Cutting 20 mm Wood with the M1 Ultra – Layered Focus Workaround Background

Because the M1 Ultra has limited focus descent options, the solution is to:

• Duplicate the cutting geometry exactly (2×, perfectly aligned)
• Assign different focus strategies to each layer
• Let Atomm process the layers sequentially, effectively extending the cutting depth

This allows deeper cutting without exceeding the software’s focus limits.

• Place the 20 mm wood on the bed
• Make sure it is flat and stable
• Perform auto focus to establish the correct surface reference

• Import the design you want to cut
• Duplicate
• The two shapes must be:
  • perfectly aligned
  • on two separate layers
• Do not move or scale either copy

This is critical for the method to work.

This layer handles the upper and mid material depth using stepwise focus descent.

Settings:

• Power: 100 %
• Speed: 8 mm/s
• Passes: 8
• Focus descent: Stepwise descent
  • Initial focus descent: 2 mm
  • Descent interval: 2 passes
  • Focus descent per step: 1 mm

What happens internally:

• Passes 1–2 → focus at 2 mm inside the material
• Passes 3–4 → focus at 3 mm
• Passes 5–8 → focus at 4 mm
• 4 mm is the maximum focus offset supported by the M1 Ultra

This layer continues cutting from deeper inside the material, where stepwise descent can no longer go.

Settings:

• Power: 100 %
• Speed: 8 mm/s
• Passes: 9
• Focus descent: Single-step descent
  • Focus offset: 4 mm

This keeps the laser focused deeper in the cut channel to finish the cut.

This step is essential.

• In the processing settings (bottom right):
  • Set mode to User-defined
  • Enable By layer
• In the layer list, ensure:
  • The top layer is processed first
  • The bottom layer is processed second

Atomm will now execute the layers in sequence, effectively extending the usable cutting depth.

• ✅ I was able to cut through 20 mm wood successfully
• ✅ The cut quality was surprisingly clean considering the thickness
• ⚠️ Deep cuts produce a lot of soot
• ⚠️ Soot can easily rub off onto fingers or nearby surfaces

From a cutting perspective, the result was very solid.

• Heavy soot buildup on deep cuts
• Longer processing times
• Not suitable for high-volume production
• Material quality (especially plywood glue layers) has a big impact

Possible Improvements

• Post-processing using UV laser cleaning (as shown in previous tests)
• Light sealing or surface treatment after cutting
• Combining this method with slower finishing passes if needed

This method shows that 20 mm cutting with the M1 Ultra is possible, even within its software limitations, by using a layered focus workaround. 

This is not a standard workflow and may not be needed often — but it’s useful to know that the option exists when:

• the machine is already in use
• parts are already prepared
• or re-cutting on another machine isn’t practical

There may be faster approaches, but during my tests, reducing the speed further caused the wood to actually ignite instead of cutting cleanly. At very low speeds, the energy input became too concentrated, leading to open burning rather than controlled material removal.

With this method, the balance between speed, focus control, and heat buildup remained more stable and predictable.