loft constrain?

[jedandva12]

Hi,

Im working on some induction design. I managed to make the shape I want using loft, and offset planes. But I'm facing an issue. When I loft I get the desired shape, then I get the issues that it makes the shape outside my sketch dimensions meaning it wont fit. 

Is there a way to constrain the loft body to not go outside of desired area?

I tried like cutting the flat part ( front, back) then extruding it, thats ok i get the straight piece but then I dont get a smooth transition ( I want my part to taper from front towards back 1 degree) from the lofted part to the extruded I can see the edges and I cant like filet or draft them.  

[jhackney1972]

Does the adding of lofting rails help maintain your shape?   Model is attached.

[jedandva12]

not really, But I have managed to, cut away the front portion then use taper with -1 degree. But I still cant control the loft boundary at the back

[jeff_strater]

Loft is doing exactly what you asked it to do.  Loft tries to make the smoothest surface it can that passes through the profiles that you give it.  Because Profile 3 is so much smaller than Profile 1 and 2, in order to achieve that level of smoothness, the surface is required to bow out in between Profiles 1 and 2.  Think of driving a car:  In order to have the minimum g force as you make the sharp turn from Profile 2 to Profile 3, it is necessary to swing wide in between Profile 1 and 2.  Now, you can give Loft extra information, such as rail curves, as @jhackney1972 suggests.  There is another control, as well:  you can control the "take off" direction from the end profiles.  In the attached, I've set Profile 1 to have its direction set to "Direction" (meaning:  the sketch normal direction).  This helps that outward bulge, not sure if it is enough for your purposes or not.  You can play with the level of influence of this direction with the arrow.  But, the more you increase the level of influence, the sharper the transition will be between Profile 2 and Profile 3.

You can also add extra profiles, too, which will help to control the shape.