re-designed again.. this time i've included a second ballscrew on the x axis, now due to my mis understanding of earlier comments i've kinda messed up a little bit in that i designed the machine to work around a single screw on one side. i've now been shown the errors of my ways and intend to fit a second screw. but i will go ahead and build the machine get it all wired and working to an extent before i order the second screw.

so here is what i hope to be my final design.

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i may change it a little as far as mounting the bearings for the x axis screws as it's come to my realisation that the spindle will hit the cross beam at the front before it gets to full extension thus cutting about 40mm off my workable area. i've also realised that had i not rushed in to buying the bits from chai i could have either reduced the size of the axis screws for the length of rails i have or better still ordered bigger rails as there is about 75mm of wasted travel along the x axis, but i'll have to live with that as long as i get my 15" mininmum cutting area i'm happy.