The last two weeks have been very productive. Not only did I finish a solution to drive the LEDs, I also have completed the mainboard box for the mainboard, raspberry pi and Hotbed Mosfet. I have also been fiddling with the new thermal camera, which is proving to be a very good tool.
Having LEDs in the enclosure is not very useful without a way to drive them. The controller I used last week was Arduino Nano based and borrowed from the fursuit project. I see no reason why not to use more permanent version of this Arduino Nano controller designed specifically for the enclosure.
I soldered up mountable version with two pull down buttons, two potentiometer and a switch. This also has a three pin fan header for the led strips to connect to as well as a small RC connector for power fed from the 5V distro block. To be honest I really only needed a potentiometer for dimming, a switch to completely turn them off/on, and maybe a button to cycle through preset colors. The extra potentiometer and button allow some customization later that would just need new code.
The complex code from the other controller was simplified. The complex eeprom memory function for combinations is not needed now, but I did end up replacing it with a simple eeprom function. This reads on startup and writes the mode the controller is in during each button press. This means that if the enclosure is completely powered down it will be able to return to the pattern and color it was set to when it comes back on. I expect the most common pattern to be solid with white as the color set at some less than full brightness.
The 5V 8A PSU I am using holds up well and only drops 2oo mV going from off to full white on all 80 LEDs. I will need to test the full current draw at some point.
Overall I am stoked about this lighting system. It looks great and the print head cannot possibly obscure the light from above from all angles its being emitted from. The aluminum foil insulation seems to compliment this with its reflective surface, but that will likely be a negative when using the thermal camera for testing. I still need to route cables into the enclosure a ensure the hood wires can get disconnected, but that's on the way.
I wanted a mainboard location that I could service without having to lay on my back under the printer frame. The mainboard cannot be too far away from the screen if I am going to use the stock display cables. The only space I could think of that would work for this is in the enclosure itself.
The more I thought about it, the more I thought it could be an opportunity to not only look cool, but provide a transition point between the interior and exterior for cables. While the enclosure is not "air-tight" by any means, having soldered ports that transfer cable runs is a great way to limit air gaps. I am using both aviator connectors as well as 1x DB25 and 2x DB9 connectors.
The two 40mm 5V fans push air from outside the enclosure and push it back out of the enclosure. This keeps it mostly separate from the air inside the enclosure and cools the electronics actively. Air can still partially escape though the ports that I found necessary for the mainboard and raspberry pi. The gaps have been made as small as possible, but still exist.
As far as looking good; I decided to put my logo on plexie and use it as a lid. The clear surface also allows to see the devices functioning. I am still not a huge fan of plexie glass, but working it with the CNC machine to the correct shape was actually not as bad as I thought it was going to be.
At this point I have only wired the hood's DB9 serial port connector up, and I think it looks really good. There will only be this and the printer camera's usb cable coming off the hood. The connectors I have seem to work really well. Made in USA.
Flir Thermal Camera
I have my reservations about the wiring on this design. I am always nervous about leaving something I just wired up running for an extended amount of time, let alone mains power. Also a big part of this project is getting the enclosure temperatures solid regardless of where I set the cooling or heating. A very useful tool for debugging both of these is a thermal camera.
I received the Flir One Pro (iOS) last week and have found it very useful so far. Aside from taking pictures of the cats and home, I have also used it to determine the temp of the LEDs as they currently run at ambient temp at full brightness. At ~43C (110F) they are already pretty hot. I also noted the temps of wires and PSU while in use.
The WS2812 LED module's Operation junction temperature maximum is 80C (176F). The glass transition temperature of the PETG mounting bars is about (87C) 190F. I will have to see if bringing the enclosure up to temp 50-60C (122-140F) causes the lights to overheat. If the PETG melts, then its probably safe to say things are too hot for the LEDs.
The main downside to the camera is that is can see temperature and cant see through objects. Also, reflective surfaces will reflect the heat profile of things around them. Simply put; I cannot directly measure the temps inside the enclosure or enclosed components without opening them up, but I can get a good idea measuring the outside temps of the containers themselves.
Honestly up next is going to be a lot of tedious wiring and soldering to get the connectors populated for the printer components. I also have the HEPA filtering system and 100W heater mounts in my sights. These should be somewhat painless to install and wire, or at least here's hoping.
The list of things keeps getting smaller. The mainboard enclosure is honestly a huge step forward. The next big hurdle is going to be the wiring harness that goes to the print head. This also has the added complexity of the liquid cooling tubes that need routing. That being said, I feel like I have a good plan for handling this.
I feel like I should be able to get the printer physically finished in the next few weeks. Programming and debugging tuning cooling/heating might take a bit of time depending on how well things go.