topic Re: Cannot create dome.. in AutoCAD Forum

Cannot create dome..

Anonymous — Sun, 10 Sep 2017 09:12:06 GMT

SO I cannot create dome in the center... I creaed spline and two arcs in the middle. When I try to loft these, it wonk work. I also tried using NETWORKSRF, but stilll havent been able to achieve it :(( What am I doing wrong here?

Re: Cannot create dome..

Alfred.NESWADBA — Sun, 10 Sep 2017 11:50:50 GMT

Hi,

please find attached a video for how to get that part done.

2 additional suggestions:

instead of turning layers off please use "freeze layers" (makes you more safe against modifying objects you did not want to and also make the display faster).
never use layer "defpoints" for your objects (this layer has a special meaning for AutoCAD and is used internally.

- alfred -

Re: Cannot create dome..

imadHabash — Sun, 10 Sep 2017 12:19:00 GMT

Hi,

use REVOLVE command to revolve the arc around the vertical and central line 360 to get what you ask for ( see below image).

Command: REVOLVE
Current wire frame density: ISOLINES=4, Closed profiles creation mode = Solid

Select objects to revolve or [MOde]: 1 found

Select objects to revolve or [MOde]:
Specify axis start point or define axis by [Object/X/Y/Z] <Object>:
Select an object:

Specify angle of revolution or [STart angle/Reverse/EXpression] <360>:

Regards,

Re: Cannot create dome..

Anonymous — Sun, 10 Sep 2017 14:14:39 GMT

What is UCS? WHy do I need radius line of circle to be closed? When I close it, then i cant join spline with other two lines... when I join them without closing, i cant revolve them...

Re: Cannot create dome..

Anonymous — Sun, 10 Sep 2017 14:26:15 GMT

I need it in solid...

Re: Cannot create dome..

Alfred.NESWADBA — Sun, 10 Sep 2017 14:35:31 GMT

Hi,

>> What is UCS?

A command to specify a User-Coordinate(you can't work without that whenever you do some 3D work.

And the help of AutoCAD can be asked first!

For a command: type in the command-line of AutoCAD

UCS<ENTER>

and then press <F1> 😉

>> WHy do I need radius line of circle to be closed?

To get a 3D-solid as result.

Only closed contours will create 3D-Solids when running commands like _EXTRUDE or _REVOLVE

- alfred -

Re: Cannot create dome..

Anonymous — Sun, 10 Sep 2017 17:48:48 GMT

I did that as You showed me in video finally :0 how can I confirm that dome is solid? Because i cant Union both parts...

Re: Cannot create dome..

Alfred.NESWADBA — Sun, 10 Sep 2017 18:33:02 GMT

Hi,

>> how can I confirm that dome is solid?

Either run command _LIST and select your object, or open the property window and look to the top line while your object is selected.

>> Because i cant Union both parts

Look to the command-line when you start the command _UNION, it tells you:

At least 2 solids, surfaces, or coplanar regions must be selected.

So as the dome is a 3D-Solid the other object is it not, and I guess the second object you selected was the array, am I correct?
An array is not a 3D-Solid (even if it consists of 3D-Solid objects).

What you can do is to start command _EXPLODE, select the array ==> so the parts of the array are selectable now ... then you can run command _UNION with the other elements + the dome.

[EDIT] if you want to run _UNION with the parts of the array, you'll need first to make 3D-Solids from that parts, that are only surfaces.

Sorry, have not seen that before [/EDIT]

- alfred -

Re: Cannot create dome..

Anonymous — Sun, 10 Sep 2017 21:02:31 GMT

When I do Explode, yes the petals are selectable. But then when I _Union, petals and frame with dome become two bodies

When I try again _union on them, It says that one of these arent solid

Re: Cannot create dome..

beyoungjr — Sun, 10 Sep 2017 22:18:10 GMT

Post 3 showed you the revolve method but the contour shown in @imadHabash's example is not a closed boundary. Thus the result is not a solid but a surface. To get a solid you would need to follow the advice in post 6 by @Alfred.NESWADBA where he explained to use a closed boundary to get a solid.

You have the full model & I see an array of the surface. I Explode the array to get individual petal surfaces and I select one of the surfaces. I then Move that surface a distance (50 units) above the part in the Z direction. I close the bottom of the petal with a Patch Surface using the edges of the existing petal. I then Union the patch surface and the existing loft surface (there is a notice that union is not recommended but I accept anyway).

Now I use Convert to Solid on the Mesh ribbon and the union-ed surface becomes a solid.

Now I can Move the solid back onto the intended assembly and array it once again after deleting the remaining surface petals. You will now be able to Union the solids.

Cheers,

Blaine

Re: Cannot create dome..

Anonymous — Mon, 11 Sep 2017 06:27:41 GMT

I think I managed to achieve that with patching and Union surfaces. I transfered shape into new file. How do I know that whole shape is truly solid?

Re: Cannot create dome..

parkr4st — Mon, 11 Sep 2017 09:02:01 GMT

select the array; Xplode once and select any part; properties will state 3D solid for all the parts.

remember way back in this thread https://forums.autodesk.com/t5/autocad-forum/extrude-object-removed-from-selection-set/m-p/7364591#M896823

I stated

there is/are problem(s) in the original line work someplace.

