Rostock (delta robot 3D printer)

Blog with project history: http://deltabot.tumblr.com
Videos: http://www.youtube.com/user/jcrocholl/videos?query=rostock
More pictures: http://flickr.com/photos/jcrocholl/tags/rostock
More details about parts: http://thingiverse.com/tag:rostock
OpenSCAD source files: https://github.com/jcrocholl/rostock
Documentation: http://reprap.org/wiki/Rostock
Ask questions here: http://groups.google.com/group/deltabot

Rostock is a delta robot 3D printer prototype with the following design goals:

Build volume: 8x8x16 inches or 200x200x400 mm
Footprint: 12x14 inches
Print surface: 8x8 inches heated glass which never moves
Mass of end effector with two hotends: less than 150g
Positioning speed: 800 mm/s in all 3 directions
Positioning accuracy: at least 30 steps/mm in all 3 directions
Simplicity: fewer than 200 parts (not including washers, nuts and SMD-mounted electronics)
Hardware cost: less than $500 USD

Inspiration: search YouTube for "flexpicker" or "adept quattro".
Closest ancestor: http://www.heliumfrog.net63.net/deltarobot/delta.html

Documentation: http://reprap.org/wiki/Rostock

I'm also uploading Rostock parts as separate things, to make it easier to post specific instructions, comments and derivatives: http://thingiverse.com/tag:rostock

July 17 update: The 3 bottom micro switch endstops are going away in the next release, because the top endstops are already micro-adjustable.

Current release: rostock-2012-06-29.zip fixes a bug in idler_end.stl, motor_end.stl, and joint.stl. All the other STL files are unchanged. Thanks to DigiFab for finding and reporting this issue!

Printing regular G-code with PLA at 50 mm/s for perimeters,
100 mm/s for infill and 500 mm/s for travel moves.
Using Airtripper's direct drive bowden extruder
with MK7 drive gear and NEMA 17 stepper motor,
Teflon PFA tubing (2mm inside, 4mm outside diameter)
and Makergear hotend with 0.5 mm nozzle.
Modified Marlin firmware for realtime delta geometry:
https://github.com/jcrocholl/Marlin

Stepper motors: 4x NEMA 17 (3 positioning, 1 extruder)
Timing belt: 3x GT2 belt (2 mm pitch, 762 teeth)
Filament drive(s): Airtripper's bowden extruder
Ball bearings: 4x 608ZZ, 3x F608ZZ, 1x MR105ZZ
Linear bearings: 6x LM8UU
Smooth rod: 6x 762x8 mm
Plastic parts: printed from PLA on Prusa Mendel
Fasteners: stainless steel, mostly M3 (some M4 and M8)
Hotend: MakerGear 1.75 mm with 0.5 mm nozzle
Top and bottom frame: hand-cut plywood (300x350 mm baltic birch)