User Defined

User Defined Features (UDF) present some difficulties, not chiefly in understanding or creating them. The chief difficulty is that they presented themselves as workarounds for features which worked badly to awkardly, such as counter bored or tapped hole construction or sheetmetal formed punch/die features. Since these deficiencies have been confronted head on, such as, with the new hole 'wizard', which provides a single, graphical input screen, plus tapped hole sizes for US and metric, the need for a UDF to accomplish this has disappeared, superceded by better basic functionality.

Another drawback to using UDFs was always that it was meant for more complicated feaures or combinations of features. A UDF, BTW, starts out life as a simple feature or series of features and, by the UDF definition, turns into a group. Any reference in the original feature becomes a reference in the UDF and needs a correlate in the part to which it to be applied. And the precise reference was needed. If you referenced a datum in the original, you'd better have one available and in the right relation, for the new part. If you had four features grouped into a UDF and those features didn't reference each other (C referencing B referencing A), then each feature would have its own references in the new part.

Complicating this even further was the fact that by the time it got this complicated, it became indispensible to save the reference part iwth the UDF. When you used the UDF in the new part, you'd get the reference part in a separate window, slopped over the part you were trying to create. What a mess!! Pro/e knows nothing of defined screen regions, using a single session with multiple windows, tiling addtional windows, moving effortlessly from window to window with a click of the pointer on the frame, none of the GUI revolution of the 90s has quite caught up with the Pro/e's UNIX gurus. So, even in Wildfire, you are confronted with the ancient, junky interface. You create your own prompts for each reference, you fiddle with the reference model window, alt-tabbing to find the new part window and specify the corresponding reference in the new part. And keep fiddling back and forth, specifying references, wondering all the time if it wouldn't have been easier doing the whole thing from scratch.

Certain of Pro/e's efficiency features are more trouble than they are worth. And, if you go through all hte rigamarole but, get to the end, and the UDF feature placement fails, you know that you could have done it quicker from scratch. In my experience, even with relatively simple features, that was often the case.

If, in spite of these warnings, you want to know how to create a UDF, I'd be happy to tell you.

David Janes

Hi Guys, For user defined option (part>feat>creat>user defined) I was able to group but I am not able to choose reference (Surface where i want to place the feature, Datum planes for positioning ect) flexibly to my convenience. ProE automatically chooses the references. Is there a way to customize the references I wanted to choose? I also want to change the dimension of the feature each time when I place it. Please help. Thanks in advance. Shankar.

You have to thinks ahead when creating a UDF. The key is in the base feature out of which you create the UDF. If you want your UDF to be 'floating', that is, to be able to move with respect to refernces, the base feature out of which you make the UDF must be contructed that way. So, if you wish your UDF cut to be able to move with respect to two datums or two surfaces or two edges, you must create the base feature that way. If you created the feature as locked to two datums, then there will be no variable position dimensions available. Only a feature which is initially created with offset dimensions for postion will be moveable.

As far as the internal dimensions of the feaure (widths, diameters, etc.) those will be variable if you define them in the UDF to be variable. Anything which is variable in the base feature may be variable in the UDF. But you must select the size and position dimensions to vary. So, if you have locked your hex feature to an axis or point, and this feature has the variable position, you must include the point or axis in your UDF definition. (A UDF may be made up of several features.) Which ever features are variable will have the variable position or size dimensions. If you have no variable position dimensions, you have locked your base feature to unvarying references, such as making the center of the hex coincident with two datum planes which themselves are unmoveable. The varying features must be included in the selection of featues for their dimensions to selectable for variation. So, if your hex sketch references a point or axis, the point or axis must have a non-zero offset dimension from a surface, datum or edge in its placement and it must be included as a feature in the UDF for its dimensions to be useable for position variation.

In the list of elements, 'Var Elements' refers to features you wish to choose to include or exclude from placement. 'Var dimensions' refers to any position or size dimensions you wish to select for variation when the UDF is placed. So, for example, if you wished to use the UDF to always place the same sized hex, you would not select size dimensions for variation in the UDF definition.

David Janes