This is a work in progress, but has been printed and tested. This is a basic cooling fan attachment for a Replicator 1 with dual extrusion. It attaches under the extruder heatsinks and fans, replacing the fan spacers. It is designed to support a 40mm 24v cooling fan, similar to the stock replicator fans and blow air onto the extruding filament.
With the latest version, I've been getting very successful PLA prints.
I printed this with .10 layer height using sailfish firmware at 120mm/sec. Instead of using bolts (I didn't have the right size laying around) to secure the fan, I used some small plastic straps instead.
If you've previously downloaded, please update to the newest version. The latest version lowers the nozzel and focuses the airflow for much better cooling. I've also split the .stl files for easier printing. You'll now need to glue the two pieces together, but you can print without support material.
After installing the nozzle onto the carriage and before attching the cooling fan, I tape over the bolt holes on the inside of the nozzle. This will help keep the nozzle pressure up. I also started using a different fan, one with alot more static pressure.
Connect the cooling fan to the extra FET on the mightyboard. Using the latest Makerbot or Sailfish firmware (7.5 at the time of this writing) the fan can be controlled either by gcode or from the control menus.