SmartAlu 80mm hotbed post-printing cooling fan support

thingiverse

The SmartAlu aluminium hotbed is incredibly effective, as the printed parts stick perfectly to it without needing glue or adhesive tape of any kind. However, it has a significant drawback - it cools down extremely slowly after each printing. To resolve this issue, I installed an 80mm cooling fan that's easily accessible in most stores. I also designed a simple two-piece support to hold the fan at the optimal angle, and it works incredibly well: the cooling time is significantly reduced! My tests show that without this device, the hotbed takes around 20 minutes to cool down from 60°C to 25°C in a room at 20°C. With the cooling device installed, it takes just 5.30 minutes to achieve the same temperature drop. To install the fan on the support, you'll need four M4x12 bolts and nuts. You can also attach the support to the bottom aluminium plate of the printer using two-sided adhesive tape, but this method may be less efficient with more hassle. The general idea is to place the cooling device in the middle of the X-axis and at the back of the printer, without touching the Z axis. When the plate is at its lowest position above the fan, it should point directly at the hotbed's center. Now comes the wiring part... For this step, you'll need a Ramps1.4 RRD Fan Extender that connects to the "Servos" of the MKS-Gen board between "5V out" and "Aux-1." You can find detailed wiring information here: http://www.instructables.com/id/Configuring-and-using-Reprap-Ramps14-RRD-Fan-Exten/. The coding part is straightforward: First, check if your new fan is connected properly by sending the following command through the terminal to your printer: M42 P11 S255 If it starts blowing air, you're good to go! Turn it off with: M42 P11 S0. Next, modify your custom ending G-code so that the hotbed plate will lower itself as low as possible without hitting the fan or filament spool at the end of printing. For example: G1 Z170 This is the optimal height for my Smartalu printer. Finally, add these lines to the very end of your custom end G-code: M42 P11 S255 M190 R25 M42 P11 S0 M140 S0 With this setup, the cooling device will start automatically at the end of each printing and continue until the hotbed has cooled down to 25°C (or any other desired temperature), then turn off.