E3D Chimera

When I first saw the E3D Chimera I knew it was the right hotend for this printer.  It provides dual extrusion in a very compact package which is important for a printer with short travels.

The Chimera is designed for a bowden setup, however I chose to use a direct feed system. Direct systems have less oozing and can handle flexible filaments as well. A direct feed system is quite heavy but the linear stages will have no problem throwing a few stepper motors around. Since this printer may include a heated chamber, I want to avoid printed parts around the extruder. To keep things simple I started with a pair of Bulldog Lites and drilled and tapped a few extra holes to help with mounting.

I want the extruder to be an self-sufficient module so I machined a small plate that will hold everything together.  I chose aluminium to provide additional heatsinking, and to ensure the assembly is rigid.

I put a small dab of thermal compound between the Chimera and the mount to help with cooling and bolted it on.

The Bulldog Lite extruders bolt on as well.

I drilled the output of the Bulldog Lite to 4mm so that the Chimera's teflon liner can extend all the way to the drive gear.  This should ensure that flexible filaments feed reliably.

Both extruders now in place...

I also chose to replace the stock 30mm fan.  A 40mm fan moves more than twice as much air and is much quieter.  The larger fan combined with a substantial amount of aluminium will hopefully keep the heatsink cool enough even when printing in a heated chamber.

Finally a quick preview of how things are coming together.  The finished assembly is a perfect fit for the MX80L linear stage.