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Need ideas for an alternative design...

Discussion in '3D printers' started by cazgram, Jul 27, 2017.

  1. cazgram

    cazgram New
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    I was given this kit partially assembled from a friend: Cobblebot Vanguard 3D Printer (Note: it is the smaller printer with the weird suspended y-axis arm.) Parts List

    After spending a very short while going through the design, I've decided to not spend the time finishing assembly, and instead want to use the parts to start with a more stable design and build from there.

    Goals:
    - Use most of the parts that come in the kit.
    - Keep additional costs to a minimum (maybe $150?)
    - A more stable structure than the current design (unsupported y-axis !?)

    Ideas:
    - an i3 Prusa clone (any recommendations for this?)
     
    #1 cazgram, Jul 27, 2017
    Last edited: Jul 27, 2017
  2. cazgram

    cazgram New
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    Major Parts from the Kit:

    4x Nema-17 stepping motors,1.8 degree (17HD40005-22B)
    1x Hexagon 1.75mm hotend
    1x Mega 2560/Ramps1.4/LCD
    1x Heatbed 250mm x 250mm
    1x Baseplate (aluminum) ~250mm x 250mm
    12x mini v wheels
    20x casted corner blocks
    1x shaft coupler
    1x 8mm lead screw (355mm)
    1x 8mm lead screw (500mm)
    2x lead screw nuts
    2x motor mount brackets
    1x nozzle bracket
    2x 90 degree joining plates
    2x 20 tooth timing pulleys
    3x Ramps1.4 endstop mechanical switches

    Various other bits, such as bearings and things...

    Vslot Extrusions:
    Code:
    Length    Width    Height    Qty
    381 cm     2cm    2cm        2
    39.4 cm    2cm    2cm        2
    8 cm       2cm    2cm        1
    11.1cm     2cm    2cm        1
    25.8 cm    6cm    2cm        2
    55.9 cm    4cm    2cm        2
    50.7 cm    8cm    2cm        1
     
  3. cazgram

    cazgram New
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    Whoops, this belongs in Concepts and Ideas. Can a mod move me over there?
     
  4. Rob Taylor

    Rob Taylor Veteran
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    The only problem I see with the cantilevered y-axis is if the actual support brackets are insufficient. There's no reason why a cantilevered aluminum extrusion shouldn't be capable of holding good tolerances with the essentially zero forces of 3D printing. Literally the only thing I'd do is lengthen the z-axis carriage so that the y-axis rail can have a much more substantial upper gusset- but even then, more than a couple of inches is probably overkill.

    Actually, I tell a lie. I'd switch out the 2020 y extrusion and the 4020 table extrusion and turn it vertical. I have a 1500mm length of 4020 extrusion and it's absurdly rigid. This problem is all in the execution, not the design.

    Edit: I mean, if you WANTED to, you could totally just get some more lengths of 4020 and just make the whole thing twice as big, and then going with a dual-column gantry design might make more sense. Everything else should be a-ok.
     
  5. cazgram

    cazgram New
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    Hi Rob, thanks for your feedback. I'm definitely leaning toward modifying it to have a dual column z-axis gantry. At this point I'm not sure how far I am away from an i3 Prusa design, but I'm thinking that if I get a stopgap version of this up and going, then I can print and mod my way toward a more i3-like design with linear rods and dual z-axis motors.

    Maybe these photos will help visualize the original design.

    [​IMG]
    [​IMG]
     
  6. cazgram

    cazgram New
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  7. Rob Taylor

    Rob Taylor Veteran
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    Yeah, I understood completely what it looked like from the link. There's really not much wrong with the design, it just wasn't executed that well. You should be fine beefing it up a little in the two ways I said, and then you can print Prusa brackets on that setup if you want, though I doubt it would make a noticable difference to print quality unless you were also scaling it up significantly. There's a lot to be said for the simplicity of single-motor axes!

    It's already 90% of the design of an i3 anyway. Just duplicate the z column mechanism to the front side and then rotate the whole thing 90 degrees. Bam, i3.

    i3s work well for what they are because they're made from sheet and rod, and are designed to make up for those limitations. It's hard to overstate the vastly superior mechanical capabilities of aluminum extrusion, which gives you a lot more freedom in terms of design options. There's nothing particularly extra special about the i3 design that makes it super worthwhile to do in alu extrusion, that I'm aware of.
     

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