RepRap Builder

November 2013

More Problems with the Heated Bed and Problems with Heating the Extruder




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November 2013

Time appeared to be critical now: as usual in the month November we change our residence and move back to the city, about 800 kms to the north. The RepRap was not finished yet and it was too fragile and too unhandy for transport. I realised that finishing the project would have to wait until next summer.

However, some time was still available to install the new RAMPS 1.4 board which had arrived one week after ordering. Installing a new printed circuit board (PCB) is easy as it is pressed onto the
Arduino Mega 2560 PCB and all wiring is connected by pressing their plugs onto the RAMPS connectors. Unfortunately my new RAMPS missed a connector for the ventilator and therefore I had to desolder it from the old board and solder it onto the new board. Apparently not all boards in the market are equipped up to the same level!

It took a couple of minutes now to connect the new RAMPS board and all the wiring. A short manual test run showed that everything worked fine: motors, heating and sensors. Considering the previous troubles with the heating I did an extra test by heating up the extruder and the heated bed to their nominal settings for printing with ABS, the highest temperatures that occur on a RepRap.

To my surprise but even more so to my annoyance both heating systems rapidly heated up to the set point but the graphical curve flattened to a steady level just 2C below set-point. With other words the temperature which I needed for printing could not be met. One might think that it should not be a problem to compensate the missing 2C by adding them in the firmware. Also why should it be a problem to print at a slightly lower temperature? The difference of 2C on an extruder temperature of 220C is less than 1%!

Correct, of course it was possible to set the temperature in the firmware at 222C when I need 220C but also of course it was possible to print at 118C! Unfortunately these considerations do not help me to print an object. The program in the host software has been developed in such a way that it starts waiting until a set temperature is reached before it starts the print procedure. In practice this means that I can instruct the RepRap to print an object at pre-defined parameters and than sit down to look at the temperature curves mounting to a flat line just under the set values waiting into infinity for the print job to start.

I was really fed up now with the project and we had to return to our winter residence. No time for new investigations to resolve this problem!

I had all winter to think about a solution for the new problem.









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Last Updated on: Mon Nov 10 21:56:10 2014