Hi Rudl, also probably if you had the original object a solid the offset would work ok in MoI too, since then the assumption of "one input vertex generates one output vertex" would hold true.

It's in this case of a non-solid object with open boundary edges like you've got here where that "one input vertex generates one output vertex" assumption does not hold true anymore, and that's when MoI will produce a badly formed result, it will have just one vertex in there instead of it branching out into more than one with a new edge between them like you see in the TC result.

So the actual goal for what I hope they'll be able to do to improve the offsetting is to actually generate I think the same result as what you don't like from TC...

- Michael

Thank you all,

@ Michael, I will tomorrow try to understand your explanations and will tomorrow also explain what my final goal is.

The file Test2 shows in a simple way, what I want.

The file sathaus3 is the file for testing with ViaCad

THe file sathaus3 Shell is the shelled version with TC

Hi Rudl,

> The file Test2 shows in a simple way, what I want.

Probably your best bet would be to form the object up as a solid (add some sides and a bottom to it), then do a shell on the solid, then possibly slice that up if needed.

When you form it as a solid you will be basically giving information on how the "side wall" areas are supposed to be formed, when you try to thicken an open surface the system does not know that you would like to have certain areas formed like this area here in your result here:



Offsetting of a plain surface will not generate something in that direction - that's a single fixed direction like an extrusion, an offset that thickens a surface will try to follow the surface normal and so wants to make a result that goes in this direction:



So thickening by offsetting a surface will not produce this kind of planar side wall that you have in your example:



But if you were to form this shape into a solid with a vertical planar wall on that area of the solid, then that's how the system will know what the desired "side wall" shape is supposed to be over there and should then have a better shot at building what you want.

Hopefully that may help explain the problem better - with the "thicken a surface" case the offsetting mechanism just does not know when it should try to deviate from a regular offset in order to make a common side wall boundary like you have built yourself there.

Thickening a solid should work better for you because the solid has all "side walls" defined for it and would not need to try and cook them up from nothing.

- Michael

Hi Rudl, check out the attached 3DM file for an example of how to solidify your object to get that sort of result that I think you want.

I duplicated the edges of the your top surface there by copy/paste, then flattened them down using the edit frame in a side view so that they would form a planar bottom face, then drew connecting lines up and built planar walls for the sides with Construct > Planar:




Now that the object is a solid, the "side walls" are existing in the object for generating a shell - select all the side-wall and the bottom faces for the openings:




Then run Construct > Shell, and those areas will become openings, while the unselected faces remain in place. That produces a result like so which I think is close to what you want:




Again the key difference here from what you were trying to do earlier is having a solid result where there are "side walls" adjacent to the surfaces that will be offset during the shell operation. When you try to thicken an open surface, the thickener does not know how to build any kind of side walls other than ones at a 90 degree angle to the surfaces, and that's one of the biggest reasons why you'll get a different type of result in that case.

Starting with an open surface tends to work best when you are thickening only a single surface, or with multiple surfaces if they are all smoothly connected by fillets, or have a symmetrical arrangement. If you have something other than those cases, you will probably want to form a solid out of your shape first before doing the shell. Then basically the side walls of the solid will be inherited down into the shape of the shelled result.

Hope this helps!

- Michael

thanks to all.

I´ve found out the resolution for me.