Making my control cabinet - what switching controls should I have?

So, I've largely finished the mechanical part of my little CNC gantry router/mill (see build log here: http://www.mycncuk.com/threads/12593-Game-on!), and am starting to get together parts for the control box. All the stuff with PSU, stepper drivers is pretty obvious, but I'd welcome opinions on what I should have in the way of front panel controls (switches): some builds I've looked at have basically just an E-stop switch and that's it, others have quite a lot of controls. So far I can see I deffo need the following:

Mains on/off (NVR switch)
E-stop
Limit over-ride (so you can jog back off the end stop)

Things that look like they might be useful are:

Spindle On/Off??
Water pump On/Off?? (interlocked with spindle)
Coolant On/Off??

Cheers,
Trevor

Quote:

---

Originally Posted by Voicecoil

So, I've largely finished the mechanical part of my little CNC gantry router/mill (see build log here: http://www.mycncuk.com/threads/12593-Game-on!), and am starting to get together parts for the control box. All the stuff with PSU, stepper drivers is pretty obvious, but I'd welcome opinions on what I should have in the way of front panel controls (switches): some builds I've looked at have basically just an E-stop switch and that's it, others have quite a lot of controls. So far I can see I deffo need the following:

Mains on/off (NVR switch)
E-stop
Limit over-ride (so you can jog back off the end stop)

Things that look like they might be useful are:

Spindle On/Off??
Water pump On/Off?? (interlocked with spindle)
Coolant On/Off??

Cheers,
Trevor

---

I’ve also got:

Estop reset momentary button (you need something to energise the latching relay)
Switch for lighting

Plus provision for cycle start pause stop and gcode rewind, plus feedrate override pot and feedrate reset. I’ve yet to implement these though . . .

I've taken a somewhat minimalist approach. Mains on/off (with pilot light), reset (with pilot light), e-stop (plus a couple of others on the machine), and spindle coolant (off/slow/fast). Nothing that is used during normal operation, just at the start of a session.

Everything else is managed through Mach3 and either a wireless keyboard with built-in touchpad or a wireless MPG. For example, "jog off limit switch" is not needed as hitting a limit trips Mach3, needing Mach3 (not control panel) reset and rehoming. And soft limits mean that hitting a limit switch is a rare event. If you have a control panel easily reached while at the machine (mine is off to one side) then things like tool zero/zero after tool change are used all the time, but again I've tweaked Mach3 and the MPG to let me do that while leaning over the machine. My machine is designed for a single user (me) and not a commercial workshop, of course.

Quote:

---

Originally Posted by Voicecoil

Mains on/off (NVR switch)

---

Don't need NVR just straight forward ON/OFF mains contactor switch.

Quote:

---

Originally Posted by Voicecoil

Limit over-ride (so you can jog back off the end stop)

---

Just use Mach's Auto limit override feature for limits, don't even have them trip the E-stop circuit as limit isn't really an emergency it's positional error and it soon becomes tiresome having to Reset mach and reset drives etc when first learning. After few months you'll hardly touch the limits. Just let the controller handle the limits. Let the E-stop handle the emergency and shut down hardware.

Quote:

---

Originally Posted by Voicecoil

Things that look like they might be useful are:
Spindle On/Off??
Water pump On/Off?? (interlocked with spindle)
Coolant On/Off??

---

If not controlling Spindle thru Mach then yes but if you are then wouldn't bother with ON/OFF unless you want to add little extra safety for when changing tools.
If using a Spindle with VFD then just let the VFD control the water pump so it only comes on when spinning.
Coolant then yes possibly but Mach got button on screen so if controlling pump thur mach then just use that and keep it simple.

The important things are you use a latching E-stop circuit so then you'll need Reset button ideally with light to show machines ready to go and drives powered up.
Power ON/OFF with light, E-stop button and Reset with light are all you really need. The rest is purely personal choice/convenience.

Thanks for the input guys and nice to see you back and active Jazz, I've learnt a lot from your past posts. I'm intending to use UCCNC rather than Mach 3, does that change anything?

Glad you making good progress. I use uccnc with the uc300eth, no problems so far

Quote:

---

Originally Posted by Voicecoil

I'm intending to use UCCNC rather than Mach 3, does that change anything?

---

No both do same job so still applies.

Sent from my SM-T580 using Tapatalk

I've hopefully future proofed my control box connections.
3x GX20 4 PIN for nema 34 for X,Y,Z.
3x GX16 4 PIN for A,B,C nema 23.
Ethernet connection for limits.
2x GX16 4 PIN for spindle control / tool changer / ancillary.
4x GX16 2 PIN for Estop, 5v,12v,24v ancillary power output.
10A 3pin kettle type connector for coolant relay.
2x 10A 3 pin mains input on the back.

Likely need another ethernet if I ever get to tool changer stage.

For my next control panel, I'll probably only go for the following-
Power switch
E-Stop
Cycle Start*
Feedhold*
SSO
FRO
MPG

Everything else I'll do on a touch screen.
The last panel I built for my mill, I added axis and step size rotary selection switches to go with the MPG, but doing it with some buttons on a touchscreen is far simpler and be just as effective.
However, all my machines I can reach the control panel from the working area. If I had a big machine, I'd have the MPG on a pendant for convenience.

*Cycle Start and Feedhold you could also do with on screen buttons, but I prefer having a couple nice big buttons to hit.

Quote:

---

Originally Posted by JAZZCNC

Don't need NVR just straight forward ON/OFF mains contactor switch.

---

Using a NVR switch wasn't so much a safety concern (I assume a power fail will reset the controller to a safe state), it was just that from CPC it's cheaper than a separate decent switch + contactor

Is your spindle vfd driven?

Yes, a Sunfar E300 - apparently according to the manual I can configure one of the external inputs to be a stop control, so I'll use that for E-stop. Whether I need to be able to isolate its power when changing tools is another question of course.

Quote:

---

Originally Posted by Voicecoil

Yes, a Sunfar E300 - apparently according to the manual I can configure one of the external inputs to be a stop control, so I'll use that for E-stop. Whether I need to be able to isolate its power when changing tools is another question of course.

---

Nice....are you going to have the drive inside the same enclosure?

Quote:

---

Originally Posted by ericks

Nice....are you going to have the drive inside the same enclosure?

---

Probably not - I have a pretty nice 19" rack cabinet lying around which needs using (saves shelling out £60 on a new box :beer: ), and I don't think there's quite enough room in it for the drive - though I will see if I can shoehorn it in!

Sounds good:)