gagalabs

New Lamp for the Living Room

Finally finished the lamp for my living room. It consists of 45 identical paper pieces (white on the outside, golden on the inside) which I cut with a laser cutter at the FabLab Munich.

See the full gallery on Posterous

The photos show the lamp with the light turned on and off.

Programming the ATtiny2313 with the Arduino IDE

The guys at High-Low Tech found a neat way to use the Arduino programming environment with small AVR microcontrollers, namely the ATtiny44/5 and 84/5. This is a great alternative to a full Arduino board for simple projects, because they are cheap and small.

I wondered if the approach could also be used for the slightly larger/more powerful ATtiny2313. And as it turns out it is not only possible, it also has been done already. Oh wonders of the Internets!

Florian Schäfer has made the effort and it works wonderfully. Just follow the instructions from the High-Low Tech page but use these files (here in a zip) instead of the original ones.

The pin mapping of the ATtiny2313 looks like this:

ATtiny2313
                  +-\/-+
            PA2  1|    |20  VCC
 RX   (D 0) PD0  2|    |19  PB7 (D 16)
 TX   (D 1) PD1  3|    |18  PB6 (D 15)
      (D 2) PA1  4|    |17  PB5 (D 14)
      (D 3) PA0  5|    |16  PB4 (D 13)*
 INT0 (D 4) PD2  6|    |15  PB3 (D 12)*
 INT1 (D 5) PD3  7|    |14  PB2 (D 11)*
      (D 6) PD4  8|    |13  PB1 (D 10)
     *(D 7) PD5  9|    |12  PB0 (D 9)
            GND 10|    |11  PD6 (D 8)
                  +----+

 * indicates PWM port

Laser-Cut “Frabjous”

“Frabjous” is a scupture by Georg Hart. It’s made of 30 identical S-shaped pieces. Some time ago I did a paper version of it, but always wanted to do a laser cut wooden one.

Finally I got around doing it. Contrary to the original, my pieces are self-interlocking, so no glue is needed.

See the full gallery on Posterous

You can get the design files here on thingiverse.

Create 3D models from photos: A quick test of Autodesk Labs’ Photofly

Project Photofly is a program and a web service, which lets you convert a series of photos of an object into a 3D mesh.

I gave it a quick test.

I made around 50 photos of a small double headed figure (around 20 cm high) and used the tool to create a 3D mesh from it.

This is the result:

Here is one of the photos:

I’m really surprised how easy it was. After reviewing the photos (and rejecting a couple of them becouse they were too dark) I just imported them into the Autodesk tool. The photos get uploaded into the cloud and after a short while the result can be downloaded. And the result was great! I didn’t do any manual editing in Photofly whatsoever, the photo/camera positions where all calculated correctly. After exporting the mesh (it contains textures too, but for 3D printing I’m not interested in them) I loaded it into netfabb Studio. The mesh was pretty much complete, only one bigger hole under the chin where I didn’t provide enough info with the photos it seems. Besides that there were only smaller holes, all of which could be automatically fixed by netfabb. I just had to cut off the base and now I have a great watertight 3D model.

Really promising, given that was my very first try.

Here’s a video showing how you should take the photos:

Stencil Painting with the Help of a Laser Cutter

A small experiment to use stencils created with a laser cutter to create a painting with acrylics.

First I took a photograph and fiddled around with the color curves:

Then I ran some filters (median etc) to get rid of noisy areas. After that I created 2 layers (one for each the darker blue tones). More filtering and some manual painting made sure the stencils can be made out of them (all parts of the stencils need to be connected with no “islands” left).

The 2 layers look like this:

Then I loaded the frames into Inkscape, where I traced them to have vector outlines, which are needed for the laser cutter:

As you can see, I also added registration marks to the top corners, so that I could align the stencils correctly.

The cut stencils look like this:

I taped the stencil on a canvas and applied the first color using a small foam roller. After drying I did the same with the second stencil/color

After some manual finishing touched (e.g. white dots in the eyes) the result is this:

Look what I have found in the Ars Electronica Center: my ellipical gears!

Visited the Ars Electronica Center in Linz today. And what do I see in their FabLab? My ellipical gears!

They found it on thingiverse and printed it on their 3D printer.

Printed a Penrose Triangle. Optical illusion + 3D printed = double awesomeness!

Printed the fantastic Penrose Triangle Illusion by chylld
The illusion works even better on video:

http://www.thingiverse.com/thing:6513

First results from our CNC mill

Over at the FabLab Munich we are currently building our own CNC mill. Almost finished now.

Here is one of the first pieces done with it:

The mill is not perfect yet, but we are getting somewhere!

