OpenLiner – The Open Source Roundnet Court Marker

by OpenCirclz (@opencirclz)

OpenLiner is an open-source redesign and optimization of the "Quickliner" (originally developed by the engineering team at Roundnet Giessen, Germany). It is the essential tool for any Roundnet player, coach, or tournament organizer who wants to apply perfect lines in seconds.

Why use OpenLiner?

In competitive Roundnet, exact lines (No-Hit-Zone & Service Line) are strictly regulated. Measuring these manually for every set is tedious and often inaccurate. OpenLiner transforms any standard broomstick into a professional court-marking device.

Key Improvements & Features:

• Integrated Dust Cleaner / Floor Buffer: This optimized version features a built-in slot for a cleaning sponge or microfiber pad. It wipes away dust right before the tape touches the ground, ensuring significantly better adhesion on gym floors.
• Universal Compatibility: Designed to fit standard 28mm broomsticks (DIN norm). You can find a compatible handle in almost any hardware store.
• Precision Compass Hook: Use the integrated hook or add a screw hook to the stick for your measuring tape. Together with the suction cup, the OpenLiner acts like a giant compass to draw perfect circles.
• Community Driven: This model is fully Open Source. It’s made by the community, for the community.

Technical Requirements:

To complete the assembly, you will need:

1. Tape: Whiteboard Tape (approx. 3mm vinyl tape).
2. Suction Cup: A suction cup with an M4 screw to serve as the center point anchor—allows you to apply circles by yourself without any help!
3. 10m Measuring Tape: A metal measuring tape with drilled holes at the relevant marks (No-Hit-Zone, serving line, boundary).
4. Sponge: A small piece of household sponge or cleaning felt to be fitted onto the bottom.
5. Hardware (Screws):
   • M5x50 screws for the main connection of the handle/frame.
   • M4x40 screws (recommended) for the suction cup assembly.
   • 1x Screw Hook to be screwed into the broomstick for easy measuring tape attachment.

How to Use:

1. Screw the OpenLiner onto a 28mm broomstick (pre-drill a small hole for the screw).
2. Insert the tape roll and feed it through the guide.
3. Attach your measuring tape to the hook on the handle.
4. Slot the measuring tape onto the suction cup screw in the center of the court.
5. Walk in a circle while applying light pressure—your perfect court lines are ready!

Pro Tip: Add a small piece of painters tape over the start and end edges of your vinyl lines to prevent peeling during intense matches.

Print Settings:

• Material: PETG or Tough PLA (for durability).
• Infill: 20-30% (Grid or Gyroid).
• Walls: 3-4 perimeters for structural strength.
• Supports: No supports needed!

Credits: This project is a remix and homage to the original "Quickliner" invented by Roundnet Gießen. You can find the original post and inspiration here: Roundnet Gießen Quickliner Announcement.

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