This is a piece of wood to inerface a lego crossbar to 8mm rods
- build 1 meter long lego compatible bar extension
- move a nut along a 8mm threaded rod with a nxt servo
- bring lego NXT to the real world
nxt servo is a motor + a reductor + a
gray code rotary encoder ( shop.lego.com/ByCategory/Product.aspx?p=9842&cn=389&d=292 )
Maybe you want to adapt to other sizes or other diameters, so i provide xxxx_wrk.odg which is a kind of source before finalization, just in case.