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….



Holidays, Wifi routers, storms and a larger printrbot.

Well, the school year is over. Which is awesome because now I have time to muck around with electronics as much as I like. Which is great. I think you get the idea. You get more blog posts.

Our home internet recently had some issues. We recently had some large storms roll through Canberra with impressive lightning and rain battering the nation’s capital. Nothing much happened in our house except for my Mum worrying about being zapped by a wireless phone. So I watched the storm and took some photos and didn’t do much else. Here’s a great photo which was taken by a kid from school showing how big the storm was. It was taken a few minutes before it started pouring down.

Taken by Luka Vertessy. All credit to him.

Taken by Luka Vertessy. All credit to him.

Okay so there was a big storm. Big deal. Isn’t this meant to be a technology blog?

Well, a couple of days later our Wi-Fi router went haywire. Usually half an hour of unplugging and cables, pressing reset buttons or messing around with control panel settings fixes it. But not this time. Our D-Link router always displays a green power light whenever it is plugged into its 5V source. It NEVER had displayed an orange power light. It also always displayed nice little blinking network lights telling you where there is activity and where there isn’t. A few days after the storm, it displayed only an orange power light. The cables were shifted the router was shaken, the reset buttons were held and nothing would fix the router. ūüė¶

So my mum called up our internet provider (I mean, it was obvious that the router was the problem, but you know, whatever floats your boat). Well it actually turned out there was a problem with the line coming in. What I managed to gather was this:

  • All ethernet/internet cables have an amount of noise just like any current passing cable.
  • A standard noise level is under 100 something. I don’t know what the unit of measurement was.
  • Ours was above 100,000. I’m guessing that’s bad.
  • Now I’m no genius but storms generate huge amounts of electromagnetic radiation. You know how people freak out about phones giving you electromagnetic radiation? It’s like that but way, way worse. Electromagnetic radiation generates¬†noise. Hence stuffed line.
  • So our line is stuffed because of the storm.

So the guy from Grapevine (our internet provider) came and fixed the noise issue. I don’t know how but he did. Now here come’s the interesting bit. He said he had come across 3 broken D-Link routers in the past couple of days. And he reckoned they were due to storms. Logical explanation seeing as Wi-Fi routers have delicate radios etc inside of them. But why would it take a few days for the fried circuitry to die? Or was it just a co-incidence. Weird.

So today I’m going out to get a new router with my dad. For now I have to sit out in the main room listening to my grandad’s noisy cricket TV broadcast. Grooveshark is highly useful for blocking out bogan beer ads.

Now the first thing that some of you guys might be wondering is what’s going to happen to the old router? Well, I’m trying to pump out a tear-down for you guys. I might even be able to see how the storm damaged the router. But it’s not going too well. I haven’t gotten past the first set of philips screws. I’m looking for some assembly hooks but I can’t find anything. Looks like I might have to resort to a bit of dremel fun.

Coming soon...

Coming soon...

On another note…

The 3D printer saving process is going well. i have already raised $450 of a $650 goal. Which is awesome. The goal has been upgraded from $500 because printrbot has released a new larger version (20x20x20cm) of their printer for only $150 more. For more on that see here:¬†http://printrbot.com/home/2011/12/9/printrbot-plus-arrives.html¬†. I might do some work on the saving helper thing but I don’t really see the point. Well, I’ll keep you posted.


Arduino saving helper

I’ve made a new years resolution already. I know it’s a little early but I don’t really see the point in waiting till the new year to commit to something. My new years resolution is to buy a PrintrBot- the $500 DIY 3D printer. See here for more on them:¬†http://printrbot.com/¬†.



Now I’m not one of those people who can pull $500 out from the back of their couch so I’m going to have to save up for this thing. And with the school holidays beginning in a week now is the perfect time to be planning to make money. Christmas means that parents want windows washed, aunts want cars cleaned and everyone wants everything to look good. They’re willing to pay and I’m free to work as much as I like. Perfect combination.

So I’ve got a great goal and time to work for it. But something is missing. Just counting up the money on a sheet of paper lacks a certain cool factor. No, I need to do something geeky to count the money that is going towards my geeky goal. Like an Arduino money-saving helper. I know the name sounds a bit ridiculous.

