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Hot End fails to reach temp during print job, but works fine manually

hammertongshammertongs
in Extruder & Bed
Ok, I'm having an issue with my hot end.  Here's my printer specs. (It's a custom built OrdBot Hadron):

Hot End: e3d v6 12v
Power Supply: 12V 30A DC 360W
Extruder: Titan
Board: Rumba
Firmware: Repetier (Dev), also (Marlin (RC), and Marlin 1.03)

I can manually move the axes with no problem. I can heat the hot end manually and squirt plastic.  I can even squirt plastic while it's moving.

However, as soon as I load up a print job (5mm Calibration Steps, sliced with Cura OR slic3r), the hot end doesn't "really" heat up.  Here's the relevant gcode:

M104 S205 ; set temperature
G28 ; home all axes
G1 Z5 F5000 ; lift nozzle
M109 S205 ; wait for temperature to be reached
G21 ; set units to millimeters
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
G92 E0
M106 S178.5

The printer waits on the M109 S205 command (as expected), but the temperature curve is clearly not happy (getting slower as time goes on).  The attached graphic shows what I mean.

image


Does anyone have any idea why this is happening?  I don't think it's my thermistor, because it works fine manually. I can include my config.json if necessary.  I'm at my wit's end with this.  :-/

Comments

  • RepetierRepetier
    Since we see that firmware is heating 100% in both cases the typical suspect is a fan that is on or not on. Some fans not only cool filament but also heater making them heat slower, cooldown faster.
  • hammertongshammertongs
    Ok, after ensuring my firmware was configured correctly, and the Fan headers were set correctly, the fan now comes on at 50C like I have configured.

    In addition, I have also run the PID auto-tune, and used it's values in my Configuration.h.  It holds temp wonderfully outside of a print job.

    However, the hot-end does not maintain temperature after it starts the job.  The temp slowly drops during a print, despite having the silicone boot around the hot-end.  I'm assuming that I'm losing too much heat during a print from the filament, and the board can't keep up?  I see the power set to full, but it's not able to provide enough current to keep the hot end hot.
  • hammertongshammertongs
    Great news! Turns out the wires running from the PowerSupply to the board were way too thin, despite being scavenged from a "standard" 3 prong CPU power cable.  The hot end was only able to pull about 8.9v.  I swapped them out with properly gauged wire (14ga), and it heats like a champ now.
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