strange, I cannot reproduce the above?
I've tried it with an object without any fillets, and still no luck. It just calculates for a long them and then nothing.
Thickness 0.5, direction flip.

The new model you have posted is constructed differently. Unfortunately there is bad curvature where the top joins and around where the arches are.

I have rebuilt the model,.. blending the top and replacing the arches.

Thank you. I must be doing something very wrong when constructing stuff in moi. Back to the drawing board.

Hello,

When making a model that is to be shelled then extra care is needed, as it can become a very complex process for calculation of the surface offsets, this applies to any nurbs package. I know some programs such as solidworks will attempt to build and give warnings of surface problems and will attempt to create an approximation, but you do need to spend the extra $.

I will put a post together to show what I did to change your model, which should help to show you how I would construct taking into account a need to try and keep the surfaces smooth.

That would be very helpful. I realize that this is not specific to moi3d, but caused by my inexperience with cad programs in general (moi is/was my first try and choice).

We will first look at the top of the model (Train2).

It looks like you have made one half and then mirror, but at the top seam/join the surface dips in, it does not make a smooth surface. This on its own will not cause a major problem for the shelling, but if you attempt a fillet along the edge then it will have problems. (it would also show up in a render, which is not always wanted)



What I did to check this was to select the model, click on the 2 end edges, then copy - paste (which will copy the edges and then paste back the curves), you can then select "show points"



In the right hand view you can better see the control points that make up the curve. The center point is actually 2 points, one on each end of the 2 curves, now as you move out on ether side of those center points you can see the next control points are higher than the points in the center, this makes the curves dip in (if you select those 2 points and move them up or down (in the right hand view) you will see this dipping more clearly.



So when creating those curves for the surface, make sure those 2 points line up with the center points, you can use the "Align". Just select the center points and those 2 points on each side, then select "Align" - "Horiz center", then click on the center point which will align those point horizontally. You can then use the curves to extrude to create the surface




When I edited your model, I actually trimmed off the top surfaces and used blend, but it is better to get the curves aligned correctly then no editing is needed.

If anything is unclear, then just ask.


(I will make a further post a little later, I need to go out now)

so far so good. Looking forward to the rest.

managed to get a few steps further by keeping everything clean. Currently, I am trying to figure out how to close the areas between the offset and the original. I've tried networking them together, but that does not seem to do the trick.

from were you are up to:


I am not sure as to how you got to this stage with the model, but if we look at the curves you have used for the doorways/ windows there are some problems.



if we look at the top of the doorway where you have used those curves to trim the surface, then zoom in to where I have highlighted




you can see there are problems with the edges produced. this will then cause more problems when attempting further work




So, lets move back.
I have taken the main skin of the train and then made an offset surface



When drawing the curves for the arch at the top of the doorway I have made sure that the curves align (basically the same as we looked at before) for the bottom of the doorway I used fillet.



Ithen used those curves to trim away the doorway.

For the windows, I just made 3 lines to get the shape I want



Then selecting 2 of those lines I used "fillet" and just used a size that looked ok for the example. I then select the 2 lines that made the other corner, and again used fillet.



I then used those lines to cut out the windows. (I have hidden the door/window cutouts to show better)




Now, to fill the gap between the 2 surfaces.

First select one of the surfaces and then select all the edges of the surface that make up the opening of the door/window. Once all selected,press "Join", this will in fact copy those edges, paste them back and join them, repeat tis for the other surface.





When done, select both of those curves that have been created and select "loft" which will create the surface needed.




sorry for the long delay in my replies, I have a lot on at the moment.


Regards,

- Steve

I ended up using merge to cut the door and windows out of the solid, after which I had to delete a couple of faces. I presume there is a better method? I tried several boolean operations, but the above was the only one which seemed to work.

>>I ended up using merge to cut the door and windows out of the solid

The model you posted was not solid. So there was some problem during your building,.. either the model was not solid before the merge or the curves you used (with the problems I highlighted) have caused the problem.
Put a sketch together of what you are trying to build and post this,.. we can go through the process of construction. At the moment we are jumping from problem to problem. lets start from base and go from there, if that is OK with you?


regards,