After some struggles and help from someone on Reddit by the name of Lost_Scavenger, I finally have my Creality CR10S laser engraving and light-duty laser cutting.
And it rocks.
Warning! You don’t want to mess with lasers without first understanding how dangerous they can be. Google “laser cutting safety” and read up on it. This post is *not* to convince you *to* put a laser on your 3D printer, but rather to tell you *how* it can be done if you too have a Creality CR-10S 3D printer with the Creality v2.1 mainboard AND a 3-wire laser with PWM signal on its own dedicated wire.
My Objectives Were…
- Mount a 3-wire laser on my CR-10S 3D printer
- Control it via the incredible LightBurn software
- Keep the CR10 still completely operable as a 3D printer without having to remove the laser.
- Cut 1/8″ Baltic Birch plywood (even if it takes multiple passes)
- Creality CR-10S 3D printer w/ a v2.1 mainboard
- 5.5W Laser w/ 3 wires: 12V power, GND, and PWM signal @ 5V. (This is an inexpensive “5.5W” Chinese laser from a 3018 Pro CNC kit.)
We need 12V, GND, and 5V PWM. This turned out to be simple:
- 12V -> Case fan (always on)
- GND -> Case fan
- 5V PWM -> Part fan’s 5V logic signal PRE-MOSFET!!!
Go ahead and splice the 12V and GND to the case fan’s 12V and GND.
The 5V PWM is the tricky bit. Find this MOSFET:
TEST. Grab your multi-meter and test this pin. On the CR10 screen, set your PART FAN to 0, 128, and 255. Your multimeter should show voltages of 0, 2.5V, and 5V respectively.
Unplug printer from the wall.
Hijack that sucker.
I put a bit of extra solder on the MOSFET’s pin, then tinned the wire w/ some solder, then melted the two together…wire in left hand, soldering iron in right. I’m mediocre at soldering small things, and this technique is low risk.
Yeah that’s right. when the PART FAN turns on, so will the laser. Obviously you’ll want to turn OFF the laser (button on top…at least for my model) when you’re 3D printing. Might as well unplug the laser using the top plug
Wait… how does LightBurn control the laser’s PWM natively?
M106 and M107, baby. LightBurn controls the laser using the same Marlin commands Cura uses to control the part fan.
Marlin Firmware Changes
LightBurn lasered (‘laser’d?) a circle just fine. But on a more complex shape, the laser stalled and remained on. Repeat: the laser stalled. It stalled while the laser was on. The laser stopped in one spot. Burning. Wood. In a wood shop.
Console showed a couple errors like G17 and G54. Here are the Marlin firmware changes to enable those. Simply uncommenting these 2 lines did the trick:
//Configuration.h #define INCH_MODE_SUPPORT
//Configuration_adv.h #define CNC_COORDINATE_SYSTEMS
Mounting The Laser
I designed & 3D printed a part that holds the laser UP high enough to avoid interfering with 3D printing mode, and OUT far enough to avoid interfering with homing. Download it form Thingiverse here!
I turn off AND unplug the laser when not in use. It’s a bit redundant, but it’s easy enough and I may forget to do one or the other since I’m a bit of a doofus sometimes.
Keep combustibles far away. Use good ventilation to exhaust the smoke. Stay near in case you need to intervene.
Here’s the safety stuff I have close by:
- Laser goggles. Both dark green and dark red – not sure which I like more yet…I think the dark green. Since everyone wants to watch, it’s good to have multiple pairs of glasses on hand.
- J-Tech Laser shielding panels. This allows some freedom to move around the garage and do other things while the laser does its thing.
- Fire extinguisher. You should have one in your shop. They’re cheap and fire is bad.
- Fire blanket. I don’t really know…somebody told me about these and I was intrigued.