Start of the nozzle heating is not stable

When I start my print the heating of the nozzle is erattic in the beginning.

During the total length of the print the temperature is stable.
Firmware is Marlin 2.0.5.4
Mainboard is SKRv1.3
Hotend is E3Dv6
And I'm heating the hotend to 140 degC and Bed to 50degC simultaneous.
When the bed reaches 50 deg the second stage heating to the desired hotend temp is commenced.
What can be the cause of this phenomenon.

best regards Piet.

Edited 3 time(s). Last edit at 11/06/2020 11:31AM by Bossie.

... seems to be intended - so more a feature, than a bug

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

... by the way - this "erratic" start is the normal curve with PID heating algorhytmus ...

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Looks to me like the nozzle temp is related to the bed temp. It waits for the bed to reach full temp before it continues heating the nozzle. This is probably to reduce stationary plastic getting heated for too long in the nozzle, preventing clogs.

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http://www.marinusdebeer.nl/

Quote
Ohmarinus
Looks to me like the nozzle temp is related to the bed temp. It waits for the bed to reach full temp before it continues heating the nozzle. This is probably to reduce stationary plastic getting heated for too long in the nozzle, preventing clogs.

Yes that is intentional, as I wrote.
But the reason "to reduce stationary plastic" is a bit obsolete because of the PID algoritme, I guess.

But my question was about the fading sinusoidal curve of both bed and nozzle reaching the target temperature.

Edited 1 time(s). Last edit at 11/06/2020 11:56AM by Bossie.