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H-Bot CoreXY Cube

Discussion in '3D printers' started by Giuliano M, Oct 24, 2014.

  1. Giuliano M

    Giuliano M Well-Known
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    They're going to be 60mm nema17 steppers from RobotDigg, pretty hefty torque at 92oz/in.

    The Z axis will be threaded steppers, Tr8*1mm lead.
     
  2. munchit1

    munchit1 New
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    hmm i'll be intrested in how they perform.. waiting to build one myself.
     
  3. Giuliano M

    Giuliano M Well-Known
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    IIRC, the 60mm threaded steppers with a 500mm length were about $55, with a 2-3 week lead time.
     
  4. Giuliano M

    Giuliano M Well-Known
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    My V-Slot arrives today!

    On that note, I've made some significant progress with the design and have started filling out a Bill of Materials for the components.

    Some of which I've already ordered today, so they'll take a few weeks to arrive.

    The official build volume should be roughly 400 x 400 x 400mm, though the X axis would be limited to 370mm... I may re-design the X carriage somewhat to increase the movement to allow for the full 400mm on X.


    Take a look at the updated Sketchup file and the BOM Excel sheet.
     
  5. Mark Carew

    Mark Carew OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

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    @Giuliano M this is really coming along nicely, nice job
     
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  6. Giuliano M

    Giuliano M Well-Known
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    Thanks!

    This is why I love doing most of the design pre-work in Sketchup, it allows me to figure out how it'll go together before I even order the parts...
     
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  7. Giuliano M

    Giuliano M Well-Known
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    I redesigned the X/Y Idler mounts at the back side of the frame to increase the strength and resistance against the belt tension.

    I've oriented the parts so that the longest side is facing down, though you will need to print with support.
     
  8. Giuliano M

    Giuliano M Well-Known
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    My order of V-Slot arrived today, packaged really well - it's like an early Christmas. :)

    The technique I used to make printed parts with V-Slot key ways seems to work well - the printed part fits perfectly.

    WP_20141126_001.jpg
     
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  9. Giuliano M

    Giuliano M Well-Known
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    Got a surprise in the mail today, earlier than I expected from shipping in China..

    The massive massive 400 x 400 mm silicone heat bed arrived!

    And it's HUGE.


    24 V, 200W silicone heat bed with 100k thermistor embedded in the middle, with 3M adhesive tape on the bottom.

    For size reference, the box that the heater is on top of is a good 24" square - it's that large.


    Coupled with a 1/4" aluminum heat spreader and borosilicate glass, and I shouldn't have any problem with uneven heating...

    Also: Room-temperature resistance of the pad measured out at around 3.2 Ohms, or calculated at 180 Watts at 24V - I'm sure the resistance will go up to match the rated 200W as it heats up.

    WP_20141202_17_47_01_Pro.jpg
     
  10. munchit1

    munchit1 New
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    looking good
     
  11. Giuliano M

    Giuliano M Well-Known
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    RobotDigg Santa delivered today!

    Parts:
    • Two TR8-2 Leadscrew Steppers, 8mm diameter 2mm pitch single-start, 500mm long, with 60mm Nema17 Hi-torque Steppers
      The nuts on them are acetal/pom nuts - not anti-backlash, but should be fine.
    • Four of the same 60mm Nema17 Hi-torque steppers - 1.5A coils, 92 oz/in torque. Two for CoreXY, two for dual bowden extruders.
    • 5 Meters of 9mm wide GT2 belt
    • Two 16T GT2 Pulleys, 9mm wide and 5mm bore.
    • 10 Meters of 4mm/2mm PFTE tubing
    • Two steel NEMA17 stepper mounting brackets - They have 5mm-wide mounting slots on the back, I believe 20mm apart - though I haven't measured them.

    WP_20141215_19_50_55_Pro.jpg
     
  12. Adam Filipowicz

    Adam Filipowicz Journeyman
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    Awesome build.. I love everything about it so far.. I want to do this.., ever consider doing the Z with a ballscrew?
     
  13. Giuliano M

    Giuliano M Well-Known
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    Not as such... the Z axis is mostly stationary, typically only moving downwards during a print job.

