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UV Laser Guide

Troubleshooting

How to Focus a UV Laser Correctly

Focus a UV galvo on the real surface, refocus when thickness changes, and stop changing focus and power in the same test.

1 min read

On this page
  1. Clean the face you will mark
  2. Measure that surface
  3. Confirm with a tiny mark
  4. Lock the batch
  5. FAQ

A UV galvo has a short window where the spot is actually small. A coaster that is 2 mm thicker than the last batch is a new focus job, even when the preset still says 100%.

On the F2 Ultra UV, xTool Studio can auto-measure the distance. Use it. The slate logs that look clean all assume the beam is focused on the surface. None of them publish a focus offset (slate chart).

  1. Clean the face you will mark

    Wipe the blank. If it rocks on the bed, it is not one distance. Shim it or pick a flatter piece. A jig only helps if the blank sits the same way every time. See self-centering jigs.

  2. Measure that surface

    On the F2 Ultra UV, run auto-measure in xTool Studio so the reading is the slate, tile, or glass, not the empty bed. Slate coasters in published logs already span 4.5 mm to 7 mm. Measure again when the stack changes.

  3. Confirm with a tiny mark

    Use a low-stakes square in the scrap margin. If the edges are fat or doubled, you are off the focal plane. Fix focus before you add power. Changing both at once teaches you nothing.

  4. Lock the batch

    Save the preset only after the grid, not after the focus step alone. Focus gets you a fair test. The grid picks the tone. That sequence is the same one in How to Calibrate the F2 Ultra UV.

FAQ

Why did my settings work yesterday and not today?

The usual cause is a thicker or bowed blank, not a laser that "forgot" the preset. Measure again.

Should I defocus on purpose for a thicker line?

Not while you are still hunting for a clean mark. Defocus hides a bad power setting. Get a sharp spot first.

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