Designing Nut and Orifice fittings (brass)

[GregFisk25]

Hi,
I get parts made in China, and I need to make a full CNC drawing.
It is a modified 1/4" BSP nut and orifice fitting. I cannot find anywhere how to draw the nut and orifice so they work correctly. This is the part they make the most mistakes with, as the tolerances are small.
It is not practical for me to try and measure the sizes and angles of an existing one. There must be design criteria available somewhere?

 

[Baluncore]

Do you have a link to a similar product?

Why can you not measure an existing one?
Use a set of very small drills or piano wires as diameter gauges.
You will probably need Go/NoGo gauges later for QC on the delivered product.

What material flows through the orifice? What flow rate? What drives the flow?

 

[pantaz]

Searching for "bsp threaded fittings tolerances dimensions" provides a number of good references, such as http://www.roymech.co.uk/Useful_Tables/Flanges/Pipe_Threads.html

 

[GregFisk25]

Hi,
Thanks for the help.
It is not the orifice or thread I am having trouble with, purely the design of the olive - they need to be designed just right so they are not too tight or too loose.