Belt tension tester

Description:

The method of measurement with my tester is similar - it also compares the tension of the belt Gates 2MGT-6 (used in 3D printers such as Prusa MK3 and Prusa MINI or similar) with the tension values recommended by the belt manufacturer.

-The green mark (min) indicates with a 30% reserve the minimal belt tension necessary to ensure that the belt wraps and meshes properly with the sprocket.

-The red mark (max) indicates the maximal belt tension limited due to bearings life by the maximal radial load on the motor shaft, although the maximum allowable belt tension could be 30 % even higher.

-When checking the belt tension, the black mark on the pointer should be between the two coloured marks.

I tried to improve some features:

-The tester is easy to read and can be put on and taken off simply and quickly.

-All three colour marks are placed in the same plane, so it doesn't matter the angle of view when reading.

-The pointer movement is limited in both directions for overload protection.

However, one feature is complicated:

Due to permanent preload, the double spiral spring loses some of its stiffness exponentially and is therefore slightly oversized. To reduce the higher spring stiffness to the desired level as quickly as possible after printing, fully load the spring for about 48 hours (see photo).

This way you can easily check the actual spring stiffness at any time:

Release the pointer so that the spring is not preloaded and if the groove on the tester body is hidden, the spring is OK. If the groove is completely or partially visible on the right side of the pointer, the spring is still too strong (see photo) and theoretically, if the groove would be visible on the left side, the spring could be too weak.

Note:

To work properly, the tester must be made from PETG material and if you want to blow it with hot air because of the strings, be careful, the heat can change its properties!