The concept is pretty simple. Have a device that sits on my desk that constantly reminds me how much money I have saved. This will hopefully get me off my bum and doing some work instead of surfing the internet for the whole holidays. I had a spare LCD lying around so I decided to use that for the display bit. And as you already know, I used the trusty old Arduino platform for the computer processing.

Getting an LCD going with the Arduino is quite easy thanks to an official library included with the IDE. Here’s the official reference page for the library:¬†http://www.arduino.cc/en/Reference/LiquidCrystal¬†. The library is compatible with most off the shelf 16×2 LCDs and can be used in both 4-bit and 8-bit modes. Here’s a more in depth¬†step by step tutorial by the awesome ladyada if you’re confused:¬†http://www.ladyada.net/learn/lcd/charlcd.html¬†. Don’t worry if your LCD starts spitting out random chinese characters like mine does occasionally. That just means that it is receiving the wrong instructions¬†– usually just a loose data wire.

The next part to the money counter saving thingy is some input for adjusting the money saved. This is easily achieved using two simple switches and some resistors connected to arduino inputs. I used the pull-up resistor method for my switches. See here for more: http://www.ladyada.net/learn/arduino/lesson5.html . One switch adds money, one switch subtracts. Simple.

So we now have the 3 basic elements- arduino, LCD, and some input. The only thing left to do is to shake a little bit of programming magic over the whole thing. Now I’m not quite done with this yet for one reason – EEPROM.

What is EEPROM you ask? The EEPROM memory bit of the atmega328 arduino core chip is a bit like the hard drive in your computer. It stores things even when power is disconnected. It doesn’t disappear when the arduino is unplugged like standard variables stored in the RAM. So it’s very useful. It means you can do datalogging and other things that require memory without having to resort to fancy SD card shields. Sounds like this thing is the go for my little money thing. It does however have a downside. It is only rated for 100,000 read or write cycles. That doesn’t sound like a problem at first but an arduino can chew through that pretty fast. So it’s important to be careful about how much we use this special little EEPROM’s bits and bytes. However that’s not really an issue as I can just write to the memory whenever the figure changes. And I’m not planning on raising over 100,000 dollars. And before you Hackaday readers out there kick up a stink I know a guy proved that the EEPROM can last for a lot longer:¬†http://hackaday.com/2011/05/16/destroying-an-arduinos-eeprom/¬†.

So this is where the problem is. My little EEPROM memory is a bit erratic. I think I may have burnt it out a while ago or something. Hmmmmmm. I might use a backup battery and have a low power mode instead. This is what I’ve still got left to do:

  1. Fix memory issue.
  2. Add some more to the LCD program to make it a bit more interesting. Things like percentages and bar graphs.
  3. Implement servo control so I can have a little saving dial.
  4. Earn some money.

So that’s what I’m up to so far. Here’s a photo:

The backlight works it's just that the camera was blinded by it.

The backlight works it's just that the camera was blinded by it. Oh yeah, and that is the actual amount saved so far.

Well, I’ll keep you posted as always.


New gear and a big clean up.

Yesterday the school design department kindly gave me a Leader LBO-522 analog oscilloscope, GW GPR-150 laboratory power supply and a bucketload of useful components such as servos, 7400 series chips, capacitors, stepper motors, LEDs and a lot more. Pretty much all of the major components were in the cabinet. The cabinet also means that I finally have somewhere that I can put my components instead of just in little resealable bags. This is an amazing gift and I appreciate it greatly. Thank you CGS design department and in particular, Mr Van Zyl as well as Mrs Atkinson. Thank you so much!

Seeing as I spent most of this afternoon cleaning up my desk and installing the new test equipment and parts cabinet I didn’t have time to write anything. I really wanted to record a timelapse of the cleanup instead but my webcam software stuffed up. So I thought I’d show you this little before and after:





The oscilloscope is awesome as it allows me to see deep into how electronic devices work. It can also aid me in designing my own. Last night I was messing around with it doing things like using it as a music visualizer and looking at arduino serial data bytes. It’s a very nice old scope that works perfectly. Thanks once again.

I might write something tomorrow detailing some of the parts etc. But until then, thank you once more. This is so cool.

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.