The thermal behaviour of machine tools is the greatest challenge of precision in manufacturing and counteracting it with a controlled environment swallows an immense amount of effort and energy. As thermal errors result from physics and physics is invincible, the solution must be generated from another principle as a workaround. The vision of a fully compensated machine tool intends to remove the thermal errors for machine tools that operate under normal shop floor conditions with the help of numerical control. Research in the field of machine tools at inspire AG and the Institute of Machine Tools and Manufacturing (IWF) at ETH Zurich is following the vision of the fully compensated machine tool. This keynote paper provides an overview of past and current work on how this vision is being pursued in the field of thermal issues in machine tools and related manufacturing systems. The paper concludes with a summary and assessment of the state of the art and provides an outlook on the challenges in thermal error research on the way towards the fully compensated machine tool by illustrating that up to now, not all thermal axis errors of machine tools can be measured in a sufficiently short time and be compensated by data driven models, and the physical models for predicting the thermal behaviour often do not achieve the required accuracy.