TERRA's linear magnetic accelerator project - Project MADELINE

Discussion in 'Electronics & Electrics' started by TERRA Operative, Jan 27, 2013.

  1. TERRA Operative

    TERRA Operative Member

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    Ok, so I've had this one brewing for a while now, and seeing as my Levin build is coming to a close (check the motoring sub-forum for that one), it's finally time to get started.

    Let's get the disclaimers out of the way...

    DO NOT TRY TO REPLICATE THIS YOURSELF UNDER ANY CIRCUMSTANCES!!

    This project will be using high voltages and currents and high velocities which if mistreated can be fatal.
    I am a registered electrician with over a decade of experience, so I have enough knowledge to know exactly why what I am doing is a bad idea. ;)



    So what am I making? A Linear magnetic accelerator, otherwise known as a gauss or coil gun.

    My design will be a three stage, SCR fired unit with reluctor feedback and 5640uF of capacitance at 400V per stage (12x 470uF, 400V caps per stage).



    Also, I'll be designing it to look the part too...




    [edit] This project has now been christened:

    Project MADELINE.
    MAgnetic DEvice for LINear accEleration


    Thanks to roomandu for the name. :)
     
    Last edited: Apr 17, 2013
  2. OP
    OP
    TERRA Operative

    TERRA Operative Member

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    So, first thing first. I need caps, and lots of them.

    Good thing I repair welders for a living and welders contain capacitors, lots of big juicy capacitors.

    I've been saving up all the spare parts from faulty inverters and storing them away like an electronic squirrel.


    Capacitors, IGBT's and SCR's, Oh my!

    [​IMG]


    When an IGBT or SCR fails in an inverter, we have to replace them in matched pairs.
    What happens to the second one that is still fine, but unmatched? It ends up with me! :D

    That big black module in the centre is good for about 400A continuous at 1200 volts or so. Might have to save that one for a rail gun or something stupid.
     
  3. OP
    OP
    TERRA Operative

    TERRA Operative Member

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    Ok, so we have the guts of the power section mostly sorted. Calculations on the coils and other parameters to come, but we also need to stick all this voodoo into some sort of enclosure.

    Well, I got a little bored today and fired up Rhinoceros 3D, my 3D CAD software of choice and started pushing some lines around.



    First up, an enclosure for the capacitor banks. One is shown, I'll have three. One for each stage.

    [​IMG]

    The purple is the busbars (copper bars), blue are capacitors and red is the housing.
    It'll be constructed using pepakura and fibreglass like ASIGN_Baz did with his Iron Man suit (see his thread for details).



    Now we need to construct the barrel, attach the cap banks, and figure some way of loading the armature samples and holding the silly thing.

    After a few hours, I had this:


    [​IMG]


    This is where it's at. It's not some concept art, or an idea of what it will maybe look like. This is the real deal :leet: It is actually buildable (well once I finalise how it bolts together as I complete the design), and once I run some FEA on the structural parts, will be pretty much what it looks like bar a few revisions as I go.

    You have the three nacelles mounted radially around a carbon fibre central tube with the coils squeezed in. The battery which sits at the back over your arm will be a 14.8V 5000mAh Li-po from Hobby King, powering a step up inverter to charge the caps as fast as the battery will allow (the battery is rated at 35-70c).
    The orange thing serves two purposes, it will help damp vibration through the carbon shaft, and looks cool too.
    All up it will be about 600mm long, so a little longer than a plasma rifle from Halo.

    I hate seeing the other ones around the place that are nothing more than a few caps and a coil screwed down to a plank of wood. The more polished units can look pretty good, but they still often look like something hacked together from scrap metal.
    I figure if I'm going to do it, it'll be done right. Fibreglass, 3D printing and a splash of style.


    Science!

    (What the hell have I done?!?!?!!!)
     
    Last edited: Jan 27, 2013
  4. mtma

    mtma Member

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    The CG seems to be really far forward
     
  5. OP
    OP
    TERRA Operative

    TERRA Operative Member

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    Yeah, it's still to be completed, I've barely done any design on the rear section. All the electronics and charging will be on the rear section to balance it out.
    I may shift the cap nacelles back a bit further too, the barrel length is tentative at this stage.
     
  6. oculi

    oculi Member

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    cool, is the timing going to be open or closed loop? i made one of these with a single found cap, a manual switch and a coil quickly hand wound around a pen casing that linearly accelerated short lengths of nail, it worked surprisingly well.

    speaking of welders I need a good arc welder, what's the best cheapest inverter that will start an arc with ease and lay down beads like stacked pennies?
     
