Debates about human–machine relationships have intensified following the launch of the world’s first commercially available sex robot ‘Harmony’, a hyperrealistic sex doll with AI-capabilities. With the likely consumer market for these devices among white, male, heterosexual sex-doll owners, their views about sex robot technology and the niche online communities in which they discuss their doll relationships have received little scholarly attention. Through a qualitative analysis of the discursive practices of male users of a major sex doll forum, this study found complex and dynamic homosocial relations characterized men’s online interactions. In their discussion of a sex robot future, men negotiate competing structures of masculinity and sexuality and create a safe, online space for others to express their sexual desires and preferences. Using the concept of the ‘seam’ or join, the results reveal the way male users of sex dolls position themselves subjectively and are positioned by technology and the increasingly porous interface between human and machine.