Vertical cut not perpendicular

Hi Guys, New to the forum.

Started with Lightburn last week with the arrival of my new machine and already loving the program.
After tinkering a lot, I still cannot seem to get all the edges of the cut in Acrylic perpendicular. I use a test square of 10 x 10mm. The horizontal lines are perpendicular, but the vertical lines are not, they slant to the left. (both edges).

I have tried everything I could think of and searched the web, but still no change. This is the case with 5mm and 10 mm clear Acrylic.

My machine has a Ruida 6447 controller, Reci W2 100W tube, 20mm lens, 63,5mm focus point. Size 600 x 900mm. 5mm on 1x 12mm/s / 80% and 10mm on 2x 10mm/s / 75%

The following things I have checked and are adjusted to be right:

  • Mirror alignment / incl perpendicular to the bed
  • Head alignment / Squared to the bed
  • Bed alignment
  • Increasing the air assis pressure (temporary with an airbrush compressor)

All of these still not give the desired result and i’m getting nuts here.
This is not a problem that I have with my 50w M2 board laser.

Can anyone give me a pointer?



Have you checked that the beam is vertical or plumb? To do that use a scrap of wood and set your normal focus pulse it to get a dot, then lower the table about 3/4 to 1 inch pulse again and you will get a much larger circle, the dot should be in the center of the large circle if not align your number three mirror (the one at the lens) until the dot is in the center of the circle and it should help.
another thing is that a 63 mm lens may be a cause due to the narrower sweet spot, I cut anything over 1/4 inch with a 101 lens.

Hi Raymond, Thanks for the tip.
I did check if the beam was going straight out of the nozzle, but indeed with the wood check it was slightly plumb.

Turns out that the laser head itself has a deviation. I squared it to the bed earlier, but it needs to be slightly angled as the casing and the heads tube are not in line. Reset the mirrors and I got an improvement.

I do still however see some cupping on the vertical cuts, but its a lot better now.
I wil order the 101 lens and check out if that makes a nicer cut.

Thanks again.


Make sure your you will lens tube can accept a 101 lens, if not you will also need a tube, to check look in your lens tube there should be threads in the tube end that slides into the collar and a boss for the lens to sit on pretty deep in the tube, I hope you understand this but if not go to and look up lens tubes there are some drawings that should show what i mean.

I will check into that. I think i understand. :wink:

Thanks again!