IN DEVELOPMENT BigBox Dual X-Carriages (Bowden)

Discussion in 'Guides, Mods, and Upgrades' started by Greg Holloway, Jan 31, 2017.

  1. W1EBR.Gene

    W1EBR.Gene Well-Known Member

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    FWIW...

    If a connection between wires can move, I am not a fan of soldering because the soldered connection is so brittle. If you do solder it, encasing it in heatshrink tubing or tape will help immobilize the connection.

    An alternative is using crimp tubes. As long as the crimp is solid (i.e. you can't tug the wire out of the tube) and the crimp isn't at the very end of the tube, you get a solid connection that handles flexing better (it has a sort-of stress reliever in the section of tube before or behind the crimp).
     
  2. W1EBR.Gene

    W1EBR.Gene Well-Known Member

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    Has anyone seen a Zesty Nimble up close yet?
     
  3. eca

    eca Well-Known Member

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    Unfortunately not, but they should be shipping by the end of March.
     
  4. eca

    eca Well-Known Member

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    I ordered one, I will post when I get it.
     
  5. Pipshag

    Pipshag Active Member

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    Installed everything but the cooling fans and when testing the motion system I notice that the nozzles hit the platform plastic. It seems I can't get the nozzles high enough up. What can be the problem here?

    Inside the X-carriages I installed the original o-rings, inserted the hotend-assembly from underneath and tightened the grub screws as much as I feel is safe. The hotend can still wobble a bit forward and backwards though.

    Has anyone other than @Greg Holloway built the IDEX Bowden yet and can help?

    16934075_1862892027318933_691684126_n.jpg
     
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  6. Greg Holloway

    Greg Holloway Administrator
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    Don't fit the o-rings.
     
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  7. W1EBR.Gene

    W1EBR.Gene Well-Known Member

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    Greg, I need to create a little platform to attach the BLtouch. What is the z distance from the tip of the nozzle to the large bottom plane of the lower half of the x carriage? When I measured the .123dx file, I got 50mm from the lower plane to the bottom plane of the fan duct.

    Thanks!
     
  8. Greg Holloway

    Greg Holloway Administrator
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    According to the measuring tool it is ~51.811mm
     
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  9. Pipshag

    Pipshag Active Member

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    That was easy! :D

    Everything is installed, firmware adjusted and flashed. I went through the threads available in a hope to understand how to set the offsets correctly. Should I do it like this?

    - Test tool changes and adjust endstop screws so T0 and T1 matches correct X0Y0 and X300Y0 positions
    - Use the pin method to find offsets by using pin center coordinates with T0 and then T1, save X and Y offsets in S3D (and Apply toolhead offsets checked)
    - Check if T0 or T1 is lowest and adjust height difference for the lowest one with M851 Z
    - Find difference in Z-height of lowest tool and set in startup gcode with M218 Z
     
  10. Greg Holloway

    Greg Holloway Administrator
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    Basically yes, but I never bother with M851. The offset to the bed is set during mesh levelling.
     
  11. Pipshag

    Pipshag Active Member

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    I'm very sorry @Greg Holloway but I really can't figure out the correct way to do it. My T1 is lower and no matter how I configure the firmware, edit the settings and do the MBL, it never takes the offset into account. I'm also quite certain I've tried so many things that I lost the correct procedure somewhere in it.

    Could you do a quick step by step of what needs to be done? Haven't found a complete on on the forums yet. MBL on which Tool? Where should the offsets be put (Marlin w/ gcode or S3D)?
     
  12. Greg Holloway

    Greg Holloway Administrator
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    You will need a point from which to measure the position of the T0 Print head. I use this tool | https://www.thingiverse.com/thing:1686515
    It is more than possible to use something else. Just make sure it is stable. I will write the guide assuming you are using the tool. G-Code commands to use are in bold for each step.

    Step 1 : Home the printer and clear any offsets.
    M218 X0 Y0 Z0
    G28

    Step 2 : Lower the bed
    G1 Z200 F500

    Step 3 : Move T0
    G1 X150 Y100 F4000

    Step 4 : Position the tool on the bed below the nozzle.

    Step 5 : Using the LCD and 0.1mm increments move the tool up to meet the nozzle. You will need to align the tool to the nozzle while doing this. The more accurate you are the better the alignment. When you are happy the tool is aligned correctly take a note of the position of Z to the nearest 0.1

    Step 6 : Use the LCD to drop the bed by 1mm.

    Step 7 : Move T0 out the way
    G1 X-44 Y100 F3000

    DO NOT KNOCK OR MOVE THE TOOL.
    If the tool moves you will need to repeat the above steps.

    Step 8 : Swap to T1
    T1

    Step 9 : Move T1
    G1 X150 Y100 F4000

    Step 10 : The nozzle will likely be off from the nozzle by an amount. Use the LCD in 0.1mm increments to position the nozzle above the tool as you did before. Take note of the X, Y & Z positions to the nearest 0.1mm.

