Searching for a driver board. What to chop for?

Is there a good source on comparing GRBL supported driver boards?
Need to rebuild from scratch an old Universal machine with burned electronics…
"easiest " way forward would be to only reuse the motors and connect to some kind board

Closest candidate right now is BIGTREETECH SKR Mini E3 V3.0 Controller Board.
Is this an “ok” choice for lightburn?
Looking for something that works but not to expensive.

What is this? Similar to a K40 or an led device?

I have one of these for a retrofit, that I haven’t done yet… They are 32 bit controllers. I assume you don’t have external motor drivers… All you really need is the board.


No external motor controllers. Looking for an “all in one” solution.
Have seen this listing but looking more against

Perhaps same same?

What are you putting this into?


No working electronics on this one… but I have a brand new 80W laser module for it.
Switching Laser and mirrors… reusing the gantry and motors.
That is the idea at least…

150W passive cooled CO2…

I’d be lower cost to use a Ruida and put the motor drivers in there… The Ruida is around $500 and the motor divers are about $20 each…

It would still be lower cost and is supported by Lightburn. The Ruida is a DSP controller…

Is that an RF excited laser?


$560 against $120?
not sure if I’m missing something?

It’s RF yes…

The link you gave me was 1,199.99… didn’t realize it was Swedish … So I’m thinking $1K +…

I know there are other settings in a Ruida expressly for RF excited lasers. Don’t know how that’s handled with grbl.

Maybe @JohnJohn has an idea if this is a supported grbl controller… I’ve never seen the one in the link before… The one I linked you to is about $60 I think…

It being an RF laser, it might take a controller more tailored to co2 machines. Few hobbyist have RF excited lasers…


There are some PWM base frequency controls in the more advanced 32 bit controllers like the MKS-DLC32. Source code and binary files are available on their Github repo.

I’ve seen some of the MKS-DLC32 controllers were shipped without the grbl V-option (variable spindle/laser option) enabled ant build-time. I’m not sure if this is a quirk of the new 32 bit build or something else.

I’d like for us to discuss MKS-DLC32 controllers further in another thread.

I haven’t done a lit review of RF fiber laser control with a GRBL controller but it doesn’t seem unreasonable.

That said, the Ruida Controller for an RF fiber laser would be a known quantity. The manual for that model of controller may offer insights to all the power supply control parameters. A list of pin-outs and signal ranges would be a great way to start.

Looking at the bigtreetech github repo and quite optimistic about the SKR Mini 3.0. Klipper might present atypical challenges.
bigtreetech (BIGTREETECH) · GitHub The pin-outs are published which is great. Another GRBL variant may be more accessible.

I’ve got a FluidNC board. Joe, (one of the devs) has one of these up and running on a small open source CNC machine he designed, built and shared called MilkCr8 CNC.

The biggest upside with FluidNC is the modular architecture. If it isn’t the right choice for your RF fiber retrofit it’s a great candidate for your next project, a CNC mill, another diode laser project or really anything.

AIUI, an RF laser requires the ability to specify a pre-ignition signal’s frequency & duration to get the tube lit but not firing. The RDC644x series calls it “pre-generation” and my KT332N says “tickle”, but the parameters are specific to RF lasers.

I don’t know which, if any, of the myriad GRBL variants include those settings, but I’d be wary about assuming a GRBL controller would Just Work™ with an RF laser.

The power supply interface uses the same signals: PWM current control and Enable switching.

One of the harder parts right now is to figure out the interface on the control box.
If I can find the data on the control signals then It would be easier to investigate in what kind of driver-board to use.
Not an easy project I accidently purchased… :frowning:
Thought the machine had a better status… but it is what it is and I hope I can manage to get it running.

Found this table…
Not that straight forward to solve…

Sooooo it’s an RF-excited tube with an RF power supply having an intimate relationship with the controller, far more deeply involved than the contemporary “how much” and “when” signals.

Unless you really need an engrossing hobby, replacing the tube and power supply will move you a lot further toward the goal of having a functional laser than attempting to retrofit something around what’s in there.

Yeah… Not an easy fix this unit.
Guess It’s on the level of reverse engineering the controller.
Some kind of modulation control on pin1. Enable on pin 10.

How does the modulation/power signal from a MKS board look like?
Converting / Level adapting a signal would be far easier than creating something from scratch.

It is not clear the power supply’s Enable pin does the same thing as a contemporary HV supply’s Enable pin.

All we know is the one you have “Enables internal DC power supply” which seems different from “Enable the output current” when the beam should be active.

I can only find one enable pin in the pinout.
That and the modulation pin.
Not sure how the modulation according to the pinout should look like.
Is it a pure PWM? Is it a current signal? etc…
And how does a normal GRBL board handle the control of the laser?
Is it “only” a PWM (“Fan control output”) and a enable on/off pin?

Is the post #14 the lps inputs?

Most machines don’t recognize a high swr (mismatch impedance between source and load).

The fiber monitor for too much reflectivity and will limit output power.

Might look and see if the proposed board states that it supports RF excited lasers.


Which is why I said “replacing the tube and power supply will move you a lot further toward the goal of having a functional laser than attempting to retrofit something around what’s in there.”

More than that, I cannot say … :man_shrugging: :