New Machine Build Custom Large Glowforge Practical?


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Thread: Custom Large Glowforge Practical?

  1. #1
    Member SerMumble's Avatar
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    Default Custom Large Glowforge Practical?

    Hi, I've built a few large 3D printers and a CNC machine, now I am looking to round out my arsenal with a laser so I'm humoring myself with what a custom glowforge design would look like. There's a handful of DIY projects here and there I'll follow for assist but in general, I don't know much about lasers other than avoid blinding yourself. I was considering a run of the mill 40W laser for cost but between the small work area, some questionable quality control, and a need to replace the laser tube a couple times a year, I'm looking at an 80W laser tube and bumping up my budget so I have something timeless.

    If you guys are fine with it, I'll update this post with names of people that answer questions or just point out something really important. I can be wordy and I'm sure many of you are busy so no worries if you throw a link out or anything, this is just for fun:

    Things I have:
    An inclination to order from Amazon
    24V rated Cohesion3D Mini 32-bit board and LCD
    Nema 17's and drivers for general X and Y (jfong: ditching h-bot kinematics and going cartesian, I like)
    12V power supply for motors and random stuff
    Limit Switches
    Half a football field of miscellaneous wire
    Stashes of screws and hardware
    Timing Belts and Pulleys (jfong: need to get 10-15mm wide belts)
    Parts to build a rotary A-axis
    12V Blower fan for air assist (maybe a 15x50mm blower is too weak?)
    3D printer to make internal parts
    CNC mill to make a case
    Automatic fire extinguishers

    Things I need:
    CO2 Laser Tube (Maybe 80W, MichaelHenry: 60W, feel free to change my mind)
    Laser Power Supply (Can I power 24V fans and control board from this or too risky?)
    Laser rated mirrors (For the daredevils out there: do these mirrors get hot to the touch?)
    Laser rated focus lens (Looking at a 20mm with a focus of 50.8mm because that's what I see most people get but not sure what's the balance)
    Water Pump, Tubes, and bladder
    Computer Fan (opposite of work area) --> Pre-Filter --> HEPA filter --> Activated Carbon Filter --> Computer Fan (In this order)
    BL Touch Probe (not sure if needed)
    Maybe some threaded rods for the Z height (not sure if needed)
    Nema 23/24's and maybe even Nema 34's with their respective power supplies and drivers for an infinite axis (not sure if needed but means this machine needs to be re plugged to switch Y-motor)
    Some kind of laser grill
    LED strips to light up the inside
    Aluminum extrusion and corner braces
    Extrusion wheel bearings to use the extrusion frame as linear rails
    Ply Wood enclosure (or maybe MDF if I'm feeling cheap)
    Tinted Plastic shield (Anyone got some color recommendations other than orange? cuz I was just going to wing it and test a bunch out to see which one made me go blind first)

    Cutting Objectives:
    ~4' x infinite x unknown height, would be convenient to cut large wood sheets direct from a hardware store or stuff I find in my local scrap yard for the occasional big project and as stock for my CNC mill, I know lasers are disrupted by the air so the farther the beam is from its source the weaker it gets, not sure if it would mean the opposite end would by 90% or 50% of the original strength which leaves me wondering if there are some equations for calculating cutting depth for dummies. Worked with a 30W laser before and it had power issues at its far end, maybe the tube was dying but was never sure. I don't mind a 2' wide machine but kind of underwhelming for a 4' long CO2 tube, feel free to bash me for this dumb idea if you want).

    Computer Paper (at minimum power I could cut this stuff with a 30W laser without setting it ablaze, I'd like to still do that with this DIY laser even at 80W but I'm not sure if possible so I don't mind duct taping a laser module on there if you guys think that's for the best whenever I want to cut thin stuff)
    Cardstock
    Single Ply Cardboard (Tangent: anyone know the secret to cutting two ply or thicker cardboard without setting it on fire? Not that it is a requirement, just curious if it is as simple as adjusting one's focal distance)
    Wood (There are a variety of densities, I'd like to grab whatever from a hardware store and butter through it at least up to 1/4" but anyone know the maximum thickness I should expect? I'll test it when I build the machine of course, just curious)
    Acrylic (Bare minimum should be no fuss to cut 3mm thick)
    Glass engraving (Sometimes glass cups with the rotary axis)
    Stone engraving

    Similar Threads:
    Last edited by SerMumble; 07-20-2019 at 02:07 AM. Reason: Updating with latest advice


  2. #2
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    Default Re: Custom Large Glowforge Practical?

    Modifying a Glowforge doesn't make much sense to me when you can buy a more technically capable laser cutter/engraver at about the same price point, especially if you are planning to put money into upgrading the GF. The GF seems to be especially well suited for the crafter that is a little afraid of technology and that needs it for occasional duty.

    A 60 watt laser seems like a good power rating if you want to both cut and engrave. If you just want to cut, then I'd go for more power.



  3. #3
    Member SerMumble's Avatar
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    Default Re: Custom Large Glowforge Practical?

    Thanks for the tip! I’m going to consider the 60w tube a lot more now.

    I think you’re right it is impractical to buy and upgrade a glowforge. I’m a bit too poor and proud for a glowforge and their ecosystem which is why I want to build a laser like the glowforge from scratch (I figured most people heard of it and probably like it’s aesthetics but I’m open to better, visually appealing designs, my family has to think it’s not an eyesore pretty much). I’m guessing for $850-1050 in amazon points plus the scraps I have from old projects I could build a mean machine. You sound like you know of some good machines that could save me a lot of time, got a name and/or link to share?



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    Default Custom Large Glowforge Practical?

