Power Supply, Raspberry Pi, Relay Module, Fan Case by anhtien

Last crawled date: 3 years ago

It's a long name but it has multiple uses: cooling down the AC/DC power supply, switching on/off the AC/DC power supply remotely. It is also a Raspberry Pi / Relay Module case.
You can refer to the included connection diagram to see how things are connected inside this case.
Hardware:
Raspberry Pi with Octoprint preloaded and ready to be accessed from a Web Browser. If not, search online to see how to set it up.
A relay module, one channel is good for this purpose but I have 2 channel module installed because I will want to remotely turning on/off other devices (light, music, or anything that will connect to my “future” power bar). With one channel relay module, everything could be turned on/off together with the 3D printer. However, controlling other devices separately might be more practical such as leaving music on and keep the 3D printer off to cool it down after so many hours of usage. The price is about the same for 2 or 1 channel relay module.
A terminal strip (optional but I recommend it for ease of connectivity and power distribution). Please use the electrical ring connectors at all connections if you can, don't be cheap on this because one loose wire can cause a very damaging spark.
Two 40mm fan, 12vdc type of course.
Also need 3 x M3 screws and 2 nuts on top right, 2 screws and 2 nuts on the bottom right (or #6 3/8” machine screws worked too)
Use wood screws (such as #6 3/8”) to fasten terminal strip to the frame. Remove existing M3 screw from the power supply (top left) and replace with longer M3 screw (spare from the Anet A8).
The design could fit different type of Raspberry Pi and/or Relay Module, if you can not snap the board(s) in you could use tie-wrap through the honeycomb holes, double-sided tape or crazy glue to secure the Raspberry and Relay Module to the frame.
Follow the attached wiring diagram to connect the components together, make sure you orient the Raspberry Pi to have the network cable toward the back or else the network cable might get caught with the X-axis / Z-axis bars & rod. Also connect the fans with label pointing outside to suck the hot air out of the power supply and not blowing dust into it.
Software:
Octopi comes with GPIO already pre-installed, use SSH to login using pi username. To check if it’s available enter command:
gpio readall
If it comes back with information then you are good to go. If not, check wiringpi.com to see how to install.
Wiring Diagram:
In order for the octopi to control the relay, the “live” wire from main power should go to the “live” port #1 on the AC/DC power supply. The neutral line from main power goes to COM port on the relay module. Connect a new neutral line from NO (Normally Open) port on the relay module to the power supply Neutral port #2. Connect the ground straight from main power to the AC/DC power supply ground port #3. A side note about my AC/DC 12vdc power supply, I think the Anet A8 comes with incorrect internal wiring and I “had” to use my neutral line as “COM” line, it should really be the “hot/live” wire to be used as COM line. Well, since I don’t have another 12vdc power supply I can’t verify if All Anet A8 are like that or not. Anyway, the point is to have the Hot wire from main power to the relay’s COM port, then Normally Open (NO) port goes to AC/DC Hot wire. I just show what works for me, you might have to switch live and neutral wires if it does not work for you.
The Raspberry Pi uses the WiringPi connection scheme so check it out and use the proper GPIO pin. To demonstrate the pinout scheme, if you have the same Raspberry Pi Rev B as mine, then the 5vdc is the first pin on the outer row, ground is the third pin, and GPIO 1 is on the 6th pin. Those are NOT the actual pin number, those are for locating where they are on the board. The actual pin for 5vdc is header pin #2, ground is header pin #6, and GPIO is header pin #12. In fact the “gpio readall” command shows the pinout for your board, dont' use the BCM pinout.
Once logged in, edit the file .bashrc and add the following two lines:
alias a8on='gpio mode 1 out;gpio write 1 0'
alias a8off='gpio write 1 1;gpio mode 1 in'
Save and exit, then enter command “source .bashrc” to activate it. If you do your wiring properly, you should be able to enter command “a8on” and see the unit goes up, “a8off” to see it turned off.
Print settings:
I used Repetier to print, needed to move object 7mm on X-axis to the right to center it. Maybe it’s my Repetier setup that was incorrect.
Slicer configuration:
Print settings:
Layer high 0.2mm, Infill 30%, Speed 37mms, Do generate Support Material.
Filament settings: PLA 1.75mm, depending on your filament I set mine to 215 deg for extruder, 65 deg for hot bed.
Update 1: Adding version 3 with stronger and thicker wall (4mm instead of 2mm) and the thin version with higher retaining tabs for the relay module (v2a)