X carriage with belt tensioner

Fits with T2.5 or GT2 belts
Hole spacing: 30mm
Upper rod belt distance: 11 mm
M3 screw for belt tension adjustment
Based on thingiverse #135353

The advantages versus a pulley-based belt tensioner are:

• a more progressive adjustment of the tension: 1 turn of a m3 screw induces a belt extension of 1 mm for the pulley-based tensioner and 0.5 mm for this one.
• a more stable system: for the pulley-based one, the idler pulley is "floating" and fixed for this one.