Well, this is what the RepScrap looks like today.
I finished the Y-Axis table late last week, and tested the moment. It's a little sluggish with the printer motor driving the bed, but will do for now. I foresee burning this poor motor out, so will probably have to replace it with a gear motor at some point in time.
The Y-Axis bed is the glass top of the all-in-one printer's scanner. The aluminum cross bars come from the bottom track of a sliding closet door.
As I mentioned in my previous posting, the frame for this was scavenged from exterior railing extrusions.
Here, I am truing up frame that houses the Z-axis ball bearing slider rail, shown below. These drawer sliders seem to be very tight, as in, there doesn't seem to be much slop at all.
At the top of the Z-Axis frame, I am placing the two DC-Motor /Encoder assemblies used for the paper feed on the inkjet printers.
I am opting to run a threaded rod through each to drive the Z-axis gantry. It had been suggested over on Reddit, that I might have success with a taught wire or line looped around the rough tubing of the sheet feed roller, but I think the threaded rod will be easier to design and troubleshoot.
And below, is my test circuit for the motor/encoder interface.
One thing that I am doing instead of having a separate Optical Endstop for each axis, is that I am making a larger black bar at each end of the linear optical encoder strip. This can then be identified as a discrepancy during the encoder interrupt routine, and trip the endstop routine.
And a few more pictures of the Z-Axis gantry assembly with the X-Axis rail attached.