If you’ve built the electronics and fired up the hot end, you may have noticed that the temperature display gets “weird” after going above 100C and returning to room temperature. The last zero of “100” gets stuck on the display because the lcd.print() routine is left justified. Here is a simple fix. Just go into the arduino editor for the Sumpod firmware, and find the first line commented below. Change the code after it as follows (the red text is what is new):
// display temp
lcd.setCursor(11,1);
int valsum=analog2temp(current_raw);
if (valsum<100)
{lcd.print(” “); lcd.print(valsum);}
else {lcd.print(valsum);}
}
Recompile and upload to the arduino board and your LCD temperature display will now work correctly.
Renaissance Engineer 
I don’t get the problem you describe on mine. It goes to the programmed temperature ok and stays there. It has Richards new part ( I machined his prototype and made one for myself) I have extruded by hand and have a video http://3d-printer-kit.com/?p=385 so perhaps you can help by viewing it to let me know if it’s acceptable?
Also I made a change to the configuration h file and saved a copy but it came up with a different or new file extension. Now I can’t find it so is there a good learners site for Arduino?
Thanks
Mike: The problem isn’t with getting the hot end up to temperature. The problem is entirely with the way the temperature is displayed by the LCD. Try this. Heat up your hot end to at least 100C or more. Then, turn off the heater and watch the display as it cools. IF your firmware has the problem then as the temperature display returns down through 100C to 99C what you will discover is it will display 990 (the 99 is the new temp but the “0” comes from the previous write of 100). What my code change does is fix just this minor annoyance.
This code is in the Sprinter.PDE file and is the first tab when you open the sketch with the arduino software. Yes, there is a lot of help on the arduino.cc site and the programming environment is explained here: http://arduino.cc/en/Guide/Environment. Not sure what happened with your configuration.h file but I keep all of the related files in one directory, but with a backup of some version that works elsewhere. Maybe search for your file through your OS? (Windows?)
I did look at your extrusion video. Looks OK from what I can see. Are you using RepSnapper for control? If so, after getting to temperature, try the extruder setting at about 100 on the speed slider and a length of 75 (mm). Richard is correct in that you absolutely need to keep the upper part of the filament cool because that is crucial to pushing the filament out through the heated end. – Eric
Which version of Arduino are you using 0023 or the latest ver 1.0? Thanks forvthe link. Study time whilst I am away. Next issue is getting a good engraving software free!
Something that doesn’t require Cad to dxf to gcode or cad to stl to gcode! It’s a minefield, fun though:)
Mike: currrently using 0023 but plan on getting 1.0 installed and tested over the break here. I’ve been tweaking ReplicatorG and it is coming along well, but I’m also trying to take some “vacation” time here with my college break.
Also, I’m adding a “links” section so is it OK to include your 3d-printer-kit site as one? I’ll probably add fixers (ideasfixer.blogspot.com) as well. The more we collect resources the better we’ll all be! Not to mention those folks who have not received their machines as of now.
Yes, a big issue with the many repraps and derivatives is that there is not a particularly nice single souce software solution… my professional machines at work spoil me, as I can go from .STL to building a part in a matter of seconds and it always works as it should. But then, I don’t have $15-$35,000 to spend either! You might say I want the best wine on only a beer budget! 🙂 – Eric
Mike: Arduino 1.0 doesn’t compile the Sprinter/Sumpod firmware at this time, or at least the copy I have downloaded from Richard’s site. There were some changes to the libraries included with the new version. I know what to change in the source code, and will get to it soon. I’ll release an update here when I’ve tested it and I know it works. However, there really isn’t any hurry to switch because 0023 works just fine. – Eric