New sketch will not revolve around the central axis

jp_lft

I'm a total beginner, I'm trying to revolve a sketch but it either warns me that it's self-intersecting when I'm trying a full revolve, or it just disappears when I try a partial, one direction revolve, what am I missing ? (the sketch extrudes fine when I try, but won't revolve)





Document : https://cad.onshape.com/documents/c53d887effac3b5ba2ed0c6c/w/3883bb8a66f35a7a79c534fb/e/4c948b67005f9a655a43aed7

Thanks in advance

S1mon

Your sketch1 seems to from your imported DXF. It's closed, but there are probably microscopic issues from the translation. You don't have any constraints so the entities may look like they are coincident at each end point, but Onshape may not internally see it that way.

A bunch of the curves are very close to arcs, but are showing up as splines. I made some assumptions and redrew the sketch replacing some of the curves with arcs and removing the very small fillet, and the revolve works just fine. I added the small fillet after. It's not clear if I needed to do that, but based on experience it seemed like a good idea.

https://cad.onshape.com/documents/65c4dbbbf26325f7584108fa/w/d9c68e0e8d9816c119837a0d/e/94aa7123eda5d81421c21b37

S1mon

Your sketch1 seems to from your imported DXF. It's closed, but there are probably microscopic issues from the translation. You don't have any constraints so the entities may look like they are coincident at each end point, but Onshape may not internally see it that way.

A bunch of the curves are very close to arcs, but are showing up as splines. I made some assumptions and redrew the sketch replacing some of the curves with arcs and removing the very small fillet, and the revolve works just fine. I added the small fillet after. It's not clear if I needed to do that, but based on experience it seemed like a good idea.

https://cad.onshape.com/documents/65c4dbbbf26325f7584108fa/w/d9c68e0e8d9816c119837a0d/e/94aa7123eda5d81421c21b37

jp_lft

Thanks a lot @S1mon, I was going crazy thinking I missed something obvious. Do you know of any ways to fix / debug or prepare DXF files for maximum compatibility ? Or maybe another format that translates better for imports?

I'm really liking Onshape so far but for more complex sketches I don't see myself redrawing everything every time.

S1mon

It’s hard to say without understanding your situation. Typically DXF imports are ok without any tweaks for extrusions, assuming they come in with closed areas. I didn’t take the time to investigate where exactly the issue was. It may have been only one curve or intersection that it didn’t like.

Revolves, sweeps, lofts may be more difficult, depending on the details. 

The real questions are where is stuff coming from and what are you trying to accomplish? The whole point of Onshape is to have parametric models, which you’re not going to get from unidimensioned DXF imports. I usually only use DXF imports for logos or sometimes PCB outlines or silkscreen layers. 

Perhaps you can tell us more about your intended workflow and we can help. 

jp_lft

Yes it makes sense to model directly into Onshape whenever possible. I was secretly hoping for the best of both worlds using more creative / freeform softwares for ideation before adding constraints into Onshape from the exported paths and iterating from there on the resulting parts. Redrawing here is not that time consuming and I'll get better at it but it's frustrating to be so close yet so far. Thanks a lot for the explanation I understand better the philosophy behind the software.