Digital comparative GT2 belt tension gauge with retractable button

Digital comparative gauge for adjusting GT2 belts, consisting of an LCD displacement indicator and a bracket designed to rest on the belt. This version has a retractable-button mechanism that helps withdraw the probe and repeat the measurement.

The tool measures in millimetres or inches how far the belt is displaced by the load provided by its mechanism. It is useful for repeating a known adjustment, comparing two equivalent belts or checking changes after adjusting an axis.

Features

• Application: comparative adjustment of GT2 timing belts.
• Reading type: digital linear displacement.
• Stated range: 0 to 12 mm.
• Selectable units: millimetres and inches.
• Functions: power, unit selection and zero setting.
• Return mechanism: retractable button.
• Power supply: button-cell battery.
• Approximate length: 115 mm.
• Bracket width: approximately 80 mm.
• Approximate maximum height: 57 mm.
• Body thickness shown in the drawing: approximately 21 mm.

Positioning on the belt

The bracket is placed on an accessible straight section of the belt. The outer contact points establish the reference while the central probe produces the displacement shown on the display.

Dimensions

What the instrument actually measures

The display indicates linear displacement, not force in newtons or frequency in hertz. The reading is affected by belt tension, but also by:

• The free length of the measured belt span.
• The width and construction of the belt.
• The exact position of the instrument.
• The bracket geometry and return mechanism.
• The zero reference used.

A value obtained on one printer should therefore not automatically be used as the target for another machine or a belt of a different width.

Recommended procedure

1. Switch off the machine and position the axes so that a straight belt section is accessible.
2. Select millimetres and zero the display in a repeatable reference position.
3. Always place the instrument on the same belt span, in the same orientation and at the same measuring point.
4. Allow the mechanism to rest on the belt without adding pressure by hand.
5. Record the reading and remove the tool before adjusting the tensioner.
6. Make small adjustments and repeat the measurement under the same conditions.
7. Move the axis manually after adjustment to check for binding or excessive resistance.

Compatibility and applications

It is primarily intended for GT2 belts used in 3D printers. It can be used as a comparative tool on many Creality Ender 3, CR-10, RepRap, Prusa i3-derived and other Cartesian machines when an accessible straight belt span allows the bracket to sit correctly.

On CoreXY machines, it can help compare both belts when measurements are taken on equivalent spans under the same geometry. This does not replace the adjustment procedure specified by the machine manufacturer.

For Voron printers and other high-performance equipment, follow the assembly instructions for the exact machine version, especially when they specify a vibration frequency or particular tensioning method. A reading in millimetres from this instrument is not directly equivalent to a measurement in hertz.

It can be used to compare adjustments on the standard 6 mm GT2 belt, wear-resistant 6 mm GT2 belt and other compatible belts, provided that they fit correctly in the bracket.

Limitations

• It is not a force gauge and does not directly measure tension in newtons.
• It does not provide a universal correct-tension value by itself.
• It must not be used while the machine is moving.
• It should not be forced onto a belt that does not fit the bracket correctly.
• A repeatable reading does not rule out misaligned pulleys, seized bearings or defective fastening points.

Difference from the other version

This model uses a retractable button to assist the return mechanism. The digital GT2 belt gauge with elastic return is also available. Readings from the two versions should not be mixed as if they necessarily shared the same calibration.

The tool does not require any Marlin, Klipper or RepRapFirmware configuration.

Contents: 1 digital indicator with GT2 belt bracket and an installed button-cell battery.