Multicolor DrawBot
Introduction: Multicolor DrawBot
I have seen many versions of the COREXY Drawbots and almost no one has enabled "Homing" function for them, even though the design already had space to fit limit switches. Today, I'd like to share how a CoreXY Drawbot can draw colorful shapes or texts by enabling its "Homing" function.
Step 1: Supplies
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Main materials:
⦾ 1set x 3D printed parts, available at: https://www.thingiverse.com/thing:2349232/files
⦾ 1pcs x Arduino UNO R3 or Combo Arduino + CNCShield + A4988.
⦾ 1pcs x Arduino CNC Shield V3 GRBL.
⦾ 2pcs x Stepper Motor Driver A4988.
⦾ 2pcs x Stepper motor NEMA 17.
⦾ 1pcs x SG90 Servo.
⦾ 2meter x GT2 6mm Timing Belt.
⦾ 2pcs x GT2 Timing Pulley 16 Teeth.
⦾ 2pcs x Round Shaft Diameter 8mm, Length 500mm.
⦾ 2pcs x Round Shaft Diameter 8mm, Length 400mm.
⦾ 2pcs x Linear rod M3 x 75mm, Z Axis. 1000
I reused these rods from old CDROMs.
⦾ 8pcs x LM8UU linear bearings.
⦾ 5pcs x Bearing 624zz.
⦾ 1pcs x M8-L530mm threaded rod and 4pcs x M8 nuts.
⦾ 1pcs x Power Supply 12/24VDC.
⦾ 2 meter x 8P/16P Rainbow Ribbon Cable.
⦾ 2pcs x Limit switches.
⦾ 1pcs x 5mm DC Female Power Plug.
⦾ 1pcs x Multicolor pen.
⦾ 2 meter x copper braided shield.
⦾ Some small cable ties, cable spiral wrap, M3 - M4 bolts and nuts.
Step 2: 3D Printed Parts and Pre-assembly
⦾ X supports
⦾ Top and bottom clamshells
⦾ Y front and back supports
⦾ Slider base
⦾ Slider and pen holder
⦾ Idle pulley and thumb screw
⦾ Arduino case
Step 3: Assembly
Detailed assembly instructions are included in the Thingiverse link. I only mention the parts that need attention, especially how to install limit switches.
⦾ X limit switches
I firstly measured the distance from 2 x limit switches located on the X supports to Arduino box, then soldered their wires accordingly.
The limit switches should be mounted on the X supports before installing stepper motors.
I reused 2 old stepper motors which have short shafts, about 12mm so that limit switches can be mounted easily on the stepper motors head side without touching each other.
⦾ Clamshell (Y) limit switch
As above, the limit switch should be mounted on the top clamshell before assembling the top and bottom clamshell together.
Its cable is threaded through a rectangular hole available on the clamshell.
⦾ Pen holder
I printed 2 types of pen holders, one is for regular pen and the other is bigger for multi-color (multi-nib) pen.
I use one of my daughter's multicolored pens. It is about 22mm in diameter.
Step 4: Cable Arrangement
I used a copper braided shield taken from a multi-cores control cable to cover all the drawbot's cables.
The cables of stepper motor, limit switch far away from control box and M8 bolt were all threaded into copper braided shield.
The servo and Y axis limit switch were also done in same way.
It looks pretty cool in the end!!!
Step 5: Connections
My Drawbot cable connection is show as below:
Notes:
* We can use 2 limit switches for X- and Y-, it is good enough for a drawbot.
* If the limit switch wire is placed too close to the stepper motor wire, it can cause interference and give an incorrect stop signal.
Step 6: GRBL Firmware
a. 1000