The starting point is the CNC in figure:

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The manual refers to it as CNC2-Axis-4030B and the laser module power is declared 2500 mW.

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After the kit assembly I started testing operation.  I was a little disappointed as I was not able to cut poplar playwood of 3mm thickness.
I had some better result with the modification here following.

 

1 SAFETY

The light from the laser module is dangerous and may permanently damage the eyes of the user or persons close to it.

- Operate the unit only when everybody is equipped with protective glasses.

When the machine is power on the laser is dangerous also when is stopped as for a software or hardware fault it could light the laser.

- Keep the laser machine power off when not needed.

The laser “burns” the target material to engrave or cut it. Some setting of engraving or cutting can cause fires.

- Operate the laser with an operator ready to stop it and extinguish eventually fire.

During cutting of material some smoke is generated. Some material may generate poison fume that are dangerous.

- Use the machine at open air or well ventilated room.

I prefer to engrave and cut just natural soft wood. Wood is easy to take fire, pay attention.

- Remember that you are responsible for the safety of your actions.

 

2 INSTALLATION

I made a table for the CNC unit using three IKEA LACK table and some aluminum profile.
Here after some pictures:

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A sheet of iron 0.6 mm thick protects the IKEA LACK table surface. Magnets are used to fix the target to the table and to keep protection panels in place. The front panel has an acrylic orange transparent window to monitor the laser operation, nevertheless use always protection glasses too.
I plan to add air blower to ventilate the cabinet.

 

2 FOCUS

The laser module has adjustable focus deep moving the lens into a 9mm threated tube. The lens module theads movement is contrasted by a spring.

The lens mount of the 2500mW laser module showed some slack. In addition, the lens vibrates during normal operation of the laser module.

I modified the lens module to a fixed one inserting some spacer (2.5 mm thick in my case) and screwing the lens to the spacer.

 

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 The spacer thickness defines the focal length. A higher focus distance causes a wider focus spot size and a wider depth of focus.

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The distance between the laser module aluminum profile bottom plane and the focal plane is about 67 mm in my setup. To evaluate the depth of focus I made some cuts and analyze a section of the cut:

 

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The limit I reached is a cut of 8mm with an estimated width of 0.25 mm with speed of F100 with three or more passes.

In a second test I cut some figures using a speed of F100 and S1000 with 8 passes to obtain a clean cut on 8mm poplar plywood. Air assist is needed to get the result.

 

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Use the lens with a fixed focus requires to adapt the height of the target plane accordingly.
I decided to modify the laser fixing to add air assist. A screw was added to the top to adjust the height of laser over the plane as described in the following.

3 AIR ASSIST

Compressed air can be supplied from a variety of air compressors. There are many factors to consider when selecting an air source for laser material processing, noise other than the air cleanliness and oil and moisture content.
I decided to use a simple blower on the laser head. The air will flow into the laser diode aluminum profile cooling it and will be forced by a nozzle to the laser cutting area.

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I carefully dismounted the laser and the electronics control board. Two blowers (12V -15mm thickness) are mounted on the top of the aluminum laser profile, while a cone nozzle is fixed al the bottom to force the air coaxial to the laser. I made test with 4, 6, 8, 10 mm air nozzle and 6 mm seems the best to me.

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The base to which the laser is screwed slides on the front plexiglass plane with four flexible skids that reduce backlash according to the Z axis and a screw allows the laser position to be corrected up to 20 mm high.

The electronics that powers the laser is mounted with some spacer on the left while a DC-DC module is added on the right to power the blowers with 14.5V instead of 12V nominal, it increases the air flow a little bit.

 

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I wired the module 12V power with bigger wires to decrease the voltage drop. The switching regulator in the laser power control should compensate the thinner wires drop, nevertheless it seems to me that it improves the laser performance.

You can find my 3D files in https://www.thingiverse.com/thing:4204645

The design is specific for the CNC2-Axis-4030B model, nevertheless ideas can be improved and generalized.

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CNC Xaxis carriage tension adjust:  https://www.thingiverse.com/thing:4188039

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CNC belt tensor: https://www.thingiverse.com/thing:4188852

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