I have been working on my CNC controller enclosure while I await my CNC to be ready for pick up. I would greatly appreciate it if those with experience are willing to take the time to offer feedback on any aspect of what I have accomplished so far. I realized quickly from my research that opinions vary on what best practices to follow for, well, most everything to do with building one’s controller enclosure. What I have tried to do is incorporate those that made sense to me.
Note: I have extra wire in some places in case I change the component locations before my final install. Also, I have 3D printed temporary supports for a few things (e.g., power module, DB9 connectors, etc) to make my temporary mock-up easier/safer to wire.
Power to the Masso G3 controller will be provided by one EDR-120-24 PSU
Power to other ‘to be added’ components – relays, sensors, contactors, etc - will be provided by a second EDR-120-24 PSU
Power to the Leadshine MX4660 driver will be provided by one SE-600-48 PSU
4 NEMA 23 stepper motors – 3.15V, 4.2 Amps, 0.75 Ohms, 3.0 mH
AC Power distribution and wiring:
Mains power (120VAC Canada) enters into a AF-C10-SD module which has a fuse, on/off switch, and EMI filter
Line, Neutral, and Ground enter into connected terminal blocks (I will most likely connect the Ground to the mounting panel with a lug before it connects to the terminal blocks)
Line, Neutral, and Ground connect from to terminal blocks to each of the three PSUs
DC Power distribution and wiring:
One 24VDC PSU is dedicated to the Masso G3, and connects one PSU POS+ to a fused terminal block which joins to one other, and connects one PSU NEG-(common) to a set of joined commons
A second 24VDC PSU is dedicated to all other components that will be added. It also has one PSU POS+ connected to a fused terminal block which is joined to two others, and connects one PSU NEG-(common) to the same set of joined commons
The 48VDC PSU first connects one POS+ to a fused terminal block which connects to one other.
The POS+ then connects to two joined terminal blocks which split to feed into the MX4660 POS+ inputs
The NEG- first connects to a fused terminal block which joins all PSU commons
The NEG- then connects to two joined terminal blocks which split to feed into the MX4660 NEG- inputs
There is a 63V 2200uF capacitor connected to the POS= and NEG- sides of these terminal blocks
Power related suggestions/guidelines I tried to follow:
Provide fusing and EMI filtering at VAC source, as well as VDC POS+. I added a fuse to the VDC NEG- of the stepper driver as well given its power and load
Use joined terminal blocks to provide star configuration for, especially, VAC ground and VDC common
Use colour coded wire, terminal blocks, and ferrule/heat shrink connections
Keep VAC and VDC power separate from devices such as Masso and MX4660 driver
Use both pairs of VDC MX4660 inputs given the peak Amperage which could be expected from the four stepper motors
Power related questions:
What amperage should the power module fuses be? Currently 10 Amp/line
What fuse size would be appropriate for the second PSU dedicated to sensors etc? Currently 1 Amp for POS+. If not enough information to answer, how would I calculate its size/what are determining variables?
Is the capacitor I chose an appropriate size? Leadshine suggests the use of a capacitor to protect driver from Back EMF. My understanding is it also protects the PSU, in this case 48VDC. Leadshine also makes a shunt regulator for this purpose - SR50W – but it is hard to find and rather expensive