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Extruded object turns out as hollow

jw3601
Community Visitor

Extruded object turns out as hollow

jw3601
Community Visitor
Community Visitor

Hi, I'm new to AutoCad and I wanted to use the 3D modelling tools to help solve one of my homework questions.

 

jw1_0-1683981666674.png

 

I want to find the volume of this object and I've tried extruding the surfaces but it only produces a hollow shape. I've tried extruding the uneven surface (the top shape) and slicing it using the XY plane of the bottom flat surface and it still turns out as hollow. I think this is due to using 3D polylines.

 

I've attached the dwg file of my attempts.

 

Any help would be appreciated 🙂

 

 

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Washingtonn
Collaborator
Collaborator

Get rid of the top spline.

Instead of one bottom polyline, make three separate areas and extrude them such that you can slice them to get the proper slope.  Then union them together.

You don't provide any information about the height/slope of the top but it appears that it slopes in two different directions so a single slice for everything won't work.

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ChicagoLooper
Mentor
Mentor

Hi @jw3601 

If you want to compute volume, you can get it from a solid. You've drawn a surface which is why it's hollow.

 

Your object's surface isn't flat, it's sloped. So to build your solid you'll need to plan and draw multiple pieces. Draw each footprint individually then extrude.  You can slope each piece by tapering the top face. When you've got each surface sloped properly you can add all the pieces together to form a solid object.

   

Chicagolooper

EESignature

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pendean
Community Legend
Community Legend

PLINEs do that, so there is nothing wrong

pendean_0-1684155356712.png

 

Use REGION command to convert the PLINE first, then 'extrude'.

pendean_2-1684155436137.png

 

 

pendean_1-1684155419968.png