UDFs and Variable Parameters

[J_E_Hyde]

I am working on a project to create a UDF library for screw threads in Creo 10.0.4.0

The goal is to have the user enter the nominal OD and TPI for UN threads and get the appropriate geometry driven by relations based off ISO 228

My problem is that it is unclear how to implement these. When I follow the instructions here after selecting features ( To Define Variable Parameters in a UDF ) the dialogue box suggested on step 3 just doesn't open, and the dialogue box stays at 'All elements have been defined. Select element(s) or action(s) from the dialogue box'. Features that are relation-driven (like the OD of the cylinder that constitutes the screw, or the pitch values used for the helical sweep ) are not eligible as variable elements or dimensions either (google results suggested you sometimes need to set the features/dimensions that are parameterized as variable before you use the variable parameters option, but this hasn't worked for me)

My next idea is to just build out a family table, but we would prefer a general solution over manually entering all the combinations of diameter and pitch, so if anyone knows the right implementation, I would appreciate the help. 

[Catalina]

Hi @J_E_Hyde 

Thank you for your question. 

Your post appears well documented but has not yet received any response. I am replying to raise awareness. Hopefully, another community member will be able to help.

Also, feel free to add any additional information you think might be relevant. It sometimes helps to have screenshots to better understand what you are trying to do.

Best regards,

[BenLoosli]

A good discussion would be on why a UDF would be preferred over a family table for standard hardware items.

I have set up many family tables for nuts, bolts, screws and washers. Very easy to put things like the head dimensions in the generic relations and only the thread diameter, thread length and thread pitch in the family table. The head information is driven from the thread diameter. Very easy to edit using Excel from the family table editor.

[J_E_Hyde]

The motivation here is that the standard hardware would be affixed to existing parts rather than used as a reference, as well as to have an option that's immediately visible in the Creo UI that points to a common space, but I can see how a family table could be used to generate geometry that could just be imported into any given part. I'll have to put some more thought into this.

[BenLoosli]

To me the difference is a UDF is used to define some feature of a part object that is 1) variable in size and 2) something that has a complex shape to it, while a family table instance is a stand alone object that is added to an assembly. 

A hydraulic fitting port with a thread and tapers, etc. can be in different sizes. This would be added to a part object as a feature using a UDF.

A bolt/washer/nut added to an assembly to hold the hydraulic piece in place would be family table instances, depending on the sizes (diameter/length) that is needed to hold the object in place.