Congratulations with winning the contest, you also got my wote. It is a great design.
I have taken two pictures showing how it is possible to twist the roller on the conduit.
Maybe my bearings outer diameter is to small they measure 22mm. But I am using the same type on the middle section where they are pressed very firmly against the conduit.
I haven’t assembled the machine completly but I cannot see how I could have assembled the rollers in the wrong way. The top bearings are pressed in between the sides. And the other bearings are securely mounted. Btw. I am using metric screws.
I have used the holes in the 3D part as they were, meaning no need for drilling.
Any suggestions ?