LasersOnly 100W JPT MOPA M7 Uneven Marking Performance Across Work Area

Hi, I’m hoping someone here can help me troubleshoot the issue I’ve been noticing with my new LasersOnly 100W JPT MOPA M7 machine.

Using an F430 lens (300x300mm area), it seems as though there is a “dead zone” in the lower right quadrant of the work area. To asses the extent of the issue, I marked a grid of squares across a 12x12 plate of (very flat ~0.3mm flatness) aluminum. Please see the image below:

The difference in marking performance is not only visible, but also audible; the laser sounds loud and aggressive while marking in the upper left quadrant, but faint and weak while marking in the lower right.

I wiped the lens with a microfibre cloth to try and solve the issue, but it had no effect.

Does anyone have any ideas how I can solve the issue?
Does the galvo head need to be trammed with respect to the bed?

Any advice is appriciated!

Do you happen to have an alternative lens that you could test to A/B test if the lens is the issue here?

Alternatively, can you confirm that your workpiece is parallel to the lens? If not, you may be defocusing on the extents of your job.

Hi Colin, thanks for such a quick reply.

  1. I didn’t notice it when using a F160 (110x110mm work area) lens
  2. Workpiece parallelism - this is quite possible since I never trammed the galvo head with respect to the bed. This means that the F160 lens could work fine, while the F430 lens would defocus at the extents (like we see happening).

Is there a specific procedure/tutorial you can recommend for how to ensure the work area is parallel to the lens?

The F420mm, at least your longest lens, has plenty of depth of focus (dof) to cover any anomalies in height variation. I think I computed mine at nearly 13mm… I doubt that you have a focus issue created by it not being square to the table…

Shorter lens, less dof – F160mm is only about 1.9mm dof

You can always check it by changing the focus when it’s running in the bottom right corner and see if you can adjust the focus enough.


Is it always that corner?

I think I’d suggest you do another lens calibration — you did load the proper configuration for the lens?

:smile_cat:

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Is it possible to rotate the lens180 degrees and see if the weak engraving area moves diagonally?

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To follow up on this, the tramming/parallelism calibration worked!
I used a digital level with 0.05deg resolution to ensure that the galvo head was trammed with respect to the bed of the machine, following the method outlined in this video.
The bed of the machine is warped, so it was difficult to level the machine along the y-direction. I’m planning to straighten it using some aluminum extrusion, which will allow me to tram it more accurately.

I’ve attached a photo of the marking results after tramming, new marks are highlighted with red circles:

Thanks for all your help and suggestions guys!

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Fantastic! Love to see our hunches get validated :slight_smile:

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