This is the 5th post in an ongoing series detailing my efforts to build a RepRap Mendel, an open source desktop 3D printer.

Previously, I assembled all of the blocks for the X, Y, and Z stages of the Mendel. In doing so, I could have a good idea of what parts were left over from the kit that could be used to construct the extruder. The blocks all constructed, it was time to build the extruder.

My RepRap uses Greg’s hinged accessible extruder. The extruder appears to be rather elegant and functional, though we’ll find out for sure later when it is put through its paces.

The Mendel-parts kit contains the parts to construct the original version of the Mendel Extruder, known as Adrian’s Geared Extruder. In order to build Greg’s Extruder, I needed a few parts not available in the kit (Hardware run!) In the picture below is a skateboard bearing I picked up from a skate shop for the extruder.

Greg’s extruder is based off of Wade’s Extruder, and as such many of the build instructions for Wade’s extruder apply in building my extruder. In particular, both extruders require the creation of a hobbed bolt. The hobbed bolt requires the use of “a common M3 file”. Common in Europe, maybe, very hard to find here in the states. (I ultimately found one, but had to search a lot of hardware stores). Below is an image of the makeshift vice I used for hobbing the M8 bolt.

There’s something about screw taps that makes them the most awesome tool ever. Not sure what it is… Anyway, this is what the hobbed bolt looked like after I finished filing and tapping it.

Putting all of the pieces together, we get the extruder shown in the figure below:

Don’t forget to solder (CAREFULLY) and insulate your thermistor. It is shown below, secured with kapton tape.

With the extruder and hotend parts done, the hotend needs to be attached. As far as terminology is concerned the extruder is the portion of the printer that pushes the plastic into the hotend and the hotend is the portion of the printer that gets hot and melts the plastic. For the printer to work, the hotend needs to be secured.

I chose to secure the hotend to the X-carriage block, rather than create a jig for the extruder. If I could go back, I wouldn’t have done this (currently, I’m dreading the possibility of having to disassemble the X-carriage block AGAIN if it turns out the extruder doesn’t function properly). Nonetheless, securing the hotend to the X-carriage block was a fairly simple matter of cutting a few slats out of sturdy metal bracket.

The slats were then inserted into the X-carriage block, replacing the washers used as spacers between the X-carriage pillars. The secured hotend is shown in the picture below:

With the hotend and extruder secured, all that remained was to put them together:

Stay tuned for more RepRap development! In the meantime, see pictures of the build process in the NBitWonder Flickr set!