Drawing Machine

cnc
lasercut
drawing
microcontrollers
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(Mike Kelly) #1

I’ve been working on this on and off for a while and I managed to make my first drawings with it recently.
It’s alive :slight_smile:

I wanted to have a self-contained box design with a moving pen. I’ve seen other plotters where the platen moves on one of the dimensions under the pen, or where a stepper motor is mounted above the drawing surface, but I wanted everything to be tucked away inside as much as possible. Maybe not the best engineering decision, but IMO it looks good.

For each axis there is a lead screw on one side only - I should probably have a lead screw on both sides and join them with a belt. I think that would improve accuracy.

So there are two stepper motors inside, and a servo motor for moving the pen up and down, all controlled by Arduino running CNC software. The wooden supports for the rods run along the x and y axis on cheap linear rails. (I started with some adapted drawer runners at first…)

I have a temporary pen holder tube for now until I get hold of a 3D printer to make a proper one. I also need to print a rack and pinion for the pen lifting mechanism as the current one doesn’t fit my servo properly so it works a bit inconsistently at times. Actually I will redesign the whole wooden pen mount to be smaller as at the moment some of the end-stop switches can’t be reached, as the pen mount is too big and will crash before the rod supports can reach the end of their travel.

TODO:
Move the electronics inside the box
Add hardware controls
Redesign pen mount and pen holder
Print or find better rack and pinion for pen up/down

Then once it is reliable and making good 1:1 drawings I will be using it for some more interesting experimental outputs.


The ply parts were laser cut at the space


Pen mount with servo, designed in Fusion360


Inside, one of the stepper motors and lead screw


Tiltable pen position with wing nut


Servo


Inside the box again


Controller gubbins


You can just about see two of the end switches here


First test


Second test

I should make the obligatory time-lapse movie too, to show it in action.


(Benjamin Hobson) #2

Looks delightful! Pop a time-lapse on! Where is the ‘original drawing’ - can it copy a scan or is it vector or something?


(Mike Kelly) #3

Thanks, yes it needs gcode format which is for CNC machines. So you need to convert an SVG or other vector format file into gcode. The first test above was from a vector graphic, the second from a photo which had been vectorized.


(Dermot Jones) #4

Interesting stuff!

The fact that it runs G-code opens up a lot of possibilities if you wanted to get experimental: different pressure, speed of line…


(Mike Kelly) #5

True! I’m not really using the z-axis control at all at the moment, just setting the servo between two points, up or down, using a spare pin on the arduino. That is adjustable though, and the z-axis lines in the gcode could possibly be adapted to control the servo.
Other possibilities are having controllable pen tilt and pen switching for multiple colours and textures.


(Mike Kelly) #6

Can you guess what it is yet?

P.S. It’s a 6 and a half minute video, running mostly at 8 x speed. So the original took about 50 mins. Pretty slow for now.


(laurent_muchacho) #7

Saw this in the lobby at work. Thought it relate


(Mike Kelly) #8

That’s a neat little thing!
I managed to improve the accuracy of my machine, mainly by tightening up the moving parts in the pen holder and servo up-down mechanism. Here’s some font rendering for example:

Now I’m designing version 0.2, this time with a smaller pen holder and pulley-connected lead screws.


(Mike Kelly) #9

Vectorizing photographs gives a distinctive look which I like, with lots of small lines and dots. These can take quite a few hours to draw.


(Mike Kelly) #10

I made an instagram account for this project: