Troubleshooting grbl-lpc + sbase (Wiring? Software?)

Hey all, first post here but I can’t seem to find the exact info I’m looking for so apologies if this has been covered before.

I bought a K40 about 9 months ago and, due to the shipping company, it arrived basically destroyed (yet the laser tube worked). I decided to gut it and build a bigger gantry and also wire up an MKS Sbase as part of the process. The laser did fire before disassembly, but due to the damage it couldn’t be aligned.

I’m using grbl-lpc, preconfigured for the MKS Sbase (thanks a million cprezzi!) and have it all wired up (see attached picture), but when I hit the test fire button in Laser Web nothing happens. I have full control over the steppers and can move the gantry, just cant get anything out of the laser.

Do I have something wired wrong? Is there something in the firmware I need to switch? I’m at a loss right now and could really use some help.

I did notice on the various wiring diagrams, the two "L"s are connected so it doesnt matter which I wire too, correct?

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Does this diagram reflect exactly how the Laser Power Supply is wired??

Yup, with the exception of the socket/wall. They’re in the proper order.

Edit: I just noticed I forgot the power toggle, which is wired in on the Hot between the socket and power supply

For testing purposes connect the “IN” signal on the LPS to the “5V” and see if it then fires.
Insure that P is grounded (you toggle it on).
If that works I recommend wiring a 5K pot as such:

Top to 5V
Middle to “IN”
Bottom to “G”

Nope, still nothing. In Laserweb I have it set to 30% power and 2ms fire time for the test, but I have no indication it’s even sending commands. I assume so as I can jog the motors, though.

Does the laser fire when you push the test button on the supply?

Add a picture of the connector end of the LPS please.

Yup, test fires with that button without issue. Wiring is a little messy because everything is be relocated outside the case for the expanded bed.

Disconnect L from the controller end and ground it.
Insure your laser is enabled.
Does the laser fire?

Yessir, seems to fire.

Really appreciate your help btw, thanks so much!

So this tells me that everything is working outside the controller.
The controller it not asserting a ground on L to fire the laser.

I see that the fire button in Laser Web does not fire but does a job run?

See if this post helps …

So it appears to fire during an actual operation. I guess the laser test button in laserweb doesn’t work for some reason. Can I then just hookup the physical test button between L and G and use it that way?

Also, do you recommend using the wired pot for power or leave it to the software, or a combo of both?

I would post the soft test button problem on the Laserweb area of this forum. @cprezzi may be able to help.

Most machines have a Laser Enable switch and a Laser Test PB on the control panel. See my earlier LPS post for wiring.

Use both as the LPS one will account for variation at the machine and the Laserweb can be used to adjust power on job basis.

I also STRONGLY recommend that you add an interlock circuit. Cover switches for personal safety, temperature sensor and coolant flow sensor for machine protection.

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Many thanks for your help donkjr, my laser is up and “running”. Just need to sort out the steps per mm and figure out howto change my y-axis motor amperage as I’m running dual motors.

So far, everything seems to be working great and i’ve added back in the pot, test fire and an interlock switch on the door.

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A hint from the 3D printing world: If you hook up the dual motors in series instead of in parallel, they are more likely to stay in sync. That way you won’t have to adjust current, and 24V is high enough that splitting it across two steppers shouldn’t be a problem. I made a parallel harness for my 3D printer that came with two Z motors and used it to keep the sides in sync until I swapped out for a closed loop belt driving both sides from one motor.

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