View Full Version : How to modify a profile of extruded object ?

30th Sep 2008, 09:07 pm
Hi there,
I’m new to AutoCAD 3D, so this question might have an obvious answer which I just haven’t been able to find yet.
I’m very familiar with 3D drawing in TurboCAD and I’m somewhat familiar with SolidWorks. Now I just received my copy of AutoCAD 2009 Student edition, and of course I want to get started on 3D immediately.

The questions are
#1 - how can I edit a profile of an extruded or revolved object ?
#2 – Once I revolve or extrude my profile, the original profile vanishes, how can I create a copy of a profile from an existing 3D object?

Now, I have done a little bit of playing and searching before I asked these questions but I haven’t been able to find the answer.

For #1, I know once I select the object I get the grip handles which I can move. But what if I need to add / remove a line or arc from the profile, how can that be done?. (If anyone is interested, in TurboCAD the profile is attached to the extruded, revolved, lofted object so you can go back and edit it later – which works only 80% of the time, the other 20% TC gets so confused that you have to start over, and clearly in SolidWorks there is no problem doing this since each feature has its sketch attached to it).

For #2, Is there any way to copy the current profile from a extrude or revolve ?

Thanks in advance


30th Sep 2008, 11:46 pm
I think you might be interested in the System Variable DELOBJ.

DELOBJ controls whether geometry used to create 3D objects is retained or deleted. Values are 0, 1, 2, -1 and -2.

For further information consult the AutoCAD 2009 Help files.

1st Oct 2008, 01:06 am
as far as i know the modeling in acad isnt parametric like in solidworks, inventor, catia, unigraphics etc. In solidworks you were able to create a sketch and use this data to alter your solid at any point. While you can modify solid object in acad in various ways, as far as i know, it is not parametric.

if you select your object and go to properties you can modify things associate with the operation used to create your solid. For example with the revolved solid. In properties you can change the revolution amount(0-360), you can change the location of the rev axis, and i think there may be another thing you can change.

There is one option. use the explode command. This will separate your solid into a surface and its defining curves. you can delete the surface, and modify the curves, rejoin them and revolve them.

Parametric modeling a great tool to have, when modeling in acad you have to be a little more careful:)

If you have access to acad inventor, the setup is similar to solidworks. I have never used turbocad

1st Oct 2008, 02:16 am
Thank you for you reply, I ll take a look at DELOBJ.

As for parametric design, I fully understand the difference between a 'fixed' design like AutoCAD, TC and many other CAD and then parametric design SolidWorks, Inventor, ProE and maybe others, but the question is not parametric related, but in general how to modify the profile that was used as base for the extrude.

Lets say I have the profile, then I extrude it and then after that I need to insert an arc like shown here. In this case I had to create the arc, then extrude and subtract it, which works in this case, but it would definitely be easier to be allowed to modify the orignal profile, and insert the arc right there.


1st Oct 2008, 02:39 am
The way you did it, by Subtracting the Extruded arc, is the way its done in Autocad. You could have also just created a Cylinder with the correct radius, moved it into position and then Subtracted it from your shape.

You might want to update your profile to show which version of Autocad you're using. It will make things easier, in the future, when trying to get answers.

1st Oct 2008, 02:45 am
thank you for the reply.

1st Oct 2008, 02:53 am
Jesper, Solidworks is parametric feature based design, autocad is not. You must use the boolean operations , union, subtract, intersect (and more depending on which version of cad you are using) just as you did above. There is no reference to the original sketch lines used to created these solids. Once the solid is created you must EXPLODE the solid to retrieve the defining curves, in which case you can modify them, re join them and re extrude them.

Depending on what kind of objects you are working on you can model things with surfaces and have the ability to dynamically changes them.

The approach to modeling in these packages are totally different(unfortunately).

If you wanted to model the same object you have drawn you can create the profile, use properties to give the object a thickness, then use the defining curves to create a REGION. This would appear the same but be a surface model and allow for modification. Depending on the acad package there is a sufrace-solid command built in(07-09). 06 and older this will have to be achieved with an autoLISP command.

1st Oct 2008, 11:29 am
I'm still holding out for resetting DELOBJ. Then you'll have access to the original profile (as you call it). Once an object is extruded or revolved or whatever (turned into a solid) you're basically stuck with the various solids editing tools plus the join, subtract and intersect commands for modifying its appearance.

7th Oct 2008, 11:32 pm
solidedit-> face-> copy to get your profile from an extruded solid...

I couldn't get it to work for revolved objects though.

8th Oct 2008, 04:22 am
It works for revolved objects too, although the round part isnt much use to anything

Another solution would be to copy face the "original profile," explode it, make the changes, region it and re-extrude it

For simple designs like that its alot of extra steps for little gain when a simple boolean operation would suffice
This is more useful with much more complicated models