Printrbot Simple Metal Z-Axis M5 0.8mm Pitch Threaded Rod Upgrade

Ok so this is a mash up between two different thingiverse listings:

https://www.thingiverse.com/thing:2011148

So When I saw this one I thought that's Nice but then I need a specific Metric Z-rod and a threaded Collar that I can only buy from a bot shop at premium prices. I saw a complaint on the printrbot site about their metric Z-upgrade that the Z - Axis falls down on itself and needs constant power on the motor to stop this so I thought that's not a good upgrade! .... thirdly I intend