Why won't my laser cut all the way through?
Your laser scores the material but won't drop the part free. Nine times out of ten it's one of these — work down the list in order, changing one thing at a time.
Check your job time →1. Focus is off (most common)
An out-of-focus beam is a wide, weak beam. Re-set focus for the exact thickness you're cutting — don't reuse yesterday's focus for a thicker sheet. This alone fixes most "won't cut through" cases.
2. Too fast, or not enough power
Drop the speed before anything else. If it now cuts through, you were simply moving too fast. Only raise power as a second step, and avoid pinning it at 100% — slower speed is kinder to the tube/diode.
3. Add a pass — but don't move the material
Thick or dense stock may need 2–3 passes. Run them back-to-back without unclamping — if the sheet shifts between passes, the beam misses the kerf and just widens it.
4. Dirty or wrong lens / mirror
A smoke-filmed lens or mirror loses real power. Clean the lens and mirrors. Check you have the right focal-length lens — a short lens (e.g. 1.5") is great for fine engraving but has a shallow focus range that struggles on thick cuts; a 2.5"–4" lens cuts thick stock better.
5. Material problems
- Plywood voids / glue. Cheap ply has hidden glue pockets that stop the beam dead. Switch to laser-grade or Baltic birch.
- Warped / lifted sheet. If the material bows up off the bed it drifts out of focus mid-sheet. Weigh it flat or use magnets/pins.
- Wrong material. Some "acrylic" is actually polycarbonate, which won't cut on CO2 (and shouldn't be cut at all).
6. Air assist too weak — or too strong
Good air assist clears smoke and helps the beam reach the bottom of the kerf. Too little and smoke absorbs the beam; way too much on acrylic can cool and frost. Aim for a steady, firm flow for wood cutting.
7. Power falloff on older tubes
A CO2 tube weakens with age — a setting that cut fine a year ago may not now. If everything else checks out and cuts have been slowly getting worse, the tube may be near end of life.
One-at-a-time rule: change a single variable, run a short test cut, observe. Changing focus, speed and power all at once tells you nothing about what actually fixed it.
Open the calculator →FAQ
Why does my laser cut only halfway through?
Most often the focus is off for the material thickness, or the speed is too high. Re-focus for the exact thickness, then slow the cut down. If it still won't drop through, clean the lens and add a pass without moving the material.
How many passes should it take to cut through?
Ideally one pass for thin material. Thicker or denser stock may need 2–3 passes run back-to-back without unclamping. If you need many passes on thin material, something else is wrong — check focus, lens cleanliness and speed first.
Can a dirty lens stop a laser cutting through?
Yes. A smoke film on the lens or mirrors absorbs power before it reaches the material, so a cut that used to go through no longer does. Clean the optics regularly — it's a common and easily missed cause.
My old settings don't cut through anymore — why?
If cuts have slowly worsened over months on a CO2 machine, the tube may be aging and losing power. First rule out dirty optics, focus and a shifted lens, but a weak tube is a real cause of gradually failing cuts.