RepRap Part 2 : It moves

It’s been a while since I assembled the Gen7 Electronic board and the extruder. I ordered the extruder together with the steppers from the Netherlands. The hot end v6 is a very nice design compared to the original, where you had to wrap the heating wire around the nozzle yourself. But it’s too big to fit through the hole of my wooden X-Axis sledge from the gffr kit. So, for the moment the extruder is tied to the X-sledge with a clamp.

When I assembled the electronics, I flashed the Teacup firmware onto it but I was never able to connect to it with the reprap host software on the computer. When I connected to it with a serial terminal, I saw a “0” about once a second.

Now after some months I found the time again to make some progress on my RepRap. Also ReplicatorG showed no sign of a successful connection. So I thought to be sure, I would flash the firmware again. But this time I didn’t succeed in doing so, not even with the ICS programmer. Looks like my avr suffered from a corrupted bootloader. That’s a known bug resulting from random operation during power down. Traumflug guided me through the process of flashing the bootloader on IRC. After that, flashing the firmware worked again. Traumflug also told me that neither the reprap host nor ReplicatorG are too well suited for operating with Teacup. He suggested to use printrun instead.

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My first night at a hospital

Last time I spent a night in a hospital was when I was born moren than 34 years ago. I was never looking forward to the next one.

But this weekend our son Levin hit the ground with his head really hard while playing. He cried badly, and the spot on his head that hit got swollen. We immediately went to the hospital with him. As we suspected, the doctors diagnosed a concussion, and wanted to keep him vor supervision for 24 hours. During the night he cried a couple of times, but because the nose was filled in. They woke him every hour to flash into his eyes with a torch. The next day he plays again as if nothing had happened.

So, my first night in hospital was not as bad …

Time Tracking with RFID on BORM ERP

Before I discovered what my Bifferboard really is, I almost disposed it, but now It found a new purpose. It’s a networked rfid Terminal for time tracking on our BORM ERP. I use a simple python script on the device because it’s easier to experiment on a device where I would rather not compile too much every time trying something. In fact, this is my first python project appart from looking through some scripts and changing a few lines here and there.

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Make an RFID tag with an AtTiny and a coil

When I stumbled across this blog post, I was sure I have to try this at home. I had some interest in RFID for a while, but the Proxmark was too pricy for me just to play with. So this experiment came just right.

The attiny85’s were difficult to get in Switzerland, so I ordered them from Germany along with an ISP programmer. I think it would also work with other AtTiny’s for example the 45 is available from Conrad. The hex file is just 1.7 kB, so the AtTiny45 should suffice.

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Running debian on a nas dongle [updated]

I used a nas dongle from ARP for a while to share an USB harddisk, and I always wondered about what’s inside. It’s a nifty little device that works reasonably well. It needed a reboot from time to time, and it had some issues with the filesystem. Because of the FAT filesystem it couldn’t store large files, but what I missed most was ssh. Not ssh itself, but scp, sftp and rsync. I knew that without further information it would be impossible to add these. But so far I couldn’t find out anything on the internet. Then somehow I found a blog post with a device that looked similar from the outside but was sold more like a hacker device. So I went to figure out if it’s the same. It looked similar from the inside as well. So, it is probably really a bifferboard. The pins for the serial console matched, which was even more proof…

The boot messages with the stock firmware look like this:  $ minicom -b 115200 -D /dev/ttyUSB0

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Refurbishing our VW Bus camper van

Refurbishing our beloved VW Bus camper van that served us so well on our great adventure in south america was long over due. After lots of offers and some setbacks, it’s finally going to happen before the rust wins.

Last week, I spent two days tearing everything appart.Removing bumpers, windows, lights, mirrors, trims, bike and kayak carrier, fridge… Scratching on every bit of rust I could spot.

Now the pro’s will handle the rust and give it a new paint. And in two weekt, I will put everything back together. Here are some Pics of how it looks at the moment:
VW Bus torn appart

Rendering Text in WebGL

Just like OpenGL and most rendering engines that I know of, WebGL has no builtin support for text rendering. And on top of that, I can’t use the approach we use in PointLine at the moment. PointLine gets the outlines for the characters from the Windows GDI. So I was looking for something cross platform.

