Hi guys,
I'm in the brainstorming stage of a 4'x4' steel frame router build. I'm going with linear rails (25mm) and ball screws. I like the arrangement used on the Shop Sabre routers where the rails and ball screws are mounted on the side of the frame. My concern is how do you ensure that the rails on each side of the bed are square, straight,and level without having it machined? On a router with top mount rails you can level the mounting surfaces with epoxy but I can't think of a way to do that with side mounting. Is there a trick that I haven't found or is that one of the downsides to side mounting?

Thanks!