  7. OP
    OP
    TERRA Operative

    TERRA Operative Member

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    It'll be closed loop with inductive pickups for each coil to sense the position of the armature.
    It'll use a main SCR to energise a coil and when the pickup sensed the armature has fully entered the coil, it'll fire a second SCR to force the first one to turn off and quench the magnetic field.

    As for the welder, what's your budget and what weldng process do you want to use? For stacked coins, you'll be looking at TIG.
     
  8. oculi

    oculi Member

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    sounds good, i just want a general garage workhorse that is good enough for me to get good at ARC welding, would only use it for steel 2mm thick and up, only mild. i'd consider a TIG but don't want to buy gas, may consider a gasles MIG but i want to get back to the oldschool. I'm considering getting an old heavy one off ebay or a newer inverter, just don't know what i'm looking at with the newer stuff. used a multi function TIG/ARC machine and didn't like it. dunno if they are all created equal or what.

    [/hijack]
     
  9. NanoDuke

    NanoDuke Member

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  10. OP
    OP
    TERRA Operative

    TERRA Operative Member

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    I did actually see that one, freaking awesome design.

    I'd say that one inspired me to take the capacitors off the piece of wood and polish it off to a complete unit more than any other design I've seen lately.


    Here's hoping mine will look as cool. :D
     
  11. OP
    OP
    TERRA Operative

    TERRA Operative Member

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    Been working on the hand grip and shoulder mount tonight.

    The red box is the battery (it will have a cover) and the charging system and electronics will be mounted in the stock above the hand grip. The blue spine section is still being finalised, but it will serve as the conduit for the control wires and a bit more space for the electronics suite.

    All up, we have a length of 643mm.


    [​IMG]
     
    Last edited: Jan 28, 2013
  12. metal-matt

    metal-matt Member

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    this looks bloody dangerous...
    but absolutely freaking awesome :thumbup: :weirdo:
    I should get back into making pneumatic linear accelerators, lots of fun to launch glow-sticks around in the middle of the night :D

    good luck though, i'd probably want some sort of faraday cage between myself and all that high voltage stuff though :shock:
     
  13. Hive

    Hive Member

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    Love coilguns!

    I'm collecting spare electrolytics for the same purpose :thumbup:
     
  14. OP
    OP
    TERRA Operative

    TERRA Operative Member

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    I've designed it so all the higher voltages will be in the front end, as far away as possible from the user. I'll be double insulating everything too, lots of heat shrink will be used everywhere to make it all nice and safe. :)



    Another thing, anyone here have a 3D printer? :D
     
  15. Hive

    Hive Member

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    An idea is an autofeed mechanism, a second EM coil which maybe pulls the bolt back to allow another round to be chambered. Only problem is it's going to be way to quick, so maybe a seperate circuit which keeps the reloading coil open for a second?
     
  16. admiralranga

    admiralranga Member

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    Would the main caps recharge fast enough for such mechanism be necessary? I'd have thought just a simple spring fed magazine or clip would be enough. Your idea is way cooler tho.

    I have access to an Up! 3d printer usable build area is ~130mm*130mm*130mm. The white plastic is 20c/g, if your interested give me a pm and we can organize something.
     
  17. RussellK

    RussellK Member

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    BOC Smootharc MMA 130 - has a very good rep from lots of users.
     
  18. OP
    OP
    TERRA Operative

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    No need for any crazy chambering mechanism.
    The armature to be fired will be held in the top of the clip by spring pressure and when the first coil is energised, it'll pull the armature down the barrel.
    Then the spring will push the next armature into position ready for the caps to recharge.
    I'm not sure how long the caps will take to charge, but I'll be using lithium batteries and pushing them pretty hard to keep cycle time to a minimum.

    admiralranga, sounds good. I was talking to a mate who can use the university printer that does a 120mm cube. He has to get approval though.
    I'll keep in contact. :)



    The MMA130 isn't a bad unit. The only real faults I've come across is a few caps going pop on the top board, but replacing them is a 10 minute fix. It's not a common fault though.
    Also, the new Cigweld multi function machines are pretty good too.
     
  19. RyoSaeba

    RyoSaeba Member

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    How heavy are the caps? The gun looks very front heavy. Perhaps you'd need to have the arm rest thingy that the other one has?
     
  20. Exige

    Exige (Banned or Deleted)

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    Re : Lithium Ion batteries, is it when they have charge they have potential heating problems or is it when they discharge ?

    Do they need any kind of cooling for what you are planning ?
     

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