I might go a single stepper on the X axis and use belt drive for both ball screws then.

Got a quote from Chai today for the SBR20 rails/carriages and the 1610 machined ball screws, ball nuts, BK & BF bearings etc. and its very reasonable (just a bit over half the price I worked out getting it from the UK would be) so will get those on order soon. Am moving house this week so will wait till the end of the month till I have done that and unpacked a bit!

Should give me time to go through the design and make sure all dims etc are correct and print cutting lists off for the steel.