. Better than my hot glue gun :D