Sanity check on my wiring, random questions

Machine: A WKLaser LC1280

Board: Leetro MPC6515 Original Board

Firmware: Smoothie

Problem/ Question:


I just purchased a WKLaser LC1280 and am swapping out the control board with my Cohesion3D board (previously used in a K40 and I loved it).

I’m in the process of re-wiring everything I just wanted to sanity-check myself and ask a few questions. I think in general I’ve got this all down pat, but maybe there are things people here might know the answers to. I couldn’t attach an image apparently because I’m a new user, but here is the diagram I’ve got so far for my (future) reference on how this is all wired together:

(NOTE: The above is supposed to be a link, but the forum is trying to render it as an image. Please click to see diagram)

This diagram is a work in progress, and there are a few things missing like the alarm wiring for the external water cooling, etc.

The drivers in my diagram are NOT the correct external drivers, they were just the ones I had available to do the wiring diagram itself. In reality the X/Y axis are 3ND583s and the Z axis (powering two steppers) is a 2M982

Things I’d like some clarification on:

  • Do I have the wiring for the stepper motors correct, as it relates to the connection between the Cohesion3D board and the external driver? I am not concerned about the connection from the driver to the actual stepper motor because that is a pre-existing wiring harness.

  • Is it okay for me to draw 5V from Z-MAX to power the relay module I plan to install to control an air assist?

  • Am I correct, in general, assuming that both my PSU and Cohesion expects signals to go to ground when activated? I.e. my limit switches should short to ground when clicked? Also, is it typical for the WP signal to go to ground when “good” and be open when “bad”?

  • I assume it’s okay to run 3 external drivers for the primary motors (which are very beefy), then use the built-in stepper driver for the rotary hookup? The rotary in question is something essentially the same as this:

  • Side note question: I know it’s not a good idea to be plugging/unplugging stepper motors while they are actively being driven. My hope/intent is to run a line to plug the rotary into so I can take it out when it’s not in use. How do I make sure my steppers for the rotary aren’t active when I do that?

  • The limit switches for my machine are installed in the top-right corner, I assume I’ll have to modify the smoothieware configuration to address this? There is, at least wires for, a Z endstop of some sort but I have yet to locate exactly where that might be on the machine (it’s cramped and very dirty under the machine after 9 years of use so I haven’t tried yet). I am less concerned about that however as I have a good feel for how much clearance I really have.

  • I already purchased and am waiting to have delivered the wire harnesses, but I’d really like to purchase the JST connections used on the board for those external drivers in case I ever need to make my own. Can someone point me toward where I might be able to purchase a JST kit with those? (I probably already have a crimper in my workshop).

  • Is there anything otherwise missing / obviously wrong about my plan here?

  • I didn’t add this yet to the diagram but I intend to wire the Laser PSU G and TL to Ground/Laser Fire on the board.

Sorry for the long post, but I’m trying to get all my questions out at once!

Since it wouldn’t let me add too many links in a single post:

My power supply presently for the Laser is this one:

I have an external laser chiller quite similar to this one, with an ALARM output that is wired into my PSU (I believe, I haven’t confirmed that yet):

Hi John,

I’m looking over the info you provided and will get back with you soon.

In the meantime, can you provide clear pictures of your machine, control panel, board, other electrical components, and wiring? We need to see how and where everything is connected.

Unfortunately I cannot upload images because I am a “new user”, but you can find them all here:

Here is an updated wiring diagram (mostly the same, added a few details).

Schmancy! We’ll try to review in more detail soon.

From a cursory look at the wiring diagram (nice work, btw), it looks like you’re using 5v from the endstop pin to run a relay board - do you know if that’s just to run an opto on the board, or if that’s going to actually power the clicking of the relay :slight_smile: ?

I know it’s low power but I always note that we want to not add anything extra to the super clean rail that’s running the brains of the board. An old cell phone charger would be better suited for this.


In this case it’d be running the relay. I’m trying to minimize the number of power supplies I’ve got installed, but now that I’m thinking about it I actually think there is a 5V in there already powering a laser pointer target. I’ll move the relay power to that 5V PSU and just provide the signal line from the LaserBoard. (ugh, another ground).



That looks to be it.

Again, just being careful about the 5v relay thing.

Have you caught the typo on the existing electronics? It’s funny in an “Oh China!” kind of way.

So when you say “That looks to be it”, you agree with the wiring I’ve presented? Would you mind taking a look at the original set of questions I presented and answering them if you could?

Yes I noticed the X Diver vs. Y Driver stickers lol I mean you’d think at least if they were going to misspell it, they’d do so in a consistent way across all of them!

Here’s my updated wiring diagram addressing the relay:

Just to give an update - tonight I successfully hooked up the X/Y endstops and all three drivers. After a few minor configuration changes to swap directions and such, the laser now homes properly and moves properly from within Lightburn!

So it would seem my wiring scheme is pretty solid at this point, as most of what remains will be minor switches and such.

I would like to understand if I have the laser-firing wiring correct, as I understand it I want to hook the LaserBoard FIRE into TL (ideally)?


One final update: Today I was able to complete all of the wiring of the board using the wiring diagram above and everything appears to be working great! I have some other questions on other topics, but I’ll post those as separate threads. Thanks for your help.


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Hi John,

Thanks for your patience while I looked through everything. It sounds like you got most of the wiring figured out. I’m back and getting caught up on posts.

Yes, this looks good and it sounds like you have it working. Great!

Sounds like you already have the relay worked out with a separate PSU, which is preferable.


From the diagram and looking at the specs for your model of mechanical switches, you should connect NC (Red) to Sig and then C (Black) to Gnd for each respective axis, using the default configuration settings. See 2 Wire Switch in Endstops Header Row image above.

Wire(s) Switch Desc Switch Pin Endstops Pin
Red NC (or NO*) 2 (or 3*) Sig
Black Common - “C” Ground 1 Gnd

*You could connect the red wire to the NO terminal (pin 3) on the switch instead of NC, but it is not recommended due to noise issues and potential crashes if a switch fails. You will also have to make a configuration change to invert the pin if you decide to connect this way. Please read the above link for more information about how the signal works.

Water flow sensors and/or lid safety switches would be wired in series to the WP (Water Protection) and G (Ground) circuit on the LPSU and would prevent the laser from firing if there is a disconnect in the circuit. More Info: Test the Water Sensor

This rotary appears to use a Nema 23 motor, which would also require an external driver to operate. Nema 17 is fine to run from the onboard drivers.

You would allow the job to finish or stop the job in LightBurn, and make sure the motors are no longer moving before disconnecting them. You could also power down the machine / board first. If there is a specific use case you are thinking of that warrants further clarity, please elaborate.

Yes, in the ## Endstops section of the config file, you will want both X and Y homing direction to home_to_max and plug in your endstops into the board accordingly. You can set LightBurn to start at different job origin points or positions and even have it finish in the location you want versus going back to the origin point at (0,0) in the lower left, after a job completes. More information: Coordinates and Job Origin

They are typically located at the top or bottom of the Z axis bed, at one of the corners of the perimeter. Z-MIN is usually at the top, whereas Z-MAX would be at the bottom of the bed. Yours may be different, but we cover the concepts with a bit more detail in our Z-Table Endstop Guide.

We carry the 4 pack of External Stepper Cables on our site.

Let me know if there is still anything that you want clarification on.

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