Installed new unfinished red oak adjacent to already exiting red oak floor. I sanded with a belt sander 36/60/80. Then applied Bona semi gloss water base poly. I can see lines cross grain with the floor. I sanded them out with an orbital and belt sander went to poly again they are still there. I then rented an screener and covered the entire floor with a 180 pad. Applied the poly again and they are still there even after two coats. I can't feel any imperfections in the floor but they are every where. Help anyone!

Sounds to me like you sanded against the grain instead of with it. I sand with 24-40-80 then screen with 80-120 before the first coat. always sand with the grain

rented machines equal chatter chatter, chatter.

Didn't sound like he was describing chatter to me.

Do you have pictures

Cross grain lines sound like it to me especially with rental equipment.

Thanks for the help local flooring guy said it looked like the drum sander I rented was out of balance.