Heated bed temperature decreases during print

[vaishu.fun]

Hi guys. A rookie here. I am printing using Wanhao duplicator 4s (ABS). I set the temperature of the heated bed plate at 110 degrees with Simplify3D software but when I start printing, the temperature of the build plate decreases rapidly and my print is getting messed up. Any advice? The extruder temperatures are constantly maintained and relayed.

[JoeJ]

Could be an electrical current issue. 110 is pretty high for the bed. If the power supply can't provide enough amps, then the bed temp will drop once you start heating the extruders and moving all the motors since these things draw more current.

[vaishu.fun]

Hi!
Thanks for the reply.. But during the preheat it goes upto that level. When I start the build, it never maintains the temperature and starts dropping. I checked for errors in my gcode as well and couldn't find any. I'll copy paste them here. Maybe there's a mistake I haven't identified.

M73 P0 ; enable build progress
G162 X Y F3000 ; home XY maximum
G161 Z F1200 ; home Z minimum
G92 Z-5 ; set Z to -5
G1 Z0 ; move Z to 0
G161 Z F100 ; home Z slowly
M132 X Y Z A B ; recall home offsets
M135 T0 ; load right extruder offsets
G1 X105 Y-70 Z30 F9000 ; move to wait position off table
G130 X20 Y20 Z20 A20 B20 ; lower stepper Vrefs while heating
M126 S[fan_speed_pwm]
M140 S110 T0 ; set target temperature for bed
M190 S110 ; wait for bed to reach target temperature
M134 T0 ; stabilize bed temperature
M104 S235 T0
M104 S[extruder1_temperature] T1
M133 T0 ; stabilize right extruder temperature
M133 T1 ; stabilize left extruder temperature
G130 X127 Y127 Z40 A127 B127 ; default stepper Vrefs
G92 A0 B0 ; zero extruders
G1 Z0.4 ; position nozzle
G1 E25 F300 ; purge nozzle
G1 X100 Y-65 Z0.15 F1200 ; slow wipe
G1 X95 Y-60 Z0.5 F1200 ; lift
G92 A0 B0 ; zero extruders
M73 P1 ;@body (notify GPX body has started)

[MikeO]

You might want to rig a quick-and-dirty draft shield out of cardboard, and put it around three sides of the printer, to see if it helps.

My printer sits in a room that often has a strong breeze coming in from the window that blows towards the printer, so for ABS I always put up a simple cardboard shield to block that. Keeping the baseplate at 110C would need a lot of power if the plate's got moving air circulating over it.

It's a quick thing to try, in any event.

[CompoundCarl]

First question - does the bed temperature drop to a specific value? For example, does it just drop by 20 degrees or so? Or does it cool all the way down to room temperature?

On one of my old printers, I had a similar issue. The bed could get up to temperature at the beginning of the print (when nothing else was happening), but when I started heating the other extruders and running the fan and moving the motors, it was too much for the power supply, so it couldn't keep the bed at the high temperature. Either way, answering the questions above would help confirm if this is the cause.

So just let the print run for a few minutes and then tell us where the bed temperature settled at

[vaishu.fun]

Hi,
I did let it run for a few minutes. It was a long print and the bed temp started decreasing from the first minute of running (The preheat took it upto 110). After a few minutes of continuous drop, it settled at around 55 degrees but by that time my print was coming off and was entirely spoilt so I had to cancel the build. And the printer does have a glass cover over it to stop cold drift influence. I don't keep the windows open either.

[CompoundCarl]

Ok, well does it stay at 55 degrees? If it actually settles at that temperature and doesn't keep dropping, then you have to figure out what's causing it to do that. There's nothing in the gcode that tells the bed to go to a temperature of 55 degrees. So most likely, it's a bad power supple, a loose cable, or perhaps also a bad firmware settings (some firmwares allow overriding the temperature in the print files, so that's another option)

[Rebekah_harper]

check the cable that plugs into the heated bed. I have burnt through a few and now have the red wire directly onto the pin.

am not too sure why it does it but it might be as simple as that.

Regards

Becky

[vaishu.fun]

Thanks I'll try that out!

[billyd]

Could be a setting in firmware turning off the bed or your gcode is turning off the bed for some reason. Check your startup gcodes. Perhaps the firmware doesn't allow 110 and is reverting to some safe value?