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SB Plotter

Discussion in 'DrawBot' started by Steven Busch, Aug 11, 2019.

SB Plotter

SB Plotter

Discussion in 'DrawBot' started by Steven Busch, Aug 11, 2019.

Large floor or wall mounted plotter design.

plotter drawbot cnc
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  1. Steven Busch

    Steven Busch New
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    #1 Steven Busch, Aug 11, 2019
  2. Mark Carew

    Mark Carew OpenBuilds Team
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    Hello @Steven Busch great looking Build so far brother!
    One thing to consider would be possibility actuators for the X axis running in sync, like we do here for the ACRO it would allow you to remove the bracing for the single sides axis there now.
    If you wanting to stay this way you could make it a little stronger by adding a couple plates to sandwich the V-Slot in place.
    Hope this helps, looking forward to seeing the first drawings.
    Capture.JPG
     
    #2 Mark Carew, Aug 12, 2019
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  3. Steven Busch

    Steven Busch New
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    Thanks Mark,

    I avoided the bottom X rail/carriage in order to make it easier to store this huge plotter when not in use. It will hopefully live on a wall in my classroom and move to the tables or floor when needed.

    I suppose if the Nema 23 motor isn't powerful enough to move the x carriage then I will need to double up and redesign the frame like the Acro. Hopefully I will be able to reuse the existing parts if this becomes necessary.

    I also had an idea to have a rack and pinion for the top X carriage, and wanted to make the Y assembly removable. If you have any thoughts on how to make that work or know where to source the rack/pinion gears affordably, please let me know.

    Cheers
    Steve
     
    #3 Steven Busch, Aug 13, 2019
  4. David Bourne

    David Bourne New
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    .

    Steve,

    Although the acro utilises twin actuators, I do think that your design is capable of running with one motor. A Nema 23 is easily capable of operating this project. Potentially a high Nm Nema 17 is capable as well.

    Stay away from rack & pinion, this project does not need that type of motion, nor will it be as accurate as belt drive, especially over distance.

    Belt drive is more than capable of handling this project, even at the length you have here but you do need a belt that is not going to stretch such as a polyurethane type. You may also want to consider adding a reducer gear to each axis for better resolution, this if course depends on what you intend to draw with your kit.

    A change to the design which would be neat would be to allow the vertical axis to fold up 90 degrees to the same orientation as the left to right axis when not in use, minimising frame and storage.

    I have worked with cutter plotters for some time but not used the cutting / drawing mechanism on a large frame so would be interested to know where you are sourcing the plotter actuator and what controller you intend to use to initiate the actuator.


    Dave.
     
    #4 David Bourne, Sep 1, 2019
  5. Jeremy Worger

    Jeremy Worger New
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    Hi, just wanted to chime in since I wanted to build something very similar (still do) but on the ground:

    Building the Acro 1515 with 1800mm extrusions

    I never got around to doing this, because I have no experience building something this large from scratch.
    I will follow your project in hopes of someday duplicating it if you figure it all out!
    By the way, there is also: Textile Drawing Machine
    Which could be converted and less expensive?
     
    #5 Jeremy Worger, Sep 14, 2019
    Last edited: Sep 14, 2019
  6. Steven Busch

    Steven Busch New
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    Hi Mark,

    I am returning to this project with a smaller build size for now. I have an Arduino CNC Shield V3 and a servo for the pen actuator. I have had limited success with a modified version of GRBL called MIGRBL and MI Inkscape Extension which has the servo control attached to the Z+ pin on the shield to control the servo using Universal GCode Sender.

    Do you have a better solution on how to get the servo + steppers working with the CNC shield V3?
    Is there an alternative to Universal GCode Sender?
    (I have been searching for hours)

    Kind regards,
    Steve
    Top view.jpg
     
    #6 Steven Busch, May 12, 2020
  7. Steven Busch

    Steven Busch New
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    Here is the circuit I tested yesterday.
    Servo + Steppers.jpg
     
    #7 Steven Busch, May 12, 2020
  8. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Checkout OpenBuildsCONTROL at software.openbuilds.com - comes with Servo Support baked in

    1) download and install CONTROL
    2) Go to Wizards and Tools > Grbl Flashing tool and flash our version of grbl-servo by setting the 2 axes + Servo option:
    2.PNG


