heat bed stops the print

Hi All.

i have this problem with my delta printer i just finish
hope someone can help me.

i am using marlin 1.1.4

when i slice a model with no heated bed it prints ok with PLA 210 hot end ( with the warping usual problems )
but when i slice the same model with the heated bed ( 60 degrees ).
it stops and gives me a thermalrunaway message.
and the power supply ( 12v DC 30A 360w ) was geting kind of hot, the fans on it went on and it feels like the power supply
was working a lot.

i bought a MOSFET for the 3d printer bed and a separate power supply just to feed the bed mosfet
and now the main power supply works great, no heating or heavy working on it, and the second power supply
heats the bed ok, slow but ok.

the thing is that when i try to print with the hot bed it still stops and gives me the
thermalrunaway error early in the print, even in a calibration cube.

and if pritn with out heat bed the printer works fine.

please help me.

Regards
Roberto

a few things to look at...

check your thermistor wireing and values in your Configuration.h file.
The wrong thermistor compared to table is possible. Both your settings are = 1 : 100k thermistor - best choice for EPCOS 100k (4.7k pullup)
more likely there is a break in the wire from the controller to the thermistor.

Usually a thermal runaway is the system saying its had the heater on long enough that it should have shown a certain reading... then for safety it shuts down because it assumes the value its receiving back is wrong.
This is fire prevention in action.

you mention that your 30amp PSU seems to be working too hard for the setup...
Perhaps a large high wattage bed that is eating all your power?

looked at your configuration.h file a bit:
#define BED_MAXTEMP 150 a wee bit him IMO.... I have mine at 110 and print ABS very well.

//#define PIDTEMPBED shows you are not using your PID settings so its on BangBang as I understand it....

Take a good look at what thermistor your using and the wireing.....

Hi.

thanks for your help.

i change to PIDTEMPBED and run the test to get the values to store in the firmware.
but no luck.

i also change the BED_MAXTEMP to 110

i will check the wiering,

question. if the wiering is bad what puzzles meis that the print stops almost in the same high.

another question i have the hot end fan (E3dv6) and also 2 more fans for cooling the filament, can it be to much air blowing in to the center of the bed and this causing cooling the bed.

image attach of the hot end

regards

ya I would say that is likely, so with that much free air blowing down the bed cant keep itself hot enough.
the heater stays on all the time trying to compensate thus tricking the system to think its on a run away heating that could end in fire....

try a print with the fans off.

I use this setup on my cube: [www.thingiverse.com]
I like it so I can remove the fan easily for when I am printing ABS

The ducting allows for the air flow to be blown across the bed rather than at it, a single medium/low velocity fan is plenty with this.
I also use a silicone sock on my hotend to prevent the air flow from over cooling it and causing the same issue we are now thinking your having.
I forgot but I had the exact same thing with my hotend b4 I socked it

Edited 2 time(s). Last edit at 10/17/2017 11:21AM by JustSumGuy.

i will try it

thanks

Hi.

i got it working, it was way to much air from the 2 fans, i think that even the hot end fan helps in small
pieces, i print a calibration cube 25 x 25 x 10mm and as soon as the fans kick in in the 2nd layer
i stop the fans and went great.

i am thinking on slicing small parts at a20% fan in the 2nd layer on.

thanks