    Step 11 : Swap back to T0
    T0

    Step 12 : Take the tool off the bed. Home the system.
    G28

    Step 13 : Usually one can use the M218 command for all three axes, but Marlin has an interesting 'feautre' where X is not reconised for the M218 command when doing IDEX. So X &Y will be offset in the slicer. Z will still use M218.

    To calculate Z...
    Z (starting position) - Z (ending position) = Z Offset.

    To calculate X & Y..
    X or Y (ending postion) - X or Y (starting postion) = X or Y offset

    Notice X & Y are calculated in reverse to Z.

    Step 14 : Adding in X & Y the offsets. If you are using S3D the X & Y offsets are in the G-CODE section of the profile settings. Select T1 from the drop-down menu and input the numbers. Make sure to check the apply toolhead offsets to G-Code coordinates box on the same tab. You should be able to see miss-alignment of model parts in the slicer preview if you have things correct.

    Step 15 : Z offset. Use the M218 command. The command can be added to either the OctoPrint startup script, or in the slicer profile starting script, the choice is yours.
    M218 T1 X0 Y0 Z(offset)

    That is basically it. If you want a little more control I recommend enabling babysetting for all three axes. You will need to recompile and flash the firmware to make that work....
     
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  13. Pipshag

    Pipshag Active Member

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    Thank you for that very well written guide. It makes it much more clearer now.
    My last question is about MBL. You run it for T0, right? It doesn't seem to activate for T1 when switching tools manually (haven't tried your guide yet). My bed is a bit uneven which makes T1 hit the side of the bed when switching from T0 to T1 and trying to move in on the bed. Is this perhaps just a bug in Marlin (running your RC6 you uploaded) or something I've missed to do?
     
  14. Greg Holloway

    Greg Holloway Administrator
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    MBL operates on a single printhead, T0. Calcaulating the offsets corrects any difference between the two. Technically there will be a slight miss-alignment between the actual bed matrix and the position of T1 as the M218 command has not be used to offset the head, but it will be so small as to not matter.

    The difference in height between the two nozzles should be no more than 0.5mm. If you are getting collisions I recommend checking the bed is actually level and not off at an angle. I have since screwed the four brass pillars in each corner of the bed all the way down tight. Then lowered the bed and used a ruler to physically measure each side of the bed and adjusted the leadscrews to make sure they are equal. Remember to correct the IR sensor if you do that.
     
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  15. Pipshag

    Pipshag Active Member

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    And I think with that I will be able to complete a successful print later today! I am very grateful for you help and continued dedication to the Big Box project. I'm one happy customer.

    EDIT: Everything up and running. Haven't tested any Dual Prints as of yet but everything seems to be aligned correctly and the nozzles move like they should.
     
    #155 Pipshag, Feb 26, 2017
    Last edited: Feb 27, 2017
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  16. eca

    eca Well-Known Member

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    When I print the pieces, should I increase the size at all to compensate for shrinkage (depending on the material I am using of course)?
     
  17. Greg Holloway

    Greg Holloway Administrator
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    There should be enough tolerance in the parts to compensate.
     
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  18. W1EBR.Gene

    W1EBR.Gene Well-Known Member

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    I thought that one of the hotends could be a volcano but a difference of height of no more than 0.5mm rules that out.
     
  19. Greg Holloway

    Greg Holloway Administrator
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    What I meant was with two standard V6 nozzles correctly installed there shouldn't be an offset between the two which is greater than 0.5mm. If it is something is probably wrong.

    You will be fine to have different heater blocks. However there probably isn't enough clearance above the upper supports to be able to fit a volcano block. You will likely need to modify the X-Carriages to raise the hotend up by ~10mm so the two nozzles are at a similar height.
    I shall look into it when I have a few spare minutes.
     
  20. W1EBR.Gene

    W1EBR.Gene Well-Known Member

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    FWIW:

    This is what I came up with (so far) to modify the y-axis rods to 10mm and use Misumi's 10mm compact linear bearings (they are 2mm thinner than the standard linear bearings)
    https://cad.onshape.com/documents/e...dae34cabdc36470582/e/25724d8316bf521964adaa55

    And this is the left side hot end with first pass stand offs for the BLtouch. I know that the nozzle does not line up with the BLtouch in the x-axis which is why it's my first pass at it.

    UPDATE: There is also a version with the stand offs centered around the nozzle. I am printing it out now :)
    https://cad.onshape.com/documents/5...ee115593d4f05f134b/e/911bb2debebcfee6b0ed8867

    UPDATE2: The spacing looks good so far with the mock-up BLtouch. I printed these in eSun PETG with supports only on the bed so that all of the channels stay open. I used M3 screws and nuts for the design because it's what I have here, so the mounting holes in the BLtouch will be tight. I might make a deeper concentric square for a 2.5mm square nut if that's what someone else might use.
     
    #160 W1EBR.Gene, Mar 2, 2017
    Last edited: Mar 3, 2017

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