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Laser Exhaust Flexible Duct 30

The Movable Gantry CNC machine fitted with a laser module moves about the work space according to the program g-code interpreted by LinuxCNC. As the machine was not totally enclosed, I had fitted a protective shoe to the laser module so that no stray laser light would be able to emerge from the target spot. Another important function of the shoe would be to act as a collection hub for any smoke. Smoke generated when the laser light burn the work piece had to be remove to prevent damage to the lens or to the work piece.

In my last blog, I discussed how I fabricated some fixed pvc piping and installed the exhaust fan for them. In this blog, I discuss how the flexible ducting was fabricated. It’s true that I can buy ready-made flexible ducting on the market, but in the spirit of diy and cost saving, I did it with raw materials that I already had available.

Some of the materials that I used included thin polyethylene sheets cut out from hotel laundry bags, 3″ diameter PVC pipes, some cellophane tapes, some galvanized wire, an empty sardine can, an empty PET bottle, and some small magnets.

As the fixed ducting was placed quite high above the cnc machine, I made the flexible ducting long enough so that it would not be stretched too much even when the movable part had to move to the furthest reach in the machine. I found out during testing that in order for the flexible duct not to collapse due to the suction pressure from the fan, the ribs needed to be placed close together. This would mean more ribs had to be installed for it. Ultimately, I had to strike a balance between having more ribs and therefore requiring more work cutting them, and producing an acceptable working flexible ducting.

One end of the ducting was attached to the top fixed PVC pipe, while the other end was attached to a cut-out sardine can. The sardine can formed quite a good fit to the laser module part.

With such a long ducting, how did I store it when I didn’t want to use it anymore? Remember, I use this cnc machine also for milling, plotting and drag knife cutting. At these times, I just replace the laser module with a milling spindle, pen holder or drag knife holder respectively whenever I need to change the nature of the work.

Since the flexible ducting could be compressed like a concertina, I compressed it like so and enclosed it into the cut-out body of a PET bottle. I then used some small pieces of magnets taken from earphones to attach it to the sardine can end. These magnets effectively holds the flexible ducting in place in storage.

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