Trouble creating complex arc

I am trying model a broken trim piece that i want to 3d print. I am having a lot of trouble with the center arch area. It has alternating and compounding slope angles. Im not really sure how to go about modeling this piece. Any help would be appreciated

A few more pictures to show the complexities of the shape . Again, strugging with opposing angle from the inside and outside of the arch

Hi Adam3D,

I would trace over the outside using pencil, followed by taking good measurements. Or do both at the same time.

Scan the tracing, then scale the measurements. Then using the sample start your drawing process. I would start with the basic shape first.

It doesn’t look easy, but it does look like fun.

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Use a vector program like Corel Draw or Inkscape to draw your curves and export as DXF. I find it so much easier than drawing with Shapr. You can import the image to draw over it easily. I would draw the base arcs and then the top surface arc and loft from the base to the top surface. Then add the 2 side parts on a plane in shapr.

If you draw half of the part import the dfx and loft it, then use the mirror tool in Shapr.


That is how i started out. First problem is the arc is a clean hemispheric shape . I attempted to make the shape with the sign tool , with somewhat success but immediately ran into problems trying to convert to 3d.

I then started using the ellipse tool to try and create the arch. This seeemd to work better , but the problem of mulitple angles is the challenge. This one is going to take a while !

Hi Adam3D,

If you send me some dimensions I can help you with the construct.

I did that and couldn’t get it to loft. I sent in a trouble ticket. Is the top flat? surface parallel to the bottom surface?

View of bottom angles

This is where i am at. Made some progress ,
but my proportion seem off. I may have to start over. I started from inside out, i think i am better outside in.

The bottom is not even either , i can only post 1 picture per post. Will make another post with bottom angles .

Another angle

Well this is where i am! Pretty happy with , going to try a test print.

The top of the arch is solid i was not able to shell it out like the original .

I wish i could tell you how i did it but honestly just a TON of trial and error and first pounding! SHAPR3D gives you all the tools you jist have figure out how to apply them !


Nice result :+1: