Cura 2.5 temps settings - pls expain what does it relay means.

[porlock 0]

I do not understand this temps stings in new cura, can someone pls explain it to me:

 

• "Initial temp" If i set 1st layer temp to 200, initial does do not nothing it start printing when reach 200, so this settings is pointless ? And why someone wants to start print before desired temp is reached ?
  
• "Final printing temp" why someone should want to lower the final print temp ? What is a sens of this settings.
  

 

[gr5 2,330]

I don't know the answer to your questions but I do know that for some materials you want to print the first layer extra hot. There are lots of tradeoffs on temperature. If you print hotter the bottom layer will stick better. I suspect this is the purpose of the initial temp.

If temperature is cooler the material is thicker like mortar and stays better where the nozzle puts it. If temp is hotter it flows more like honey and you get droopy errors and stringing and leakage. If you print hotter you can print faster. For ABS if you don't print hot enough you get bad layer adhesion from one layer to the next. If you print too hot you get clogs with ABS.

Also with dual head printers while one nozzle is printing the other cools down so you have these other temperature settings - something like "idle" temp and seconds before switching to start heating up the idle nozzle.

[porlock 0]

I don't know the answer to your questions but I do know that for some materials you want to print the first layer extra hot.  There are lots of tradeoffs on temperature.  If you print hotter the bottom layer will stick better.  I suspect this is the purpose of the initial temp.

If temperature is cooler the material is thicker like mortar and stays better where the nozzle puts it.  If temp is hotter it flows more like honey and you get droopy errors and stringing and leakage.  If you print hotter you can print faster.  For ABS if you don't print hot enough you get bad layer adhesion from one layer to the next.  If you print too hot you get clogs with ABS.

Also with dual head printers while one nozzle is printing the other cools down so you have these other temperature settings - something like "idle" temp and seconds before switching to start heating up the idle nozzle.

I think You miss understood :-) please look at the material pane in Cura there are 5 temp settings

1) Default temp - It seams that it is only for reference do not affect anything directly, it have no sens for me also.

2) Print temp - that is understandable

3) Print temp 1st layer - that is understandable too, and this is what You describing.

4) Initial print temp - this is one of my initial question, what it this do ?

5) final print temp - this is second of my initial question.

[tomnagel 128]

Initial print and final print temperature are a new feature in Cura 2.4. It is designed for dual material printing.

This is designed to prevent oozing. The nozzle that is not printing is warmed to 'initial printing temperature' just before it is due for printing. Immediately after the nozzle starts printing, the temperature is raised to the normal printing temperature. At the end of its turn, things go the other way around.

In the standard Cura profiles the difference is 5 degrees.

In practice, this trick enables you to turn off the prime tower, as oozing is minimized already.

[ultiarjan 1,223]

Standard PLA profile of the UM3, final temp is 15C lower than the printing temp, MUCH more than the 5C you mention.

I understand that this setup is nice for printing trinkets, but I'm worried about the effect on the mechanical strength of parts.

I also notice the predictability of dimensions on the UM3 is lower vs the UM2.

Did Ultimaker do any testing on the effect of temperature swings on the mechanical properties?  It might be a good idea to have specific profiles for "looks" and for "engineering"

Finally, IMHO there are still many situations where a prime tower is really needed, for example I printed flex-pla in combination with pla today, the flex needs a higher temp, and therefore a prime tower is really needed. Unfortunately the flex-pla combi has the same issue as the PVA-PLA combi, the adhesion is poor.  So an extra tower design where material is printed only on it's own, is still one of my main wishes for cura....