@fotiadis1 - this is an interesting case, thanks for sharing it. Loft is a tricky beast at times...
There are basically only a handful of knobs and switches you can use to control a loft shape, but with those few controls, you can get a huge range of outputs. To get the output you want, it requires understanding those controls, and a lot of patience to tweak them. The controls are:
- profiles - both the number of them and the geometry in them. IMO, this loft has more profiles that it probably needs. The geometry of the profiles, though, is nice and simple
- rails - again, the number and geometry is a factor here. There are two types of rails - centerline rails (IMO, these are often overlooked. I love using centerline rails, as it is a way to "influence" the result without all the accuracy needed by "side rails". Side rails are very precise instructions to Loft - you must follow this curve (with a few exceptions) exactly
- end conditions - specifying the "takeoff direction or condition" is a way to influence the shape at the start or end profile. There are some techniques that you can use which include constructing "helper surfaces" to control the loft. There is also a "takeoff weight" knob which can be applied to these conditions, which influence how far along the first span of the Loft the shape is affected
- point mapping. This is actually a problem in your loft. I'm not sure why, but it can be tweaked to help. See the screencast below
The "bulge" you refer to is just kind of an artifact of the loft algorithm. Think of Loft having some momentum (like a go-cart going around some sharp corners). If the corner is too sharp, you are going to swing wide coming out of it. Something like this:
![Screen Shot 2020-10-23 at 8.54.07 AM.png Screen Shot 2020-10-23 at 8.54.07 AM.png](https://forums.autodesk.com/t5/image/serverpage/image-id/835529iC7105DD23E35AE45/image-size/large?v=1.0&px=999)
Partly, the bulge is from too many profiles, and partly it is from those corners being too tight, and loft drifting wide to try to get to the next corner. I'll do another reply (only one screencast per post annoys me...) on some ways to deal with this.
The mess at the end is a "point mapping" problem. I have no idea why the default point mapping is so bad here, but you can clean it up. Those white points are draggable:
![Screen Shot 2020-10-23 at 9.02.50 AM.png Screen Shot 2020-10-23 at 9.02.50 AM.png](https://forums.autodesk.com/t5/image/serverpage/image-id/835542iA12B8769A7F2BF69/image-size/large?v=1.0&px=999)
here is a screencast showing how to edit the point mapping on this loft. It helps, but is not perfect:
Jeff Strater
Engineering Director