Hi Peter

I have wondered the same The print heads are not a big deal, Usually just a close temperature controlled, but small, metal block nozzle heated to just the right melting point for the plastic being used. The feed is based on pushing the plastic into a drilled hole in the block. the force being provided by a small step motor that drives the plastic filament through pinch rollers. The feed has to be in sync with the machine X.Y. feed vector. There is an added complication….At the end of each run the plastic feed is reversed a small amount pulling the filament back into the nozzle and cutting of the feed. There is no valve as such.

In a way similar to a hot glue gun, but they don't normally have a stop mechanism.

I have been toying with the idea of building one. A starting Google search on "RepRap" will lead you to hundreds of posts. and no doubt lead you to other key words to search on, "additive machining" being one.

It would be nice to use an existing CNC machine. I wonder if someone has made a Mach 3 Macro and published a small circuit for the interface? Most of the posts I have read are dedicated machines using a small Arduino processor. even starting from scratch not that expensive if you can scrounge around and already have a manual mill and lathe.

Cheers

John

Edited By John McNamara on 09/07/2012 14:19:31