topic Re: Converting polyline array to solid in AutoCAD Forum

Converting polyline array to solid

bert_Greeley — Mon, 13 Mar 2023 17:15:50 GMT

I am tryiing to create a roof section for a model railroad car. I have the shape created in a 3D series of polylines, but I can't figure out how to make it a solid.

Note that I have tried to start with making a solid but the shape is a 3D parabolic curve in the XY plane. Well, actually it wold be half of a parpbolic curve. I created it using an elipse, then using DIVIDE I created points that I could use to guide making a polyline. I connected one quarter of the elipse, then snapped to CENTER and to the next quadrant. I continued with this method stepping back through the desired shape, then rotated to the LEFT view and repeated the process in the XZ plane.

But I can't turn this into a soid.

Any help would be appreciated.

Re: Converting polyline array to solid

Patchy — Mon, 13 Mar 2023 17:40:03 GMT

Try LOFT

Re: Converting polyline array to solid

Valentin_CAD — Mon, 13 Mar 2023 17:46:24 GMT

@bert_Greeley ,

Sounds like you need to create a 3D modeling or surface.

Take a look at these links:

Also, look at the videos related to 3D for Tips and Tricks:

Webinars: Build Your AutoCAD IQ

Re: Converting polyline array to solid

GeeHaa — Mon, 13 Mar 2023 18:17:56 GMT

If you created a "closed" polyline which means it totally encloses an area you can use the extrude command to turn it into a 3d solid.

Re: Converting polyline array to solid

dmfrazier — Mon, 13 Mar 2023 19:41:48 GMT

In case none of the previous replies has led to a solution, if you were to post the relevant part of your model one of us might be able to help you find one.

Re: Converting polyline array to solid

bert_Greeley — Tue, 14 Mar 2023 00:50:33 GMT

Extrude will give me a chunk exactly the same size as the polyline. I need to have it progressively shrink in size. Even using PATH would simply build an arched shape. This needs to be a 3D curved surface. Thik of a half-cone in the shape of a oblate in two dimensions.

Re: Converting polyline array to solid

bert_Greeley — Tue, 14 Mar 2023 01:20:26 GMT

Here is a PDF of what I'm trying to create. Remember that I'm building a model raailroad car. I design everything in real-world size. Then, if I want an HO model, I create an STL at 1:87; if I want O scale, it's 1:48, etc. With the given second scaling of 25.4 because none of these stupid 3D printers understand imperial measurements!

I have designed a Shay engine (3-cylinder vertical steam engine) complete with passageways. I've used some pretty convoluted extrudes based on multiple plines and then unioned together. Look at the exhaust system on the second PDF. This is the engine and truck that poweres the McKeen cars.

Re: Converting polyline array to solid

Patchy — Tue, 14 Mar 2023 02:31:08 GMT

Loft and use 3 guides as shown.