I have a Wanhao I3 Plus

on third model it started to lift and curl

what do i do

We would need more information to help. What model is curling? What models have you printed successfully? What material are you printing with and what are your temperature settings?

As general advice, make sure your bed is leveled properly so that the first layer adheres properly and make sure your nozzle and bed temperatures are set appropriately for the material. If you are printing with a skirt, then try again with a brim or raft.

viewed lots of youtube. printing normandy pillbox default tempsettings were a bit low and speed a bit quick. Adjusted those and all is fine thank you. Need to speed it up a bit after the float is laid.

Ian