    If I were going to make this into a CNC router or the like, then a ballscrew would be more applicable due to the accuracy requirements.


    I don't even have an anti-backlash nut on the lead screws yet due to the smaller lead/pitch of 2mm - though I think I did find a source if I needed one.
     
  14. Giuliano M

    Giuliano M Well-Known
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    I've have been struggling to find a suitable controller/firmware combo that meets these requirements:

    • ARM-based CPU
    • 24V Input for Heat Bed and Hot-Ends
    • CoreXY Support
    • Multi-extruder Support (2+)
    • DRV8255 Steppers for 1/32 Stepping Support
    • Z-Probe & Auto-Bed Leveling / G29 / G30 code.

    I think I've pretty much decided that a BeagleBone Black controller (full linux!) and a Replicape stepper cape/shield will do nicely, and the Redeem G-Code interpreter seems to be actively developed.

    There also appears to be a "Reach" expansion board in the works, to add 3 more extruders/hot-ends.

    http://www.thing-printer.com/product/replicape/
     
  15. Giuliano M

    Giuliano M Well-Known
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    I've made a design change to the Mini-V Gantry plates that serve as the Z axis ends - by removing two of the wheels and chopping 15mm off the side of the plate.

    The wheels would then ride along the inner side of the rails, allowing me to easily attach an acrylic sheet to the sides to form the structure of an enclosure.

    One side will have the fixed wheels, the other side will have the cam-adjusting wheels.


    This should also allow me to reduce or eliminate over constraining the Z axis rails by having too many wheels clamping on either side.

    Z Plate End - Right.png

    H-Bot CoreXY Cube - Sketchup Build.png
     
  16. Mark47ru

    Mark47ru New
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    Giuliano,

    Thank you for sharing your build, I like you CoreXY concept and I intend on building a smaller version. I was going through the BOM you've provided and I have question about the plates you use to mount your Aluminum Sheet.
    Mounting Plates copy.jpg
    Are those 3D printed or did you get them from a specific vender?
     
  17. Giuliano M

    Giuliano M Well-Known
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    They're simple Sketchup components that I'm intending to print.

    The bed and mount designs are still in flux - I'm considering using a sheet of Ultem 2300 as the print surface.
     
  18. Mark47ru

    Mark47ru New
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    Ok, thank you for the information.
     
  19. Vectoraxis

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    Hey G,
    Stalking from ARC.
     
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  20. WZ9V

    WZ9V New
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    I believe the SmoothieBoard fits those requirements.

     
  21. Giuliano M

    Giuliano M Well-Known
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    Not exactly - SmoothieBoard has A4982 stepper drivers rather than the DRV8825 stepper drivers I want.

    I'm keeping an eye on the Replicape board and the python code / firmware that is in development, just haven't gotten around to ordering the hardware yet.
     
  22. WZ9V

    WZ9V New
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    Right. The Azteeg X5 which runs Smoothie has DRV8825 drivers but only one extruder.

    The AZSMZ Mini from AliExpress runs Smoothie and accepts DRV8825 via Pololu style driver boards and supports 2 extruders.

     
  23. TomH

    TomH Well-Known
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    Love your build!!! Looking forward to seeing your progress. I've started designing a variant with an inverted CoreXY system that moves the entire X/Y/Z planes and leaves the build plate immobile. So far I think I have managed to make it work using only openbuild components and without cutting any of the 500mm rails and retaining a 400x400x400mm build volume (using the L-bracket trick suggested by Keith D.) . It's only on paper thus far though - need to work it up in 3DSMax and verify the wheels will work as desired... Will post some pics when I get farther along (may be a few weeks)...
     
  24. WZ9V

    WZ9V New
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    I would be interested in that. I have a Delta because I like the idea of a fixed build plate.

     
  25. TomH

    TomH Well-Known
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    How about this board;

    https://www.kickstarter.com/projects/1177488680/bbp-making-your-3d-printer-faster

    I think this is the unit I will be using for mine...getting ready to kickstart...


