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Cool circuit plotter with conductive ink

Discussion in 'General Electronics Discussion' started by chopnhack, Dec 21, 2014.

  1. chopnhack

    chopnhack

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    Kudos to the students!

     
    Arouse1973 likes this.
  2. ketanrd01

    ketanrd01

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    Nice one chopnhack....looking forward to making one myself...
     
  3. BobK

    BobK

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    A better idea would be to use a 3D printer to put down plastic on a copper clad board, then etch it. The accuracy of 3D printers is much higher than they achieved.

    Bob
     
    chopnhack likes this.
  4. hevans1944

    hevans1944 Hop - AC8NS

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    I have a similar plotter in my basement waiting for an application. AFAIK it still works, but the interface is serial RS-232... slow but accurate. I would trade it in an instant for a comparably sized laser printer with the same plotting accuracy and paper size, but I don't see that happening. Didn't even think about offering it up on Craig's List! It uses an external "brick" power supply that really is about the size and weight of a half-brick. I thought about using the X-Y servos for something, but that's probably not going to happen either. <sigh> Another example of fine technology made obsolete by newer technology. Thanks for posting the video @chopnhack !
     
    chopnhack likes this.
  5. chopnhack

    chopnhack

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    True Bob, that is a great idea. I think though, the students showed great intuition in piecing together the project - especially from scraps. Very cool. A 3d printer is still really pricey (at least ~$500 if you DIY) and not as fast.

    @hevans1944 - my pleasure, I am glad you enjoyed it!
     
  6. hevans1944

    hevans1944 Hop - AC8NS

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    It brought back some memories from the 20th Century. Glad to see that kids today are willing to re-purpose "obsolete" stuff. It's an excellent way to learn.
     
    chopnhack likes this.
  7. BobK

    BobK

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    Yes, but I want one for other purposes anyway! When I get it (probably after I retire next year) I will try it out.

    Bob
     
  8. chopnhack

    chopnhack

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    Just wanting one alone is good enough reason :) They are very cool!! I hope you post some pics when you do get it, let the rest of us live vicariously ;)
     
  9. hevans1944

    hevans1944 Hop - AC8NS

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    I would like to build a 3D printer that fuses successive layers of plastic powder (instead of melting plastic string) with a high-powered pulsed laser diode. Not real sure how to go about laying down an even thicknesses of powder for each layer though... maybe "dump powder and scrape to a uniform thickness" before fusing each layer? Shake off excess powder at the end of the build. Maybe use a piston in an open cylinder, lowering the piston a few micrometers for each layer, pouring in an excess of powder to overfill the newly exposed volume, then scraping the excess off with a blade passing across the open cylinder end. I think something like this one, that is used for metal powder sintering with a 200 watt fiber-optic laser, but using plastic powder and perhaps a 5 watt diode laser to scan and melt the surface.
     
    Last edited: Dec 23, 2014
  10. chopnhack

    chopnhack

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    That would be really cool! When I first read the thread I was wondering how you would keep the powder out of your restricted areas, but then when I saw the video, I understood that the laser would be used like a cnc, but to fuse, not cut, the areas desired.
     
  11. hevans1944

    hevans1944 Hop - AC8NS

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    There are problems with sintering plastic... you need the right kind of plastic. Fortunately progress is being made and a German company has stepped up to address this emerging market.

    The maker community is not going to give up their plastic string and jump on plastic sintering... the design and construction of reprap-style 3D printers is just too simple and inexpensive to ignore for entry-level 3D printing.

    My first "exposure" to 3D printing was sometime in the late 1990s while attending a "hands on" class for one of the major 3D modeling program venders, a not-so-thinly-veiled sales presentation more than anything else. In the lobby they had an early 3D printer that was operating, verrrry slowly building something. It was still at it hours later when the sales presentation... er, class... was finished.

    I wasn't impressed then, and still am not impressed, with the speed and accuracy of commercial additive manufacturing machines. But the state-of-the-art advances year by year. Some of these accurate metal-sintering 3D printers are almost affordable now.

    IMHO the major additive-manufacturing market will be custom medical prosthetic devices and "reverse engineered" replacement parts for expensive equipment no longer in production. With an accurate metal or plastic part, you can make a mold to cast metal parts using the "lost wax" investment casting process, a very accurate and inexpensive mass manufacturing process.
     
  12. BGB

    BGB

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    hmm...


    this leaves me wondering about possibilities of directly extruding with or printing traces with metal of some sort (such as lead or tin), though there would be an issue with getting it to stick well to paper.

    one idle thought would be using a compressed air source and a venturi, to essentially spray down a thin layer of molten metal, which should then hopefully stick to the paper (possibly an adhesive such as an epoxy could be added to the mix to aid with adhesion, but this should be unnecessary with a plastic substrate), and will cool off quickly enough to hopefully not burn the substrate.

    though, there is a problem that if one tried to solder onto solder traces, they would probably be prone to melt and separate.

    pure lead would have a higher melting point though, so could be soldered onto, but would likely assimilate into the solder in the process (hindering or preventing subsequent desoldering and resoldering).

    zinc, should not readily assimilate, but would likely be prone to crack and flake off of flexible substrates (was looking into possible alloys, such as ZnPb or ZnCu).

    aluminum or maybe a AlPb or PbAl alloy could work.

    possible issues is if it could be applied without burning the substrate, but then again, soldering on paper is also likely to be an issue (extended exposure to a soldering iron will burn paper).
     
