A cool Lego CNC testing pattern

I was doing some tweaking of my Lego CNC’s motor power and I managed to print out this half decent test grid. It took a few minutes. I’ve really got to make this thing beefy enough for a drill….

That's a 50c Australian coin for scale.

That's a 50c Australian coin for scale.


Making Christmas cards with a Lego Robot

Ho, ho, ho, merry christmas!

It appears the festive time of year has crept up on us again bringing with it much joy and panic. Panic about procrastinating to buy presents until Christmas Eve. Which is someone what of a tradition in my family. Christmas is not only a time for panic and running around shopping centres madly in a fit consumerism, it is also a time for us who enjoy making stuff to show our skills by indulging in some festive hacking/making.

Well sadly our house is not big on christmas lights so that was pretty much out of the question as a source of electronic engineering entertainment (EEE). Besides, the world record for home christmas lights is just up the road in Forrest so I could hardly compete. It’s a solid 50mx20m mat of RGB lighting!

So with no RGB lighting fun to be had I looked around my desk and spotted my old Lego
CNC hiding in a corner. Time for some robotic christmas card decorating!

The first thing I did was cut up some paper for some test cards. I just cut sheets of A4 paper and then folded the two pieces in half. Which made nice little card sized test pieces.

Christmas cards are largely about effort. Buying a christmas card from the shop is about a 1 out of 10 in terms of effort. Making a really nice handmade card like the one’s my sister makes is about a 9 out of 10. Making one with a robot that you built yourself? I award myself a 10 because I am so modest. Even though mine will have precise pen patterns on them my sister’s will still be better. They’re amazing.

So let’s get started with some cool sharkfin patterns. Not exactly sure what they have to do with christmas but they’re easy to draw with some simple maths. Now I’m really sorry but I can’t show you the code for these drawings. Not because this is a secret closed source project. No it’s because wordpress.com doesn’t suppourt  .rcx file type uploads. The sharkfin pattern is basically go across and then back then make it a bit thinner then go across and back etc….

Early on in the printing of a sharkfin pattern.

Early on in the printing of a sharkfin pattern.

So I made some adjustments to the maths of the pattern so it printed larger and eventually I managed to print a nice upside-down sharkfin card. The merry christmas was added by me.


Do give you an idea of the scale of the machine here’s a pic showing it on y desk next to my laptop:

Stay tuned for some cardboard ones…. I’ve also got to make some more festive patterns….



X and Y Lego CNC

As you guys all know I’ve been recently working on a polar Lego CNC. A polar CNC is one where the base rotates instead of moving on standard X and Y co-ordinates. This means that they can draw incredibly accurate circular patters. And they use fewer parts as they do not require two linear movement assemblies.

The reason that I built a polar Lego CNC in the first place was that it produced amazing drawings and didn’t use as many parts as an X and Y machine. However, after a while a polar CNC becomes frustrating as it is very tricky to get it to draw say, squares or triangles. This is why an X and Y CNC is useful. It can draw any shape with little effort (with the exception of circles).

So just after finishing off the instructions and 3D models for my polar Lego CNC I set to work on building an X and Y version. Here’s a picture:

It’s features are:

  1. X and Y movement means it’s able to draw standard geometrical shapes.
  2. Low profile design means it can fit almost anywhere.
  3. Large expandable build area for a machine of it’s size. Around 10×13 cm.
  4. High print speed. Measured at 130mm/s on both axes. Don’t believe me? Please refer to yet another low-res mobile phone demo video: 
  5. High Precision. Just have a look at these pictures:
Showing the quality of the changes in direction with the pen.
Showing the quality of the changes in direction with the pen.
These were early squares before I figured out how to print gaster without having spikes on the end of lines which are caused by the recoil of the motor's auto correction.
These were early squares before I figured out how to print faster without having spikes on the end of lines which are caused by the recoil of the motor’s auto correction.
Very slowly drawn awesome square.
Very slowly drawn awesome square.

So the X and Y version is off to a good start. It’s smaller, lighter, faster but not stronger. It still needs some work to improve its structural qualities so it can print more accurately at high speeds. Then I’ll start work on the software.

Sneak peek at an X and Y Lego CNC

Just after I finished off the designs and instructions for the original Polaris Lego CNC I figured out a way to build an X and Y version. I’ll tell you more tomorrow once I’ve figured out some other things but here’s a picture to keep you happy:

More on this tomorrow.

More on this tomorrow.

Trust me, I’ll tell you more tomorrow and I’ll be taking it out to Make, Hack, Void tomorrow as well for anyone who lives in Canberra.

A lot of Lego CNC photos.

In keeping with open-hardware practices I will be publishing full build details and designs of my Lego CNC this weekend. However, a certain kid who I help with robotics is busting to build one. So I whipped out my webcam and shot as many photos as I could to help him build one. Sorry that some of them are blurry it’s just that my webcam is dodgy and I don’t have a real camera. Instead of uploading them here which would have taken forever because wordpress is very slow with media uploads I’ve uploaded them to flickr. Enjoy.


Here’s a couple of tips for the build:

  1. You’ll notice that when it’s done as per the photos the top rail is at an angle leaning forward when it doesn’t have the pen motor on it. This is to counteract the weight of the pen motor. Dodgy but it works. This will probably be fixed this weekend.
  2. Make sure the bottom screw gear thingy is strong and tight. It prints a lot better if the grey nut things are tight. Also make sure that the top gear rail is strong and tight.
  3. Use as many black pegs as you can to strengthen the beams. I didn’t have too many but the more you have the more stable the printer is so you can write more accurate programs.
  4. You’ll need a long NXT cable for the top motor. Make sure it isn’t snagging or rubbing on anything as this will affect the accuracy of the X axis.
  5. And feel free to improve it. Even now looking at the photos I can see some areas of improvement. Hint: The two diagonal beam supports could be stronger.
  6. And if you need more photos I’m happy to take them.

Another Lego CNC!

My friend conor merrigan just got his working!

It appears to use some kind of cord system to move itself but has pumped out a pretty accurate drawing so it must be good.

It’s not the same drivetrain or structure design as mine but it uses the same concept of an X axis and a spinning platform.

Now another 5000 people need to build them and It’ll be as famous as Makerbot!

I’m not going to be able to write any proper blog posts this week because I’m in exams. Sorry. I’ll be able to write heaps come this weekend.