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wilkes704

trying to create a pie shape for a dome that will be cnc cut

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wilkes704

My grasp of auto cad(version 2004 here) is tenuous at best. I've attached two .dxf files. roof.dxf demonstrates what I am trying to create, roof panel 3d.dxf is what I actually need.

 

From what I've gathered from reading and research that autocad won't "unroll' the shape so that I'll end up with a pattern that I can cut. I realize that there are 3rd party programs that will do just this. I'm trying to create a dxf file that will import. I'll have to cross that bridge when I get there.

 

From what I understand my shape needs to be a mesh, but I am having trouble turning it into one. I can't seem to get the polylines to join to create a solid object.

 

This is my first foray into something 3d and I hope I am on the right track. I'm kind of on a dead line with this fabrication project at work and I need to get some progress made.

 

Any direction and pointers would certainly be appreciated.

roof.dxf

roof panel 3d.dxf

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ReMark

To create a solid you would have to sweep a closed profile (made up of a vertical line, horizontal line and arc) along the path of the circle with the 24.00 radius.

 

To create a surface you would have to sweep only the arc along the path of the circle.

 

Use the MESHSMOOTH command to create the mesh although the results may not be exactly what you are looking for.

 

I'd suggest using a mesh primitive but I have no experience in working with them. Who knows, maybe it would be easier. Perhaps another member can educate us both.

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ReMark

DomeHead.jpg

The yellow object is a surface. The magenta object is a solid.

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wilkes704

What steps did you use to create the surface?

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ReMark

I mentioned that previously. I swept an arc along the path defined by your circle.

 

This is one of those problems that might be better suited to Inventor.

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ReMark

Think about it. You have everything you need in the roof.dxf file you uploaded. You don't need the whole arc that goes all the way across the circle you just need half of it. Reorient your UCS, draw a vertical line from the center of the circle through your arc. Trim the arc then sweep the remaining piece of arc along the path formed by the circle. Should take no more than 30 seconds.

 

SweepanArc.JPG

The three things you need.

 

I still think in the end Inventor will provide you with a better solution.

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wilkes704

I understand the concept, but I don't understand the steps to actually create the sweep in autocad

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ReMark

Invoke the Sweep command. Look at the command line and what you are being asked to do. Pick the object you want to sweep and then pick the path you want to follow. Object = part of arc. Path = circle. It doesn't get any easier than that.

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wilkes704

I keep getting sweep is an unknown command. I'm using an older version of autocad. 2004.

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ReMark

I thought that was a typo since your profile says 2014. There was no Sweep command in 2004.

 

You'll have to use another command called Revolve. You also need to use the Object option and pick the vertical line. Specify an angle of -45 degrees and you should get the wedge shape you are looking for.

Edited by ReMark

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wilkes704

I can get the outer ring to extrude up, but not in any way that is remotely useful.

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wilkes704

Sadly, it isn't a typo, it is what came with the cnc plasma cutter. I'm having to make do with it.

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ReMark
I can get the outer ring to extrude up, but not in any way that is remotely useful.

 

See post #11.

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ReMark

Sorry but I got things to do. Download and open the attached drawing. I'm giving you a wedgie.:lol: It is saved in 2000 file format. You're on your own at this point. Adios amigos!

 

Wedgie2004.dwg

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wilkes704

I appreciate it

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ReMark

It's early morning and I've just had my tenth cup of coffee. Now that the brain is fully functional I figured out how to create the curved wedge as a mesh. I really should have remembered this yesterday but I was in a bit of a rush.

 

MeshWedge.jpg

 

Start with a portion of your original geometry (shown on the left) and add a vertical line. Trim the two arcs. Use the Rulesurf command and when prompted to select the first and second defining curves pick a different arc segment each time. The result will be a mesh object as seen on the right.

 

For a smoother result change the variables SURFTAB1 and SURFTAB2 from their default of "6" to something more like "20".

 

Or just download the attached (saved in 2000 file format).

 

MeshCurvedWedge.dwg

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wilkes704

Ah thank you! It's the compound curve that was giving me problems. I'll see if I can get this unrolled and see what happens.

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ReMark

I'm not sure how you would go about doing that without using another program.

 

I found a program that will unfold a surface (not a mesh) here...http://www.solid3dtech.com/autocad_link/default.html

 

There is a program at a website called Black-cad that will also unfold (flatten) a surface. Find it here...http://www.ant-ares.de/

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wilkes704

Not so much luck with unrolling it.

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