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.
Main equipment:
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:
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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
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Use joined terminal blocks to provide star configuration for, especially, VAC ground and VDC common
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Use colour coded wire, terminal blocks, and ferrule/heat shrink connections
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Keep VAC and VDC power separate from devices such as Masso and MX4660 driver
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Use both pairs of VDC MX4660 inputs given the peak Amperage which could be expected from the four stepper motors
Power related questions:
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What amperage should the power module fuses be? Currently 10 Amp/line
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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?
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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
