Kossel Mini

The Kossel Mini is an FDM 3D printer from Johann with a 170 x 170 x 240 mm build volume.

Specifications

The Kossel Mini (also known as the Mini Kossel) is a landmark open-source Delta kinematic 3D printer designed in 2012 by German engineer Johann Rocholl. Developed under the RepRap project framework, this printer is named after Albrecht Kossel (a pioneer in genetics) and remains one of the most significant motion platform designs in the history of additive manufacturing. It demonstrated how parallel link arm mechanisms driven by three synchronized vertical axes could control a three-dimensional coordinate space, minimizing moving mass and removing the heavy Cartesian gantry.

• Kinematics: Delta robot motion architecture.

Calibration

Calibrating a delta printer is mathematically complex compared to Cartesian printers. Because carriage movements are translated into curved space coordinates, small mechanical misalignments can cause the nozzle to dome (move higher in the center) or bowl (move lower in the center). Follow this calibration process:

• Mechanical Frame Alignment Verification:

Before adjusting firmware settings, verify that the vertical towers are perfectly parallel.

Common defects

• Hardware defects and mechanical weaknesses
• Diagonal Rod Joint Play (Ball Joint Slop): The stock plastic ball joints wear out quickly from constant three-dimensional movements. This introduces mechanical play.
• Symptoms: Ripples on the print walls (ghosting), shifting patterns on layer changes, and erratic auto-leveling results.

What it is used for

Suitable applications

• Printing Tall, Narrow Geometries: Vase-mode prints, columns, and architectural towers print exceptionally well. Because the print bed remains stationary, tall prints do not wobble or fall over due to bed movement.