Thanks.

So let's just say that I was going to use threaded bar I know it's not ideal and it won't be as accurate as lead screws but it's the way I'm going for mk1. Would putting 2 lock nuts on the bar with the 2 flat ends facing each other, backed with washers and a strong spring in between the 2 actually help at all? Obviously the nuts will be captive in the bracket of the sliding part and the ends will be held with bearings, but would it be worth taking the time to fashion a bracket where I could spring in between the 2 nuts?

I'm not looking for a highly accurate machine. If I can stay within a mm over the length (A4 size) then I'll be happy. I'm using mk1 as an exercise in getting the thing to move and working well with the PC.

I've got my tin hat on ready so fire at will! :naughty: