Jim,

No worries. My thinking is that if the temperature prevents adhesion to the next lower level, then a longer run might exhibit more distortion than a shorter run would as it cools. You had indicated that the shorter runs seemed ok, but not the longer.

Also, if the issue is adhesion but not a temperature issue, then it might be a question of having enough material to adhere to. With a 20% fill, the lower level does not provide a lot of surface area for adherence. That is why I suggested you might try a higher fill rate to see if that helped. Again, if it is adhesion, I would think that longer runs would exhibit more distortion while cooling than shorter runs.

Having said all of that, I only have worked with PLA and do not have any experience with ABS. Hope it helps.