Last week the Ultimaker 2 gave an ominous ERROR – STOPPED TEMP SENSOR message.
The Ultimaker 2 temperature error
After consulting Ultimaker support and measuring the resistance over the Pt100 sensor in the printer head (only 138 Ohm when heated up, which would correspond to only 100 C ) the culprit was quickly identified. Luckily the Ultimaker support page contains a very elaborate step-by-step instruction on how to replace the Pt100 sensor. Although the instruction is very clear it takes quite some time to perform all of the disassembly and subsequent assembly steps to replace the Pt100. Be also sure to replace the temperature sensor and not the heating element since they have both the same shape, the heating element is only slightly bigger.
Heather element on the left and new Pt100 temperature sensor on the right
After removing the temperature sensor with the help of some WD40 from the heatblock it is pretty clear that the sensor was, for unknown reason, completely destroyed. Replacing the Pt100 with a fresh one from the factory directly solved the problem and we are happy printing again.
The broken Pt100 temperature sensor
A common problem when 3D printing with ABS is the wrapping that occurs when printing larger objects. Wrapping is the bending of the outsides of the printed object due to shrinkage of the ABS when it cools down. There are already plenty solutions around (ie this instructables where Kapton tape is used) but I found this one working particularly well without any Kapton tape.
I found it works best to dissolve left over pieces of ABS in acetone and let is dissolve for about an hour (preferably use a glass jar since acetone dissolves several common plastics). The resulting solution becomes pitch black and is a bit viscous. Next heat up the glass bed (110 °C) of the printer and apply a thin layer of ABS around the outline of your print. Watch out for the fumes of acetone, since acetone is a very very flammable liquid! Use a ventilated room.
When the first layer of the brim is printed, add drops of the ABS solution on the corners of the brim. This will partly dissolve the brim but makes is stick even better to the plate.
Note that this ONLY works with ABS and not with PLA because PLA does not dissolve in acetone.