SummaryIn the past I patiently drilled the 8mm ID hole to 9mm and later tapped it to M10. I hope this solution is going to be as effective but less tool and time consuming. Part hole is slightly conical and it will get a M4 screw.InstructionsTap the inner hole with M4 and use a 25mm M4 screw to keep it firmly in place. Do not tap the part while inside de rail but before, this way the topmost area will barely be touched and that will maximize the grip once the screw is in place. I printed in ABS and they seem to be able to resist as good deal of abuse.