When inserting the steel rods into their mounts on the y-axis it was apparent that the only securing force keeping the rods attached to the frame was the friction between the precision cut steel and the rod. This means your whole y-axis and print bed carriage is depending on friction to hold it all together.
Either by fault of my own or tolerances in the steel rod or frame (read: my fault!) after successfully wiggling and inserting the rod, they did not fit snug and were not tight enough, i.e. there was insufficient friction between the rod and mount to keep it solid. This caused the rods to move as the print bed went back and forth.
I did not want any possible movement in the rods, so investigated Thingiverse for a simple clip bracket to hold the rods in place at each end. A couple of minutes later and there was a simple little bracket design by user Hobsie which looked perfect and resolved the issue. His design can be found here – http://www.thingiverse.com/thing:1560498, and you can go straight to my make here – http://www.thingiverse.com/make:229007.
A quick print later and we have the four clips:
These secure to the frame perfectly and lock the 8mm smooth rods like a glove. Such a great little design – simple, effective and perfect! Can’t fault them, thanks Hobsie!