topic Re: 3D solid edges not connected, looking for possible fix. in AutoCAD Forum

3D solid edges not connected, looking for possible fix.

raybryant1998 — Thu, 14 Jan 2021 15:12:31 GMT

I was working with the following solid when I noticed that my snaps were not accurate at the corners of the model. When I zoomed in I noticed that none of the edges were connected. I'm not sure how this occured or how to fix it. I have more screenshots available if needed.

Re: 3D solid edges not connected, looking for possible fix.

leeminardi — Thu, 14 Jan 2021 15:28:16 GMT

If the design goal is to have 4 flat polygons that have a thickness I would explode then delete all the geometry except the 4 profiles. Define a ucs for a specific profile and create a polyline on that profile using "c" to make sure the polyline is closed. You can then extrude it to the desired thickness. Repeat for the remaining profiles.

Re: 3D solid edges not connected, looking for possible fix.

raybryant1998 — Thu, 14 Jan 2021 15:47:53 GMT

I believe this is approximately what I did to get to this point.

In the first picture are the three separate panels I made via extructions and some surface modeling. I attached them all together using corner snaps. I then created a very thin green 3D shape and subtracted that from the three panels to union them together, and level out the bottom of the assembly since it was uneven. The reason I need to join the parts is to create new panels that fit together, which I can do by sculpting out the correct shapes from the unioned assembly.

I'm not sure why the subtract command compromises certain connections on the model.

Thanks,

-Ray

Re: 3D solid edges not connected, looking for possible fix.

leeminardi — Thu, 14 Jan 2021 16:00:59 GMT

Why make the green shape thin? Make it much thicker than necessary to get the flat bottom surface I think you want.

It is difficult to interpret what the problem may be from just images. Can you post the dwg file?

What is your final goal?

Re: 3D solid edges not connected, looking for possible fix.

raybryant1998 — Thu, 14 Jan 2021 16:47:41 GMT

Here is the dwg file. I made it thin so that it didn't affect the geometry too much. So I used a 0.01 inch extrusion. I could make it thicker in the other direction, but I'm not sure what that would achieve.

Re: 3D solid edges not connected, looking for possible fix.

leeminardi — Thu, 14 Jan 2021 16:56:44 GMT

Again, what is your goal? Are you trying to get 4 flat solid panels, one 3D solid without extraneous artifacts or something else? I assume you want to get rid of the overlap at "A" but what do you consider the attributes of an acceptable solution? The more information you provide the better.

Re: 3D solid edges not connected, looking for possible fix.

raybryant1998 — Thu, 14 Jan 2021 17:03:12 GMT

The separate 3D models overalap each other. I wanted to combine them into a 3D solid, that I could then separate in a way to create 3 panels that don't overlap.

I'm also trying to iron out a couple of issues like the one you circled. But thats not possible with edges that do not connect.

Re: 3D solid edges not connected, looking for possible fix.

leeminardi — Thu, 14 Jan 2021 18:55:05 GMT

Given the 3d solid model of the entire shape, use successive uses of the slice command, 3 point option, to define slicing planes to make the individual parts.

Re: 3D solid edges not connected, looking for possible fix.

raybryant1998 — Thu, 14 Jan 2021 19:50:37 GMT

Thats what I was planning on doing, but I can't slice them properly without connected edges, since slight modifications have to be made at the overlaps.

These parts have to be designed to be welded together, so I will be adding grooves and other welding features to the parts.

Re: 3D solid edges not connected, looking for possible fix.

leeminardi — Fri, 15 Jan 2021 03:45:23 GMT

So is it this area of the model that you want to fix before slicing it up?

If so, define a ucs along the top surface and and add a box.

union it with the existing solid and use slice and Boolean subtract to trim it. Sometimes slice would post an error that the slice plane did not intersect the solid although it did. In these cases I created a box and used Boolean subtract which did work.

I got to this point in the process and found that one of the surfaces I thought was flat is not flat.

One way to ensure a flat surface is to create a UCS at the orientation that should define the flat surface and then create a polyline starting at the UCS 0,0,0.

The following image shows the 3 points used to define a ucs. The green polyline are the points1, 2, 3, 4 and 5 projected to that plane.

I extruded the green polyline to with a taper of -30° to ensure that the edge surfaces of the extrusion would go beyond the adjacent surfaces while anticipating that they would be trimmed later.

The union of the two solids failed! This leads me to think I should go back to your original geometry and work with the 3d wireframe model before it is given thickness and make sure the 4 surfaces are flat before making the shape a solid.

The image below shows the result of rebuilding the 4 shapes so that they are planar. The shapes were then extruded with a taper of -20° and a thickness of 1. The taper helps to ensure that gaps between extrusion are filled.

At this point we can use slice and Boolean subtract the clean up the geometry. I had much better success with subtract than slice.

Here's the final trimmed shape.

Good night!