Don’t forget, the steel and the plastic will change size depending on the temperature, and at different rates. I don’t think the water absorption is the issue, it’s the temp swings. I had several of my pla parts split on me as well, and my router lives in an unheated barn in Ohio, where if you don’t like the weather, wait 5 minutes and it will be a different season! It was in the mid 80’s a week ago, and we almost had frost this morning. So far my pet-g parts haven’t broken.