Modeling with driving dimensions from irregular shaped surfaces

[ptc-3796374]

Hi everyone,

So. I am looking to design an irregular shaped surface. Currently I am using an intersection of 2 lines as spline along which I am creating a boundary blend that uses multiple cross sections along the spline for the shape. This comes very close to the surface that I want to achieve, however, it becomes difficult to call out the defining dimensions on a drawing as none of the ones I am using are driving dimensions.

Did anyone encounter a similar problem? Do you have any ideas how this could be solved? Is there maybe a good tutorial that helps me achieve this?

Ideally it should be possible to define multiple CS along the surface that have driving dimensions and may be used for other geometries as reference.

Thank you

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[TomD.inPDX]

Parts like this are most commonly controlled by "templates". Simply put in this era, it just means it must meet the CAD model within a certain specification. Your drawing would simply have a profile tolerance for the whole surface. your drawing should also make clear the requirements with regard as to what is used as the master model.

Of course, your drawing could use sections where you defined the boundary blend. they simply become points of reference or allow for inspection dimensions. You can, if desired, provide profile plots of particular sections which can get involved but is manageable with intersecting datum curves through a planar profile. IGES files are easy to extract data from if you place points along a curve at intervals. From this, you can create an inspection table. There are simply so many methods out there that you can utilize that there is no longer a standard means. I haven't figured out if this is bad or good, but it is what it is.

I suggest you work with your in-house inspection team; your supplier(s); and purchasing to figure out the best means to achieve your end game. Also consider how critical the shape is. If this is an industrial design where "feel" or "look" of the product is critical, then this too needs to be noted with accepted industry notation.

[ptc-3796374]

Hi Antonius,

Thank you for the immediate response. The IGES solution with inspection points sounds interesting. Do you have more info/ a tutorial on that?

Unfortunately the profile tolerance will not suffice.

Thanks again

[TomD.inPDX]

It sort of depends on which solution you are settling on. If you want to do a profile (similar to a cam profile), you can save the curve to an IGES file. If you need specific point locations along the curve at regular intervals (linear at equal distances along an X-trajectory), you will need to add the geometry points with an intersecting feature (a sketch is recommended). If you want arc length distances, you can pattern a point along a datum curve. When you save an IGES file, you can relate it to a coordinate system other than default. You can edit the IGES file and extract the relevant data. normally, you can manipulate this in Excel.

You can also create a graph in the model and show it in the drawing. Not a very powerful feature (no frills) but it can be done. A model graph can Get Data (import data) as well. Again, it is all about how you want to manage this profile on the drawing and inspect it.