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Overview of 3D-printer types and architectures

Discussion in '3D printers' started by Naurdan, Sep 12, 2016.

  1. Naurdan

    Naurdan Well-Known
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    Hello OpenBuilds!

    I'm a mechatronicengineer student and together with a group of engineerstudents are going to design and build a 3D-printer that prints chocolate. We've got some design ideas and have made a few prestudies about the mechanics and constructions of 3D-printers.

    But i've got a problem wrapping my head around the 'lango' and types of architectures of the 3D-printers.
    The coordinate systems (carthesian, delta and polar types of architectures) are quite self explanatory, but i'd need some help with the types of bots out there.

    Is there a good overview of example what differentiates a c-bot from a d-bot, whats the pros and cons of a h-bot vs corexy. Can a c-bot utilise the h-bot belt construction? and so on.

    I'd be very greatful for any links, references or explanations.
    Also, for a 3D-chocolate printer, what construction type would you go with, and why?

    Thanks alot!
     
    Mark Carew likes this.
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    For anyone to offer reasonable suggestions there you will need to provide a better explanation of the nature of the anticipated output. A machine for decorating sheet cakes with chocolate will be entirely different from one creating highly detailed chocolate micro-figurines. What is your anticipated working area/volume? Will the end product have issues with bed motion? Also have you worked through the conveyance and depositing system for the chocolate? Will this require a lot of weight be accounted for at the print head? Will motion affect it? Will it be done Bowden style?

    You need to be thinking through this process in reverse. The end results will help determine the process and the process will help define the mechanism. If you start machine first, the end results will be dictated by the machine which may not ultimately result in what you desire.
     
    MaryD likes this.
  3. DiggerJ

    DiggerJ Master
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    This oughta be a hoot! We have a life-sized butter cow at our state fair every year in August, and a couple of us keep thinking we can make a butter printer.
     
    MaryD likes this.
  4. Naurdan

    Naurdan Well-Known
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    Thanks for a thorough answer. The printer, when finished, are going to be exhibited at school publicity events to recruit new students and such. So i don't think the volume is a priority, though design, functionality and to be easy for a lot of people to see (not alot of covers that is). Also i'm sure a good end result of the printed chocolate is preferable, but not a priority.
    We've also worked out a system of pressurized tanks at the sides of the printers, with a tube of melted chocolate connected to the printers head. (Bowden style) There won't be any extra weight or resistance to the head.
    But i see the point you are making with that we've got to start in the other end with specifying the end product, and i agree.

    If i may ask, how did you learn about the different types of bot? Is it just by experience, reading about different builds and bots?
    The main thing that confused me right now is the difference between c-bot, d-bot and h-bot.

    edit: Spelling
     
    #4 Naurdan, Sep 14, 2016
    Last edited: Sep 14, 2016
  5. MaryD

    MaryD Master
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    This sounds like a really neat project and one that will grab the interest of the students! Can't wait to see the build. Be sure to contact the Parts Store and line up your education discount before ordering. CONTACT@OpenBuildsPartStore.com.

    Best to you.
     
  6. cazgram

    cazgram New
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    ^this
     
  7. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Sorry, but I was hoping one of the experts from this section of the forum would jump in here. (This is not my area.) From an outsider's perspective though, if you're looking for a visual crowd pleaser, you can't beat a delta. They are mesmerizing to watch. But they will only be worth watching if you can get the chocolate to cool fast enough that you can build vertical figurines (i.e. rabbits, vases, etc.) Have you carried the process through far enough to verify if the chocolate will build upward or do you already expect that you will be limited to flatwork?
     
  8. cazgram

    cazgram New
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    I'm a complete noob to 3d printing, and Naurdan's comment definitely echoed what I've been wondering. I have a technical electronics background so a friend asked me if I could help him assemble a kickstarter 3d printer he got that has sat in a box in pieces for far too long. That was about three weeks ago and I've been swimming in the 3d printing sea of terms since. So...

    As an attempt to figure what the heck it all means, I'll try to answer the question and reference what I find along the way.

