ORD Bot heat bed problems

[Tomas1337]

Yep, Its the blue Lava heat bed.

I'll try those tests as soon as I can but I see that the heatbed now maintains the temperature at 110 and only goes down to about 107 while printing for around 20 minutes. No lifts so far! This was done with the off anyway. Haven't printed longer since I think I fried my stepper driver and I'm now ordering some.

The removal of the setting of the heatbed on the gcode really helped.

[brnrd]

The removal of the setting of the heatbed on the gcode really helped.

It doesn't make a difference whether you set the bed temperature in pronterface or in slic3r. The g-code command to change the bed temperature is issued either way. Perhaps you forgot to set the bed temperature for both the first layer and the other layers.

[SystemsGuy]

I suspect he talking about the fact that most of the host programs wait until the M140 temperature is reached before starting the print.

The removal of the setting of the heatbed on the gcode really helped.

It doesn't make a difference whether you set the bed temperature in pronterface or in slic3r. The g-code command to change the bed temperature is issued either way. Perhaps you forgot to set the bed temperature for both the first layer and the other layers.

[brnrd]

I suspect he talking about the fact that most of the host programs wait until the M140 temperature is reached before starting the print.

He's able to print and the problem with the bed temperature happens during the print. So, that means that it got past the waiting part.

To be exact, it's not the host that waits for the bed temperature: It's the firmware. There are two M commands to set the bed temperature. M190 waits for the bed temperature to be reached. Slic3r uses this to set the bed temperature at the start of the g-code file. This causes the firmware to wait until the temperature is reached before moving on. The host is merely waiting for the firmware. M140 doesnt' wait. It is used by Pronterface when you manually change the temperature. It is also used to set the temperature of the bed for the remaining layers after the first layer.

[Tomas1337]

Could this be a problem with the MOSFET overheating? How do I tell if it's over heating?

[cvoinescu]

The MOSFET is not "smart" like the motor drivers, which shut down when they overheat. You know the MOSFET has overheated by the fact that it's now broken. Sometimes there's smoke too.

Before you touch to check, please be aware that a MOSFET can reach a temperature that burns skin before it suffers any damage, so be careful.

[Tomas1337]

So the mosfet looks like it's operating within temperature.

I tested out my heat bed to see if I overlooked some elementary details and it looks like I did.
I used my extruder thermistor and mounted it on top of the heatbed platform (held it down) to see if there was a heatbed thermistor was giving me a false reading. The extruder thermistor gave me a 110C reading while the heatbed thermistor gave me only 80!

Just goes to show that you should never under estimate the basics. Stupid me.