Extrusion heater not turning off
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@phaedrux
You are correct I am getting confused.
When working through the Web Controller the heater has three settings.
Off, Active, and Standby. Before updating to 3.3 when a print was finished the heater would be turned off.
If just setting the temperature to zero turns off the heater why have the option to turn the heater off?That is why I am confused.
Thank you.
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Short answer is legacy commands and how heaters have historically been handled with 3d printers.
The M568 command will let you put it in an "off" state.
Most slicers still use the old M104 commands for compatibility sake.
To put your mind at ease, the heater can't go back "on" until it's sent a new temperature command. Deselecting the tool (and having the standby temp set to 0) means it won't act on a new temperature command until the tool is activated again.
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@phaedrux
I added the M568 lines to the End G-Code and I will run a test print.I really appreciate your help.
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@phaedrux
Hello, so I placed the following M568 codes in Cura and unfortunately it made no difference.
;End G-Code
M568 P0 A0
M568 P1 A0
;Retract the filament
G92 E1
G1 E-1 F300
G28 X0 Y0
M84
I know you state that it makes no difference but I personally dislike the idea of the heater being active.
So if you have any other ideas I would like to hear them.Maybe I should also contact Modix support and see what they say.
Thank you.
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@dnvm84 said in Extrusion heater not turning off:
I personally dislike the idea of the heater being active.
It's not the heater, it's the tool. Use T-1 if you want to deactivate the tool.
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@phaedrux
So does that mean I need T-0 and T-1?Thank you.
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No T-1 means deselect the current tool.
You may even want T-1 P0 to deselect the current tool but don't run any tool change files.
But remember. When you deselect the tool it will put the heater into standby. If you have a standby temp above 0 it will turn the heater on. So if you want the heater to stay off make sure the standby temp is 0.
I have to say though, this illustrates that you're more concerned with the word "active" than the heaters actually being off.
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@phaedrux
You are correct. I see Active as powered on, even if the temperature equals zero.
When you look at the PanelDue the heater icon is red, again showing me that the heater is powered on.What do I do when I start using dual print heads? If T-1 only deselects the current head then the other head will stay in standby mode. And if it has a set temperature it will stay hot.
I don't understand why there is not an easy way to turn the heater power off. Not just set the temp to zero. To me this is a safety hazard. Hypothetical if this was a manufacturing setting there is no way a company would allow the heater to stay energized. All it would take is one mistake and somebody could get burns.
Again thank you for you help.
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@dnvm84 said in Extrusion heater not turning off:
You are correct. I see Active as powered on, even if the temperature equals zero.
Active refers to the tool. The heater is associated with the tool along with an extruder motor. The tool being active means it is selected and ready to accept commands. The heater is only turned on when a temperature command is sent.
@dnvm84 said in Extrusion heater not turning off:
showing me that the heater is powered on.
No. The heater power is controlled by a mosfet. If the temperature is 0, no power is flowing.
@dnvm84 said in Extrusion heater not turning off:
What do I do when I start using dual print heads? If T-1 only deselects the current head then the other head will stay in standby mode. And if it has a set temperature it will stay hot.
Yes that's the point. In order to save time on tool changes it's common to set a standby temperature low enough for the filament in the head to not ooze out, but in a warm state so that when the tool is activated again it takes less time to get to the printing temperature. These temperatures are usually set in your slicer.
@dnvm84 said in Extrusion heater not turning off:
Hypothetical if this was a manufacturing setting there is no way a company would allow the heater to stay energized.
I assure you this is used in manufacturing settings every day without issue. The heater is not energized if no temperature is set.
@dnvm84 said in Extrusion heater not turning off:
I don't understand why there is not an easy way to turn the heater power off.
There is. M568. Or setting the temperature to 0.
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@dnvm84 what @Phaedrux has mentioned and how the Duet operates is pretty standard for most 3d printers. No power being sent means 'off'. You can deselect tool etc so it is not active, but you can just as easily reactivate a tool as you can mistakenly set a temperature demand. Ultimately 3d printers are CNC machines with very hot bits that move around so an amount of user caution is expected.
If you really want it off, and are thinking from an industrial safety point, then you'd be looking at a method to isolate the power supply, so that even if the Duet went crazy (bricked firmware, wiring short, user error etc), the heater gets no power. I use a relay on the mains that cuts the 24v supply to the board, as well as the typical switches and Estop buttons. The relay can be controlled via the PS_ON pin on the Duet so it can shut down the power after a print is finished and things have cooled, or if it detects a heater fault. I have a separate 5v PSU which powers the Duet CPU meaning I can still access it and work out what went wrong. Modix (and probably 99% of other 3d printer suppliers) obviously think this is not necessary though...
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@engikeneer
Thank you for your reply.I understand my way of thinking is based on a very hypothetical possibility.
With working around machines and tools all my life it is just the way I think.Thank you for the information, I will have to look into that relay system.
@Phaedrux
Thank you for your patience and the detail of your explanations. -
@dnvm84 Think of it like a thermostat on a HVAC system. The system will always be on unless the user turns it off completely or via a time switch. But nothing will happen until the thermostat calls for heat. My domestic boiler is always "on" but it doesn't actually do anything untill either the room or hot water thermostats call for heat.
I haven't checked the wiring diagram for Duet boards but I know that the MOSFETs switch the negative side of the heaters. So it's likely that they have Vin fed to one side all the time the machine is powered up, regardless of whether the status is displayed as active, standby or off. If that is true, shorting the other side of the heater to ground will turn it on at full power, even if the display shows it is "off".
Similar things happen with fans and motors (which need to have a holding current applied) so the only way to be "safe" is to turn the machine off at the wall.
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Hello, everyone, thank you for the replies.
As my final entry what I have done is place M1 at the end of my End G-Code.
And that does exactly what I need it to do.
Again, thank you for all off your suggestions and help.
One last question. How do I mark this as solved?
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undefined Phaedrux marked this topic as a question
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undefined Phaedrux has marked this topic as solved
