Say goodbye to 3M painters tape and hello to 3D lac

I have used blue 3M painters tape on my Prusa Mendel i2 since I started 3D-printing in 2012. I could use the tape it for more than one print. Removing some prints would damage the tape, and then I had to replace some of it. The cons: the underside is not complete flat, and big objects still had warping on the edges. Note that my 3D-printer does not have a heated printer bed. On the edges the tape would stick to the object, but is tape is lifted from the bed. With the 3D lac the underside is completely flat and the warping is gone. And the printer still does not have a heated bed. An advantage of the headed bed would be easier object removal: after the bed and the object cools down, it comes of easily.

Investigating the cause of failing hour long running 3D-prints

Short running and small 3D-prints have never caused any problems on my Prusa Mendel i2 RepRap 3D-printer. On the other hand, bigger, hours long running 3D-prints often fail. Figure 1 shows the profile of a model that failed initially. The object is 10 cm wide and 3.5 cm high. Figure 2 shows the failed print.

Figure 1: profile of the printed object. It is about 10 cm wide and 3.5 cm high

Figure 2: failed 3D-print

As you can see, the top of the object is not closed. You can see that the printer had trouble extruding the filament. In the end, extrusion totally stopped because the hobbed bolt had eaten into the filament. My first thought was that a dirt particle had obstructed the nozzle. As the print is not finished, you can see the honeycomb infill inside the object.

Figure 3: filament of failed 3D-print

Figure 3 shows the filament used for this print. The hole is the point at which the hobbed bolt had eaten into the filament. If you look close, you can see marks of its teeth on the left side of the hole. To clean the extruder, I heated it and then tried to push some filament through the nozzle. That worked without any problem! I did not expect that to work, if there was no dirt in the nozzle, what could have caused the hobbed bolt to eat into the filament? 

Figure 4: tightening these bolts on the extruder fixed my problem

When I looking closer at the failed print at figure 2, I noticed that the print did not stop at once, but that it had trouble extruding for some time. That led me to the idea to tighten the bolts that push the filament against the hobbed bolt. See figure 4.

Figure 5: successful 3D-print after tightening the screws on the extruder

Tightening the bolts that push the filament against the hobbed bolt solved the problem my printer had for a long time.

Gas fireplace repair

Our Barbas Sirocco 350 gas fireplace

Our Barbas Sirocco 350 gas fireplace is functional but makes a rattling noise after ignition. The rattling noise stops after some minutes, but is quite annoying. Over time, it seems to take longer and longer before the rattling stops. I went online to see if I could find some information about this issue, but there was hardly anything out there. That is why I decided, after successfully repairing it, to write this post. Two warnings before you try this yourself:

• there is no inspection hatch. You have to take it apart completely; which is not easy and a lot of work.
• do not forget to switch off the gas and mains power!

What I did found online, was the website of the manufacturer. I contacted them by e-mail and phone, they are very friendly and supportive. I called them and they sent me the documentation and told me the problem could be one of the three values or the modubox. The modubox contains the control circuit board. To test which value causes the problem, I was told to swap the outer valves. If the problem does not change, than the cause is probably in the modubox. I took photo's while I was taking the fireplace apart, I could refer to those photo's when I had to put it together again. I recommend you to do the same!

Front frame and glass removed

As I already mentioned, there is no inspection hatch. You have to take it apart starting at the front frame, working inwards. First remove the metal frame using an Allen wrench / screwdriver. Remove the metal clips and then the glass.

Red circle shows the panel that gives access to the gas connection

Remove the fake wood and all the screws. Take out all metal parts. The panel in the image above gives access to the gas connection.

Use a wrench to disconnect the gas connection

After removing the panel, use a wrench to disconnect the gas pipe. Make sure the gas is closed!

The unit removed

When the gas pipe is disconnected from the unit, you can lift it and disconnect the electricity. Make sure the mains power is turned off! Note that the unit has sharp screws pointing down. You don't want those on your wooden floor or table.

The unit with the modubox and the valves

The image above shows the opened unit. The modubox on the left and the three valves on the right. First thing to try is swapping the two outer valves pointed to by the arrows. Remove the cable lugs and the nut and washer on top of these valves. You can then push the valve to the back. In my case there was not enough room to remove them. I first had to remove the two black screws on the modubox side and use some force. After swapping the valves and putting it all back together I switched the mains power and gas back on. First the gas was not flowing. It worked when I tried fifteen minutes later. I read online that this is due to a safety valve in the gas meter. If after waiting for fifteen minutes, the gas is still not flowing, you can try to blow in the gas pipe to move the safety valve. In my case the issue with the rattling noise did not change. Next thing to inspect is the modubox.

The modubox enclosure and circuit board

After coming this far I decided to take the fireplace apart again and inspect the modubox. The image above shows the modubox enclosure and circuit board.

This stain took my attention

The stain under the electrolytic capacitor on the circuit board on the left, above took my attention. I used my multimeter to measure the capacity of this electrolytic capacitor. It turned out that it had lost all of its capacity.

Replaced capacitor

In one of the circuit board that I have in my drawer, I found a capacitor with the correct capacity and voltage (47uF, 50V, 105℃). This time the fireplace worked like a charm after putting it all back together again! 

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.