As some of you know, my work is more and more related to SMD design. I just love how compact and robust these designs can be. I have no problems soldering the components by hand but as I’m moving in to the realm of reflow I wanted a solder past dispenser. The professional ones are not that expensive but you need an air compressor and I was trying to avoid that extra cost and noise. So I came up with this design.
It uses a PICAXE M14 microcontroller and ULN2003 Darlington driver to run the 28BYJ-48 stepper motor. As a stepper the 28BYJ-48 sucks with its gear ratio, but for this purpose it is cheap and has lot of torque. For my type of work and one-off prototypes it works great. It is not as precise as a professional system that pulls the plunger back with a vacuum but its way better than a manual system or using a toothpick. The system also has a trim-pot so that you can change the speed of the solder paste flow.
I have some extra boards and might put them up on https://www.tindie.com if anyone would be interested (leave a comment).
Neatly done. Just as a thought, if you replaced the buttons with either a pressure sensor or capacitive touch pad (I don’t know about for picaxes, but there’s a capsense library for arduinos that’d work, with just an extra resistor) you could increase the solder flow dependent on how hard you pressed, which might be neat.
I have not measured the travel of the plunger but by design it probably can’t be more than max 50% of the total travel. I only use a small amount of solder paste at the time and keep the rest in the refrigerator. But am I right in thinking that you are from Oslo? (I’m from Sandnes) then shoot me an email from the contact page and I’ll help you out
I finally managed to get my hands on a 3D printer so I could print the parts, but unfortunately the pcb is sold out. If you have some spare pcbs left, I would also buy an empty one and reflow it myself, if you have some left ?
