Roaddog Labs Bart

From Roaddog Labs Docs

Introduction | Bill of Materials |Frame Assembly |Y-axis Assembly | X-axis Assembly | Connecting X-axis and Z-axis | Heated Bed Assembly | Extruder Installation | Electronics and Wiring | Validation and Testing | Working with Files and Printing

Roaddog Labs Bart Introduction

The Roaddog Labs Ltd Bart is our latest variant of the Prusa i3 Rework. The machine is named for one of our late cats, Bart. It's a mashup of parts from existing i3 Rework designs, mods to those parts and some original parts.

Designed for DIY

While we are offering a full kit and components for you to build your own machine, the intent of the design is so that anyone with access to basic makerspace tools could fairly easily build the design. We opted for a laser cut melamine frame design based on the Graber i3 that eliminates the need for a threaded rod frame. This also adds rigidity that allows the machine to print faster and more accurate than a rod framed based design.

Fewer parts, easier build

The mechanical component requirements have been simplified. The number of parts have been reduced and the assembly simplified. Where possible we have made the parts so they connect in positive fit, one way as to take much of the guess work out of the build. We are reducing the need to square and level parts by integrating the main structure in such a way that it screws together so that no further squaring of the structure is required.

Reducing build complexity also reduces the time and effort required to build the mechanical structure. We’ve cut the volume of plastic required by the printed parts by using the new frame which reduces the time required to print the parts for the machine by about half. That means if you print your own parts you don’t have the tie up the printer at the makerspace for 10-12 hours for a set of parts.

New hot end, extruder

We are now providing the E3D v6 Lite as the stock hotend. We’ve been testing one since they were released and are quite pleased with the results. The thermistor and heater element mechanically fasten to the hotend, no Kapton tape required. The Lite version of the hotend is easier to use than the standard E3D v6 and is more forgiving for the beginner. For those that are building a Bart from source, the extruder will accept any generic JHead style groove mount.

The extruder is a direct drive design, taken from mrice’s direct drive Wilson/i3 Rework extruder. The hobbed bolt/ geared extruder has been eliminated and replaced by an MK7 hobbed gear as the direct drive. The lower, lighter mass of the extruder enables the machine to print faster with less vibrations compared to an i3 single plate or i3 Rework in a stock configuration. This version swaps the motor orientation so the motor is on the left had side (the -X side) of the X axis.

The printed parts mass is reduced to a third of what is required for an i3 Rework. We've take about 5-6 hours of parts printing and replaced it with about 20 minutes of laser work.

Each axis endstops mount positively on a bracket. The X and Y endstop placement requires no adjustment. They are where they need to be for the full build envelope. The X carriage has been modified to use a new endstop trigger. The extruder motor was reoriented so the machine takes advantage of the full 200 mm of X build envelope. The Z endstop uses a screw adjustment design from the i3 Hephestos. The endstop switch mechanism is mounted directly to a bracket with the screw in the X motor end used to adjust the Z travel.

Another change to the X axis is the addition of an adjustable belt tensioner using ramkam's i3 Rework design. On other i3 designs the X belt does not have an adjustable tensioner.

Open means open

The hardware design and firmware configuration is a truly open platform with parts files available as well as the firmware configuration files and version of firmware they were compiled against. In some cases there are only STL files and no editable source. In the case of any parts designed by Roaddog Labs Ltd, full, editable source is included. No restrictions, no posturing, open hardware. Even the build docs are open source.

Roaddog Labs Bart Specs

Base and Frame
Full melamine frame, printed parts, latest design for maximum stability and print speeds
Build Envelope
200 mm x 200 mm x 200 mm
Resolution (layer thickness)
low res .3 mm; normal res .2 mm; hi res .1 mm; extra hi res .06 mm
Filament Diameter
Compatable Materials
More than 15 types including PLA, ABS, Laywoo-D, HIPS, carbon fiber reinforced PLA, flexible filament, conductive PLA
Max Printing Temp
248° C
Heated Bed
MK2A, 12 volt
Bart Direct Drive MK7, low profile, reduced weight and mass
RAMPS 1.4 configured for Bart with Marlin firmware
Power Supply
12 volts, 30 amps compact form factor
X Axis Motion
GT2 belt and pulley; 8 mm precision bearings and chromed, hardened rods
Y Axis Motion
GT2 belt and pulley; 8 mm precision bearings and chromed, hardened rods
Z Axis Motion
M5 threaded rod; 8 mm precision bearings and chromed, hardened rods
Average Speeds
100 mm/s (stock extruder, perimeters based on average tune)
Machine Footprint
410 mm x 470 mm x 400 mm (610 mm with spool holder)
Optional Display/SD Card Reader
Optional full graphic LCD display and SD card reader for standalone operation

Build Doc Sections

  1. Introduction
  2. Bill of Materials
  3. Frame Assembly
  4. Y-axis Assembly
  5. X-axis Assembly
  6. Connecting X-axis and Z-axis
  7. Heated Bed Assembly
  8. Extruder Assembly
  9. Electronics and Wiring
  10. Validation and Testing
  11. Working with Files and Printing



Material specific to the Bart components and documentation that are not derived from other sources are released under the Creative Commons Attribution 4.0 International license.

Where applicable, the license of any derived work will be posted as well.

The original Prusa i3 single plate files ( from Josef Prusa licensed under GPL v3.

The original i3 Rework ( printed parts files from eMotion-Tech are released under GPL 2.0.

The original i3 Hephestos files ( from bq Department of Innovation and Robotics are licensed under Creative Commons Attribution 4.0 Sharealike International.

The Graber i3( is licensed under GPL v3.0.

The original modified i3 X idler with adjustable belt tensioner from ramkam ( licensed under Creative Commons Atribution-Sharealike, no version stated.

Marlin firmware ( from Erik van der Zalm licensed under GPL, no version stated.

The original direct drive extruder for Wilson/i3 ( from mrice licensed under Creative Commons Attribution- Share Alike license, no version stated.

Z coupler from Yet Another Prusa Mendel Z Coupling, by Nophead licensed under GPL, no version stated.

Introduction | Bill of Materials |Frame Assembly |Y-axis Assembly | X-axis Assembly | Connecting X-axis and Z-axis | Heated Bed Assembly | Extruder Installation | Electronics and Wiring | Validation and Testing | Working with Files and Printing