I have been using the Prusa i3 from MakerFarm for about four years now. My first experience with one was during my last year in college. My landlord was not the wisest with money and decided my first month’s rent should be spent on an 8″ i3 kit. It arrived a few weeks later and I was put to work building it. About a month later, we had a 3D printer sitting in the kitchen printing ABS parts. I was addicted to printing as soon as I saw it in action. Creating designs on my computer and having them physically in my hands only a few hours later was an incredible experience and I could not stop creating new designs to print.
After a few weeks of experience with the printer, I started to notice that the air from the cooling fan was causing the part to prematurely cool. As a result, large parts would fail as the corners warped and curled upwards, causing the part to be deformed. I solved this problem temporarily by taping a small cut piece of paper underneath the fan to keep the air from blowing over the print bed. A college friend found this design on Thingiverse. With my taped piece of paper still intact we were able to print a crude version of the Magma Cooling System. It wasn’t perfect as it had still warped a bit during the print, but with it now installed on the printer, we were able to print a second iteration that was much closer to the original design.
Now, I have a 12″ Prusa i3v all of my own. I have had the Magma Cooling System installed on my printer since I first built it a little over a year ago and it had worked great, allowing me to print ABS parts. The problem now is that I want to print PLA. PLA has this problem where it expands more with heat than ABS does. Because of this, PLA creates more forward pressure before the hotend and causes the extruder hobbed bolt to chew away at the filament, stopping it from being fed into the extruder.
The basic problem with the Magma hotend is that its all metal construction allows for heat to creep up the cooling section a prematurely heat the material inside the feeder tube. When using PLA, the filament expands enough to get stuck and stop the extrusion process. To solve this I wanted to design a better Magma Cooling system based on the original but would deliver more cooling air to the feeding tube to prevent the PLA from getting stuck.
Version 1 of my design is available here. It has a few flaws including; it is too deep for the cavity it it supposed to sit inside of and runs into one of the mounting screws on the extruder carriage, it is too tall (well almost) and gets too close to the hotend capable of melting it, and the fan duct allows too much forward pressure in front of the cooling fan so air is merely thrown about instead of funneled in to cool the feeding tube and heatsink.
Version 2 of my design is available here. I started with the original Magma Cooling System main duct, stripped out the interior ducting and cleaned up the model, reworked the wedge so it would clear the rear bolt as well as duct air better, and made a much better fan mount with a rear cone in an attempt to keep the airpressure constant from the rear of the fan to the end of the duct.
The duct on version 2 does a much better job of keeping airflow consistent but the cooling problem still remains while trying to print PLA, the material still jams.
Version 3 will certainly use a centrifugal fan to better push air through the ducting, they are able to build up pressure much better than regular axial fans. Also, there is a large gap between the top of the fan duct and the extruder mount, that’ll need to get filled in to make sure air doesn’t escape.