After a succession of failed prototype fan ducts …
Trying again and this time I’m using ‘the brim’ (thanks Idolcrasher!) to stick the print down more firmly, and a fan to stop the edges from curling up.
My new design for a cooling fan duct for the Mendel90 just turned to a pile of spaghetti.
Steep angles and curling edges caused the print head to knock it over while I was out.
Best print quality ever!
My Mendel90 finally found its sweet spot, so I just had to capture the settings I used to make this bottom half of the Raspberry Pi case.
Firmware: Marlin
Flow dialled down from the default setting of 42.3 to 36.0
Software: Slic3r 0.8.3
Layer height = 0.25 mm
Extrusion width = 0.45 mm
Filament diameter = 3.0 mm
Extrusion multiplier = 0.9
Print speed = 30 mm/s
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Most RepRaps are capable of printing whilst disconnected from the host computer as long as they have an SD memory card attached. But usually this means that the printer just carries on regardless until either it finishes the print or you pull the plug.
Not any more.
This clever little accessory is a real bargain at £30 as it includes an SD card reader, a click controller and a backlit LCD display panel. The display can show 4 lines of 20 characters and the click controller, in combination with the Marlin firmware that I’m already using, operates a menu system that provides extensive control over most of the printer’s functions.
You have to make your own case and control knob but , hey, that’s what 3D printers do best!
Two weeks ago, the heated printed bed on the Mendel90 suddenly stopped working. The cause was pretty obvious on closer inspection. The power connector had overheated and melted the plug.
Nophead had warned in his build instructions that it was better to bypass the plug and attach the wires directly to the metal body of the power controller but I didn’t bother to make the change and the plug failed :(
Worse still, when I tried to repair the connection using nophead’s method it still didn’t work, leading me to conclude that I had damaged the circuit board as well.
And then, in my sorry, tired state, I committed an even bigger blunder whilst testing the circuit, accidentally shorting two pins together and sending 12 volts down the 5 volt line which destroyed the processor and all four motor controllers.
Fortunately, I was able to afford a replacement board, swiftly supplied by Think3DPrint3D, and a set of spare chips to repair the old one. So now, two weeks later, I have a complete spare set of electronics which I intend to keep at hand for the Mini-Maker Faire in Manchester at the end of the month.
And then after that, maybe they’ll find their way into my next 3D printer! Who knows?
Finally got back to doing some printing after a holiday and a string of printer problems. I liked the shape of this Siamese Orchid Vase and also the challenge of printing it without support structures.
Last week I entered the RepRap 3D printing competition (purely for fun) and came first in the judging. This was my entry.
Last night I finally solved a problem that has been dogging my Huxley printer for weeks. I previously wrote about how I had managed to find the correct PID settings for the Mendel90 and how this was now benefiting from very stable temperature control.
Well, I’ve been trying to achieve the same thing with the Huxley and failing miserably. All of my recent prints have had to endure ridiculous swings of +/- 20 degrees C and the quality has been suffering as a result.
I’ve read more and more articles and forum posts about the art of PID tuning and failed to understand why I couldn’t fix my problem. Finally, I stumbled across one line that proved to be the key to finding a solution - “sort out any hardware problems before attempting PID tuning”.
I took the hot end off the printer and inspected it carefully. Sure enough, there was a completely dry, loose connection between the thermistor and the heater block. No wonder the controller was having a hard time getting the temperature right - the readings must have been changing every time the head moved!
Squirting a little heat sink compound down the thermistor socket and replacing it cured all the temperature swings and now I’m looking forward to seeing a real improvement in surface quality of my prints.
