Summary

My take on Misan's drawing machine. I made one with a grbl controller and a CNC shield and adapted Misan's parts to be 3D printed.

Please read Misan's instructions as well.

The drawing machine is a small three axis robot that controls a pen or any drawing implement over a canvas. It is a complete open source design and aims to teach the basics of robotics. Budget for one is about 80$. You will need a 3D printer. The Z stage does not use a servo, as in Misan's machine, but rather one of those cheap 28BYJ stepper motors you can find for 1.50$ on eBay.

NOTE: The photos are of the current prototype, some of the modifications to the various bits and pieces have not yet been tested.

If you have a question, first search in the Comments section. If you can't find an answer, then ask in a Comment. I will answer as fast and as much as I can.

Please, share your makes!

Print Settings

Supports:

Auto, on build plate, critical regions only.

Resolution:

0.2 mm

Infill:

15% minimum

Filament: Your favourite filament brand PLA 
 

Notes:

The Y end stops take a lot of tension from the belt. Making them as strong as possible to prevent flexing is not a bad idea. You may want to increase perimeters.

How I Designed This

This thing was made with Tinkercad. Get it here.

How-to

Grocery list

Definitely not 550US$ worth of parts...

Below are some searches on eBay that you could use for your own machine. I am not affiliated with any of the vendors that those searches may yield. Please proceed with caution on eBay.

You will need:

1 x Arduino (any cheap clone will do) with USB cable

1 x CNC shield. Look for the ones with included jumpers. It's a drag when you don't have them and you need to configure microstepping.

3 x Stepper drivers

1 x 12V power supply (the one I have is a quite beefy 12.5A, salvaged from another project)

4 x 8 mm diameter rods, any length you want (by pairs though). I used 2 x 400mm for X and 2 x 300 mm for Y (recycled from printers and scanners.) With these lengths, and the new Z stage, I get about 312(X) x 212(Y) x 23(Z) mm of workspace.

2 x X lengths of 10 mm (or 3/8") threaded rod, with associated bolts, washers and nuts

8 x LM8UU linear bearings

2 x NEMA 17 steppers

Cables and connectors

5 x smooth idler pulleys (16 teeth or 10 mm, 3 mm bore)

2 x pulleys (16 teeth, 5 mm bore) (you can also use 20 teeth with different grbl settings)

GT2 belt: to know how much you need, add your X to your Y, multiply by two and add two inches for luck

An assortment of M3 bolts in various length and their nuts

For the Z stage:

1 x 28BYJ-48 stepper motor (12V)

1 x M5 bolt to secure the pen to the Z carriage

2 x 60+ mm of 6 mm diameter rod (I got mine from an old scanner)

Model Files

If you experience difficulties with the OBJ format, go to TinkerCad here, copy the project to your account and export to STL.

Assembly

Before installing the stepper drivers on the CNC shield, install jumpers for microstepping. I installed all three jumpers on the three axis. Such precision may not be necessary for the Z axis, unless it's holding a brush and you want to control the strokes.

You may have to open the stepper to cut a trace on its PCB to disconnect the red wire (see here) and use: orange, pink, blue, yellow, in that order (blue, yellow, orange, pink should work too) Adjust the potentiometer on A4988 counter-clockwise until the motor runs but does not overheat (check this article for details).

The last model file and photograph show (hopefully) how it all fits together.

grbl

You will need to re-compile grbl to activate CoreXY control.

Before you compile, change config.h as such:

#define HOMING_CYCLE_0 (1<
#define HOMING_CYCLE_1 (1<

// and this below goes uncommented
#define COREXY

Control Software

For control, I am using CNCjs. Neat package.
I use Inkscape with Gcodetools extension to generate gcode. YMMV.

grbl Settings (YMMV)

$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=3 (status report mask:00000011)
$11=0.010 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=0 (soft limits, bool)
$21=1 (hard limits, bool)
$22=0 (homing cycle, bool)
$23=0 (homing dir invert mask:00000000)
$24=25.000 (homing feed, mm/min)
$25=500.000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=1.000 (homing pull-off, mm)
$100=96.000 (x, step/mm) or 80.000 if you used 20 teeth pulleys
$101=96.000 (y, step/mm) or 80.000 if you used 20 teeth pulleys
$102=814.000 (z, step/mm)
$110=20000.000 (x max rate, mm/min)
$111=20000.000 (y max rate, mm/min)
$112=2200.000 (z max rate, mm/min)
$120=200.000 (x accel, mm/sec^2)
$121=50.000 (y accel, mm/sec^2)
$122=200.000 (z accel, mm/sec^2)
$130=212.000 (x max travel, mm)
$131=312.000 (y max travel, mm)
$132=23.000 (z max travel, mm)

Extensions and Derivatives

For stronger Y axis ends, see Drawing Machine - thicker walls for rod fix screws by FiX2k.
For cable management see Simple tube system for the Drawing machine by Valiox.
To secure the drawing machine see Drawing machine brackets by RC-3D, and also Clamp for Drawing Machine by Floppynator.
For an alternative Z stage using LM8UU bearings see Drawing Machine, LM8UU derivative by gigl.

Thank you guys for your contributions!

This video was made by 3DMake. It shows the assembly step by step. Nice work!

Updates

20190224 Moved to new TinkerCad format

20171118 New video by 3D Make

20171112 New "Assembly" and "Extensions and Derivatives" sub-sections in the "How-to".

20160910 Alternative Z stage that uses metal LM6UU linear bearings. The bearings should snap in their receptacles. Tinkercad model is here.

20160614 New Z stage, now integrated into the Y end. Unimaginatively called "v2". Same gear, same pen holder, a bit stronger, a bit better (one less part, less screws).