Quick solution for gap formed between an extrusion and patch surface?

mattdpalladino · January 19, 2021, 1:24pm

Id like to use the patch command to make quick 3D surfaces from extrusions. What good is the patch command if the the surface it creates leaves a wonky gap along its edge that should be connected to the extrusion it was created from?

I know I could plane cut the patch edge and then extrude down from that but then I would have to rebuild the whole model to fit it.

I tried join naked edges but it only works in small sections and is inconsistent.

Any thoughts appreciated.

-Matthew

pascal · January 19, 2021, 3:43pm

Hi Matthew - Untrim the patch surface, extend the extrusion through it, and trim them to each other.

-Pascal

mattdpalladino · January 19, 2021, 3:58pm

Hi Pascal

Thank you for the response. I will try that.

I thought I was getting close with JOIN as the two edges are very close, but I can only select two small sections of edge to join, wondering if there is a way to select entire edges to join.

Thanks!

-Matthew

mattdpalladino · January 19, 2021, 4:10pm

Hi Pascal

Untrim, extend extrusion, trim created even worse hole/ naked edge problems.

pascal · January 19, 2021, 4:17pm

hello - it looks to me like the extrusion was not extended through the patch surface. Feel free to post the surfaces. You might also try Patch with a good deal denser spans setting - but it is not ever going to hit that edge cleanly all around, you’ll need to extend/trim. Or, SubD.

-Pascal

mattdpalladino · January 19, 2021, 4:18pm

I thought to use join, but it will only let me select on small section of edge at a time. There must be a way to select the entire first edge then the entire second edge then join, right?

Any help appreciated.

File attached under image

helpedge.3dm (6.4 MB)

spb · January 20, 2021, 4:03am

As far as creating a denser patch, PatchFor_helpedge.3dm (864.7 KB) was made in another CAD application. The trimmed surface is degree 5 x 5 surface with 174 x 144 control points, but the edge discrepancy from the rest of the polysurface is still up through 0.008. If you set the model’s tolerance to 0.004 (_DocumentProperties , then go to Units - Model - Absolute tolerance), you can join the polysurface and surface into a solid. After doing so, since the model has edges as short as 0.0014, it is best to then set the tolerance back to 0.001.

How will the model be used: rendering, export mesh for 3D printing, etc.? If you only need a mesh and need to make more of these, maybe someone has a script that can “bubble up” selected planar regions of a mesh.

pascal · January 20, 2021, 5:50am

I really-really would do this in SubD surfaces in V7 - even if you need to learn it from scratch, for this type of thing, it just makes no sense to use surfaces, with SubD available.

-Pascal

mattdpalladino · January 20, 2021, 1:05pm

Hi Steve

Thanks for the response. I will look into changing tolerance and joining into solid.

I will eventually want to export mesh for 3D print.

mattdpalladino · January 20, 2021, 1:08pm

Hi Pascal.

I think you’re right, I will dive further into subD.

This was suggested originally, but I didn’t fully grasp how to manipulate subD object. I was also fond of starting with a curve drawing which didn’t seem subD friendly but I’m working on it now.

Expect me back on the forum with new questions soon…

Thanks!

M