Archive | July, 2014

Project: Makeblock 3D printer

13 Jul

Project: Makeblock 3D printer

Up until now I've had two 3D printers. My first one was the Ultimaker Original and it now has more than 4000 hours of printing behind it. An incredibly solid machine! The next printer was the Printerbot Jr that my son put together. I haven't seen much of it as he's more or less confiscated it, but it's been a great investment into making him try out some real engineering.

The Ultimaker Original is probably the best Open Source 3D printer available today. Now I've built a third printer from scratch, using the Makeblock aluminium extrusions that I've become quite fond of. You can find the build log here, but why did I want to make a new printer?

Makeblock advantage

When you are making a printer based on Makeblock it is really easy to adjust the design as you go. It's also easy to add new elements when you need it. Not only that. When I at some point retire the printer, I can re-use all the Makeblock parts for something else! Makeblock was started as a Kickstarter and they really listen to their customers.

Less hassle!

The single thing that takes the most time for Ultimaker owners is clearing out blockages. They don't happen if you're careful, but every now and then you'll forget turning off the extruder and the heat'll sneak up the pipe to cause a block. When blocks happen this far up in the extruder, it'll take 10-15 minutes to clean it out. The new all-metal hotend from e3d & extruder design solves this completely and changing filament is done in a snap. Over all, I'm REALLY happy with this!

Polulu DRV8825 FTW!

I'm using original Polulu DRV8825 stepper drivers. This gives me 1/32 stepping that is noticeably more silent than the typical A4988 drivers with 1/16 stepping. These are also more powerful, but in reality I'm not using that advantage. If you have a noisy printer, be sure to check this video for a comparison. They're a direct replacement for 4988's on most Reprap hardware, so odd are they'll make your printer more silent too.

More space

The new printer has a bigger print area (31 x 31 x 34 cm). This was one of the goals of the printer and I'm very happy that I managed to go even a little bigger than anticipated. For comparison - it's 32600 cm2 are more than 4 times the volume of the Ultimaker (7700 cm2). It makes levelling the bed a little harder, but it's totally worth it just to have the ability to print larger objects.

More materials

I've changed the design to a Direct Drive Extruder that takes up less space than the original design. This allows a second extruder to be added at a later time. A Direct Drive Extruder it has one major advantage over Bowden-based systems: it supports virtually all the materials I want to experiment with. Flexible plastics, nylon, wood, clay, bronzefill and more. The current setup allows the extruder to go to 300C. With modifications, I can go all the way up to 400C if I want to.

Flexible

Using Makeblock makes the entire design flexible, but the compact extruder design itself is also quite flexible. One addition I'm working on is adding Dual extrusion as in this video. It's the best approach to dual extruders I've seen to date, so expect an update when I get this working! The design allows me to easily swap out the print head fairly easily so I can play around with extruding chocolate and other fun materials.

So - all in all I'm very happy with the printer! All issues are now resolved, so the design phase is complete. Only minor tweaks remain & the BOM is now online at reprap.org. For now the page contains links to resources & the bill of materials, but I'll also add build instructions to it later.

But - I've got more plans! My Ultimaker with 4000 hours of printing on it's back will soon move to Bitraf and in November I'll (hopefully) receive my first SLA-printer - the Titan 1!

Project: wifi-enabled RGB LED displays

08 Jul

Project: wifi-enabled RGB LED displays

Every now and then there's a project you can't say no to and this was one of them. Finn.no is sort of Norway's version of Craigslist, a big online market where you can sell just about anything. As a marketing stunt, they opened a physical store downtown Oslo. I was called in via some friends in the agency that handled the project and they needed lots of things quickly. Since I was fully booked, I couldn't say yes to all the projects suggested so I passed some of them to my friend Thomas Winther who did a great job making an in-store Selfie-app using Unity & LeapMotion.

In the store they needed a way to show information from the finn.no website and this was the job I couldn't say no to. Apparently it isn't very easy to get hold of a wifi-enabled LED display that can pull data from the web? Also - most commercially available displays are small, monochrome and use tiny LEDs so they're not that visible when mounted high up on a wall. The agency wanted 5 large displays, perferably with more than one color display. Having recently read about Teensy 3.1 and the OctoWS library I promptly said I'd do it!

The Teensy microcontroller is a great alternative to using Arduino's in installations. It has a really fast ARM processor and lots of RAM, but it is still 99% Arduino compatible. This means that pretty much all Arduino code will run on it, but at blazing speeds. After installing a little extra software, you can use the normal Arduino IDE to program it, so it's really an "Arduino compatible". It's so compatible (and affordable @ $20!) that I feel that this is really the path that the Arduino Team should have taken instead of making bigger and more complex boards. Here's how the Teensy 3.1 looks next to an Arduino Nano. It's soo tiny that the Nano looks big!

For the parts, I could have saved some money by picking it up from different places, but I didn't have much time. I picked up tons of Neopixels & Teensy's from Adafruit since they'd ship the parts so I had them within a week. Buying parts from Adafruit really makes a difference since the whole process is completely trouble free. It's a little more expensive, but worth every dollar.

This is how the test-display looked when running the rainbow sketch:

Lovely, isn't it? You can see the neopixel strips lying in front. I stuck these to the back plate using the same clear silicone that I used to fix the panel to the front. The first test showed that we'd have to compensate a little for every 50cm as the neopixels are put together of 50cm segments and loose a few mm in the overlap between these.

