topic Re: Cut Plane Modifier - Part Builder in Civil 3D Forum

Cut Plane Modifier - Part Builder

boutlaneyoussef — Wed, 25 Aug 2021 08:25:01 GMT

Hello everyone,

Can anyone have any idea how to use cut plane modifier in part builder ?

I'm following the Help instructions but it does nothing.

Thanks in advance,

Re: Cut Plane Modifier - Part Builder

boutlaneyoussef — Wed, 25 Aug 2021 13:50:49 GMT

Just to give more information about what I'm trying to do.

I want to model a headwall for a box culvert like you can see below :

In part builder, I have modeled this :

Now I need to use a cut plane to have the appropriate slope for my wing wall.

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P.S. : I tried modelling the wing wall using different methods. For example, i used a custom work plan representing one of the wing walls faces.

I have modeled the part like this (this is what i want) :

However when I insert this structure in my drawing, the wing wall and the rest of the structure are modeled separately :

Thanks in advance.

Re: Cut Plane Modifier - Part Builder

makourani — Tue, 24 Oct 2023 07:57:44 GMT

I am facing same problem. Can someone help?

Re: Cut Plane Modifier - Part Builder

tdivittis — Sun, 02 Feb 2025 14:46:27 GMT

This is one of those curiously (and inexplicably) top secret subjects that (apparently) no one who knows is allowed to discuss publicly under threat of grave bodily harm, or something.

I've come to the conclusion that the closest you can get is to approximate the shape you're looking for with a Transition between two rectangular profiles, one at the face of the endwall and the smaller one at the end of the wing. The end will be parallel to the endwall, instead of being perpendicular to the wing wall face, of course, but that seems to be the closest you can get. (I do hope to be proven wrong about it.)

Re: Cut Plane Modifier - Part Builder

tdivittis — Sun, 02 Feb 2025 21:30:43 GMT

It hit me after (finally) finishing this endwall, that it should be relatively easy to put a small, triangular extrusion at the end of the wingwalls to make the ends perpendicular.

If anyone is interested in the intent, this is a PennDOT Type D-W endwall, RC-31 in Publication 72. This ONLY handles the Skew 90-60 degree scenario for each pipe size from 36" to 72". Each skew will have to be another part. I believe they could all be done in one part, but I'm out of patience for it, as this was mainly a learning exercise for myself for now.

If anyone wants any explanation on specific aspects of what I did, I'd be happy to share. I don't have the time to write it all up at the moment, or I would give that a try. I hope someone finds this useful. It's really unfortunate that the documentation is so bad on Part Builder. One key thing is that you cannot have non-orthogonal work planes. I spent several hours trying to cheat one in, and that didn't work. Also, I had zero success with cut planes. They simply did not do anything. If it was something I was doing wrong, I would LOVE to see how they work.

Re: Cut Plane Modifier - Part Builder

Bratz2 — Tue, 07 Apr 2026 19:36:25 GMT

I would love an explination, as I'm currently trying to do this for TXDOT wingwalls

Re: Cut Plane Modifier - Part Builder

ScottSEYQW — Wed, 01 Jul 2026 13:04:29 GMT

I am looking for this endwall. would you be able to share this .dwg file for part builder with me along with the other few files that are saved in the structure folder?

Re: Cut Plane Modifier - Part Builder

hippe013 — Wed, 01 Jul 2026 22:14:02 GMT

I don't use the Cut-Plane Modifier as it cannot be defined parametrically. When cutting out the slopes for wing walls or the tapered slope of a flared end section (my example here), I create a vertical center plane that passes through the insertion point of the part. I then define the wedge (used to cut out the slope) on that plane as a MidPlane Extrusion. Please note that I am omitting the other subtraction modifiers that make up this part to keep this post short and to the point.

This works parametrically, as the part size changes, so does the wedge. This same idea can be used to cut the slopes of the wingwalls.