PLA supports for ABS - part cooling fan triggering heatbed thermal error
I've recently discovered the joys of using PLA supports with an ABS print. I have a project enclosure that has a shallow recess (0.8mm) on the front panel for a vinyl overlay insert. If I use two interface layers of PLA, defined as soluble supports with the interface pattern spacing set to 0mm, I get a beautifully smooth supported layer of ABS, which is good for sticking the vinyl overlay onto.
Those two interface layers are layers 3 and 4, since I'm using a 0.2mm layer height. I quickly realised that I needed to match the heatbed temperatures for the PLA to those of the ABS, otherwise the heatbed cooled down too much while printing the PLA, and the ABS lifted very quickly.
I've also now noticed that the part cooling profile for PLA is different from the ABS. For ABS the cooling fan is disabled for the first 4 layers, whereas for PLA the fan is on at full speed from layer 3. So at layer three, the first of my PLA interface layers is laid down, and of course they print rather slowly, and the fan is at full speed, and in the case of my model they surround a small window in the model, which just happens to be near the middle of the build plate. All of this combines to mean that the part fan is blowing at full speed very close to the exposed build plate, and the heatbed heater can't keep up - I watched it trigger a heatbed thermal error when the temperature dropped by several degrees.
As well as having to modify the heatbed temperature profile for the supporting PLA I now realise that I should probably match the cooling profile too. In that case the main difference between my ABS profile and this modified PLA profile is now just the nozzle temperature.
So I'm wondering if I should just print the PLA with the ABS profile. Would there be any problems with this approach? Which is best for printing the PLA interface layers:
- default PLA profile with adjusted heatbed and cooling profiles,
- ABS profile with adjusted nozzle temperatures, or
- just use the raw ABS profile?
Any other suggestions to prevent the part cooling fan from triggering the thermal error?