Heating issue in this post refers to both the lost and gain of thermal energy.
Over Heating issues
When heating up and during long prints, I noticed that my Polulu stepper controllers were getting quite hot even with the heat sinks. I figured that it was probably because of their proximity to the MOSFETs but I couldn’t be sure. The MOSFETs sometime ran hot and at other times ran cool enough during heating so that they could be touched directly without pain. Although I am not completely sure what a MOSFET does, I am pretty sure that it amplifies either the voltage or the current going into the heat bed because the MOSFETs are right next to the terminal blocks that lead to the cartridge heater on the extruder as well as the MK2A heated bed.
So in order to solve this problem, I went back into the old desktop computer that I sourced the ATX power supply from to see if I could find a few case cooling fans. From the old desktop computer, I salvaged two ~ 8 cm x 8 cm 12 volt fans. These big fans were a bit overkill for what I needed them for. When I connected the fan to the 12 volt rail, the draft generated was strong but the noise was too! Because of the noise, I decided that it would probably be sufficient if I just hooked up the fan to the 5 volt rail so that it would still run but just underpowered so that it would not be as loud. I mounted the fan with a random steel mesh that I found at robotics and then bent it to shape.
The result is what one might call “jank” but it works! My stepper controllers and MOSFETs now have quality cooling and can operate at any voltage they want! (just has to be between 0.4V and like 1.5V)
Under Heating Issues
To address the problem of the heat bed not heating fast enough, I took two thin pieces of cardboard and cut them so that they would fit under the heat bed but at the same time not obstruct any wires or zip ties for the matter. I sandwiched a layer of aluminum foil between them to reflect some heat and also taped a layer of aluminum foil between the top piece and where it touches the heat bed PCB directly so that the heat is transferred and hopefully insulated by the cardboard instead of flowing “off”. My memory on thermo dynamics isn’t crystal clear anymore and I have no idea why I would try to insulate something with a heat conductor but it seems to work! My heating time is now reduced to about 10 minutes as opposed to 15+ minutes. I am satisfied with my handiwork but will probably upgrade the insulation later on.