Because you use the Thread command to add thread information to an existing cylindrical face, the cylindrical face diameter must match a value listed in the Holes.txt or Pipethreads.txt files.

For external threads, the cylinder diameter (1) must match a value in the nominal diameter column in the Holes.txt or the Pipethreads.txt files. For internal threads, the cylinder diameter (2) must match a value in the internal minor diameter column in the Holes.txt or the Pipethreads.txt files.

For example, to add a Rd 24 x 1/8 metric straight pipe thread to an external cylinder, the cylinder diameter must be exactly 24 millimeters, which matches the nominal diameter for this thread in the Pipethreads.txt file. To add the Rd 24 x 1/8 metric straight pipe thread to an internal cylinder, the cylinder diameter must be exactly 21.142 millimeters, which is the internal minor diameter for this thread in the Pipethreads.txt file.