I’ve started to think about how to make plastic propellers for rubber band airplanes. This would allow me to have a custom propeller for the Squirrel model airplane project as well as other projects. The current offerings are actually pretty good. I’d like to go for something a little lighter. Perhaps 2-2.5g. The current offerings are between 5 and 6″ so I’d like to make something around 6 or 6.25 inches.
There are three parts. The propeller itself, a shaft and the nose-piece which allows you to easily mount the propeller at the front of a stick plane.
I found this interesting molding machine.
If the the mold could make 10 propellers at a time, I bet this could be made to be computer controlled.
Of course, construction of the hub might be a different process.
Another idea is to use a reprap or a makerbot-cupcake machine. As is, they are much too slow.
I’ve been talking with Micheal Grant and we’ve been talking about a custom plastic extruder in order to lay the plastic out (rather than molding it). If the extruder had a large nozzle (perhaps even slot shaped), it would be faster and perhaps could be done in one layer. Perhaps an A-axis would allow the prop to be poured out without running the plastic. I’m assuming with a larger nozzle that the plastic will take longer to set. Heres a picture of a possible A-Axis that Michael sent me.
The female mold incorporates a hub. I think this sort of thing could be poured directly. This might simplify manufacturing drastically as well as provide a quality part. It’s easy to imagine adding the shaft to the hub area of the mold during pouring. The propeller would not overrun but it would simplify the construction process.
A lot of people make propellers by hand out of a pop bottle. Here are a few examples: Plastic Propellers. There is a good example over at http://www.sciencetoymaker.org/plane/propeller.htm as well (Can you recognize the plane in that article? It’s a Squirrel. Also, the example he posted from India is an interesting plane). Also if you look around the Squirrel Plane site there are a few more examples of people making propellers.
There may be a way of making the blade in multiple parts. Perhaps the hub can be made using one process and then blade paddles can be made using another process.
Food for thought.
There is a contest hosted by Make Magazine: http://www.marketwire.com/press-release/Bring-Out-Your-Best-Innovative-DIY-Creation-for-the-MAKE-Green-Project-Contest-1365514.htm