Hows my wiring?

Machine: Custom Build

Board: C3D Laser Board

Firmware: I have a new board and I’m using whatever it came with

Problem/ Question:

Hi all, still working on building my laser engraver.
Was hoping you guys could have a second look at my wiring, and the parts im using together.
Keep in mind, this is my first time building one, and i have little experience with electronics, i’ve been learning as i go, by reading the forums.
Thanks for your help.

Here’s my wiring diagram:

Here is a list of the parts in the diagram, a link to its product page, and a few details about the parts.

Parts and Details

Water Flow Sensor
Product Page

Product Page

Water Temperature Probe
Product Page

  • Voltage: 5V-24V wide voltage

E-Stop Switch
Product Page

EMI Filter
Product Page

Product Page

Digital Ammeter
Product Page

A few questions i hope i can get some answers to:

  • The Digital Ammeter and power supply were purchased from Cloudray Laser, they provide a wiring diagram to connect the two.
    is there any conflict in comparison to the normal way an analog ammeter is wired?

  • I have two water temperature probes, that will monitor the temperature before and after the laser tube.
    These probes are rated for 5V-24V, do i have these plugged into an appropriate location on the board to power them?
    or perhaps i should power these with their own power supply?

  • Do i have the EFI Filter in the appropriate location?

  • How are the Laser Ground, and Mains Power Ground different?
    Should they be both grounded to the frame?

  • and in general are the parts all compatible in terms of amps and volts.

Why do you have the two water temp probes on the air assist pins? Those should probably be on the 24V rail and powered all the time. Those pins are used for a solenoid or relay closure or something to control the air assist in software (obviating the need for your ‘air compressor override’) switch.

The wiring otherwise looks OK. The EMI filter should be the first thing the power goes through when it enters the unit; put it after a fuse but before the e-stop switch.

Only ground the mains power to the frame.

I seen on a diagram that these pins output 24V, i know their meant to control things, but i wasn’t sure where else i could hook them up.

Are you refering to the “24V From Laser (Unused)” as pictured below?

what kind of fuse would i need?

Ok, only ground the Mains power to the frame, and do not ground the “laser ground” to the frame.

Tie in you 24 v unused connection to you temp sensors. You should be able to use the open screw terminals for 24 v and ground on the c3D board. This voltage is sourced from the LPSU. In this way you are not using up any un-necessary power on the c3D board.

I would lose the manual switch for the air assist and use the air assist output from the c3D board for control. Make sure you use a control relay if the current draw is approaching the max the board can source.

I would also add a analog milliammeter in series with your digital. When the laser is engraving, the numbers on your digital meter will be flashing all over the place. Having an analog gauge will allow you to see more about what’s happening. You will be able to see the laser pulse and also see the peaks of the pulses. Obviously it has some lag but still allows you to monitor your process differently than the digital gauge. I use my digital gauge only to setup my max current with the pot and record accurately the current when experimenting.

I actually installed some DIN rail mounted terminal strip and ran the 5v, 24v and common to it so I have a buss I can tap into for lights and such. I also purchased a 24 to 12 v converter so I have 5, 12, and 24 all available to use as needed. Worked out well for me since I have 12v led strip lights mounted in the cabinet to light my acrylic power panel engraving

Also, I am not sure about which grounds are which but the ground on my pot is hooked up to the ground on the LPSU that is next to the 5v and input control signal. Not sure if that is an isolated loop from the laser power ground which you currently show it connected to. Maybe someone more familiar with the inner working of the LPSU could chime in

Here is my updated diagram after feedback.

This is now reflected in the updated diagram, lemme know if this is right, or if i misunderstood.

I’ll probably be doing this eventually, but i think ill leave it as is for the moment, just so i can try and get this project done faster.

This is good advice, i didn’t realize they did that, ill look into getting one.

I currently have the pot hooked up to the ground/IN/5V (green/black/red wires) on the LPSU
I think the two grounds are isolated from each other, i think i read that somewhere on the forums… up above @loather also says:

so i assume this to be the case.

Did you also use a fuse on the main power lines like Loather mentions? if so what kind?

Be careful not to create a ground loop, they will introduce interference to your machine behind the filter causing all all manor of problems.
Like missing steps or even destroying equipment . Wile it safe to ground all your electronics together using a star type topology, Its best to ground your chassis to a direct ground.
What I did was in the closet close to the machine I drilled a hole in my concrete floor and drove a grounding rod. I then used a solid 8 gauge bare copper wire to connect the laser to the machine. The laser tube can use up to 24kv that’s 24,000 Volts, If you have a failure where the High Voltage sinks into the chassis you do not want it to go onto the same ground as your electronics/rest of house.
Instead you want it to dump down your fat 8 gauge wire grounding rod saving your electronics and probably your life if your touching the laser. this is why there is a ground lug on the machine.
If you notice all electronic grounds are connected to the Lug on the machine anyways.
This fine because electricity takes the path of least resistance. and your 8 gauge wire will have a lower impedance then your general house ground thus making it the most likely place your shorts will leak into.

Wile you could use a fuse i would recommend using a din-rail mounted breaker .Wile fuses are faster to react and can be safer for electronics. A 3 pole breaker can be used as a secondary safety layer. Connecting your Line and Neutral for normal protection and the 3rd to your Ground lug you effectively create a switch that if it detects a leak onto your ground IE 24kv it will throw the power.

