View Full Version : Wiring diagram for 4x4 cnc router

19-07-2013, 08:10 PM
Hi guys!

I am a complete novice to electronics as you may tell by the diagram i am about to post. Could you please make any comments on the diagram good or bad and point me in the right direction if there is something obvious and is likely to go bang!
I think all the details are there as to steppers / drivers used and key components. Im not to worried about the wiring of the steppers to the drivers, its mainly the safety system.
The questions i have are:
What fuses do i need?
What cable sizes do i need?
Should the spindle be earthed to the spindle mount / frame or should i take it back into the main point in the control box?
Linking the charge pump to cut the safety circuit how is this done - via a relay or software driven?
Am i ok linking the power supply connections at the terminal block with small linking wires - one to the other etc?

A massive thanks to Dean for getting me this far, just wanted to clear the last few questions up as hopefully the diagram will be easier to follow than me typing it out.

I will be splitting the power supply and control side up by having to cabinets / boxes.


19-07-2013, 11:14 PM
Hi Dan,

Well your sort of on the right track and nothing dangerous just a bit cluttered and unclear.?

While drawing shows Relays it doesn't distinguish between relay coils and contacts so I'm not sure if you fully understand what your trying to achieve or just skipped over these and just showing a general layout.? . . . . Being honest, the way you have shown the master relay not interacting with other relays etc then I'm not sure you do follow completely.! . . . It won't work if don't.!

Also not sure what the 12V & 5V PSU's are doing.? Does the BOB need 2 supply's to work IE: 5V for Logic and 12v for relays etc.?
Nothing wrong with this just a pain in the arse.!

Regards the water pump then your better running the power thru the VFD onboard relay so it only comes on when spindle is running.

what do you want to know about fuses.? Type to use or sizes to use.?
Sizes need to be rated to match the components there protecting with a bit of overhead choosing the nearest size above devices rating. IE 4.5A max draw then use 5A fuse.
Type can be any you like or prefer so long has they can handle the loads. Personally For mains AC then I use MCB Din type and for DC just ordinary Din rail glass type fuse holders. Car type fuse box holders would also work.

AC wire needs to be 2.5mm/2 flex wire cable not ridged stuff like in walls.
DC wire then 1.25mm/2 (Awg 16) for higher loads IE: Drives.
0.5mm/2(Awg 20) for smaller loads relays etc.
Signal wires like Limits, Estop etc need to be shielded cable around 0.3-0.5mm/2 (awg22-20)
VFD wire needs to be Shielded with minimum 1.5mm/2 and preferably 2.5mm/2 but problem with using this size is fitting it in the connector fitting.!!

Regards VFD earthing then it's best running Earth from Spindle body back to Earth point on VFD. Best way to do this is to use 4Core wire and use the spare wire for earth. ONLY ground the cable shielding at one end not both, best done at the VFD end.
Same goes with signal wire shielding Only ground back to the main Star ground point and leave other end free.

Now check your PM's.!!