First I wanna say thanks to those friends helped me about this design they helped me solved a very big problem.The target of this design is to design a big printer in a cheap price .some of the size of the parts will be given in the Assembly drawing you can find it in the package.I will also share all of the original files designed by solidworks.You can redesign them by yourself.Hope you like this design there are also some problems of my designs.If you have any good ideas just do it!This design i have already used half an year Ithink it is good HAHA!! The diameter of screw(T8) and Optical axis are both 8mm the Linear bearing are LM8UU idler I just use some 623 bearing the bed(3103103mm) if you use a different bed you will need to redesign the holder of the bed!For the idler holder i just use 2 M3 screws to fix 2 623 bearings without nuts.Anyway hope you like it.