We have reports from users having problems getting the forearm’s timing belt a bit loose. We have detected that the problem comes from a slightly longer timing belt (we check the ones we ship but if you get it by yourself, you can have this problem)

Knowing that and after prototyping many new models, we have a final version of the forearm. This new forearm allows you to adjust the tension of that belt just sliding its parts. Photos below

Basically, I have split the UPPER- forearm into two pieces. Now you can adjust its total length just extending it and fixing it tightening the bolt indicated below. If you are having problems with your forearm, just print the STL files and mount the forearm as below. All the other parts stay the same. I will update the assembly guide ASAP.

As the total length may vary, the Arduino CODE has to be modified.
For the Arduino CODE (file configuration.h ):
 You will need to measure the GAP and add this distance to the default value in this line of the Arduino CODE:

// Robot configuration
#define ROBOT_ARM1_LENGTH 91.61 //92.84  FIRST SEGMENT   <-IF THE DISTANCE MEASURED IS 1mm, change the value  from 91.61 to 92.61
#define ROBOT_ARM2_LENGTH 105.92 //106.79 SECOND SEGMENT

STL files of the new FOREARM