3D Printer Extruder Notes

IN PROGRESS!

An extruder is the print head for a 3d printer. It acts like a hot glue gun, pushing plastic filament into a hot end, which melts it and lets it out through a small hole.

There are already many open source designs for extruders. The Open Source Ecology project wants to develop one that is as simple as possible to build and can be attached to the CNC machine in place of a cutting tool.

The MakerBot Plastruder MK5 has excellent documentation on its assembly and usage, is built using cut out flat parts, so it doesn't need an exiting 3d printer to build, and has tons of experience and testing put into its design. On the downside, it may be a little more complicated than it needs to be. Some potential features for simplification are:

• Using straight cuts instead of curved cuts for improved rigidity and speed and easy of construction, especially by hand.
• Using fewer different types of parts. Its simpler to source parts, build, and document if is uses 10 of one kind of screw instead of 5 of one kind and 5 of a different kind.
• Using round spacers instead if bolts to mount the hot end to the plate in the middle, similar to how the plate is mounted to the feeder. They'd need to be made out of something that can handle more heat and then we might want to replace the existing plastic spacers.

Instead of those plastic spacing rounds, they can use metal ones, then use the same diameter metal rounds for the second-level spacing as I mentioned in the paragraph above.

It requires many different pieces of hardware and the curved cuts for the mounting bracket add build complexity if cutting by hand without necessarily adding usefulness.

I've done some research into what's out there and here are my current thoughts.

Wade's Geared Extruder seems to be one of the simplest out there - http://reprap.org/wiki/Geared_Nema17_Extruder. It's got