I've built my X, Y, and Z Axises in their entirety, but I don't seem to be able to find much information on how far back on the y-axis to place the aluminum frame.
In the images I've seen it appears to be about 2/3s of the way back, or in the middle of the y-axis.
The goal is to make the entire bed plate accessible to the extruder nozzle. You position the Y axis assembly so that the nozzle can reach both the front and back edges of the bed plate.
Start by pushing the bed all the way back on the Y axis assembly. Now position the Y axis/bed assembly so that the nozzle is at the front edge of the bed. Now move the bed forward and make sure the nozzle reaches the back edge of the bed. Tighten the Y axis assembly down.
