When using ballscrews we recommend to use these shaftcouplings. Since they are backlash free, they match in terms of performance with ballscrews. The rated torque is 12,5Nm so in theory it could be used with our 12nm motor. In practice we use this coupling for the smaller motors Nema 23 0,5nm to 2,5nm or the NEMA34 4,5nm motor. It is possible to make combinations of different shaft sizes. So for example if your steppermotor has a shaft of 14mm and your ballscrew has a size of 8mm, order one hub of 14mm and one hub of 8mm. Ofcourse for each 2 hubs you need one spider.