Community Highlight: Solder Paste Dispensing Head

Solder Paste Dispensing head by S&I Engineering

A few Projects we covered are as structured, well documented and useful as the one from S&I Engineering, a Greek Company specialized in a series of digital manufacturing, software and hardware oriented activities.
The project in question is a Solder Paste Dispensing Head, a custom FABtotum head build upon FABtotum own Head Development Kit (HDK) capable of Solder paste deposition. By using the FABtotum as the multipurpose platform it is, they were able to use it to lay drops of solder paste on printed circuit boards (PCBs).
In other words this custom head is meant to do the dirt and boring job of preparing PCBs for soldering in the reflow oven, a huge advantage when dealing with very small quantities of prototypes.

There are many reasons to take a look at this project:

It’s made with off-the shelfs components for the most part.
The remaining components are easily replicable on the FABtotum itself with 3D printing, Laser Engraving or PCB milling.
All the parts, codes and PCB layouts are provided.
Assembly and everything else is well documented.
It actually solve a problem.

Solder Paste Dispensing Head developed by S&I Engineering

Head Development Kit

The 3D printed parts

The mechanical components (nine in total) are used to convey motion from a stepper motor to a leas screw that in turn squeezes a siringe.
During the project these componets have been adapted from TwinTeeth design then 3D printed with the FABtotum personal fabricator itself.
On the left the assembly (minus the electronics, syringe and motor) is presented.
The base in particular has been modified to be fit the Head development kit and in particular to screw on the metal plate provided with it, on top of wich the head development board itself is mounted.
Aside from the syringe moveable clamp (on top) there are no 3D printed moving parts.

The total assembly is a bit higher than the standard head enclosure so it had to be mounted without it.

In action

Electronics & Coding

To control the stepper motor a PCB has been made in kiCAD. it is a FTDI circuit.
The head is equipped with an Arduino Nano, connected to the HDB in order to receive serial commands from the Totumduino controller inside the FABtotum via the flex cable.
If it sound complex it’s because it is, and S&I Engineering went the extra lenght in implementing all the communication protocols .
As a side note it is also important to notice that other options to control motors with less components exists, like using the 5th axis native port (on the bed connection board inside the FABtotum Core) or using the newest FABlin feature to send steps/dir directly via software and the HDK board pins (SCL=Feeder Step , I2C SDA=Feeder Dir, SERVO +5v =Feeder Enable).

This FTDI circuit PCB has also been milled with FABtotum using FlatCAM to generate the gcode and the Milling Head V2 with a V-Carve engraving bit, wich makes everything even more impressive.

Back to the serial comunication, the Arduino sketch has been developed to act like an intermediary, executing stepping controls directly from the head to the attached stepper motor.
The *.ino file can be opened in the Arduino IDE, can be flashed on the Arduino Nano, and is open source so can be studied and modified to fit custom needs.

Assembly & Testing

As per documentation the non replicable parts are the following
An Arduino Nano v3 , a 28BYJ-48-5V step motor and a ULN2003 driver.
for the syringe 1 x 10cc syring pump with an 20G-0.6mm ID-1.5 inch length dispensing needle
For the actual paste : Diluted Leadless Solder Paste with IPA (Isopropil Alchool).

Once the assembly is completed and the electronics wired, the serial comands can be tested in order to check that everything is working as intended.

Gcode commands can be executed manually from the JOG menu of the FABUI or one can plug into the FABUI Colibri and wirte their own Gcode controlling script or FABUI Plugin on the onboard Raspberry Pi.
A nice video of the head being controlled is shown on the right, curtesy of S&I Engineering Youtube Channel.

How to assembly Solder Paste Dispensing Head

Resources & Credits

In the IT industry the success of a platform can be expressed in the number of users it serves. Another way to measure success it looking at the number of projects taking full advantage of said platform.
This project actully does that and more. it Exploits the FABtotum for what it is on multiple levels.
While the FABtotum is primarily a tool to make things, it is also more than that.
This Head parts has been made with the FABtotum CORE, a manufacturing device to make things first, but also a multipurpose device on wich this head is fully justified and fulfill a vision of multipurpose /multimaterial manufactuing for wich we strive everyday by provinding more and more expandable heads,software and documentation.
This project not also expand the range of possibilities but it’s been made possible by the very tools we provided, the Print head, the Milling head and the head Development Kit, wich makes us -in turn – very proud of the results.

Special thanks S&I Engineering for sharing their work with us.
All the projects are available at: thingiverse.com, youmagine.com and grabcad.com.

We always look for exciting new projects to showcase what personal fabrication is all about.
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