Tiddy CNC.

[TonyD]

Hello.
Naming the machine seems the thing to do so I’ll call this one Tiddy after my sons favourite teddy

I’m creating the basics of my electrical control system while aspects of the mechanicals of my machine are still in the design stage. I’ve looked at several build logs and the required wiring diagrams for my components. I would really appreciate it if some folks would help me validate my assumptions and help with a couple of questions.

Background.
The hardware I have purchased should see a machine with a 1.5M X Axis, 1.1M Y Axis and a 0.2M Z Axis. I will be using a total of 4 Stepper Motors. My basic electrical bill of materials purchased so far is:
Power:
1 x PS806-5 PSU (3x68V-6A, 1x5V-1A).
1 x PS408-12 PSE (3x36V-3A, 1x12V-1A)
Steppers:
4x SY60STH88 – Nema 23 – Anticipating wiring in parallel (2.73V-4.2A)
Drivers:
3 x AM882
1 x PM752 (Z Axis)
BOB:
ZPA5A-INT 5 Axis breakout board.
Plus PLCM-E3 Mach 3 Ethernet Interface



Component rationale:
I’m not an electrician and although I could see from the forum comments it was possible to build my own PSU I didn’t want to and so bought the higher output unit for the X and Y Axis and then the smaller (and cheaper) PS408 for the Z axis, BOB feed and spare capacity. I did not want to stretch my budget to 4xAM882’s so settled for 3 and the PM752 for the smallest Axis. I liked the ZPA5A-INT 5 and purchased the PLCM-E3 because I wanted to run the machine from a lower power and spec PC. I’m not convinced of the PLCM-E3 yet.. So these are the choices I have made and from this basis and looking at the photos can I check these assumptions please.

1) I am bringing mains into the panel and switching the Live through a 10A 600V toggle switch, in order to show the mains in live I have wired a Neon light with appropriate resistor in parallel with the switch. The circuit then continues on to a 10A 20mm fuse in a fuse holder.
Assumption, have I wired the Neon correctly? Is 10A the right choice of fuse for this stage of power distribution? Is a toggle switch rated for 10A sufficient?

2) From the panel the mains will continue to the main board via a 30A ‘chocolate block’ connector so I can remove the panel from the enclosure for maintenance/installation etc. Mains power is then sent in parallel to both PSU’s.
Assumption: I’m assuming this is ok.

3. From the PSU’s I’m using 22AWG wire to distribute the live to each stepper driver via a 6.3A fuse for each driver. I’m using ‘spade’ type connectors rather than soldering these connections.
Assumption: Is this size of Fuse OK, the steppers should draw no more than 6A so I thought this would be a good size to choose. I believe the wire size is good for 11A 600v so I’m assuming this is OK for the HV (but not mains side) of the PSU’s.

From this point on, assuming I fix any identified issues, I plan to:
A: Connect the HV output side of the stepper drivers to the enclosure panel sockets with my CY cable (detail below)
B: Connect the BOB to the stepper drivers
C: Generally tidy the wiring up.

I’m looking at buying shrouded (but not shielded) cable for the signal connections between the BOB and Stepper derivers.. but I do have some CAT5 Ethernet cable around.

4. Can I use CAT 5 cable within the enclosure for the signal side of the steppers to the BOB?

So far I haven’t attached a component to the board that requires an earth connection (other than the mains-in) but I have a connector block set up as my central earth point.

5. Have I missed anything that requires connection to the Earth connector within the case so far? (based on what you can see in the photos)

6. I am assuming that the Earth connector on my board will go back to the Earth connector on the mains-in socket?

My panel has connectors for the steppers, limit switches and some potential expansion. My plan with these is to make up small junction boxes on each stepper so that I can unplug the motors from the cable, hopefully this will make the connections tidy and maintenance/installation easier. I have a small reel of CY cable at 4x1.5MM2 cores for the connection between the motors and the enclosure.

7. I am assuming that I should somehow Earth the CY cable shield at the enclosure panel. I am confused how to do this, should I just connect an Earth line to the panel that houses the connector sockets (Same one the mains in and on/off switch is on)?

Out of scope for now.. I have the ubiquitous Chinese water cooled spindle and VFD, for now I’m happy for these to remain out of scope and on their own mains lead supply.

8. I am assuming I can do this and effectively use the VFD ‘Manually’ without any need for electrical control?

Finally, I realise there is no E-Stop in the plan right now nor Relays used to switch the mains. I have not been able to find good material or circuit diagrams on how to wire this up. Right now I am willing to use the on/off switch I have to get the unit running and ‘upgrade’ to an Estop later.

9. If the enclosure must have an Estop and/or relay switching the inbound mains, can anyone point me towards an easy to follow circuit diagram?

Thanks for taking the time to read and for any advice.