Searching on the internet there are two main approaches:

  1. Render the alphabet or the word in question to an image, and then use that image to texture some triangles.
  2. Trace the outlines of the characters and triangulate the polygons.

Although I prefer the second approach, I found an example of the first that looked simple enough on nehe. It was based on FreeType and for OpenGL.  I started converting it to WebGL, but it was not as easy as it looked. It makes heavy use of display lists which are not available in WebGL.

So I looked further, and found the FTGL library which is also based on FreeType. It sounded like just what I need, but for OpenGL. So, I extended the library to allow me to extract the triangles for processing in WebGL. I sent my patch to the FTGL developers and hope for inclusion.

Meanwhile I can render texts in WebGL with my modified version of FTGL …  of course it’s only so easy to do when using Wt::WGLWidget from the excellent witty library.

Here is my research prototype which now has text.

Here are the important parts of how it’s done with the modified libftgl:

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Is Windows 7 based on MS DOS?

Yesterday I copied an InstallAware Project on the Jenkins continuous integration server. The copy always failed to build while the original succeeded. They were really the same at this point, so WTF!!!

In the InstallAware forum I found out that the path name was getting too long. Well, yes, the name of the copied jenkins project was slightly longer and thus the resulting path had some more characters.

In the installaware forum they say that Windows still has a limit of 256 character for absolute paths. According to Wikipedia, the limitation doesn’t come from the filesystem. So it must be somewhere in the OS. Now, Microsoft told us that WindowsNT which Windows7 is based on, was no longer based on MS DOS. Were they lying? I mean, this is a 64 bit operating system with limitations from its 16 bit pre-pre-pre-pre-predecessor….

A co worker ran into the same limitation lately when trying to copy a folder structure from linux to Windows.

Helicopter flight around the Jungfrau

For my last birthday I got a helicopter flight, and now I wanted to make that flight before the gift certificate expires.Takeoff was in Gstegwiler near Interlaken, from where we slowly ascended passing the Männlichen to the Eiger north face. The ascend was with a constant 4 m/s climb rate, and I was not too impressed, as I flew around this area a couple of times with the paraglider. When we hovered in front of the north wall, I remembered how such a helicopter pushed me away from the wall some seven years ago. Paragliders have priority, as we’re less manouverable. It was strange for me to approach the wall head on, and then just hover. With regular aircraft that need the forward velocity (such as a paraglider) you can’t do that. When we climbed higher it got more interesting. Lots of new terrain. We saw some very interestingly built refuges. And of course the famous Jungfrau Joch from a new perspective. Also the glaciers towards the Wallis were very impressive. We flew very close to some rock walls and some glaciers. As we left the glaciers and descended along Mürren and Wengen, it felt like routine again as I’ve seen this landscape from the air a couple of times before.

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The livetracking didn’t work so well.

PointLineWeb research prototype

Google employees can spend 20% of their working time for their own projects. We at cubx (The CAD development department recently split from BORM) have now something similar. We get to spend every second friday afternoon for some projects of our own. The only restriction is that it has to do with computer graphics.

I chose a project that I had in mind for almost as long as I have been working for BORM. I wanted to run PointLine as a web service on a linux box. Wit the old core, that was so tightly tied to MFC, this would have been impossible. But the new unfinished core is designed to be platform independent. So, I took it as a base.

Some three years ago, I looked at vrml and x3d for the 3d in browser part. These standards didn’t have as broad support as I thought. You couldn’t do much without buying proprietary browser plugins. So I never made much progress on that. But then came WebGL. All mayor Browsers support it natively, and on top  of that, my favourite web application framework recently got a WebGl widget.

So far, my research prototype doesn’t do much, but I already learned a lot that I can also use in my everyday work. I gained a better understanding of rendering pipelines, learned about shaders and ray picking …

As a side project, I set up a jenkins continous integration server that compiles the project on ubuntu and windows after every commit. Additionally, I learned about CPack, so that the result of the jenkins build is a binary deb package ready to install.

You can see the web application as it progresses here:

http://webglcad.ulrichard.ch

Usually, I would also provide a link to the sources, but this is closed source, sorry…