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Fab Academy

Miguel Lourenco

Mechanical Design, Machine Design

From January to June 2013 I worked in FabLab Coimbra, weekly, and have produced some small tasks about Mechanical Design and Machine Design, shown at the end of this page.

More recently, from September 2013 until now, I have been worked hardly to design and build my 3d printer machine. To this project I developed some new mechanisms that have been worked with very good results. Nevertheless, three of these devices are undergoing a process of patenting in Portugal and for that reason are not thoroughly explained here as I would like to. Even so, I wish you visit Project Development page to see more details about these items.

The pictures on the right side show 3D CAD modeling used to design some of the mechanical devices that I have been developed.

The pictures below show the real prototypes that I have built using mostly aluminum, machined in CNC router, and ABS parts printed in 3d printer machine. A few parts were made by hand from aluminum profiles or even steel.

For this purpose (Machine Design assignment), I must to say that during my project development also worked with electronics and coding. I used arduino software to modify the firmware and send it to my machine, I did it for several times because It was necessary adjust so many parameters to match all the devices of the machine with the controller (have used a sanguinololu).
At the beginning I had some problems with alignment of the Z axis, and could not tune the Z motor that was constantly loosing steps. So, I changed the movement device of the build plate and corrected the issue. Other issue was that I had the endstop of the Z-axis on the top and the extremely hardness tempered glass of the build plate hit the brass tip, then I had to change the endstop to Z-max (down position) and coding again of course.
In my project development I had to work with sensores (Thermistors for tip and heated bed, on/off endstops) as well adjust PID controller (configuration.h of firmware) to tuning tip and heated bed temperature. Had to manipulate manually the code several times to tuning the machine that I design and build up. So, please see my project development to complete the present evaluation.

Work that has been done in 2013

Team work:

In FABLAB Coimbra we have got a 3D Printer open source model (reprap prusa) and the team have worked to improve it.
Most issues are for mechanical type, and worked to get some construction simplifications.
So, the first task was to design and build a holder for abs spool and for power supply. We used acrylic and some parts of abs (3d printed) to reinforce the assembly. The acrylic was cut in the Spirit LS-60.

Here is the result, although, the work is not complete, we are planning to insert the circuit boards inside of this housing and use another fan to cool the electronics.

Individually, I redesigned the bracket for z axis endstop because the original has broken due its defective geometry without curvature between the arc and the planar surface.

I increased the thickness, modified hole and screw position. Mainly, added a fillet that ensure more strength without decrease the flexibility.

The bracket is ready to go to 3d printing.

Other task is to solve shaft coupler issue from z axis. The coupler sometimes releases for the stepper motor shaft and drops from the z axis. I redesigned the two parts, the holes with a perfect circle and a bit less diameter than the shaft diameter that results when it's covered with a plastic sleeve.

The new parts are more strong and will work better because now it uses a perfect cylindrical geometry of holes that holds the shafts supporting a greater surface.

Note: For more detailed information about mechanical design and machine design, please see my Project Development.

CAD modeling

(New mechanical devices designed to build a new 3D printer machine).