Loft with torsion.

[gparente]

Hi,

I am rather beginner to Freecad. So, apologies for my ignorance and for the noise.

version: FreeCAD_0.19-24276-Linux-Conda_glibc2.12-x86_64.AppImage
OS: Fedora 33

I am doing a simple part in part design. I am using "additive loft" feature to create sort of diagonal profiles. One of these lofts is sort of twisted. The other three shows as I am expecting.

My questions are:

- is there any better way to do this instead of using two sketches + additive loft ?
- how is the additive loft feature choosing the edges to map both sketches ?

There's probably a config value that I am not taking into account and it's rightly set in the other three additive lofts but not in the twisted one.

Attached the screenshot and my FCStd file.

Thanks a lot,

Best regards,

German.

[Shalmeneser]

* No loft
* PolarPattern

[drmacro]

Yes, there's a better way.

Create a sketch on the appropriate plane. Sketch the trapezoidal shape and pad it. Or if using Part workbench extrude.

The loft shafts need to be created in the same order. I.e. both have to be created in a clockwise or both counterclockwise.

The ones that worked were probably accidentally create correctly.

[Shalmeneser]

The twisted loft came from the construction of sketch006 (or 005 ?) : if you redraw it differently, modifying the order of the edge, the loft will work.

The loft try to match a vertex / an edge from the first sketch with one of the second sketch. Sometimes there is a mismatch, only from your point of view.

[chrisb]

You have to add another section in the middle of the loft.

The order of drawing is only important if you have inner and outer loops, but not if there is only one outline.

[Shalmeneser]

You have to add another section in the middle of the loft.

The loft solution is not the better one here.

The order of drawing is only important if you have inner and outer loops, but not if there is only one outline.

But modifying the order of drawing solve the problem. Is it important or not ?

[chrisb]

The loft solution is not the better one here.

Right, drmacro's proposal is definitely the better solution.

But modifying the order of drawing solve the problem. Is it important or not ?

In that case you are right. Can you upload the corrected file?

[Shalmeneser]

In sketch006 :
* select the rectangle -> construction style (everything in blue).
* redraw the rectangle (white) using the same vertex.
According to the order of the construction, you can get torsion or not.

[gparente]

Hi,

I appreciate a lot all these answers ! I love this product and the community is definitively great.

I will try the better solution you have proposed (drmacro) but also I will try the order of build just to understand.

Thanks a lot.

Best regards,

German