Your switches Wile id keep the LPSU and C3D I would just direct wire you lights I mean your going to need them whenever the laser is on why not just have them on all the time. the Air assist and Fan can be wired to a SSR hell you could wire up a SSR for both a DCtoDC and a DCtoAC using the same signal wire. so you can just Gcode start them.

The emi filter is correct

Hope this helps

I don’t think i have a ground loop in the current diagram posted, did you spot one? thanks for this info though, diddn’t know about ground loops.

while searching for ground loops in my diagram, i realized that the cohesion3d power brick, doesn’t actually use a ground, so i’ll have to remove that from my diagram

im not sure i understand why grounding to the earth is better, than grounding to an outlet… the house/outlet is grounded to the earth as well…
is it that 24kv is too much for house wires?

as for damaging electronics that are using the same ground, wouldn’t the electricity, go straight from its source, through the ground wire, to the outlet, and to earth? bypassing all electronics?

Just for clarification, I assume when your talking about a “ground lug”, you’re talking about the screw or bolt that comes on the K40, or pre-built machines? where the wire going to a rod, pushed into the ground, is attached on the machine?
I guess on my custom machine, this could/would be the spot i ground to the frame in my diagram.

from main power, which would be first? the breaker? or the fuse?

ill probably be doing this, just not right away, trying to get this machine up and running sooner, rather than later.

im still learning, so every little bit helps, thank you.

From what I see you don’t have any ground loops This is just something to keep in mind wile building your machine or adding components.

Grounding it really depends on your house/shop wiring and how long its going to be exposed to the fault.
But typical houses cables are not rated for 24,000VoltsDC if you your machines creates a fault at some point dumping 24kv onto a small 14 to 16 gauge to the outlet is a fire hazard. As long as your house wiring is good the chance of electronic damage is low for the rest of the house.
its more about fire then anything.
But also grounding your case to the same ground as the electronics will effectively create a ground loop.
So you can think of wire like a road the larger the road the more cars can travel at one time IE resistance or impedance . As electricity takes the path of least resistance it would dump the fault through the case lug into your grounding rod. Wile its not necessary to do this its just extra precaution to protect yourself and your property.
Yes the ground Lug is the Bolt on the back of the machine/chassis you connect it to a ground source.

Sorry what i mean by the breaker is it replaces the fuse on the main input by using a 3 pole it also covers the ground witch if the ground leaks/faults it will flip . Otherwise just because you have your L and N fused it wouldn’t matter if your Lpsu shorted on the output side it would just continue to dump and if your touching the machine you will inflict harm to yourself. So you would want the Case ground running through the 3 pole.
You can still individually fuse the inputs onto your electronics for there safety this would occur after the breaker.

Hope this clarifies a little bit for you .

What size of breaker would i need?
I think most houses have 15a or 20a breakers.
I assume that i would want a 15a breaker (or less? 10a?) for the laser engraver, so that it trips before the room breaker trips, keeping the electricity from going through house wires.

just for clarification, all electronics, including the LPSU should ground to my wall outlet, but the frame of the machine, is grounded straight to earth? is this correct?

Don’t try and power anything off the laserboard’s 24V rail. The power supply included with the board is rated for the board’s logic and the stepper drivers and that’s it - so to avoid damage to the board, it’s better to just add a small power supply (yes, another one) to the machine to run the water temp sensors. If you don’t want to add another power supply try tapping into the LPSU’s 5V rail and see if that will do what you need. Note the rails on those LPSUs are notoriously weak.

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Those terminals are input-only and unused; this will not work. The LPSU in question doesn’t even output 24V.

ok i will give this a try, ill connect to 5V and ground on the LPSU for the temp probes. If this doesn’t work, then i’ll have to get a power supply i guess.

do you have any further comments on breakers or fuses in the machine?

Here is an updated diagram:

No, you absolutely do want to sink it to the structure ground. What you describe here creates a huge ground loop. There’s a reason the US NEC specifies against a second grounding rod for singular equipment (there are exceptions to it, but this isn’t one of them).

No! In the US, If you install a circuit breaker it should only be on the hot (black) line, and absolutely not on the ground. The equipment safety ground must be connected at all times, even (especially!) in the event of a circuit breaker trip. If you’re using 220V mains, it is acceptable to put a circuit breaker on both input power lines (in the US this will be a second “hot” - it varies elsewhere in the world).

@loather aside from the 3 pole breaker being a problem, do you see any other problems with my most recent diagram?

do you agree or disagree with the frame being grounded straight to dirt, but NOT grounded with the electronics, and the outlet ground?

Ditch the separate ground rod and just allow the safety ground in the outlet to do its work.

do not do this.

do you recommend a breaker, or fuse on the main power coming into the machine? is this necessary? or optional?

if so, would it be a 15A 2-pole breaker? or 15A fuse? or something else?

Personally I would not use anything other than a fuse on the input. Look at the ratings panels on all the connected devices to determine the fuse rating - A good rule of thumb is to take the rated input currents of all devices, add them together, then add 10% of the resultant value. This ensures all connected devices can dissipate their maximum load and gives a 10% headroom before the fuse goes.

The fuse is optional, but I’d highly recommend installing it.