On a side note about your drawing, I like how you added vertical stiffeners to the sides of the gantry walls. I did this to a wood machine with amazing results, and no real downside. It added no practical width to the machine since the motor and bearing stick out anyway, and is cheap and easy. Maybe this is a wood machine, I donno. If it is, glue the stiffeners; don’t just depend on those screws. Stiffeners could also be added to the back of the beam and the bottom of the gantry connect plate/leadscrew nut holder.
IMHO that single rail across the top of the beam just does not look right to me, but hey, give it a try. You can always add a second rail later.
Steve |