Cura extruder temps behaving strange

[jens3 7]

I am in the process of dialing in a new two extruder printer and am using Cura as a slicer. There are some unexpected extruder temperatures that I am wondering about.

Extruder 1 is set to 190C print temperature, first layer to 210C and standby at 170C

Extruder two is set eor 190C during all extrusion and 170 for standby temperature.

In actual operation, it seems that Cura calls for 210C on extruder 1 after every colour change ... as if it's saying 'this is a new model and I am on the first layer'. I am using an elevated first layer temperature for better bed adhesion and don't want the temperature this high in the middle of the model.

Standby temperature is specified as 170C for both extruders but seems to go to 175C early in the print process before going to 170C later on

There are some other oddities ( sometimes the temperatures call for 185C which, like 175C, is not called for anywhere) but I am hoping that understanding the above will help me understand the rest.

BTW, I am getting a lot of stringing with PLA which is why I am trying to reduce extruder temperatures

Edited July 10, 2019 by jens3

[tinkergnome 731]

22 hours ago, jens3 said:

I am in the process of dialing in a new two extruder printer and am using Cura as a slicer. There are some unexpected extruder temperatures that I am wondering about.

 

The easiest way is probably: type "temperature" in the search bar of Cura to see all temperature related settings. I guess, at least some of the odd temperatures you noticed are the values of initial and final printing temperature (separate for each extruder).

 

Extruder start and end scripts in the machine settings may also contain temperature related gcodes (you don't mention, which printer definition is used).

 

Good luck!

 

[johnse 29]

Also, make sure you don’t have any post-processing gcode scripts running, like are used for temperature towers. These hang around in Cura until cleared.

[jens3 7]

Thanks for the replies.

There are no post-processing scripts running

Typing 'temperature' in the search bar does not reveal anything unusual that would explain why the nozzle temperature of the extruder that has a 'first layer' temperature defined goes to that temperature every time the nozzle changes.

Initial and final print temperatures are not visible as I do not feel that they have anything to do with the situation. To explain this a bit further, the initial and final print temperatures are indicated as those temperatures where printing can start even if the nozzle is not up to temperature. In my case, the nozzle temperature that is called for is shown as 210C which is the temperature I have set for the first layer for better adhesion. The rest of the print is supposed to happen at 190C. What would make Cura call for 210 degrees in the middle of the print after a nozzle change ? It only stays at 210 degrees for the first layer after the nozzle change.

I have found similar reports in the old messages in this forum but the one link that promised to explain all the goings on is no longer valid 😞

Oh, the only nozzle switch codes active is a position change to the nozzle location after a nozzle switch to prevent it parking over the model while it is dropping a blob of filament.

 

In the digging I have done, I found references to the behind the scenes code messing with temperatures on very small models to prevent wild fluctuations in temperature. This is a possibility for the affected settings but does not apply (as far as I can see) to the business of extruder 1 switching to the first layer temperature every time that extruder starts up a new section (Extruder 1 is the extruder that prints the very first layer on the build plate).

 

Again, to explain, extruder one goes to 210C, prints the first layer of a model then drops to 190 as it should. I then use extruder two for something (it is at 190 because it has no initial layer temperature specified). After extruder 2 is finished, extruder 1 starts with it's next layer and that layer is done at 210C rather than 190C .....the next layer after that, with extruder 1, is done at 190C.

 

This is where I found the previous mention of this issue. Note that the link given in the thread no longer works.

 

What the heck ?????

 

Oh, I did not use a predefined printer as a start for all my settings, I created everything from scratch .... so maybe I am missing something ?

 

Edit: Tried finding the previous posting that had similar temperature problems but was unable to find it.

Edited July 12, 2019 by jens3
additional data

[jens3 7]

 

Again, thanks for the replies. I have now made initial and final printing temperature visible and set them all to the same 190C as the regular printing temperature. I have left 210C as the initial layer temperature for extruder 1.

While I still don't understand the logic behind things, for the purposes of this question my problems appear to be solved. The temperature settings that were applied by Cura to the invisible temperature settings were a bit weird and probably caused my issues. I say 'probably' because I tried many different things and lost track of the exact details. Suffice it to say that I am currently running a dual color test print and I had 210C for the first layer only and all subsequent layer temperature swing between 170C (inactive) and 190C (active) as they are supposed to.

 

No I can try and figure out why I can't get a clean dual color print even though I have a prime tower as well as an ooze shield enabled.

 

Many things to learn ......

 

Edited July 12, 2019 by jens3