Hi. I’m assembling my printer, and up until now everything went well, and I’m at the point when I just mounted the Z motor, and I have the coupler attached to the threaded rod.
However, the motor shaft won’t go inside the coupler hole further than 1-2mm. It seems the coupler hole diameter is maybe 0.1mm too small. Am I missing something?
This picture is from the manual, not mine, just to illustrate what I cannot do :
Please, no jokes about how my shaft is too big, this is a serious matter ! 
Please inspect the coupler closely.
Maybe there is a small brim which prevents the shaft from entering. Most likely, it can be removed.
If not, please provide your address to support at velleman dot be, so that we can mail a spare coupler.
I had the same problem. The coupling is 4.9 mm and the shaft is 5.0 I did a dirty work around using some fine grain sand paper rolled up and drilled the hole a little bigger with the sand paper. Even worse With the coupling is that is not alligned prperly. So the Z-axis wobbles. I see that a lot of users have this prblem. My tip to Velleman : Switch to another supplier for the Z-coupling.
Thanks both. That’s exactly what’s happening to me. I’ve managed to make the coupler hole slightly bigger. That said, the Z-Axis wobbles a lot indeed. Without additional support, I’d say the top end of the rod attached to the motor shaft moves along a 2cm+ diameter circle. Once assembled, since the top end is held in place in a bearing, I’m afraid the motor will be the one enduring the lateral movement.