Zoom in on the end of a petal and you can see the petal does no align with the part below it. very minor stuff and may be acceptable.

after the surface patch it may pay to extrude that surface down 5 units and replace the bases with that solid if you need exact alignment.

good luck with the project. you have done well working through the project.

dave

Re: Cannot create dome..

Anonymous — Mon, 11 Sep 2017 10:02:04 GMT

Dmn it, im gonna have to start over... im so lost here...

Re: Cannot create dome..

dieters — Mon, 11 Sep 2017 14:28:06 GMT

That's how we learn.

But first, as Alfred suggested, get very comfortable with the User Coordinate System. The UCS is essential to establish construction planes (UCS + 3 points), orthogonal directions, and axes of revolution (UCS ZA). Use the attached DWG to practice on: draw a circle on every plane. Make the UCS Z axis align with the ridge and use ROTATE to make the swing rotate.

Next create profiles in 3D by creating 2D geometry, using BOUNDARY to create a closed polylines (or regions) from objects that enclose an area. With the ZA option of the UCS command, establish axes of rotation and rotate the closed polylines into place.

Then, use EXTRUDE, REVOLVE, and SWEEP to generate 3D solids from the closed polylines.

Finally, combine the results with Boolean operations such as UNION, SUBTRACT, and INTERSECT.

Tip: Turn off DELOBJ to retain your original profiles and put them on a reference layer. You'll likely need them later for sanity checks and for recreating some of your 3D solids.

Dieter

Re: Cannot create dome..

Anonymous — Mon, 11 Sep 2017 18:18:04 GMT

How does one convert extruded object to solid?

Re: Cannot create dome..

dieters — Mon, 11 Sep 2017 18:33:54 GMT

The extruded object in your DWG is already a 3D solid. You can verify objects in your drawing with the LIST or PROPERTIES commands. You might want to use the Conceptual or X-ray visual style to view your model.

What kind of dome? Hemispherical, parabolic, faceted, trimmed?

Dieter

Re: Cannot create dome..

Anonymous — Mon, 11 Sep 2017 18:48:14 GMT

There, I have prepared for another try to create this flower (in .pdf) I only extruded polygon and circle, did not _Union them. Dome (this part also should be solid) and petal surface (Not solid) and the polygon itself I have aligned with UCS - Thanks for Advice. Now Since I have everything ready, I need this flower to be just like in .pdf, & solid shape. What are technical details to create such object, so I am sure that it is in solid form? 🙂

Re: Cannot create dome..

john.vellek — Mon, 11 Sep 2017 22:04:04 GMT

Hi @Anonymous,

I took a look at the sample file you sent me.

I noticed you had the base drawn correctly with a height of 5. (but with only 9 sides and not 10)

Then I noticed that the petal also has a base height of 3 before it arced.

The inner dome (with a height of 7) sits upon a base with a height of 3.

So, on your base, I create a cylinder (at the center) with the height of 3 to act as the base of the dome.
Next, I took the outline of the petal (making sure that the inside radius where it meets the dome had the correct diameter) and PressPulled it to a height of 3.
Next, I took the center line of the petal and lofted it with both side of the petal outline.
Next, I drew a horizontal line from the center of the dome base to the edge of the dome base (length of 12.5)
I drew the vertical curve from this endpoint back to the centerpoint (top) of the dome. I used JOIN to connect the arc and the horizontal line.
Then I used Revolve on this joined linework and revolved about the vertical center axis of the dome.
Lastly, I uses ARRAY to get a total of 9 petals rotated around the center of the dome.

Now I could UNION all the pieces to make a single solid.

I have attached my version of this process with copies of each phase in its construction. I hope that I interpreted the sample correctly and that you can follow all of these steps to create your own (hopefully better) version of this design.

Please select the Accept as Solution button if my post solves your issue or answers your question.

Re: Cannot create dome..

Anonymous — Tue, 12 Sep 2017 06:41:28 GMT

Does polar arraying of 1 segment creates other 9 in solid form?

Re: Cannot create dome..

parkr4st — Tue, 12 Sep 2017 10:13:50 GMT

John, nice job. Kudos to you

Aleksandras pay attention to John's added cross sections to form the petal. a cross section at each node along the sides, that fills out those minor voids of your petal.

but the solid petal part, go back to blyoung post using SURFPATCH and form a "bottom" to the petal;

as stated in that poat

I close the bottom of the petal with a Patch Surface using the edges of the existing petal. I then Union the patch surface and the existing loft surface (there is a notice that union is not recommended but I accept anyway).

Now I use Convert to Solid on the Mesh ribbon and the union-ed surface becomes a solid.

Now I can Move the solid back onto the intended assembly and array it once again after deleting the remaining surface petals. You will now be able to Union the solids.

Aleksandras, give out the kudos to all the helpers in your post, all are well deserved.

hope you can draft this and other objects like it now.

Kudos to all the help here!

dave