By drawing on the specific lessons learned from one case study, this paper will discuss collaboration, and issues upon knowledge communities in technical work domains. The results are based on a case study in a manufacturing process, thermal spraying, which can be characterised as very complex and technical. In order to understand the concept of knowledge communities in technical work domains I argue for an elaborated approach by going across different collaboration levels and organisational cultures, into issues of communities of practice. The discussion ends up with three main challenges for forming and supporting knowledge communities. These challenges might inspire an adequate work milieu, cultivated by both shared meanings and technology support.