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Thread: diy laser galvo engraver

  1. #1
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    Default diy laser galvo engraver

    Hi everyone,
    I've spent a few days on google searching informations about laser galvanometer engraver and i couldn't find too much about it.
    I have a few electronics and cnc knowledge, but i cannot understand how this galvanometer is driven.
    basically we have 2 motors which drive the 2 mirrors, let's say (x and y) but how you drive them? how they sync to draw a perfect circle for example?
    here's an example of what i like to achieve:
    https://www.youtube.com/watch?v=U0Q4romu9bw




    thanks in advance for your help!
    Justin

  2. #2
    mixedgas's Avatar
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    Galvos are limited rotation motors controlled by a +/- 5 or +/- 10V signal roughly proportional to desired position. They take time to get to that position, and then have to dwell there for the laser to cut. While the hardware is very similar, a laser marking controller is quite a bit different in programming then a laser show controller. You also need some fairly difficult to understand, expensive optics for what you want to do. While for a small marking field, say 5 degrees wide, you might get away with a simple lens and a raw laser beam, for a larger field of view you need an up-collimator before the scanners and a F-Theta lens to maintain a tight focus across the geometry errors that occur due to the physics of scanning a laser through a wide angle.


    What your looking at in that Video is probably an industrial laser with a 3,500$ F-Theta Lens. That is a 25,000$ or more machine your looking at. With used parts and a year of spare time, maybe 4000-6000$ to get going, if you have awesome tech skils and a lot of outside help.


    It can be done on a amateur scale, but it will NOT be something that can be published on Maker Faire as a simple project nor turned into a easily copied design.


    You are better off top purchase used marking hardware from EBAY then to build this as a one off from scratch. Unfortunately what shows up on Ebay or at HGR Industrial is rarely complete or working.

    What your looking at in that Video is probably a Q-Switched laser with a 2,500$ F-Theta Lens. Thats a 25,000$ or more machine your looking at. With used parts and a year of spare time, maybe 4000-6000$ to get going, if you have awesome tech skils and a lot of outside help.


    My experience: Qswitched YAG laser Marking to sixty watts and CO2 based cutting and marking to 400 watts. As well as femtosecond engraving of glass. I have friends that do cutting / marking with lasers in the 4 Kilowatt class.

    This is NOT a cheap hobby to do right. There is a thread in the Blue lasers section on how to do low end marking with gray scale on a very, very, small area, inexpensively. Start there.

    If you go to a X-Y gantry based machine, with a fixed focus, no scanning, a 60-100 watt Co2 Laser and a assist gas feed, you could do something similar for a lot less.

    If you have unlimited budget, I can suggest some people who can set you up right. :-)



    Steve
    Last edited by mixedgas; 02-03-2015 at 04:17.
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  3. #3
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    Hello,

    I am looking to do something similar for a final year design project for my mechanical engineering degree. I was wondering if you ended up completing this project or found a good place to start?

    Thanks

  4. #4
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    Start here.
    https://www.thorlabs.com/newgrouppag...group_id=10766
    You can buy these lenses new (extremely expensive as Steve says) or used on eBay for around $100 from someone who doesn't know what they took apart.
    Then go here.
    https://www.thorlabs.com/newgrouppag...tgroup_id=6057
    This shows all the bits and pieces, scroll down to see the complete assembly.
    -Dan

  5. #5
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    swamidog is online now Jr. Woodchuckington Janitor III, Esq.
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    i have a yag based laser engraver that is untested, but contains everything pump the pump laser.

    galvos, amps, f-theta lens, the works.

    Click image for larger version. 

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    make me an offer i can't refuse
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

  6. #6
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    Wink

    Quote Originally Posted by swamidog View Post
    i have a yag based laser engraver that is untested, but contains everything pump the pump laser.

    galvos, amps, f-theta lens, the works.

    Click image for larger version. 

Name:	engraver.jpg 
Views:	12 
Size:	1.66 MB 
ID:	53701

    make me an offer i can't refuse
    Thats actually a RMI LE-100SA or similar from RMI lasers circa 2000 .... and it's actually a 10W Nd:YVO4 made to run off an external LMT diode controller (which is not usable without the scan head) built around a coherent 30W 808 FAP module. The diode controller includes all the laser current and temp controls, the YVO temp controller, the q-switch driver, and it is meant to use an old PCMCIA DAQ card that isnt made anymore. You still have it? I have all the other parts, I'll give you 250 for it.

  7. #7
    swamidog's Avatar
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    yes. i still have it.

    i'd like more than 250$ since i could part it out and get more than that.

    Quote Originally Posted by aaronvt View Post
    Thats actually a RMI LE-100SA or similar from RMI lasers circa 2000 .... and it's actually a 10W Nd:YVO4 made to run off an external LMT diode controller (which is not usable without the scan head) built around a coherent 30W 808 FAP module. The diode controller includes all the laser current and temp controls, the YVO temp controller, the q-switch driver, and it is meant to use an old PCMCIA DAQ card that isnt made anymore. You still have it? I have all the other parts, I'll give you 250 for it.
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

  8. #8
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    Yeah, that what sort of a joke What were you thinking for it? I bought an entire system off ebay a while back, scan head diode driver with the DAQ card) for $1100, granted the laser diode needed to be replaced but all else worked. if you keep your eyes out you can get the diode controllers every once and a while pretty cheap.... grabbed a second one for $350..., you could rig something together to run it, but 80 MHz q-switch drivers are really hard to find used. if you do end up parting it out, i may be interested in just the laser resonator if the price was reasonable.

    Quote Originally Posted by swamidog View Post
    yes. i still have it.

    i'd like more than 250$ since i could part it out and get more than that.

  9. #9
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    Does anyone have any examples of free or relatively cheap software that runs galvo laser setups?

  10. #10
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    ... I'm using BeamConstruct from HAlaser - http://halaser.de/feature.php

    The software is free and can drive diferent types of scanner controllers or software-drivers:

    Click image for larger version. 

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    When starting with it, I've got it working too with an ILDA compatible analogue DAC and a crappy cheap chinese galvoscanner set, but this was a crude "workaround" with writing a special plugin, so not meant for the public ...

    Viktor

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