Prusa i3

[2] The i3 series is released under an open source license, which has led to many other companies and individuals producing variants and clones of the design.

Parts changes allowed for snap-fit assembly (no glue required); fewer tools were needed to construct and maintain this version.

[12][13] It was clear to the RepRap community that the threaded-rod, triangular Z axis frame construction was limited in strength and stability, and that it would be necessary for the printer's footprint to grow substantially for the maximum printing height to increase.

In May 2012, Průša released a major redesign, focused on ease of construction and use, and no longer structured around the simplest available common hardware as previous RepRap printers were.

[17] The Prusa i3 used a rigid, single-piece water jet cut aluminium vertical frame with a large opening for the printing area and hard mounting points for the Z-axis components, similar to the Mendel90.

It used a single piece, food safe stainless steel hot end called the Prusa Nozzle which printed with 3 mm filament, and used M5 threaded rods as lead screws instead of M8.

Features included a larger build volume, custom stepper motors with integrated lead screws, a non-contact inductive sensor for auto-leveling, and a rewritten version of the Marlin firmware.

"[32] Starting with this model, the base and Y axis were assembled with aluminum extrusion, eliminating the last of the structural threaded rods from the Mendel design.

Included were a new extruder with dual Bondtech drive-gears, quieter fans with RPM monitoring, faster print speeds, an updated bed leveling sensor, a new electronics board named "Einsy", quieter stepper motors with 128 step microstepping drivers and a magnetic heatbed with interchangeable PEI-coated steel sheets.

The printer also offers dedicated sockets to connect Raspberry Pi Zero W running a fork of the open source OctoPrint software for wireless printing.

[36] MK3S changes include a simplified opto-mechanical filament sensor, improved print cooling, and easier access to service the extruder.

[39] This model features a new version of their "Nextruder" extruder system first seen on the Prusa XL, no-adjustment load cell bed leveling, a modular replaceable all-metal hot end, a color touchscreen, and die-cast[40] aluminum frame, Y-carriage (heat bed support), and extruder frame.

[41] The 32-bit main processor board includes additional safety and monitoring circuits, a network connector, a port for the MMU3, and a Wi-fi module.

Switching to 0.9 degree stepping motors, and the addition of input shaping and pressure advance, allow the Mendel-style design to print faster while avoiding ringing artifacts and other undesirable patterns imposed on the object being made, even though it does not have the advantages of the box-like structure of CoreXY printers.

When announced, software for input shaping, and sensor data collection were not finished, and the Multi Material Unit was not ready for release.

The load cell sensor automatically compensates for variations in nozzle size, and thickness and expansion of the heated bed surface, eliminating stored settings for the purpose.

[82][83] Some mass market i3 derivatives, such as the Creality Ender 3, use rollers against the extruded frame itself instead of precision rods and bearings to reduce cost and complexity.

[84][85][86] Prusa offered a collection of functional cooking tools and programs under the name "MK3 Master Chef Upgrade" as an April Fools' Day gag in 2018.