  13. hevans1944

    hevans1944 Hop - AC8NS

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    Folks have been trying for years to lay down conductive traces on an insulating substrate... paper, card board, thin and thick plastic, fiberglass, etc. The only "tried and true" method so far, suitable for both prototypes and manufacturing, is either chemical etching or laser ablation of a copper-clad insulating substrate. This provides sturdy high-conductivity interconnections that easily accept solder and mechanically supports components. Laser ablation is not attractive for mass production, nor is any technique that requires "X-Y scanning" of the "circuit board" to produce conductive traces... it's just too slow.

    @BGB: Squirting molten metal through an orifice to deposit metal traces on a substrate could work for prototype production, but the engineering challenges are huge. Why bother when there are less expensive and simpler ways to do it? I think the OP (@chopnhack ) just wanted to demonstrate what clever students could accomplish with a minimal cash outlay, re-purposing what many would today consider "junk".

    Kudos to them indeed!
     
  14. BGB

    BGB

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    I think it could be cheaper (and less messy/toxic/corrosive) for "medium-scale" hobby work than buying blanks and doing chemical etching by hand (the PCB blanks seem to be reasonably expensive, as in, several $ per board or so), and not everyone has access to a laser cutter or similar.

    likewise, the extruder shouldn't be particularly expensive to make, as it is essentially a modified airbrush pen with a heated reservoir for molten metal (possibly heated with a glow plug). the main hard part is finding a good metal to use with it.

    the actual X-Y mechanism would probably be similar to the plotter in the video, with a solenoid valve to turn the air flow on/off, and probably a portable DC car-tire inflater used as an air compressor (or buy an airbrush that comes with a compressor).

    (ADD: though for small-scale hobbyist stuff, perfboard is still a reasonably good option. and, note, it would likely require a solid-steel airbrush pen or similar so not to be damaged by exposure to high operating temperatures).
     
    Last edited: Dec 23, 2014
  15. groovejet

    groovejet

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    Why such a ridiculously BIG Capacitor ???
     
  16. hevans1944

    hevans1944 Hop - AC8NS

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    Umm... the guy said in the video "we have this big guy over here that's powering all the motors on this giant capacitor just to stabilize everything." And that is not such a ridiculously big capacitor. Might even be a little on the small side if it's less than 10,000 μF or so, depending on current draw. Servo motors start and stop A LOT, creating large surges of current as they do so. The capacitor allows the motor power supply (the "big guy") to play "catch up" in between power surges.
     
    Last edited: Dec 24, 2014
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  17. chopnhack

    chopnhack

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    I think its an interesting thought, but my first issue with the process would be maintaining a high enough temperature of the "pot" to accommodate heat loss while being blown onto the surface. Convection would take a lot of heat away, so the pickup tube would have to be fairly short or you would have to "super" heat your metal. Either way, I think it makes it less practical - it can be done, mind you - just thinking it would not be practical. I would also consider adhesion issues to the substrate, metal shrinkage, metal wetting/balling when it hits the surface, etc.
    LOL, kids love supercaps :D I don't know either, maybe that's all he had laying around, we are talking college kids here! (Edit: see more intelligent response above, thanks @hevans1944 )
     
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  18. BGB

    BGB

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    possible.

    I was thinking likely both the reservoir/pot and airbrush would need to be at fairly high temperatures (yes, with the metal probably super-heated to some extent). maybe also the brush would need to be heated to some extent, and maybe also the incoming air (such as by coiling the air intake tube around the reservoir, so that it picks up some heat before it hits the metal).

    though, yes, need to keep the metal hot while also trying to avoid overheating the substrate.

    for paper-based substrates, adhesion could be an issue, likely requiring some sort of adhesive coating (or plastic). for printing on plastic, it should be easier, as the molten metal would likely melt into the substrate (adhering itself into place).

    I guess a lot depends on how much heat one can get out of a glow plug (from what I can gather, 150W is typical). if not enough, maybe multiple glow-plugs and a beefy power source could be used.

    (ADD: apparently 150W is when an engine is running at temperature, the plugs can apparently output around 720W to 1kW, which is their output range when starting a cold engine).

    I suspect it may need to be tested though to see how well it works...


    yeah, dunno there...

    that is a lot bigger than I have used for anything though.
     
    Last edited: Dec 24, 2014
  19. hevans1944

    hevans1944 Hop - AC8NS

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    Testing is good.
    Energy storage capacitors, i.e., capacitors specifically built to store an electrical charge and then discharge very rapidly into a switched load, come in a huge range of voltages, capacitance, and physical sizes. You would be amazed at what you can find stored away in forgotten corners of most college physics laboratories, remains of once-funded research now abandoned.

    As far as BIG capacitors are concerned, one of the largest I have seen (there are larger) was one set (three or four IIRC) that consisted of large high-voltage capacitors, about three or four feet in diameter and about four or five feet tall, that were wired in parallel and charged to several thousand volts. This capacitor bank was then discharged into a thin disc of aluminum foil mounted in vacuum. The foil instantly vaporized, propelling hot aluminum gas at hypersonic velocities into a target. Sounded like a large cannon going off when the capacitor bank was discharged. It took several minutes to recharge the capacitor bank and replace the aluminum foil load (through an air-lock) in between shots.This was early in the US space program and this Air Force laboratory was testing the effects of micrometeorite impacts on vehicle materials.

    That was my first, brief, exposure to high-power pulsed energy, sometime around 1968. Much more "fun" came later.
     
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