    3) After flashing successfully, connect to the controller
    4) If we detect grbl-servo properly, the pen up/down buttons are enabled: But before you can use them refer to step 5 below

    pen btn.PNG

    5) First calibrate your pen-up and pen-down positions from Wizards and Tools > Calibrate Servo Pen Up/Down
    (write down the numbers you get, you'll need them for CAM later)

    calib.PNG


    Our free OpenBuildsCAM allows you to create GCODE for plotters too:

    1) Go to OpenBuilds CAM Gcode Creator - Public Beta
    2) Add an SVG, DXF or Bitmap from the File Menu2
    3) Select a path and click Add under toolpaths
    4) Configure a Pen Plotter toolpath: Remember to set the values you saved from calibration above for pen up/down values

    example toolpath.PNG
    Once all your toolpaths are setup how you want them to be, click Generate Gcode (use the little floppy icon to save the gcode, or use the bottom, right window section inside CAM to send it to CONTROL)
     
    #8 Peter Van Der Walt, May 12, 2020
  9. Steven Busch

    Steven Busch New
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    Hi Peter,

    Thanks for the quick reply. This will work with my Arduino CNC shield? Servo control still in Z+ (D11)?

    Steve
     
    #9 Steven Busch, May 12, 2020
  10. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Yes, it will, refer the first screenshot: Uno selected on dropdown for controller type.
    Servo PWM is on the default Grbl PWM pin, which on the chinese fake of Protoneer's CNC Shield, is Z Endstop (If you bought the official CNC Shield from Protoneer it would have been labelled correctly)
     
    #10 Peter Van Der Walt, May 12, 2020
  11. Steven Busch

    Steven Busch New
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    Just tested it. Brilliant!
    Thanks.
    I may have some questions about calibrating. At the moment, the steppers are spinning like mad for even short distances. I think that I need to put some jumpers onto the stepper drivers to force micro-stepping. I will also need to calibrate for belt driven carriage rather than screw driven.
    Thanks again for the help.
    Steve
     
    #11 Steven Busch, May 12, 2020
  12. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Yes, you want 1/8th microstep (do that first)
    Set steps per mm using the calculator buttons in Grbl Settings next to $100-102 initially
    Then fine tune using Wizards and Tools > Calibrate X/Y respectively
     
    #12 Peter Van Der Walt, May 12, 2020
  13. Steven Busch

    Steven Busch New
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    One other thing. Bottom right of GCode app says that it can't connect to the Control app. Do I need to install drivers?
    I was able to export GCode and run it successfully.
     
    #13 Steven Busch, May 12, 2020
  14. Steven Busch

    Steven Busch New
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    The stepper drivers can go up to 1/32. Is that useful for better resolution?
    Pololu DRV8825 Stepper Driver configuration:
    MODE0 MODE1 MODE2 Microstep Resolution
    Low Low Low Full step
    High Low Low Half step
    Low High Low 1/4 step
    High High Low 1/8 step
    Low Low High 1/16 step
    High Low High 1/32 step
    Low High High 1/32 step
    High High High 1/32 step
     
    #14 Steven Busch, May 12, 2020
  15. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    No drivers are for USB if you can connect to controller you are sorted there already

    If CAM can't connect to CONTROL its local firewall, browser version, something like that. Blocking access from browser to mymachine.openbuilds.com:3001
     
    #15 Peter Van Der Walt, May 12, 2020
  16. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    higher microstepping = lower torque
    Those little breakouts are pathetic already :) if you bump up the microstepping the motors will stall all the time. 1/8th is a good compromise.
     
    #16 Peter Van Der Walt, May 12, 2020
  17. Steven Busch

    Steven Busch New
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    Got it.

    OK. Thanks. I am very new to this hobby so a appreciate your help today. Thanks.
     
    #17 Steven Busch, May 12, 2020
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  18. Steven Busch

    Steven Busch New
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    Hi again, I've finished building the OpenBuilds mechanical parts. I am trying to figure out the limit switches. I have the Arduino CNC Shield. Do you know if the limit switches should be normally open or closed? There are 2 pins on the shield and 3 on my limit switch cable. On the cable, normally open are the 2 outer wires. Normally closed is middle and one of the outer.
    Thanks for any help you can suggest.

