40W Chinese Laser: More upgrades

Made some upgrades over the long weekend:

Took out the stock work holder in preparation for the adjustable Z bed. It is hard to see in the first picture, but all but two of the posts were standing about 10% off of vertical. Even the allen screws securing the original work holder were at an extreme angle:

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The LED strip lights got installed. If there is any upgrade that adds instant polish to your rig, its this one. The lights look amazing:

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Also removed all of the original cooling system and installed fresh tubing. Added reservoir, radiator, fan and anti-freeze:

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40W Chinese Laser: First cuts with open-source toolchain

Now, since I haven’t removed the stock work area, and because of the way the machine homes before the cut, I had to rest the test piece up higher than the normal work height. Outside the ideal laser focus width. Therefore the cut width is a bit thicker than if the material was a proper distance from the lens.

Still, I’m pretty happy with the performance – this is an example of a vector drawing:

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Digital source:

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40W Chinese Laser: Public Service Announcement: Clean your mirrors and lenses!

Don’t trust that your mirrors and lenses will be even remotely clean.

Remember when I mentioned I saw some soot on the lens carrier? Well, today I took it out for a closer inspection:

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And the mirror wasn’t in much better shape:

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I cleaned them up with some alcohol imbibed lens wipes:

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40W Chinese Laser: Brain Transplant!

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I’m removing the stock controller board. The proprietary software is terrible. It is getting replaced with the Open Source RapRep RAMPS G-Code controller. Thanks to the customized Marlin firmware by TurnkeyTyranny, this gives us several new advantages:

  • open source software chain (thanks again to TurnkeyTyranny and the Inkscape G-Code Export Extension)
  • programmatic control over the laser output power (ditching that terrible manual pot)
  • A slick new LCD control panel
  • I’m surprised I’ve not seen this elsewhere, but I plan to use a thermistor in my coolant tank to monitor the coolant temperature. Hopefully I can hack the firmware to stop firing the laser if the tank temperature rises beyond the set threshold.

    I ordered a new ribbon connector and made a new transfer cable to connect to the RAMPS pins. I was too impatient to design and order a wiring harness board, so I just soldered the cable right to the pins on the connector. I covered the contacts with some Liquid Electrical Tape.

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    Below is a diagram of the wiring. Thankfully this was my exact power supply, so I didn’t have to get creative. Now, on the RAMPS, the servo pins are marked 2B 2A 1A 1B and the diagram has A- A+ B- B+. Here is the translation:

    A- -> 2B (ribbon cable pin 9)
    A+ -> 2A (ribbon cable pin 10)
    B- -> 1A (ribbon cable pin 11)
    B+ -> 1B (ribbon cable pin 12)

    It’s also not very clear on the diagram, but the XHOME goes on the first Signal pin on the endstop header and YHOME goes to the third signal pin. Even though it shows the 5v and GND going to the AUX-3/SPI header, you can use any 5V/GND connections on the other AUX or SERVOS header blocks.

    The Y stepper cable connects the following colors to pins:

    red -> 2B
    blue -> 2A
    white > 1A
    yellow -> 1B

    I’m borrowing this photo from TurnkeyTyranny’s git repo and putting this here so I can find it later:

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    This is not the greatest photo, but some of the wiring choices can been seen here:

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    I made sure to test the steppers and homes before I even hooked up the laser fire and PWM controls to the RAMPS board. Once everything was moving as I expected, it was time to test the laser! Something about this screen preparing to push the button had me feeling like a mad evil genius set to take over the world: “FIRE ZEE LAZOOR!”

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    As you can see by the burn, the initial tests were a success:

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    Now its time to mount the board and get the wiring cleaned up to make room for more upgrades!