Dimension of the internal circle of external threads in views

You have applied an external thread to a cylindrical part.

Then, you create the view of this part displaying and dimensioning the thread, but you want to know how Inventor calculates the dimension of the internal circle of the thread.

The calculation is based on the values in Threads.xls file.

For instance you have applied the ANSI Metric M Profile thread (M50x4, Class 6g) to a cylinder with a diameter D = 50 mm.

In this case the diameter d of the internal circle of the thread in the view is calculated with the formula below.

d = D – [Major Dia Min (column H) – Minor Dia Min (column L)]

That is.

d = 50 mm – [49.465 – 44.642] mm = 45.177 mm

In case you apply a thread and its column L is empty in the Threads.xls file, as, for instance the ANSI Unified Screw Threads and the majority of the Pipe Threads, the diameter d of the internal line of the thread in the view is calculated with the formula below.

d = D – [Major Dia Max (column G) – Minor Dia Max (column K)]

Soruce: http://beinginventive.typepad.com/