    Serial Stackup vs Parallel Manipulator Systems:
    One of the first distinctions between a lot of the common printers is if the motors are arranged in a serial stackup or a parallel manipulator system. CoreXY - RepRapWiki In a serial stackup system, at least one motor is being moved by another motor. In the photo below from RepRap Machines - RepRapWiki, you can see the serial stackup arrangement in the Prusa i3 design. On the Prusa i3, the y-axis moves the bed. The x-axis motor is being moved up and down whenever the z-axis motor runs. The x-axis motor is seen on the side of the machine, with the shaft pointing toward the camera. The two z-axis motors can be seen at the bottom on each side of the vertical frame. Even though there is an additional motor in middle of the photo near the print head, this motor drives the extruder and doesn't effect the axial movement of the printer.

    [​IMG]

    With respect to the OpenBuilds categories, the serial stackup arrangement seems to be seen primarily in the Cartesian Style Bots.

    Contrast this with a photo of the C-Bot, seen below. The two motors on the front are running the x- and y-axis, while there are two motors at the back of the base of the frame driving the z-axis. All of the motors on this machine are fixed with relation to the frame and each other.

    [​IMG]

    Core-XY and H-Bot design:
    All the designs you mentioned (C-Bot, D-Bot, and H-Bot) fall in the "H-Bot and Core XY" category of OpenBuilds. The C-Bot and D-Bot are both types of Core-XY designs, while the H-Bot is a little different. Note that the distinction between an H-Bot and Core-XY design is specifically regarding the way the belts are ran to move the motor with the printer head.

    For the differences between H-bot and Core-XY, read this: Double Jump Electric I'm going to pull a few images from this article to make my point, but I'm definitely not doing it justice. Just read the article.

    H-Bot
    The H-bot seems to be named as such because of the way the belt structures make an H shape...? As seen in the doublejumpelectric.com article I referenced, there are two sources of torque seen by the green arrows going in opposite directions that end up putting a lot of stress on the frame.
    [​IMG]


    Core-XY
    The Core-XY design removes the opposing torques seen in the H-Bot. I'm not going to explain what is going on here because I'm still trying to wrap my mind around it.

    On OpenBuilds, most of the Core-XY designs I've seen are parallel manipulator systems, but the don't have to be. By fixing the printbed, and moving both the x and y axis with the z-axis, you can make a Core-XY in to a serial stackup, which seems to be what is going on in this build: CoreXY W/ Fixed Build Plate & Enclosure Since Core-XY is just a belt configuration, it can get applied to a lot of different types of systems, which makes it confusing...
    [​IMG]

    C-Bot
    The C-bot, designed by Carl Feniak, is a Core-XY design that attempts to improve on the general Core-XY design. Carl says the C-bot has "no crossing belts as found in most core XY printers" and instead uses "two offset parallel belt runs". C-Bot I can't seem to see the belts well enough to appreciate what is happening here. Maybe someone can chime in...

    The D-Bot
    On thingiverse.com, spauda01 posted a design they called the D-Bot Core-XY 3D Printer. They conveniently list the differences between the C-Bot and D-Bot on that page, which I've included below:

    D-Bot and C-Bot Differences
    1) The lead screws and Z motors were moved forward to better lift the print bed from its center of gravity rather than use a fully cantilevered print bed.
    2) Increased printable Z height to 330mm (~13")
    3) Use of 20mm rails for the bottom sections to save cost and reduce bulk.
    4) Various adjustments of printable parts, either to add plastic where it seemed like more rigidity was needed or to subtract plastic where it was not needed.
    5) Accessories such as a simplified spool holder a cable chain for bed wiring
    6) Relocated endstop mounting to maximize Y travel and utilize default homing scheme.
    7) Overall reduction in cost compared to the original bill of materials (2$ square nuts vs 40$ Tnuts, etc.)​

    I have no idea if spauda01 was the D-Bot "creator", but FWIW, there you go.

    I've got lots of questions now but I'll try them out on another thread. Thanks.
     
  9. Naurdan

    Naurdan Well-Known
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    Thanks alot for your help, alot of questionmarks have been straightened out! Especially Cazgram, for the effort and a very good explanation!

    and for those who are curious, when the planing phase of the project is complete and if we've got the time, we'll be posting the build here on OpenBuilds.
    Again, thank you.
     

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