Welcome to Our Community

Unlock hidden features. Sign Up for Free Today!

Move the bed up/down instead of the router ?

Discussion in 'Concepts and Ideas' started by KronBjorn, Aug 23, 2016.

  1. KronBjorn

    KronBjorn New
    Builder

    Joined:
    Aug 21, 2016
    Messages:
    5
    Likes Received:
    0
    Hi,

    Are there any designs that move the bed up and down, instead of the router head ?

    Maybe with four lab-jacks or similar ?
    It would make the z-axis a lot simpler I think,...

    Thank you,
     
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
    Staff Member Moderator Builder

    Joined:
    Dec 20, 2013
    Messages:
    1,102
    Likes Received:
    406
    Here's one I suggested a while back. It offers depth without the loss of rigidity from dangling down a long z-axis. The basic concept uses 4 C-beam actuators connected by a single belt to a stepper mounted at the base. Plywood sides attached to the vertical C-beams give the system its rigidity. It could also double as the world's most robust 3D printer although it probably wouldn't be very zippy.

    Suggestion.jpg
     
  3. KronBjorn

    KronBjorn New
    Builder

    Joined:
    Aug 21, 2016
    Messages:
    5
    Likes Received:
    0
  4. Rick 2.0

    Rick 2.0 OpenBuilds Team
    Staff Member Moderator Builder

    Joined:
    Dec 20, 2013
    Messages:
    1,102
    Likes Received:
    406
    The problem with using 4 separate motors is connecting them to a controller. Most controllers only have connections points for 3 to 5 steppers and such a design would require 7. While you could double tap a couple of the connections it can be a risky proposition should one of the steppers get out of sync. Using a single stepper and a connecting belt is also a far more cost effective method, a method which several of the larger printers over in the 3D Printer section use.

    Sketchup
     
  5. KronBjorn

    KronBjorn New
    Builder

    Joined:
    Aug 21, 2016
    Messages:
    5
    Likes Received:
    0
    Those are very good points :)
    My 3D printer almost tore itself apart when two steppers got out of sync !

    What is the longest you can have a drive belt, do you know ?
    And could four lead screw carry the weight of the base plus material, or had you planned on some weights/springs ?

    Thanks,
     
  6. Rick 2.0

    Rick 2.0 OpenBuilds Team
    Staff Member Moderator Builder

    Joined:
    Dec 20, 2013
    Messages:
    1,102
    Likes Received:
    406
    You can get gt2 belts up to 2.2 meters from SDP/SI and 1.5 meters from Robotdigg. Other sizes have different max lengths.

    Just choose a screw appropriate to the load. I'm not a big fan of the TR8x8 screws for the Z-axis as they seem a bit too aggressive for an axis that doesn't go very far or need to get there very fast. I'd be more inclined to go with something along the lines of a TR10x2 which should carry just about anything and you don't have to worry about the screw turning the motor when the motor powers down.
     
  7. KronBjorn

    KronBjorn New
    Builder

    Joined:
    Aug 21, 2016
    Messages:
    5
    Likes Received:
    0
    I think I might go for something like this:
    draft.png
    A wooden frame, with v-slot linear rails, and one NEMA with one or two belts driving the four z-axiz lead screws.
    I am a bit unsure if simple bearings can carry the axial load of the lead screws ?

    (I apologize for the rendering, I only know OpenScad (guitar for scale))
     
  8. Rick 2.0

    Rick 2.0 OpenBuilds Team
    Staff Member Moderator Builder

    Joined:
    Dec 20, 2013
    Messages:
    1,102
    Likes Received:
    406
  9. KronBjorn

    KronBjorn New
    Builder

    Joined:
    Aug 21, 2016
    Messages:
    5
    Likes Received:
    0
    Ah, excellent, that's what I need :)
    Did not know they existed.
     
  10. dean knipping

    dean knipping Journeyman
    Builder

    Joined:
    Mar 24, 2015
    Messages:
    81
    Likes Received:
    15
    I don't know how something like this would actually work because you are going to be limited by the height of the gantry. Yes you can have a long bit but you still have clearance issues. for a printer there wouldn't be an issue because you are doing an additive process then
     
  11. Rick 2.0

    Rick 2.0 OpenBuilds Team
    Staff Member Moderator Builder

    Joined:
    Dec 20, 2013
    Messages:
    1,102
    Likes Received:
    406
    You will only be milling the top surface of whatever you put in there. If you've got a 2" bit you will only be milling the top 2" of the object no matter how thick it is. The best example would be engraving the top of a fairly substantial (already assembled) jewelry box.
     
  12. Metalguru

    Metalguru Master
    Builder

    Joined:
    Dec 29, 2015
    Messages:
    332
    Likes Received:
    175
    If you use separate stepper driver modules you can easily drive 4 modules/motors from a single set of Arduino outputs. Having said that, you may run into a bit of an issue with the maximum current sink capability of the Arduino outputs, but a simple transistor driver like a ULN2008 or even just discrete Mosfets would easily be able to do the job. Leveling the bed would be a challenge, however, since you could not independently control the motors. Leveling would be a manual process of turning the motors by hand.

    MG
     

Share This Page

  • About Us

    The OpenBuilds Team is dedicated helping you to Dream it - Build it - Share it! Collaborate on our forums and be sure to visit the Part Store for all your Building needs!
  • Like us on Facebook

  • Support Open Source FairShare Program!

    OpenBuilds FairShare Give Back Program provide resources to Open Source projects, developers and schools around the world. Invest in your future by helping others develop theirs!

    Donate to FairShare!