Status light for our Cruise Control build server

I created a Cruise Control build server status light for the Scrum team I am in. This project contains many things I love:

• Writing a Windows application to control an Arduino over USB
• Writing Arduino code to act as remote control
• Designing and soldering a shield for the Arduino Nano to send the IR signal
• Designing and printing a 3D-printed enclosure for the project

Clearly visible status light for our Cruise Control build server

As you can see, the light is clearly visible for everybody. In Scrum this is called an 'information radiator'. I published the code and plans (check the wiki) on github:
https://github.com/robertmoro/MagicLightingRemote

Disable Automatic Reboot After Windows Update

I was installing a new computer that I also use to control my 3D-printer. Besides installing the software to control my 3D-printer, I remembered one special Windows setting I had to take care of: disable automatic reboot after windows update. I leaned this setting the hard way. One evening I started a long running 3D-print. The next morning I found out that my 3D-printer stopped halfway because the computer had rebooted.

Honey, I Shrunk the Kids - how I scanned and 3D-printed my kids

The kids scanned and 3D-printed

Medio 2011 I bought a Xbox Kinect sensor and adapter. This adapter feeds power to the sensor and has a normal USB-connector to connect it to a PC.

Adapter to connect a Xbox Kinect to a PC

I did no buy it to play games with, but to play with it on the PC using the than just released Kinect SDK for Windows. At the end of 2011 I saw the Kinect Fusion presentation held at 28C3 about reconstruction of 3D surfaces using the Kinect sensor by David Kim, a PhD student from Newcastle University sponsored by Microsoft research. Since then several software products were created that did something similar. I have tried several and liked Skanect the best. It is not free software however. You can scan and recreate a model using the trail version, to save the model file you need the licensed version. To scan a model, it is better not to circle to much around it. Try to do it in one go. I thought: the more times I go around the model, the better. But that’s not how it turned out. The resulting file was big because there seemed to be a model inside the model. So, it’s best to go around the model just once.

Self portrait

I like the full body scanner rig they build at 3Dify. Hope to find the time and space to create one myself.

Align STL model to bottom plane

Sometimes I am handed a STL-file with a model rotated such that is hard to print on a FDM (Fused deposition modeling) type of 3D-printer. Like the heart in this model (created using tinkercad.com):

The model is opened in netfabb Studio Basic 4.9, which is the freeware version. For a FDM type of printer, most of the time, you want the biggest plane facing down. You can do that by performing following steps in netfabb Studio Basic:

Click the 'Align to bottom plane' button from the button bar.

Now rotate the model (right mouse button + move) such that the part you want to be facing down (the backside) is visible. Once it is visible, double click it.

Alakazam: now its back is aligned to the bottom plane. Save it by a right click on the model and select: Export part - as STL.

Retraction Lift Z

Some designs from thingiverse I could not get printed correctly. This chain always failed to print and this bangle sometimes failed.

Chain that always failed to print until I found the retraction option 'lift Z'

Also this tree frog failed from time to time, having three instead of four feet. These designs have in common that they do not have a lot of printer bed contact and that they have discontinuous layers. With discontinuous layer I mean that the design contains gaps in one layer. The solution was the retraction Lift Z option of Slic3r. This option makes the printer head jump over the gaps. It moves up on one site of the gap and moves down on the other site of the gap. With this option set to 0.5 mm I was able to print all of the above designs without any problems. You can set this option using the config.ini file or the Slic3r user interface. In the config.ini file this option is  called 'retract_lift'. You can find this option on the Slic3r userinterface on the 'Printer Settings'-tab. If you select 'Extruder 1' on the left, you find the option 'Lift Z' in the group box 'Retraction' on the right.

Filament feeder

My printer uses 3 mm filament. 1.75 mm filament is also available. A hot end can support only one diameter, so when you buy a hot end, you have to decide if you want to use 3 or 1.75 mm filament. Switching to another diameter means buying a new hot end. The filament I use is quite stiff and springy and has a strong tendency to tangle. This get worse to the end of the spool, where the diameter gets smaller and smaller. I can imagine this less of a problem if you have 1.75 mm filament. This makes feeding the filament to the printer a non trivial task. In my first setup, I had a spool with filament laying besides the printer. That was far from ideal, because I could not leave it alone. I constantly had to monitor the unwinding and every few minutes, I had to untangle the filament. It would be great, if I could start the system and leave it alone until the print is ready. In my current setup, I use a printed spool holder.

Printer and spool holder

The spool holder has bearings for optimal unwinding. To avoid tangling of the filament between the spool and the printer I use a PTFE-tube. To prevent the tube from getting pulled into the extruder, I have printed a washer which is placed at the end of the tube at the extruder. It lets the filament go through and blocks the tube from getting pulled into the extruder. Up till now I am very happy the results of this setup: now I can start a print that takes for example five hours and leave it alone until the print is ready. Mission accomplished!

Optimize (PLA) print

Update Slic3r
The first improvement in print quality was achieved by upgrading Slic3r from 0.7.1 to 0.9.8. As described in my post of last January 17.

Airflow
My first print was a glass from thingiverse. The foot printed fine. The stem was troublesome. I had to blow air (with my mouth) to get a reasonable quality.

Left blown by mouth, middle with small 40 mm fan, on the right with big fan mounted in the printer frame

When printing the stem, the nozzle keeps adding hot PLA to the same small spot without waiting for it to cool down and harden. I added a small 40 mm fan to automate my mouth blowing. When I tried the glass again with this fan in place, it turned out that the airflow of the small fan wasn't enough. See the glass in the middle on the image above. In this interview with Alessandro Ranellucci, the developer of Slic3r, I noticed that he had a fan mounted in the back of his printer frame. I took a fan scavenged from an old computer power supply and mounted it on the frame using some tie-wraps.

A fan is mounted on the printer frame using tie-wraps

I noticed that when  printing big objects (objects touch a lot of the printer bed surface), the corners will bend more when the fan is on. So for some objects you want the fan on and for others you want it off. I installed a switch to easily switch the fan on and off, depending on the object to be printed. I assume a heated bed will take care of the bending in case of printing objects that touch a lot of the printer bed surface, but for now switching off the fan works okay for me.

Finer steps
My printer has a 0.35 mm nozzle and I originally had the layer height set to 0.25 mm. You can set this value in Slic3r. I tried a value of 0.1 mm. Slic3r will do all calculations necessary to deliver the right amount of filament for the height and speed setting. The result was very smooth. Downside is the much longer print time.