Ugg just checked my drivers and they are only rated at 50V, looks like im going to have to start replacing electronics anyway.

I am starting to have a change of heart, the way I see it at the moment is that I have a machine that is working ok at the moment so I am not in a huge rush to get this one up and running so as James has pointed out lets do it right the 1st time. I will tweak the design to include twin X screws that way I can order the steel in and get on with making the frame while I save up for other bits.

Where did you get your 75V power supply and drivers from was it zapp?

Didnt think about the Z backdrive, maybe some sort of solenoid brake that retracts in the powerd up state and locking the z when controller is switched off. If I dont do something like that I know for sure I will forget and end up ruining something :)

For those who have not seen it before here is the pully system I was talking about.
Click image for larger version. 

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At least with replacing the drivers and power supply I wouldnt have any excuses not to make a scratch built cnc mill I've been wanting to build, cant have those bits sitting there gathering dust :P