    Kind regards,
    Steven
     
    #18 Steven Busch, May 29, 2020
  19. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Checkout gnea/grbl
     
    #19 Peter Van Der Walt, May 29, 2020
  20. Steven Busch

    Steven Busch New
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    That's good. Thanks. I'll use normally closed. Do I have to change anything in the Openbuilds software, or on the Arduino CNC shield to tell it that my switches are normally closed?

    Thanks for yoiur help.

    Steven
     
    #20 Steven Busch, May 29, 2020
  21. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    That Grbl Wiki is a must-read (;

    gnea/grbl
     
    #21 Peter Van Der Walt, May 29, 2020
  22. Steven Busch

    Steven Busch New
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    Yes, I tried that but it does't seem to work.
    I changed the following in the Openbuilds control 'Settings' panel
    First I set $21 Hard limits enable to Enable the limit switches.
    Then I set $5 to Invert the limit pins.
     
    #22 Steven Busch, May 29, 2020
  23. Steven Busch

    Steven Busch New
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    I've switched them to normally open and things are working. Your link does suggest that NC is safer though.
     
    #23 Steven Busch, May 29, 2020
  24. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Did you remember to reset/reboot the board after so it comes up with the settings
     
    #24 Peter Van Der Walt, May 29, 2020
  25. Steven Busch

    Steven Busch New
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    I think I found a clue. After I set $5 to Invert the limit pins I ttested the following:

    If I trigger one switch, say X- while a program is running, the program continues to run. But if I manually trigger X- and X+ the program stops and I get the alarm mesage.

    I believe I read about wiring the switches in parallel vs serial, but I don't think I can change this on the CNC shield.

    I hope this made sense, and thanks for your advice.

    Steven
     
    #25 Steven Busch, May 29, 2020
  26. Steven Busch

    Steven Busch New
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    Got it!
    I put both X switches in series and pluged into just X- on the shield.
    Now when I trigger either switch it causes GRBL alarm.
     
    #26 Steven Busch, May 29, 2020
  27. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Parallel for 2x normally open, series for 2xnormally closed
     
    #27 Peter Van Der Walt, May 29, 2020
  28. Joe Dun...

    Joe Dun... New
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    I will mention that I saw a commercial product, that was designed like this, back in the later 1980's, or perhaps early 1990's. If I recall correctly, it was around $800 at the time, while standard pen plotters were around $2,500. I was surprised that it was apparently a commercial failure, as I never saw that type of plotter again until now. There is no question that this sort of potter is not as precise as other types. There is more wiggle to the system, which introduces error. But, historically, high precision was an important feature of a plotter, since you would manually measure things on the paper, using a ruler. Nowadays, the drawing almost certainly was done in a CAD program, where you would go to obtain your measurement. So, precision is not as important now.

    Now for something useful. When you go vertical for plotter, remember that you need pressure on the pen. Depending on the weight, and its distribution. that may be an issue. However, if necessary, I think it could be easily fixed by having a place were you could insert a weight on the end of a stick. Perhaps 8oz of weight on a 10" long stick, that you place near the pen holder, so that it protrudes away from your whiteboard. This would help shift the center of gravity away from your whiteboard, so that it tends to hang with more weight on the pen.

    I realize that you are well on your way with the project. But, if viable, I would request that you avoid the temptation to use the 80/20 style of aluminum extrusions... at least for the long axis. These weigh more and cost a lot more than something like plain aluminum square tubing. Here is below a link to a guy who made a different style of plotter, but manages to only use aluminum angle, available at Home Depot. Though, aluminum angle is much more prone to twisting than tubing, and Home Depot is not that cheap of a source. Another potential materiel for the long rail is electrical conduit, since it is cheaper and available as long as 10ft.


    -Joe
     
    #28 Joe Dun..., Jun 9, 2020
    Last edited: Jun 9, 2020
  29. Steven Busch

    Steven Busch New
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    Thanks. I've actually just finished building it with 2040 v-slot. It is a smaller version which sits on my worktop at about 2m x 1m. I am redesigning the pen mechanism, but overall things are looking good. I may have to add a second X rail if there is too much wiggle but I haven't tested it with a large drawing yet. Thank s for your ideas though.
    Regards,
    Steven
     
    #29 Steven Busch, Jun 9, 2020
  30. Steven Busch

    Steven Busch New
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    When opening an svg drawing, does anyone know why I am getting "Generating, please wait... for ages? upload_2020-6-15_10-47-12.png
     
    #30 Steven Busch, Jun 15, 2020
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