FLSun i3
This is one of my first printers, which I assembled and tuned with the goal of being able to print my own designs. Building this printer gave me a better understanding of the mechanical systems used in the FDM method. With this printer assembled and dialed in, I began designing and printing my own models and parts. I also began performing various upgrades in order to optimize printer functionality.
= Upgrades =
Long-Life Extruder Components
The OEM extruder system had poor durability and useability, and the degradation of parts would eventually lead to failure or hindered print quality. An improved version of the filament runout sensor bracket was printed and installed to prevent failure due to the poorly affixed design of the original. The original Bowden tube was replaced with Capricorn PTFE, which provides improved durability, temperature resistance, and lubricity for optimized filament extrusion. The standard brass nozzle has the benefit of high thermal conductivity, but as a soft alloy it wears out quickly, throwing the printer out of calibration. It was replaced with a stainless steel nozzle, sacrificing some thermal conductivity in favour of substantially improved durability.
Customized Marlin 2.0 Firmware
The original firmware made the printer a fire hazard, as it had no failsafe to account for thermal runaway. As such, any failure in thermometer wiring that caused an erroneously low temperature reading would result in a positive feedback loop, with the printer pumping in heat to a system that is already sufficiently hot. This may continue until the system fails or begins to melt, with potentially disastrous results. To remove this concern, the printer was upgraded to the Marlin 2.0 firmware with thermal runaway protection, improved user interface, and more. This firmware was then tweaked and customized to adjust various parameters of the user interface and printer behaviour.
MacEwan3D Flexi Plus Extruder.
The plastic OEM extruder body had poor durability and wore out quickly. In addition, this extruder provided a large amount of clearance about the extruder gear. This clearance prevents the use of flexible TPU, which has a proclivity towards escaping out of any available gap in the extruder feed. Rather than implementing a direct drive extrusion system—which would have increased printhead mass and required substantial modification—a MacEwan3D Flexi Plus extruder was purchased. This aluminum extruder body is strong, durable, and decreases the extruder gear’s clearance to a tight ~1.5mm. As a result of this upgrade, the FLSun i3 can now print flexible TPU parts with ease.
Base-Mounted Filament Stand
The i3 came with no filament holder of any kind, which was highly inconvenient as the filament has no location from which it could freely unspool throughout the course of a print. To remedy this, a base-mounted filament holder was designed in SolidWorks and 3D-printed. This spool holder includes interchangeable fittings for different spool sizes, and allows filament to be smoothly pulled off the roll by the extruder motor throughout a print.
Vibration Damping
This printer, while provided with a strong aluminum extrusion frame, was not as sturdy as it could be, and the fast-moving x and y-axis stepper motors mounted on the frame produce substantial vibration. This results in resonance through the frame and its components, producing a buzz or whine as the printhead travels. Printed parts also suffer as a result, often experiencing a "ghosting" effect along outer faces due to the vibration in the frame. To remedy this, motor dampers were installed on both steppers, all fan mounts were damped with rubber washers, and the base of the printer was cushioned with a foam bed. As a result, the noise pollution of the printer has been all but eliminated, and the slight ghosting effect of vibrations has been removed from subsequent prints.
CR-10 Printhead
This printer originally came with no parts cooling fan, which has a substantially negative effect on print quality. This was initially addressed with the installation of a 3D-printed fang shroud, but its mounting on the E3D-style hotend made it flimsy and insecure. The decision was made to overhaul the entire printhead, with an entire assembly of 3D-printed parts being assembled and affixed to the y-axis to emulate the printhead of a CR-10. The E3D-style hotend was replaced with a Micro Swiss, and the CR-10's tried-and-tested petsfang shroud was reprinted for use on the i3. The printhead's inductive sensor was replaced with a simple and reliable endstop switch. With this printhead assembled and wired, the printer was then reassembled and calibrated for its new geometry. The i3 now has a much higher print quality as a result of this solid and well-designed printhead.
Borosilicate Glass Bed
This printer originally came with no build surface, requiring the application of painter's tape in order to obtain any kind of successful print on the heated bed. However, this produced an uneven, ugly print surface, with fibers from the tape frequently embedding themselves in the printed part. Additionally, the use of painter's tape required frequent maintenance and reapplication. For improved print quality and ease of use, a plate of borosilicate glass was installed, with its strength and resistance to thermal shock making it a solid choice of build surface.
External MOSFET Bed Relay
The low-cost design of the i3 meant that some corners were cut in the design of its electronics. The heated bed draws a substantial amount of power, and the original design configuration had this current running directly through the mainboard. This is a poor setup, as the circuitry is not equipped to handle such large current draw, which presents a fire hazard and puts the mainboard at risk of premature failure. To circumvent these concerns, an external MOSFET board was installed, acting as a switch that the mainboard could remotely enable to direct current to the heated bed.
High-Flow Silent Cooling & PID Tuning
The original fans on the i3 were of sub-optimal quality, resulting in noisy operation and premature failure. For improved cooling and reduced noise pollution, all printhead and control board fans were replaced with silent Noctua A4x20 fans. These fans provide significantly improved airflow and reliability while simultaneously being nearly inaudible during operation. Following this upgrade, the hotend was PID turned to optimize temperature regulation.