     
  26. TomH

    TomH Well-Known
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    Seems the FastBot BBP is steeped in a bit of controversy at the moment....if they answer the right questions I may still get one. Otherwise, the Replicape is looking at lot more enticing at $99 vs. $179: http://www.thing-printer.com/product/replicape/

    I would like to be able to support 4 extruders (though I am beginning with just two to minimize initial cost). Though I have more work to do to complete the model, I am almost ready to post pics to get input before I commit and start sourcing. In particular, I want to make sure my build will sufficiently account for deceleration dipping or heaving while using only 2 Z-axis steppers (I could easily use 4, but again I am trying to make a solid cost conscious build). I think I have solved my X-Y control issues to allow control to be on top vs. inverted while retained nearly 400mm of Z travel. The only things I am missing to complete the drawing are a 3D model of an openbuild 20mm v-slot gantry plate and some single L brackets. If anyone knows where to find them please send me a link so I can save some drawing time.

    Cheers!

     
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  27. Giuliano M

    Giuliano M Well-Known
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    The Replicape board is the one I've been watching, good thing the price dropped from $179 to $99 - though I'm going to wait for the Revision B boards at the same price.

    Although you still need to spend another $50 or so for the BeagleBone Black to power it.


    Another thing that is nice about the Replicape is the Reach expansion board - which will allow for an extra 3 stepper motors and hot ends eventually:

    http://www.thing-printer.com/reach-expansion-board-replicape-ready-review/

    Hasn't been developed into production yet, though.


    I also invested in their kickstarter for their Manga Screen LCD panel - HDMI and touchscreen for the BeagleBone Black / etc.


    As for the 20mm V-Slot Gantry plate, try this Sketchup file - The components are from OpenBuilds, although I modeled the 20mm L-bracket myself.
     

    Attached Files:

  28. TomH

    TomH Well-Known
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    Appreciate the bracket file! Sorry I wasn't more clear, this was the one I was looking for (http://openbuildspartstore.com/v-slot-gantry-plates/) but I finally found it in one of the example builds.

    Your critique of my mod of your design would be much appreciated.

    view1.png view2.png

    I really wanted a fixed build plate - so in order to get the gantry inside the cube, I either need to trim the three green rails by 6-8mm or add 2-hole joining plate spacers (4mm) on each end of the six purple rails. The gantry frame uses large wheels with L brackets to increase the span in hopes of preventing dipping or heaving of the frame due to gantry acceleration/deceleration. The gantry itself uses three large wheels on the ends (one on the top ends and two on the inside bottom ends). The gantry plate is the 20mm v-slot gantry plate noted above. It is the perfect size for 2 e3d Chimera's though it needs new holes drilled - I could mod the model and print one but I figured mounting the hot ends to a metal plate would provide and extended heat-sink. The X-Y belt routing is effected by adding extra pulleys on the gantry frame rails.

    I have managed to do it with all OB components except for one 3D printed part to mount the hot ends (the L bracket is just there as a place-holder). So far all of the geometry is looking good except for OB threaded rod plates which don't line up right (will require extra holes drilled). It does look like I will be limited to about 380-390mm in the Y and Z directions but may be able to squeeze out a few more mm's...

    I'm planning to use 84 oz in 42x47mm steppers in order to keep everything as much within the cube frame as possible so that it will be simple to add some plastic/lexan sides and top for an enclosed unit. The top mounted rails for filament also provide an easy way to add two additional bowden steppers.

    Thoughts? Any issues I'm not seeing?

     
  29. runninfarmer

    runninfarmer Well-Known
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    Nice work, you've captured what I've been thinking of doing for a while now! I like the idea of a fixed bed, especially for a large scale printer. I'm interested to see how each version of this build turn out.
     
  30. Giuliano M

    Giuliano M Well-Known
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    The fixed bed idea is rather neat - I haven't cut my rails yet, so I may try to incorporate that somehow.

    I've been experimenting with using the large V-Slot gantry plates for the hot end carriage, but the plates are really wide and would limit X travel unless they were cut down to be narrower.

    I'll see if I can come up with something similar for a floating X/Y/Z carriage.
     

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