DIY 3D Printer
Through the past summer, I’ve been working on a homemade 3D printer. The goal was to make a fast printer with comparable size and quality to other hobby printers at a similar price. This project lasted nearly a year, took four design iterations, and around $200 worth of new components to build, and achieved all the objectives set out.
Version 1:
My first attempt at the 3D printer was November of 2020. I was determined it could be made for under $50, already having the extruder, aluminum framing, most electronics, and the build plate. It used a CoreXY kinematic style, with the Z axis moving the bed. The Z axis used 4 leadscrews, driven by two stepper motors connected with belt. The XY motion used an aluminum profile which doubled as the frame, and 3D printed bearing covers fit inside the groove. The hotend was taken from a BCN Sigma 3D printer. It provided easy mounting with screw holes on the top, and enough of a heatsink to make the entire extruder assembly 3D printed.
The printer produced a few partially successful prints, but had many issues making it unviable for long term use. The Z axis would often come out of sync, with the belt slipping and leadscrews sticking. This would cause the print to fail and require releveling. The print quality also wasn’t great because the bearings had some play, resulting in the nozzle shaking while extruding. Finally, the hotend was meant for 2.85mm filament, which meant any retraction caused hot plastic to solidify above the hotend and jamming the printer.
Version 2:
Version 2 was a larger and more ambitious design. I began it in March 2021, determined to fix many of the issues of version 1. For the Z Axis it used 4 independent motors, each with their own leadscrew to prevent from getting out of sync. It kept the 3D printed bearing cover design for the Y axis, however the X axis used a linear rail I found at school, eliminating the wobble on the X axis. It also integrated the electronics into the base, simplifying from version 1 which had an external box and about a dozen wires for motors, sensors, heating elements, etc. The hotend was swapped for a style common on Creality printers. This also provided fairly easy mounting, and resolved the jamming issue.
The printer was never completed however, due to issues with the Z axis still coming out of sync (motors would often skip), and the linear rail not providing enough support to prevent the extruder from wiggling.
Version 3:
Version 3 was started June of 2021. Its goal was to fix the motion issues that plagued the previous two versions, switching completely to linear bearings and shafts. The X, Y, and Z axis were all supported by linear bearings, with the Z axis using both a linear bearing and leadscrew on all four ends. It also changed the Z axis style, actuating the entire XY gantry instead of the build plate. The build plate was also replaced from the previous two iterations from a piece of acrylic to an actual headed build plate.
Despite the improvements, it too did not produce a print. The Z axis motion was improved, but would still often skip if the leadscrews got misaligned at all. In addition, the pulley controlling the XY gantry was rearranged for flexibility in mounting, however the pulleys would often move when the gantry did, causing the belt to loosen and skip.
Version 4:
Version 4 was one last hail mary before leaving for college. It was started while disassembling Version 3 during cleaning for college, about 3 weeks before I’d leave. I knew after nearly a year of work I wanted to get a printer working, so I put in one last attempt. This printer dramatically simplified the previous few. The overall size was reduced by about half (in all the previous ones I didn’t want to cut shafts or extrusions for fear a future project would need the length, but this would be their last use). I rethought the Z axis, instead using a single leadscrew and two linear rails on the same side, inspired by the Makerbot Replicator. I had tried to avoid this early anticipating the end not supported would be too flimsy, which it was to a point but a worthy tradeoff compared to the previous Z axis. I once again used linear bearings on all three axes of motion, however improved the pulleys to be fixed. Additionally the frame was made out of lasercut wood instead of extrusion, giving more flexibility while modeling. I tried a new technique to fasten the lasercut wood, adding tabs which insert through perpendicular wood panels, and screw together with a square nut. This worked great to fasten the panels, however the flexibility in the panels caused the structure to wobble when bumped. Finally, to aid with tensioning the belt an additional four pulleys were used to loop all belt around back (similar to the Voron printers), and the stepper motors were attached linear slides to move forward and back, with springs adding tension. This caused the belts to be actively tensioned while in use, and could be pulled forward when configuring the belts to reduce extra slack. It worked great for setup, however had a fairly loose connection, resulting in the pulleys easily skipping if the print head was met with too much resistance.
In the end, this printer created a few quality prints much better than any of those before it, and similar in quality to other hobbyist printers. It is capable of printing faster than most, going up to 100mm/s easily, without the artifacts left that plague cartesian printers.
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