...avoid replacing ALL downstream references in timeline?!?

Brad_Goodman · August 2023

I had a sketch (from an imported DXF) with a bunch of parts in it. I extruded them each with a single "Extrude" operation from which I got like 6 parts. I then take those 6 parts and do a milion other operations on them - transform, basis of other sketches, etc.

Turns out - I had the wrong initial DXF was wrong. So - when I use the corrected DXF (from a new sketch) and change my extrude to refernces these sketch entities - it generates all new/different parts. This means that now all the parts reference in my timeline are wrong/different!

Is there a way that I can make the sketch/extrude changes to make Onshape think they're all the "old" parts - i.e. so I don't have to change EVERY reference to them downstream in my timeline??

MichaelPascoe · August 2023

It depends if the downstream features rely on the edges and faces of the original extruded part.

If they do rely on those specific faces and edges, you will have to re-do everything. Or keep the original sketch entitles and re-constrain them to match the new dxf.

If they don't rely on them, and all they need is a body to merge with, then there are some work arounds for keeping the original body id's. One work around, which may be the only one in this specific case, would be to keep the original dxf, sketch, and extrudes. Then, modify the extruded parts so that they are small enough to be completely consumed by the new extruded parts. After the new parts are extruded, boolean the original counter parts with their new ones. This will preserve the body id of the parts, but your face id's will all be lost.

Evan_Reese · August 2023

Yep, this is a pain for sure. I think at this point, you're painted into a corner, but there are some techniques to use next time to make things more stable:

Reference the import as little as possible - For example, set up some variables for the height, width, and depth, and use them preferentially over referencing imported geometry. Another example is to create some additional references that you can hang everything else off of, which can easily be reattached to something new. That might look like creating a plane, extruding the dxf to the plane, and always referencing the plane instead of the end cap faces of the extrude.
Plan for an ID body - As Michael suggested, you can create some teeny tiny bodies at the top of the tree, and make sure all of your parts merge into those. That way you can swap out the parts, and the body ID will be stable as long as they boolean to the right ID bodies.
Assign Identity custom feature - @lana put together some featurescript functions that will let you manually set entity IDs, which could help you plan ahead for swapping things out later. For example, if you have a sketch arc as a fundamental part of your model, but you know you may later want to change it out for a spline, I think you could set it up ahead of time with this feature. I'm not sure if it will help much in your situation once the model is done. Take a look at the example part studio with the feature and change the configurations to see that the mate connector is still able to find the face it's looking for because it has had a custom ID assigned to it.

lana · August 2023

We don't have a reference repair mechanism for DXF re-import. 3d import has Update functionality which makes an effort to preserve references.

...avoid replacing ALL downstream references in timeline?!?

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