3D Printer - V2
Project: 3D Printer
Timeline: 3 months (Jan. 2014 – Mar. 2014)
# of participants: 1 Person
Project Goals:
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Improve print quality from V1
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Modify design to allow for easy disassembly and transport
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Upgrade for dual extrusion
XZ Frame:
The XZ Frame's design has the approximate dimensions of 610mm x 610mm x 150mm (24in x 24in x 6in) and is made of all single extrusion aluminum. Placed directly at the bottom of the XZ Frame, are two NEMA 17 stepper motors mounted using custom 3D printed mounts. As in the first version, two threaded rods are connected to the shafts of these motors using a flexible collar, and supported using a linear shaft mount. Similarly, two hardened linear rails are attached to the XZ Frame using a linear shaft mount on both the top and bottom
X Carriage:
The X carriage hosts the extruder assembly and it is supported by the linear rails and threaded rods in the XZ Frame. The carriage consists of platforms at either end that support two linear bearings that allow the extruder assembly to freely move back and forth. At the same time, they each host a coupling nut that mates with the threaded rods that force the carriage to move vertically as they are rotated by the stepper motors. The linear rods of ther carriage are connected to the platforms through the use of of shaft collars that are press fit into each platform. The left platform hosts the idler gear tensioner, that allows the belt to be pulled taut if any slack occurs through repeated use. The right hosts the 5th and final stepper motor for controlling the motion of the extruders.
While my first 3D printer successfully made its first round of parts, it still had quite a few problems, the most significant of which was the high likelihood of the X-carriage jamming on its track causing the print to fail. This failure was likely due to the misalignment of the rails and threaded rods since the components used to build the printer were not machined to tight tolerances as they were made with simple hand tools. Moreover, the design was bulky and could not be easily moved between rooms. To remedy these issues, I decided to redesign the printer and make it more reliable. This time around, I was not limited to simple geometries that I could machine with basic hand tools and a drill, as I could simply model components on the computer and print the parts out with version 1.
The first major design change I made was to the frame. The design was to split up into multiple parts, so it could easily be assembled/disassembled. I took inspiration from the Lulzbot Taz 4 3D printer after watching an unboxing video. Since the printer was on the larger end of the off-the-shelf printers, it needed a way to be easily shipped. As such, the printer was split into two major assemblies: a box-shaped frame that would be used as the X and Z axes of the printer, and a rectangular frame that would serve as the Y axis. This change served a second purpose for my printer, as changing to a box structure for the Z axis greatly increased the rigidity of the printer when compared to the previous design leading to a much smaller risk of deformations in the print. Both of these assemblies are built primarily using the same aluminum extrusion in the previous design.
Y Frame:
The Y Frame has the approximate dimensions of 750mm x 350mm x 50mm (30in x 12in x 2in) and consists of a mixture of single and double extrusion aluminum. This mixture is to allow the Y frame to be placed and lock around the XZ Frame. The rectangular shape hosts two linear rails mounted using linear shaft mounts along the longer direction of the frame. Below and in between the rails, a stepper motor is mounted to control the Y motion of the print bed. The print bed will slide along the linear rails using two linear bearings. At the opposite end a idler gear is placed onto a single extrusion bar within the frame using a custom printed belt tensioner. The Y Frame is mounted to the XZ Frame through mounting holes in custom made Z brackets.
Figure 1. CAD model of 3D Printer v2
Figure 2. XZ Frame Assembly
Figure 3. Y Frame Assembly ISO (upper) and bottom (lower) views
Figure 4. X Carriage Assembly for extruder assembly
Figure 5. Extruder Assembly
Figure 6. Completed assembly of 3D Printer v2
Extruder Assembly:
The extruder assembly is a platform hosting the dual Lulzbot's Budaschnozzle 2.0c hot ends and rides on the X carriage's linear rails via two linear bearings. The extruders are fed through two Kysan 1040220 stepper motors with a 14:1 gear head supported with 3D printed cold ends from Unique-Prototyping.