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 http://www.thingiverse.com/thing:1794, and the drive gear from the Mk5 Plastruder http://www.thingiverse.com/thing:3290">. It also get's a viewport from the Printruder II - Rear Breech Loading http://www.thingiverse.com/thing:3178, it's Electronics board holder from the Prinstruder II http://www.thingiverse.com/thing:1980, and it's legs are 2 of the DINO2 from Zaggo's Printable extruder holder http://www.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.
Detailed instructions for Brustruter will be over at the Reprap Wiki. http://reprap.org/wiki/Brutstruder
First print the Idler, and the Makerbot block, attach your motor with the Mk5 drive gear on it (the gear will be tight, and the grub screw will eat out a track for itself as it spins. Spin it 2-3 times to grind a track before assembly). Once the drive gear is attached use 2 25mm m3 screws to attach the Kysan gearmotor to the block. Place your 606 bearing firmly in the hole provided.
To attach the idler, you will use 4 50mm m4 screws (the same as a Wades Extruder), the order of assembly is bolt, 1 washer, idler RP, 1 washer, 1 15mm spring (the harder the better), and a 3rd washer. Thread the m4 bolt into the block and secure them to the m4 nut on the other side.
Just screw the hot end into the block and secure it to the 2 captive m3 nuts.
The mounting legs for this extruder are Zaggo\\\\'s http://www.thingiverse.com/thing:1912, but just print 2 sets of his Dino 2 legs.