Owners keep asking how to use the CO2 side of the M3 Ultra. So I took my plywood crate job and turned it into a tutorial: every step from the DXF files to finished parts, in 9 mm plywood. And because it happened to me, what to do when the laser head hits the sheet.
Below is the written version, with the settings I ended up using, so you don’t have to scrub through the video to find them.
Before anything goes to the machine
I open every DXF in QCAD first. The classic problem is double lines: two lines stacked on top of each other. The laser then cuts that edge twice.
The material is 9 mm plywood. The M3 bed is 1380 by 920 mm and my sheet was 2400 by 1220 mm, so two saw cuts give three blanks: one for each laser job. I had one sheet and no spare, which makes everything below matter a bit more.
Power up and switch to CO2
- Pull out the emergency stop, turn the key switch and press the chiller power. I just leave the chiller’s own switch at the back on.
- In MLaser, go to Laser and select CO2 Laser. If you skip this, it complains that the fiber laser isn’t on.
- Close the door and press Go Origin. The machine won’t home with the door open. I film inside the machine, which is why it’s open in the video.
- Jog the head with the remote. The arrow keys move it, and Fast/Step switches between fast and slow. That works with the door open.
Set the focus
Raise the bed first so the nozzle can reach. In MLaser, the start tab has the lifting platform control. The bed only moves while you hold the button.
The machine comes with a small transparent focus gauge. Loosen the screw on the head, put the gauge against it and tighten the screw again. The one in the video is a copy of the original. If you make one, match your original and check the focus distance in the manual.
Air
For 9 mm plywood the internal air pump is enough. Use the high air connection.
Load the job and set the start point
- In MLaser, import the first laser job.
- Jog the head to the corner of the sheet: fast to get close, slow for the last bit. Leave a little margin to the edge.
- With the head on the corner, set the mark. That’s where the job starts.
- Run the red dot along the edge to check the sheet is straight. If it sits at an angle, the far end of the job can run off the edge. How much that matters depends on your margin.
- The USB stick that comes with the machine has parameter files. Import them once, then pick CO2, plywood.
Cut settings: the preset, the AI and what worked
This is where it matters. Too much power or too slow, and the laser burns away too much wood. The finger joints end up loose.
| Where the number came from | Speed | Notes |
|---|---|---|
| GWEIKE preset for 7 mm plywood | 3.5 m/min | Full power |
| An AI answer a viewer got for 7 mm | about 0.5 m/min | A big gap with the preset |
| My starting point for 9 mm | 2.5 m/min | Then 2 m/min in the second test |
| What I ended up using | 1 m/min | 100% power, 5000 Hz, high air |
At 1 m/min, one panel took about seven and a half minutes.
Test first
- Draw a small circle, 20 mm wide and high, and cut that first.
- Move the test to an open edge of the sheet, so you can look underneath and see if it went through. In the middle of the sheet that’s hard to check.
- If the shape doesn’t fit from the mark, MLaser throws an alarm. Clear it and move the mark.
- Check the chiller and the extraction, switch on the CO2 laser power and turn the current knob all the way up. That knob is the hardware limit, and the power percentage in MLaser only works underneath it. Knob at 10% and 100% in the software still only gives you 10%.
I filmed the cuts with the door open and CO2 laser glasses on. Don’t copy that. When it’s cutting, close the door.
My first crash, and how to straighten the head
During the second test, the nozzle hit the plywood, dragged through it and knocked the laser head crooked. Honestly, I’m not sure why. Maybe the sheet wasn’t flat, or it was lying on something. With one sheet and no spare, that hurts. But the head comes first.
- Switch off the CO2 laser power before you touch the head.
- Lower the bed and put a set of parallels on the sheet, right under the head. They give the head a flat surface to line up on.
- Loosen the two screws with a 3 mm hex key. The head drops onto the parallels and lines itself up.
- Tighten the screws again.
- Nozzle back on, air line back in, bed back up, and set the focus again.
The lesson: make sure the sheet lies flat before you frame and cut.
Engraving the markings
- Give the text a linear fill. Without it, the laser only engraves the outline.
- Put it on an engraving layer and pick a scan direction. I went bottom to top.
- The default engraving preset is 18 m/min at 7%. I switched to high air and 10%.
- The cut job starts from the same mark, so the cuts line up with the engraving.
- Before you start, return to the mark, select everything with Ctrl+A and press Frame. Watch the border and check that it stays on the sheet.
Looking back, the same look at twice the speed is what I’d use for these markings: 36 m/min at 15%. For engraving, go faster than you think.
Quick reference: 9 mm plywood on the M3 CO2 laser
- Set the focus with the gauge.
- High air. The internal pump is enough.
- Test a 20 mm circle at an open edge.
- Start slower than you think. I ended up at 1 m/min, 100% power, 5000 Hz.
- Current knob all the way up.
- Make sure the sheet lies flat before you frame.
- Engraving: go faster than you think. 36 m/min at 15% for the markings.
Download the DXF files
These are the three laser jobs from this tutorial: base and lid, back and front, left and right, with the shipping markings included. Free to download. They’re drawn for 9 mm plywood with finger joints, and plywood is never exactly 9 mm, so cut a test joint first.
How the crate was designed with AI, and what the buyer said when it arrived, is in the crate build post. More M3 answers are in the Gweike M3 guide & FAQ.
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