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Upgrade for your DIY plotters

Make better use of all your CNC plotter projects with cross hatching

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Many of you have built a little CNC plotter from scrap parts. I know because I've seen countless examples on Youtube. But once you draw a few line images, some hollow text, and perhaps some rasterized black and white pictures, the machine gathers dust on ye olde projects of yore shelf until it's dismembered for parts.
But wait! What if you could draw greyscale images? What if you could draw in color?
How? you ask. The answer is cross hatching my friend. And I shall give it to you.

What this project consists of:

Software(for you):

  • Takes an image(svg, png, or both at the same time!) and generates a set of cross hatches as well as any paths from the svg file if desired. (see pictures in the gallery to the left)
  • Hatch parameters such as number of levels, spacing, angles, thresholds, etc. are all easy to adjust.
  • The image is then output as a set of tool paths for your plotter. It speaks directly to your controller via a serial connection.
  • Color images can be made using red, blue and yellow hatch directions.
  • Flip book style animations can be generated from gif files.
  • And more... still coming up with ideas.

Hardware(for me... and you I guess):

  • A mini pen plotter built from DVD drive mechanisms. It's an easy and free way to play around with it.
  • Uses Arduino, some H-bridge chips, maybe a servo.
  • Might include an automatically feeding paper source(roll of receipt paper) for continuous drawing fun.
  • Easily set up to make flip book animations like you've never seen.

Why this project matters: It provides the hacker community with a tool to get more out of their cnc drawing creations. On a greater scale, it may inspire more beginners to jump into the hardware making world by making simple cnc plotter projects much more fun and rewarding. And since everything will be open source with no restrictions, anyone can build upon this and make it their own.

MiniPlotter.ino

Arduino code for the small plotter used for testing.

ino - 9.71 kB - 10/14/2017 at 13:28

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HatchPlotter.zip

Contains processing sketch and two example picture files

x-zip-compressed - 36.08 kB - 04/10/2017 at 12:42

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  • log 4: challenges and lessons

    shlonkin6 days ago 0 comments

    Way back I mentioned making this thing speak gcode, which would greatly improve its usefulness for the masses. I tried to do it. I got stuck learning about gcode and trying to figure out the best way to make it happen. Sadly I've had to accept the fact that I just don't have time for that right now. So for now it will just speak my own custom language for transmitting instructions to the plotter. That's not such a bad thing. It has worked fine for me so far.

    Another thing I've had to accept is the limitations of this technique. I learned this lesson with my "Automate the art" project as well. The image is just not going to look as good as I want it too. With lots of tuning and way too much time spent I might end up with something OK, but then I have to ask myself "Was it worth it?" In some cases, yes. But usually not.

    I want to include something positive in this log too. I learned many things and increased my proficiency with coding and machine making. I produced a nice little plotter that works very well and can now draw crosshatched pictures that look pretty good. I also built an egg-bot type machine for drawing on balls that can make use of the same code.

    I hope that someone else is finding this project useful or educational. If so, then at least I can say it has accomplished the goal of the hackaday prize: making something that matters.

    Oh, I almost forgot. Here's the arduino code that I promised before. (See the files for this project.)

  • log 3: progress update and video

    shlonkin09/27/2017 at 12:23 0 comments

    It's been a while since my last update. I've been... busy. I made a video of the little plotter drawing some pictures with a very rough description of what's going on. Here it is.

    So, about that busyness. I finally got a 3D printer and I've been producing lots of toys for the kid, robots for me, and parts for projects. I also drew up and printed a thing like an egg-bot to draw on ping pong balls. I tried this crosshatching code with it and it worked, but the thickness of the marker combined with the tiny canvas just makes it too messy. Oh well, it was just for fun.

    As for code updates, I fixed a couple simple bugs and cleaned a bit, but it is functionally the same. I wanted to make a gcode version, but found my gcode skills are lacking, so it still makes use of the clumsy protocol for talking to an Arduino. It works fine, but is worthless unless I upload the Arduino side of the code. I'll get that up this week.

