Extruder temperature keeps on raising?

Hey guys, recently I've started building my very first reprap and so far everything went smooth.

Just now I've been testing the heatbed and extruder temperature. I've followed instructions on wiki [reprap.org] . The heatbed works flawlessly upon calling the M140 S50 command, it heats up to 50°C and keeps it there. However when I call M104 S50 for the extruder, it keeps on going over 50°C. I though that it probably wants to go to the desired 185°C to melt the PLA, so I let it go to 185°C but it kept on going higher, eventually it reached ~200°C and I shut it down manually.

Any ideas what am I doing wrong here? Thanks!

P.S.: I'm using Teacup firmware with Pronterface

Edited 2 time(s). Last edit at 03/28/2013 01:54PM by tomasbird.

what kind of hardware are you using for heating the heater?

I'm using Jhead Mk IV hotend and NTC 100k thermistor

If you set 50 °C it might go to 60 °C shortly. Seeing it going to > 100 °C indicates there's something wrong, however.

I have no good idea on what's going wrong. It might be heater and temperature sensor not being connected in the firmware logic. They need the exactly same name in config.h.

Could you try to disable (comment out) the heated bed in config.h? Then there's only one pair left. This could help finding the misconfiguration.

Another vague guess is, both temperature sensors are shorted somehow, so you always read both.

---

Generation 7 Electronics	Teacup Firmware	RepRap DIY

So I work with tomasbird on building this particular printer and we've managed to get the thermistors working by using the "M104 P0 Sxx" command followed by "M116". Anyway, we've stumbled upon some other problems:

a) The printer is probably not homing correctly. We're not getting the bounce-back/debouncing momentum after each axis triggers their endstop. For example - when we commad the X axis to home, it travels and stops after hitting it's endstop, keeping the endstop triggered (x_min = 1). Is that a problem? Somebody on IRC told me, that this could mean we're losing steps.

b) The heatbed is taking really long to heat up. It took probably around 20 - 30 minutes to get it up to 90°C. Is that ok, or should we get concerned?

Quote

b) The heatbed is taking really long to heat up. It took probably around 20 - 30 minutes to get it up to 90°C. Is that ok, or should we get concerned?

Connect the bed to 12V directly and see how long it takes then (you can keep the thermistor for measuring temperature). This is your reference. While hooked up to the electronics it shouldn't take much longer.

Quote

using the "M104 P0 Sxx" command followed by "M116"

M116 is "wait for temperatures to be reached before continueing with the next G-code". Shouldn't affect how heating happens at all.

If you require this "P0" it means your extruder isn't named "HEATER_EXTRUDER" ... or gcode_process.c has a bug in M104 handling I'm not aware of. It's line 479 ... 487.

Quote

The printer is probably not homing correctly. We're not getting the bounce-back/debouncing momentum after each axis triggers their endstop. For example - when we commad the X axis to home, it travels and stops after hitting it's endstop, keeping the endstop triggered (x_min = 1). Is that a problem? Somebody on IRC told me, that this could mean we're losing steps.

No problem here, as long as the X position is set to zero.

When homing, loosing steps isn't relevant. That's why most firmwares do a hard stop when hitting endstops, not caring about loosing steps. Teacup was changed last week to not loose steps even when hitting endstops: you should see the axis decelerating properly after hitting the endstop.

If you think the new endstop handling code doesn't work fine, please try the master branch, which currently has the old behaviour. Should work fine on a Gen7, too.

---

Generation 7 Electronics	Teacup Firmware	RepRap DIY

Ok, so we've managed to deal with pretty much all of the problems we've listed, but... another bunch of issues came up.
We've tried printing some ABS filament and it seems that there is something going on with the hot end. After heating it to 230°C we start pushing the ABS out of the nozzle (via pronterface with 100mm/min extrusion speed), but only a tiny bit of it actually comes out. For example, for every 5mm only about a 1mm comes out.. We've tried making the idler more tense, heating it up a bit more, fiddle with the extrusion speed in the firmware, but nothing really made any difference. When we tried printing the 20mm test cube, the ABS didn't really come out of the nozzle at all, even though the wheels kept spinning.

Another problem we encounter is that one of the Z axis motor is losing steps. Again we've tried adjusting the acceleration, microstepping and turning with the pololu potentiometer, but it didn't make any difference, every now and then one of the Z axis motor just stutters, eventually ruining the level of the X carriage.

z axis motor loosing steps: lower max z feed rate in firmware to 3mm/s or 180mm/m. many slicers do not limit z feedrate


extruder issue: it seems like your temp is not calibrated. do you have any thermometer/ thermocouple to check with?