    Use standard Cartesian instead of h-bot. This keeps the x axis belt length shorter. For the size of your machine, use wide belts. Almost all large format lasers are Cartesian using 10-15mm width belts. Even though the laser is moving a fairly lightweight lens head, it does operate at very high speed. There is also the weight of the air assist, led cross hair positioning etc. I do laser rasters scans 400mm/sec sometimes which is the limit for my machine. Other machines can go much faster. This is several times faster than my 3D printer.

    I just don’t think a large format h-bot can be made to go those speeds without problems showing up.

    The glowforge has to much proprietary hardware to even bother with. You can’t re-use the controller etc. Just get the lens, tube, power supply from a place like light objects.com or similar. Get a Ruida DSP controller and Lightburn laser software.



  5. #5
    Member SerMumble's Avatar
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    Default Re: Custom Large Glowforge Practical?

    Good points, I’ve never done an h-bot this big before, I think you’re right there would probably be an unhealthy amount of play. Cartesian it is, I certainly don’t mind a simpler build.

    As for belts, you’ve got the right idea, I should give those wider types a look.

    Glad to know about the proprietary glowforge hardware, guess I should be thankful I won’t be touching that stuff, Ruidas are a bit too expensive for me to justify when I have several boards lying around that can do the job, what do you think of the cohesion3D mini running something like smothieware or marlin? I also have some Re-ARM RAMPS 1.5’s but I figured I’d use the cohesion since it was designed to replace k40 boards. If neither work, no hard feelings!



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    Default Custom Large Glowforge Practical?

    I use a Cohesion3d first gen mini board on my K40. It works really well with Lightburn.

    I also have a Re-Arm and many other controllers.

    I recommended the Ruida because it is more common.


    If you are comfortable with smoothieware and hooking up to control boards such as Cohesion3d, than it is a good option. The new Laserboard has Trinamic drivers which works really well. I did most of the hardware beta testing for that board before it was released.



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    Member SerMumble's Avatar
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    Default Re: Custom Large Glowforge Practical?

    Awesome, great to know about the boards, I’m flattered you suggested the Ruida, I’ll keep it in mind for this project and recommend it my friends if their shopping too.

    And wowzer, did not think I’d live to meet someone part of the developement, the new board looks outstanding, helped get me back interested in cohesion’s boards. Yup, should have no problem setting it up, I’ve been hooking it up from machine to machine to cross check if I ever broke a RAMPS so it would be great to get this trooper of a board a permanent job.



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    Default Re: Custom Large Glowforge Practical?

    I don't have a laser machine, but I bought some hardware from a guy who was scrapping one. The XY leadscrews are 30mm and 35mm, driven by 1KW and 2KW Mitsubishi servo motors. This suggests to me that there is a requirement for speed that your nema17 stepper motors might struggle with.



  9. #9
    Member SerMumble's Avatar
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    Default Re: Custom Large Glowforge Practical?

    Glad to know Zorbit, no worries if you don’t have a laser, same here haha.

    Those are pretty thick screws, I normally work with 2mm pitch 8mm diameter lead screws in printers in the Z axis and only recently used 5mm pitch 16mm diameter ball screws in my cnc machine for the XYZ. I like the rigidity of screws over belts but I am not sure they are the most nimble motion system. What was the name of the machine that you got these parts from? Maybe I could look it up because this is a first for me.

    I agree the Nema 17’s are the bottom line minimum to build a laser, I do have the biggest 84 oz-in types I could find and a couple similar 400 step pieces. Maybe if the motors are strong enough and I combine with some TMC drivers, I can gear them to speed them up. It will take some testing to get the optimal settings and I might find myself just using Nema 23/24’s. Yeah, just not sure on what I am doing for motors exactly.

    Anyone have thoughts on hybrid steppers?

    I looked up the mitsubishi servos and they are meaty and expensive, no joke, one crazy machine you must have gotten them from. I don’t know the first thing about picking servos for a cnc machine so I guess I best do some research and maybe leave enough room in my machine to mount some for testing.

    Thanks!



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    Default Custom Large Glowforge Practical?

    Ya those servo motors are high speed probably greater than 3000rpm. I’m assuming this is for a large machine that moves a fairly sizable gantry laser system. Maybe a industrial metal cutting laser. The ballscrew, motor and servo drivers new cost is more than a lot of laser cutters

    Way overboard for a basic 40-120watt CO2 cutter engraver.

    Good nema23 size motors are more than adequate. Most CO2 lasers of this kind use steppers. High end Epilog and Trotecs use small servos but they run $15k or more. They advertise those machines to go 1000mm/sec or more. Even my small laser is using nema17’s and can run the laser head 400mm/second.



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    Default Re: Custom Large Glowforge Practical?

    Thanks jfong! Alright, then Nema 17's it is for now, I'll keep a little space for upgrades down the road. Talking with you guys really opened my eyes to quite a few curious things I'd really like to test out.

    Hmm guess no better time than the present to start assembling a model, I'll post a picture down below how it might look in the near future and just add details and work out kinks as I go.

    And still a bit new to this forum but I can't edit my original post now I guess since there is a limit to how far back in posts one can edit, oh well.

    Hey and no worries Zorbit! Really glad to learn that there are machines that use high end stuff like that, maybe one of these days I'll be lucky enough to be commissioned to design a machine like that!



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    Default Re: Custom Large Glowforge Practical?

    If you are asking whether or not modifying Glowforge is practical, the short answer is No.

    If you intend to design and build a new machine from scratch, the biggest challenge would be the mechanical design. To get good engraving/cutting results you will need to have very smooth and tight mechanical action. Selecting the electric and electronic components would be relatively easy and should depend on the level of mechanical performance.
    Using servos would make sense only if you pair them with top of the line mechanical components. If you are going to design and use this mostly for fun using cheap parts and steppers would make more sense.



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