need help with lofting

marc_tinio

how do i fix the outward twist of loft 2, while keeping the shape of sketch 5?
 https://cad.onshape.com/documents/9661cd133439e3f949a2b4b5/w/1bbcaf60c98fb617e998cddc/e/68ea4f25044fbf15bbf73f1e

steve_shubin

@marc_tinio

In the document below, the bottom of the part is flat — on plane.

If you’re looking for something like this, you could step through the document and see how it was done

SEE POST BELOW

steve_shubin

@marc_tinio

I updated the model to reflect more of what you were doing

There are two different parts studios

https://cad.onshape.com/documents/9948714d8c2ff4eda254bc4c/w/8514d2cb187b989a766e935a/e/6c2566fb61fe403aa890d889

steve_shubin

@marc_tinio

The so called twist is happening because you’re using THICKEN. When you thicken a surface, it thickens NORMAL to the surface. 

So what is a NORMAL? Take any surface, and take any given point on that surface, and what is normal at that point, is a vector that is pointing in the most direct route away from that surface — VERY ROUGHLY SPEAKING, a vector perpendicular to that surface

In your document (see picture) the surface created by lofting is pointing somewhat skyward around the top edge. So when you thicken that surface, it’s going to project directly away which is up and above the top plane. And that projection above the top plane is what you were referring to as the twist

So rather than taking curves and lofting as a surface and then thickening it, in this case, you need to avoid using the Thicken tool. Here you should be using SKETCH PROFILES  TO LOFT AS A SOLID and then use SHELL.

There are times that you want to avoid surface modeling. This is one of those times. In fact, you may find it’s better to do solid modeling rather than surface modeling more times than not

steve_shubin

@marc_tinio

I made a correction to the terminology in the above post. The correct wording is SKETCH PROFILES

Here you should be using SKETCH PROFILES  TO LOFT AS A SOLID and then use SHELL.