Thanks to Jens Dyvik at Bitraf, making the wooden parts was short. Jens is really good at Rhino and CAM software, so the process from sketch to finished product was really swift. His huge Shopbot CNC'd all the lattices and backplates in one go! Nice to have good tools, right? Two things to note about the CNC'd parts:

  • When using MDF as material, make sure each protuding part has a certain minimum size or they'll break off easily.
  • Research carefully what kinds of silicone that will remain fully transparent over time. Most clear silicones will get a yellowish tone over time. The ones that are made for aquariums appear to be the most suited ones.
  • When exposed to heat for a long time, MDF will want to "bend". Make sure you stick it down properly to avoid too much maintenance.

Soldering and gluing together the displays took quite some time, but it was made a lot easier by Paul Stoffergren releasing these neat adapter boards. I added a 2.4Ghz radio to each of these and tucked it away on the back of each display. Here's a photo showing 1920 pixels running at once. Note that the Mac to the left is on full brightness! The displays are so bright that they're visible in daylight as well.

Each sign requires quite a bit of cable and with the amount of current going through them, this was the first electronics project I've made where I've had to calculate the correct diameter of each cable. A good learning experience!

I could have built a Wifi adapter inside each of the displays and in hindsight, that would have been an easier choice if it wasn't for wifi issues. What I went for instead was a server-client solution where a single box would connect to the internet as well as serve up a webserver that could be used to control all the 5 signs. It has a Teensy 3.1 that holds a custom webserver, uses cable for internet access, has a display that shows status and the IP address of the webserver as well as a nrf24l01 radio (2.4Ghz) that sends data to the signs. This is put together in a nice 3D printed box that is wall mounted.

It's a pretty versatile solution and it works rather well. There's two drawbacks to this solution:

  • The NRF24L01 radio's are dirt cheap, but they have a limited range and are affected by other 2.4Ghz radios (bluetooth, wifi & more)
  • The Ethernet library for Arduino is a synchronous API. When the device fetches data from the internet, it'll freeze a short while until the data is received.

None of those issues are big problems, but they're worth noting if you are building something similar. Initially I planned to use a Raspberry Pi to be the webserver, but it turned out to be really hard to make the NRF24 radios work reliably with GPIO on the Pi. I've since noticed that the NRF24 dislikes fast CPUs, so if you're trying to make this readio work on the Pi, make sure to add a delay to your main loop. The Teensy 3.1 is also too fast for this radio.

The final result is that you can use any device such as your phone to control what is displayed on each of the signs. I've also built some remote admin to it as well. Every time the displays power up they'll await instructions from the server. The server fetches API data such as how many tractors are for sale or what are the latest boats available, and sends this to the displays. It's super flexible and a true IOT solution.

Disregarding some (serious) mounting issues beyond my control, I really loved solving this project and you can check it out if you're in Oslo. 

Postnote

After making this, my wife said that I should start making and selling these commercially. It's probably a good idea, but I really can't see myself selling LED signage. However - if you have some weird project in the Internet of Things domain - feel free to contact me. I love a good challenge!

 

 

Summertime

07 Jul

Summertime

I really love those squeezed-in weeks of work in between family holidays. It's a rare time to catch up on thing like blogging, reading & updating a few personal projects. I just finished reading The Martian by Andy Weir that I got recommended from @hpeikemo. It's a really thrilling book that I'm sure we'll see as a hollywood movie soon. The story is kind of a "Robinson Crusoe meets McGyver on Mars". After reading it, I gave it to my son who completed it in just two and a half day. Great summer read!

I finally got around to update my Arduino Companion app. It's ratings have suffered quite a bit since Android 4.4 is now pretty common and it took Adobe a LOT of time to fix the bugs. When the fix finally was available, I was stuck with client work and didn't manage to set aside the two days required to fix it. I can only apologise that it took this long.

It sucks to loose the 4.6+ rating on Android, especially since it's mainly due to ppl like Nicholas Castle that wrote the 1-star review to the right. I don't mind a 1-star review that says that the app does not work (when it does not), but this is kind of harsh from someone that hasn't even seen the app? It's not like he paid anything (it's a free app) or that I have a 100 person customer service department. I make the app on my spare time, I give it away and my email is listed below the app. Oh well. I guess I'll rather thank users such as John, Daniël, Luiz, Thomas, Tim, Bryce, Samantha and many others for nice and polite feedback with reminders to fix the problems. As soon as Apple approves the app, the more than 105.000 iOS users of the app can download the update to version 1.2. The more than 102.000 Android users can get it today. More than 200K happy users… Crazy isn't it? grin

The months since December is sort of a blur as I've done more client work than I usually do. The most fun commercial projects this autumn was building a series of custom wifi-enabled LED signs as well as working with UNO. After summer I'm really looking forward to teaching another half-year of Embedded Systems at NITH here in Oslo. There is something really special about seeing computer science students actually understanding the core operations that enable the computers they use every day. It's all just one's and zero's, but you don't really get it until you have to create the bits yourself by turning power on/off at the right intervals… The students were really happy with the course last year and I have plans to make it even more fun this year!

Since I've worked long days, I haven't had that much time for my hobbies but I've gotten quite far on building a X/Y robot that I have plans to complete before going to the Maker Faire in Trondheim in August. It'll be able to draw, print and probably also do some light CNC'ing when I'm finished.

Just before the summer holidays I managed to squeeze in two weeks to build a brand new 3D printer from scratch using Makeblock! This new printer will have a bigger build envelope, but it will also be able to use flexible plastics, nylon, wood and bronze materials thanks to it's construction. Read more about all the advantages here. With that you would think that this fills my appetite for 3D printers, right? Not quite. I spent my tax return on signing up for the Titan 1 SLA printer as well. It'll give me extremely high resolution models as well as solve my problem of printing parts over night without disturbing the family. That said - the Makeblock-based printer is much more silent than my Ultimaker. Looking forward to November & meeting the Titan!