My design goal for this extruder was an extremely reliable, no compromise, extruder for the Makerbot, that builds on all the most successful ideas currently available in thermoplastic extrusion. At the same time I wanted an extruder that could easily be printed on a Makerbot build plate with a as large a raft as possible to allow those who do not have a heated build plate to print it easily.
Brutstruder is a hybrid of many successful current extruders. It get's its idler wheel from the Wades Extruder thingiverse.com/thing:1794, and the drive gear from the Mk5 Plastruder thingiverse.com/thing:3290">. It also get's a viewport from the Printruder II - Rear Breech Loading thingiverse.com/thing:3178, it's Electronics board holder from the Prinstruder II thingiverse.com/thing:1980, and it's legs are 2 of the DINO2 from Zaggo's Printable extruder holder thingiverse.com/thing:1912.
This design has been endurance tested in multiple ways.
I made the extruder lift 27 lb of water (this was before adding a 4th spring, and going to harder spring, no telling what it would lift now).
I fed it 3d Ink Plastic only throughout testing.
I have printed 36 hours straight with this extruder at this time with 0 failures.
I also fed it 1/8 inch ABS welding rods from the local welding shop.
Now you see why I call it Brut.