Modified Z Switch for the RapMan

I have upgraded my RapMan with a heated print-bed and needed a modified z switch holder (the z switch normally is mounted directly on the print bed, which is not a good idea if it is heated). I tried Laszlo’s one, it works, but I had problems with it. It is attached to one of the 3 screws the print bed is hold by. These 3 screws are equipped with a spring mechanism, allowing the print bed to back down if the print head by error tries to go down below the print bed surface.
When attaching Laszlo’s z switch holder, this spring has no effect any more. Laszlo says he doesn’t have the problem and I think the reason is that I have a RapMan version 3.1 while he has a previous version. My RapMan z stage platform has threaded holes for the 3 screws I was talking about which seem to be the reason for problem.

Anyway, I designed a different solution, where the z switch is not attached to the print-bed but to the z stage platform instead. This also makes fine-tuning the print-bed/extruder distance easier. You can do that with the 3 screws now and you get direct feedback about the new distance. Before you had to turn the distance screw at the print head and run a home sequence to get the new adjusted distance.

With this new mechanism the z switch is not pressed directly, but there is a arm which presses it. The arm reaches up where the distance regulation screw comes down during the home sequence.

Here you see my RapMan with the heated print-bed and the new z switch mechanism in the left back corner:

Here a couple of close-up photos. In case you wonder, I added a bit of duct tape because I needed a M3 screw to hold the arm and the only one I had left was a bit too short, so the duct tape holds it in place :-)

See the full gallery on Posterous

The OpenSCAD and STL files for the 2 printed parts can be found on thingiverse.

My new heated print-bed

It is already a couple of weeks since my heated print-bed from László arrived. I was busy so I didn’t find time yet to update the blog, but finally here is my experience with building and installing it.

The print-bed is made of aluminium. It’s heated from the bottom side using power resistors. The print is done on a Kapton-covered steel sheet which lies on to the of the aluminium bed and which is hold in place by powerful magents.

The bottom side has threads to attach 9 power resistors and pits where the magnets will find it place. First I covered it with Kapton tape, cut out holes for the resistors (I only used 5 in the beginning) and the magnets:

Then I added the magnets.
U/D stands for up/down for the orientation of the magnets.

László recommends to add iron bars on top of the magnets. This makes the magnetic force stronger. Neodym magents don’t stand heat that well, but short-cutting them with the iron bars also seems to improve this.
I decided to mount all 9 resistors I ordered at that point, so I added the remaining ones too:

Then I wired the resistors. For a start I was only using 6 of them, this is why the middle 3 are not conencted. Here the 3 mounting screws an the z-switch holder are already added as well.

I tested the bed in this configuration, but it was not getting hot enough. Even with all 9 resistors it hardly reached the temperature where ABS sticks to the steel sheet, which should be at about 100-110°C.

So the next step was to add heat insulation. To prepare that I added the heat-resistant insulation for the connecting wires. I chose not to wire all the resistors together but have two groups with 6 and 3 resistors to have more possibilities later.

Then I covered the bottom side with the rock wool. I also attached a thermistor to the bottom side of the bed, so there are now 5 wires coming out there.
Shouldn’t have done this in our living room really, it’s quite a mess. I’m lucky I have an understanding wife.

OK, now the bed was ready to be installed. Removed old bed, replaced it with the new one, attached the power transformer, covered the steel sheet with Kapton.
I wasn’t happy with the z-switch holder, so I replaced it with a newly designed one (more in an extra post later).

See the full gallery on Posterous

Turned out that the temperature now was ideal for printing ABS. I now always switch the print-bed on about 5 minutes before the print and leave it on for the whole print. With all 9 resistors connected (all parallel) the power transformer which comes with the kit is a bit too weak by specification. It gets a bit hot, but it works fine. I’ll probably add a fan for it later.
I didn’t measure the temperature, but the ABS sticks very well on the Kapton. I didn’t have to do anything (like sanding) to improve the adhesion.

See the full gallery on Posterous

Here’s a finshed print (lots of strings, but that’s not the fault of the print bed). I’m using the scraper which came with my RapMan to remove the steel sheet (it’s not that easy, the magnets are really strong). I added small pieces of card-board on both sides of the scraper so that I do not burn my fingers.
When the print is cooled down a bit you can remove it from the sheet.

Right now am really happy with the print bed. Its a bit costly, but it is nicely made and very flat. And it probably cannot be made cheaper really. You would have to go for a different approach like a circuit board, but I haven’t seen one which covers the full RapMan print area.I do not sand the Kapton, so the bottom faces of my prints are really nice, flat and shiny. I did not have any warping issues any more when using it.
I didn’t print really big objects yet, this is one of the next things I will test, but I do not expect problems.