Creating a Solid or surface from a mathematically generated curved line

[Anonymous]

Hi all.

Apologies first of all, as I am a total noob to CAD software. 

My issue is that I am trying to get to the point where I can 3D print a few acoustic horns so I can explore the frequency cutoff of each one for my degree (I'm a Sound Engineering student).

I have a specific curve thats been generated mathematically (Base Curve.dwg). From here I have tried several ways to revolve the curve around the central axis, and have finally landed here (Revolved Curve.dwg). This is exactly how I want the horn to look when I print (Ideally I'd like to model it to look like a gramophone horn, but that is not necessary at this point) So, I try to export the horn to STL format, but get the error "Selected Objects must be solids or watertight meshes". Which makes sense still. So I have tried a number of ways to convert to solid, or surfaces (I'm not sure the difference, but I'd have thought that I don't want the horn to be a solid as I'd loose the internal cavity, wouldn't I?)

Anyways, when I try to convert to either, I am told "Can not convert an open curve" when using the 'Convert to Solid' option in 3D Operations menu, and simply 'Objects can not be converted' when I try to convert to a surface, from the same menu. This is where I fall over. I can't for the life of me work out how to convert to a solid or surface in order to export to STL. 

My University are unable to help with autocad specific problems as its not an affiliated piece of software (seems a cop out to me) and have suggested I use their recommeded software (Blender), however this does not have the facility to execute scripts (This is how the curve has been generated).

Absolutely any help or advice would be massively appreciated as i am at a total dead end!

Thanks,

Tony.

[maxim_k]

Hi Tony,

I added thickness to the initial curve (0.1 unit), revolved this new curve and got 3D Solid which (inside red rectangle in your drawing) I was able to export to STL file (see attached Revolved Curve - low resolution and Revolved Curve-HiRes - high resolution).

If you need the horn with a smaller "wall" thickness, you need to reduce initial curve thickness - I colored it cyan.

Maxim

[Anonymous]

Maxim_K....

You sir, are a scholar and a gentleman! Thank you so much for taking the time to help!

Maxim - I aim to be producing a selection of horns of differing dimensions, based on the same method, for acoustic analysis. Would you be so kind as to briefly explain the process of increasing the thickness of the original curve please? I have just tried to use the 'thicken' option in the 3D Operations menu to replicate your work, but without success.

[maxim_k · Accepted solution]

You can use OFFSET command to offset the initial curve for the desired distance (0.1 in my example and I offset it inside).
Than connect the endpoints of two curves on the both ends with lines, than use PEDIT command to join curves and lines to single closed polyline.
Now use REVOLVE command to create the horn.

Maxim

[Anonymous]

Ahhhhh! Ok, that makes plenty of sense! So, the long and short of it is I wasn't specifying a wall thickness for the horn, which is why I couldn't convert to solid. I will have a play about with this overnight tonight!

I owe you one Maxim, thanks!