Mixing filament types in one model

Newbie, printing for 2 days now. So far successfull, the P1S is what i always hoped 3d printing would be. Simple.

But. Yesterday I tried my first 2 color print. This is a lid for a starwars shatterpoint tray system which consists of 2 STL files. The lower part is green PLA Tough. The upper part i choose black PETG for. It did not really stick together (see picture).

I am wondering:

a) maybe i assembled this wrong?
b) Maybe PETG is not really sticking to PLA tought?
c) I had to have a pause at layer 16 to insert some magnets. Made a mistake, and had to pause manually in the middle of the layer print.

Before i try that again (with a correct pause setting in the slicer), i was thinking to get some collective wisdom about the error of my ways…




In general, PETG and PLA bound is poor. The combination is often used as a support interface or to print stacks due to the easiness of splitting. It is possible to successfully print both materials (maybe not with a strong bond), but it is too demanding to be worth it, at least for me.
Did you pause between the filament change? If the pause is long, the top layer may be too stiff to bond with the next one strongly.
One piece of advice: when doing this experiment, try before with a smaller print to avoid filament waste and also allow you to tune up the settings.

To get it together somehow, if necessary, I would change the model. Anchor the upper part in the lower part. In other words, create recesses in the lower part that are filled by the upper part (print in print). This means that parts of the upper part protrude into the lower part and layers of the lower part cover parts (layers) of the upper part.


You should also avoid warping.

Thanks for the tips. I think for this particular build, i will just buy the colors i want in PLA and be done with it, instead of modifying the STLs etc. Seems like the much easier fix.

Interestingly, there are claims in the net that PETG and PLA go together ok, that’s why i thought i give this a try.