  • log2: Hardware - test plotter built

    shlonkin04/27/2017 at 14:15 0 comments

    Hardware - Keep in mind that this is not the main part of the project. It is simply an easy to make testing device for the software. Everyone and their cousin has built a little plotter out of optical drive mechanisms, so it's nothing too exciting. On the other hand, it might inspire other beginner tinkerers to make something fun using parts from their junk pile.

    Sorry, I didn't take many progress pictures, but it is pretty easy to figure out just by looking at it.

    Here's a brief overview.

    • The two metal mechanisms were taken from junk DVD drives. Don't bother with CD drives as they just have geared DC motors rather than steppers.
    • A chunk of wood was screwed to the plastic optics carriage on on drive. The second was placed perpendicular to the first and its carriage was then screwed to the wood as well. It should be as precisely perpendicular as possible.
    • Some scrap wood was cut into a hinge shape and attached to the upper drive. A pen is inserted through a hole in the moving piece of wood.
    • A servo is attached to the wood and a piece of steel wire runs from the actuating arm to the upper drive's frame.
    • The wire is bent into a simple spring to keep a light pressure between pen and paper.
    • To keep it securely in place, strong magnets are attached to the base and it sits on a steel surface. This holds the paper and the machine securely, but can simply be lifted up to move the paper.

    Tests - As you can see above, I have drawn several pictures using the crosshatching software, which by the way is the main portion of this whole project and is still in early development.

    Anyway, these pictures are all about 3x3cm which is really very small. Despite the tiny size in relation to the pen stroke resolution, I was able to get some really clear images with fine detail. I am happy. Oh, and these were made using four hatch levels/angles.

    And to show the ability to draw both vector paths(from SVG files) as well as shading, here is your favorite logo. By the way, that writing you see was just something printed on the other side of the paper.

    And while I'm at it, I like to explore the resolution and reliability of the plotter by drawing a tiny Hilbert curve.

    What's next? In the next log I should be giving you the arduino portion of the code used in the plotter as well as a schematic. Stay tuned.

  • log 1: Initial code offering and outline

    shlonkin04/10/2017 at 12:59 0 comments

    Software: As you can gather from the pictures, the basic algorithm has been implemented and it works well. But it is far from complete. Here I'll describe what I have so far and present the (probably buggy)code to you.

    An outline, in graphical format to reduce wordage.

    I hope that makes sense. If not, ask questions.

    For now the coordinates are sent to the Arduino using a protocol I made up long ago for another plotter. It is simple and works well enough, but I know that's not what you want, so I plan to make a G-code/Grbl type version to make it more useful for you. Just wait a while.

    Here's the package: HatchPlotter.zip (also found in the files section)

    It contains the Processing sketch in its current form as well as two example picture files. Just extract the HatchPlotter folder into your Processing sketch folder and run it. It should draw the example picture.

    Hardware: Those X and Y mechanisms are DVD drive assemblies. They contain small stepper motors which move the laser carriage in the usual way. The carriages, the chunks that hold the laser and optics, are attached firmly to each other so that their motion is perpendicular. One outer frame is stationary and the other is free to move in the horizontal plane. The moving one carries the pen and servo parts.

    I'm sorry for this vague text description. It will be clear once I get things put together and take pictures.

View all 4 project logs

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Jarrett wrote 03/23/2017 at 19:20 point

Following this, because, if it can also output as several 1-bit bitmaps, it should be ideal for PCBs,  too. You have 5 solid colours, no shading, like so:

https://hackaday.io/page/2852-giving-your-pcbs-a-facelift

I also wrote a converter to get bitmaps into Eagle, Altium, or CircuitMaker, so I'd definitely be curious to play around with this. In my five minutes of searching online, I couldn't find any decent pure B&W crosshatching plugins/tools.

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