Problems creating soft Blend/Transition


i’m modelling a phone case from a physical sample that i have. It works 99 % fine. There is only one thing i could’t make with the tools shapr offers. Maybe someone has an ides how to build it properly. I will describe the problem:

As you see in the pictures above, on the top part of the case there is a rounded border. I have created that with the sweep tool. So far so good.

The problem is that this rounded contour finishes softly at the end of the case. To achieve this i used several construction planes and lofted 6 round shapes with different sizes. The result is ok but not very clean. Look:

Does anyone has an idea how this could be done properly? I guess if the sweep and the loft tool could be combined like “different shapes at different points on a rail” this would do the work. Or maybe something like with the fillet tool in Rhino, where you can define different radiuses on an edge. What do you think?

Thank you for having a look at this topic!

Hi there, I like your idea but that way it is hard to get the required references for a clear transition.

What you need is a cross-section of the case on each plane you have created. Then you can draw the cross-sections to blend the rounded contour into the case. You should look for is to make the blended cross-section tangent to the projected cross-section on each plane.
The challenge is that you cannot create a simple intersection between the planes and the case, so you should do that for yourself with the available Boolean tools.

Instead of planes, you should create solid bodies. Create a plane parallel to the base plane and draw a sketch on it which kinda follows the order of the planes you started with.

Select the cross-section between two lines and extrude it out as a new body. The goal is to get a slice of the original case, so you should use the Intersect tool with the case and the last extruded body. The result should look something like this:

On each slice like this there are two planar surfaces which is perfect for creating the cross section for gradual loft of the rounded contour. Select one planar side and draw the cross section to loft/sweep together. Please take care to make the curves tangent to the edge of the cross section to get a smooth continuity when Unioning the case and the rounded contour.

You will probably need 3 or 4 or these sections to define a smooth transition and you are ready with the case. I hope it will be helpful

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Hi Peter,

thank you a lot for your quick help and the effort you have put into it!

This way looks really promising. Great move to work with solid bodies instead of using planes only. The problem (that you perfectly identified) was, that i couldn’t draw the curves with precision. With your way i can make the use of the “make it tangent” constraint. Great! I will try this out.

This is not an easy task to perform in 3D Shaper, due it is NOT JET a design surfacing tool with freeform options still missing, even SUBD will not be available the coming every year although ALL CAD systems of value do have the versions published and coming now!!. Still fillets are not worked as a function covering following 3D surface shapes of any kind jet! But I suppose this will come as the first update soon in 3DShaper as it looks to me! Boolean substractions of the inside of your phone case is a must as so far sheet modelling functions in 3DShaper will come sooner then you might expect. 3DShaper is still in Avery fast developing mode, faster then Rhino was and improving functions like those desired of you in an enormous speed, so sitt down and follow 3DShaper lokeI do…it is a strong CAD- program becoming a copyeditor rooted in Siemens Next world which has all these functions already coded and in use!

Hämta Outlook för Android

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Here’s something you might wan to try. The object in this video represents your internal rounded shape that you wish to contour at one end of the case. I made the body a “D” shape for demo purposes. I show 3 examples of how you can use the Scale tool to create a uniform taper or contour. Hope this helps.



Hello Mike,

thank you for another good idea and the nice little video tutorial. Great!