Adjustable Parametric Kobra 3/Kobra 3 Max Z-axis tensioner

Kobra 3 / Kobra 3 Max Z-Axis Tensioner

This tensioner is designed to resolve common Z-axis issues on the Kobra 3 and Kobra 3 Max 3D printers, such as out-of-alignment gantries, leveling problems, and visible layer lines. By providing proper tension to the Z-axis belts, it helps ensure a more stable and accurate printing platform for high-quality results. The design uses standard hardware and can be easily modified in OnShape if needed.

Bill of Materials (BOM)

Note: Any screw head type can be used, and the design can be modified in OnShape for different hole sizes. A ~30mm M3 screw is recommended, but a 20mm screw may work. Longer screws are suggested for very loose belts.

Assembly Guide

1. Wheel Assembly Press a 608 bearing into the Roller part. Next, place the PullyShaft1XAdapter - Outer on top of the bearing and inside the wheel. Use glue if necessary to secure it. Finally, take two PullyShaft1XAdapter - Center pieces and press them into the bearing. This entire assembly should be flush and spin freely when holding the center adapters.

2. Main Body and Front Cover Position the main body so that the Z-axis belt is placed within the longest ⊔ shape of the unit. The other side of the ⊔ will slot onto the square bar. Now, attach the front cover (the one without a center hole) to the main body using four M3x12mm screws.

3. Pulley Block Insert three hex nuts into the outside of the pulley block. In the center hole, screw in a ~30mm M3 screw all the way. It should stick out like a wheel holder. Do not attach the wheel assembly to this yet.

4. Attaching the Wheel Carefully slide the assembled wheel between the Z-axis belts and then slide it into the back of the tensioner. Next, slide the pulley block down the back of the tensioner. Align the holes on the wheel assembly, the pulley block, and the access hole on the main body. Use an M3x20mm screw to attach the pulley block and the wheel assembly together.

5. Back Cover and Final Tensioning Slide the back cover onto the main body and over the ~30mm M3 screw. Secure the back cover with the remaining four M3x12mm screws. Screw the wheel onto the nuts pressed into the back of the wheel until you achieve the correct belt tension.