Laser Cutting - Problems 9MM Ply

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I have recently being doing some laser cutting using 9mm ply from the space’s materials shop. However, I’ve been having problems, specifically with cutting.

The SMLS 9mm presets in Ruby aren’t coming close to cutting the material - I’ll grab the full settings when I try again tomorrow. The settings are configured for a single pass for cutting, I’ve found I have needed five or six to get through. This has also led to some flare-up when cutting on subsequent passes.

I appreciate it’s difficult to give guidance without a better idea of the settings, just wondering if there’s any obvious I’m missing?

FYI @lasertechs

Is the laser properly focused? I’d assume so, but worth asking just in case that was overlooked.

Do you have problems with other materials and settings e.g. 4mm ply?

It might be that the 9mm settings haven’t been tuned very well

Feel free to have a play with the settings (being careful with things like flame/smoke etc.) and see if you can help find better settings for it

I have noticed that the laser is out of square in the z axis (laser to bed) both back to front and left to right.

So if you cut a piece of say 10 mm acrylic the cut edges are not square to the faces.

Not sure if this is down to the laser mounting being out of square or the lens not perfectly central in the holder.

Best way to demonstrate this error is to have the bed fully down. Mark on a piece of paper where the indicator dot hits then raise the bed. And re- mark
This is the error.

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I spent a while tuning settings this morning. Having done some Google-based research I started with the following settings:

  • Power: 100%
  • Speed: 0.2

This did a great job, but it was still a mm or less too shallow and was causing break-outs when trying to remove cut sections. I then adjusted to the following settings:

  • Power: 100%
  • Speed: 0.1
  • Z-offset: -2 mm

This worked great, like a knife through butter! I was a little anxious playing with the z-offset parameter for the first time, given it changes the focus of the laser. Do we have any concerns with z-offsets?

P.S. This post reads as if I tried two settings and magically the second was the one that worked. Rest assured there was a lot of trial and error in between!

I’ll take a look when I am in the space

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The z-offset only applies to your settings only, none others, so if you’re experimenting then it’s fine. Before it begins cutting, you’ll notice the bed adjust for the z-offset, then once done it goes back to it’s previous state. Just make sure not to set the z-offset to a number that will make the bed/materials collide with the laser head and you’ll all good to experiment.

Might be worth summoning @SquigLeah who makes the awesome frog jewellery?

She’s does some really interesting stuff with multiple passes at lower power to do gradual cuts. Two passes with lower power seem to produce better results than one pass at high power?