Laser cutter producing dotted line cuts edges are very rough even when cut completely

[worldspawn]

Brand new, 500x700 bed,100w (120max) chinese laser cutter with Reci controller and runnung RDWorks, power is 75% of machine max steady 21mA power reading, I've been unable to get it to give me a smooth cut, tried adjusting the frequency (factory was 4khz) tried values of 10 and 20khz, zero change in appearance, tried with and without air assist, no change in appearance. I can't figure out why the cut is so inconsistent. See images below for RDWorks settings and a photo of the back side of the cut.

https://i.imgur.com/1oIrkeM.jpg

https://i.imgur.com/pK6tUOy.jpg

Any help in getting a smoother cut is appreciated. I have about 10 years experience running laser cutters, and have never encountered this issue before that wasn't a PPI setting, which these lasers do not appear to use.

Similar Threads:

• Need Help!- Rough / Jagged Diagonal Edges
• Problem- jagged edges on cuts
• K40 & Moshidraw 2013 - dotted horizontal line issue
• What causes "rough" edges when laser cutting acrylic?
• Getting Rough edges on Taig milling aluminum, please help

[grawley]

This is your image from the link shown in your question. In this laser cut sample, we see that the issue (single laser dots rather than a contiguous line) shows up in a single axis of the rectangle, rather than both axis--so probably need to examine other issues rather than a PPI setting that affects the entire cut rectangle.

Try checking that axis for a mechanical issue.

Check the mirror in its mount (as this is a new laser machine, there may be a part that got loose during shipping). For example, the final mirror or second to final mirror may be vibrating because it is loose (more likely the mirror overtop the focus lens).

Power off the machine, then use your hand to drag the problematic axis back and forth. Is it smooth, or is it rough? If it is rough, disengage the motor belt and check again. If the problem persists, then there may be a problem with the bearing block, so you can disassemble further and look and listen for a bearing problem. The motor has bearings as well.

The vibration of the machine may be causing the safety switch to toggle (it directly stops the laser from firing). Seek out the magneticly triggered safety switch, then defeat it and test.

[worldspawn]

Thanks for the suggestion, I have already checked the axes smoothness and tightened all 3 of the mirrors, those do not seem to be responsible for the issue. The rough cutting is occuring moreso in the X axis than Y but is present in both. There are no magnetic safeties on the machine, it will happily operate with the doors open.

[grawley]

Thanks for the suggestion, I have already checked the axes smoothness and tightened all 3 of the mirrors, those do not seem to be responsible for the issue. The rough cutting is occuring moreso in the X axis than Y but is present in both. There are no magnetic safeties on the machine, it will happily operate with the doors open.

To determine if the problem is the laser turning off and on, do the following: Stand in the back of the machine while the job is running, and look at the laser tube, to see if it illuminates on and off during the job (producing the dotted lines). If the problem is that the laser is turning on and off, then check that the wiring is snug going into the electronic connector in the power supply (perform all necessary safety precautions before touching the power supply, and keep in mind that the capacitors inside hold the high voltage charge for several hours before fully dissipating).

If the laser is not turning on and off during operation, and you are seeing dotting lines, then likely something mechanical is jerking the laser during operation, or vibration is causing the focus lens or focus lens assembly to wobble.