Lofting

doug_hills

Hi everyone,
I've never done a loft before, and I'm having a hard time with this one, likely way to complex for a beginner, but its what I need. Unless ther is a better way to join the upper and lower sections.
The upper is wider than the lower, and will need to be hollow, with a .062 wall thickness.
Sketches 8,9,10 are the crossections, and seketch 11 is the shape I want (I was trying to create a path). It will have a fillet to join with the upper nipple..

https://cad.onshape.com/documents/e80b1b3ae08927502d18d581/w/9fd1adb5c3713b133ac38315/e/2381988d43d2e21c01f8e9c7

Thanks for your help.

glen_dewsbury

@doug
Lofting can be a bit tricky. When you use guide curves they want to be at pierce points with profile curves.
Here's some ideas that might help.
https://cad.onshape.com/documents/f72c7797b0e05baebf133137/w/e8cbe8e0bb87b85ab5e93461/e/bfd754f9cbbb366ca915f7fc  

eric_pesty

Lofts don't handle "hollow" profiles, so you need to loft it as a solid and then hollow it out using shell (or a second loft with the remove option). You also had other issues
- The profiles not being in the right order
- The guides not actually piercing all the profiles
- The guides "fighting" the end conditions (guide perpendicular to profile at the top but end condition normal to profile)
- Lastly the transition is just too steep, I improved a bit by moving the mid profile down but it's still not great, removing it altogether might be a better option.


Something like this;
https://cad.onshape.com/documents/c2dfdcbc013272be7c6dd505/w/aecc512efbdb39544fd029e9/e/52b5040581caafb1c5f9d338

ian_bottomley909

Hi Doug

From one beginner to another - I had a battle with lofting too. I suspect you are asking too much of the lofting algorithm trying to solve the whole, 'three pipe into one' question in one go. I have had more success working in stages.

1). Make a solid loft that is the outer shell of the require part.
2),3), & 4). make individual cores that represent each flow path from one of the manifold pipes to the main pipe
subtract 2,3,4  from 1 in a sequence of Boolean operations...

And hey presto ...

Maybe ...

Ian B.