Low-Profile PCB Clamp for Genmitsu Cubiko CNC

Overview

I recently started experimenting with DIY PCB milling on my Genmitsu Cubiko CNC and quickly realised that most PCB holders online were designed for 3018-style CNC machines using aluminum extrusion beds and T-nuts.

The Cubiko instead uses a flat threaded bed with M5 mounting points, so many existing PCB holders either:

• don’t mount cleanly

• sit too high

• or waste precious Z clearance

While learning the PCB milling workflow, I came across this excellent PCB CNC tutorial by: Gomez Gimenez PCB CNC Tutorial. The PCB holder concepts there inspired this design, but I redesigned the system specifically for the Genmitsu Cubiko platform and low-clearance workflows.

This version:

• mounts directly using M5 screws,

• avoids 3018/T-nut dependencies,

• keeps the profile as low as possible,

• and securely holds PCB material during milling.

Included Parts

• Fixed holder

• Extended pivoting holder

• Printable thumb nut

Hardware Required

• M5 x 12 mm screw

• M5 hex nut

(Depending on your spoilboard thickness, longer screws may also work. I use them without one for maximum Z clearence)

Tolerance Variants

The thumb nut uses a press-fit hex cavity for the M5 hex nut.

Because fitment can vary depending on:

• printer calibration,

• material,

• shrinkage,

• and slicer settings,

I included multiple tolerance variants:

• 8.0 mm

• 8.1 mm

• 8.2 mm

For best results, it is recommended to print the thumb nut variants first and test which fit works best for your printer/material combination.

How It Works

The system uses:

• a fixed low-profile base,

• a pivoting extended arm,

• and a printable thumb nut with embedded M5 hex nut.

The arm rotates into position and locks the PCB in place while minimising vertical height usage — important on compact CNC machines like the Cubiko.

If you find this model useful, please consider leaving a like — it helps a lot and is always appreciated!