CNC Beginnings

The beginnings of my CNC project, in the form of parts for the XY table, and associated tool pile:

The motion capability will be 9” in the X dimension and 6” in the Y direction, the Z axis is on hold until after the semester is over, there just isn’t time to design it in now.
Drives:
Each axis will be driven by a 130 oz-in NEMA23 Stepper (Lin Engineering 5618S-58-01)
The lead screw to run the axis is a 3/8” coarse threaded rod, cut to length
The travel nuts are 1.125” coupling nuts (long, to help with backlash without spending money)
One remaining problem is couplers for attaching the lead screw to the drive shaft, there are lots of options, but they all seem to cost at least $10/axis. I suspect unless something better appears I’ll end up with lovejoy couplings.

From aluminum square tubing (1” OD, .062” walls):
8”x8” (outside) square frame for Y axis
6”x12” (outside) rectangle for X axis
The framing will be assembled with bolts, tabs cut from 90deg angle stock, and a bit of epoxy to make it easier.

The next big fuss is figuring out the driver circuits. The motors are rated for 2A at any practical voltage, and only show about 2.6Ohms/coil of resistance, so its going to require proper current-controlled drivers, which may be expensive.

The thing I’m liking most about this project is that I’m learning a huge amount of practical, hands-on knowledge about metalworking and mechanical devices in a hurry, in a low-investment environment so I can experiment and really get a feel for things. I’m not sure if I’ll ever do much more metalwork, but its a good skill to have.