topic Betreff: Two perpendicular lofts greet and 'corners' erroneously overhang in Inventor Forum

Two perpendicular lofts greet and 'corners' erroneously overhang

Anonymous — Thu, 28 Dec 2017 21:43:14 GMT

Hi all,

I can't figure out the logic of how to handle the following. I have three tubes intersecting, two lofts form a V shape. I've used two sketches to define their end shapes. What I am getting is some overhang where the lofts penetrate one another leaving an 'excess' at the corners. If this was an extrude, I would use the 'extrude to next face / body', then the bodies would terminate at each other's curved surface. But even if that could be done in a loft, I would need one body already formed and defined by a sketch for the other to terminate at - leaving the first loft overhanging the second. Only half of the problem would be solved.

In trial and error, I have lofted one and tried to create copy>split of that, leaving a surface>thicken to which the second tube can loft... but I've not been successful. I'm attaching a few images to try to show what the problem is.

Here you can see the three tubes, and the pair meeting at a V interval. The green and yellow lines are the sketches to which each is lofting. At the highest green line visible you can see where the horizontal loft is penetrating the vertical loft and leaving an overhang. The same thing happens at the right-most green line (extending from the yellow).

This is the vertical loft, waiting for the horizontal loft. In an ideal world, the solution should also help terminate the tubes at the cylinders surface - I've been getting rid of this penetration using a copy>sculpt>delete void. It might be that I can kill two birds with one stone here.

Always learning,

OLC

Re: Two perpendicular lofts greet and 'corners' erroneously overhang

jhackney1972 — Thu, 28 Dec 2017 21:50:42 GMT

Please post your part so others can troubleshoot it for you.

Re: Two perpendicular lofts greet and 'corners' erroneously overhang

S_May — Thu, 28 Dec 2017 22:03:40 GMT

jhackney1972 schrieb:

Please post your part so others can troubleshoot it for you.

please upload the file

Re: Two perpendicular lofts greet and 'corners' erroneously overhang

Anonymous — Thu, 28 Dec 2017 22:07:44 GMT

Available here

Re: Two perpendicular lofts greet and 'corners' erroneously overhang

S_May — Thu, 28 Dec 2017 22:41:09 GMT

I tried to understand what they want to do
the execution is not opimal but feasible, the problem is the production

Betreff: Two perpendicular lofts greet and 'corners' erroneously overhang

S_May — Thu, 28 Dec 2017 22:47:22 GMT

Re: Two perpendicular lofts greet and 'corners' erroneously overhang

johnsonshiue — Fri, 29 Dec 2017 14:24:13 GMT

Hi Aaron,

I am still trying to visualize the design intent. But, I think the problems you are encountering might be related to using Solid Loft. The problem with solid modeling feature is that you cannot control the intersection. When one feature acts on a body, the toolbody is either joined with the solid or formed a separate solid. This paradigm is good for traditional machining process. However, it can be fairly limiting for more stylish design like a bike frame. The last Loft feature in the part shows the limitation. If I were you, I would use Surface Loft instead. Then I can extend the surface to see where intersection is needed. Then you can use Trim command to cut away unneeded faces. Lastly, use Sculpt or Stitch to turn the surfaces into solid.

Many thanks!

Re: Two perpendicular lofts greet and 'corners' erroneously overhang

Anonymous — Sat, 30 Dec 2017 09:12:16 GMT

Thanks very much for your effort here - I need to update to open your attached file. I'll get back to this when I've updated. Thanks.

@S_May wrote:
I tried to understand what they want to do
the execution is not opimal but feasible, the problem is the production

Re: Two perpendicular lofts greet and 'corners' erroneously overhang

Anonymous — Sat, 30 Dec 2017 09:17:20 GMT

@johnsonshiue wrote:
Hi Aaron,

I am still trying to visualize the design intent. But, I think the problems you are encountering might be related to using Solid Loft. The problem with solid modeling feature is that you cannot control the intersection. When one feature acts on a body, the toolbody is either joined with the solid or formed a separate solid. This paradigm is good for traditional machining process. However, it can be fairly limiting for more stylish design like a bike frame. The last Loft feature in the part shows the limitation. If I were you, I would use Surface Loft instead. Then I can extend the surface to see where intersection is needed. Then you can use Trim command to cut away unneeded faces. Lastly, use Sculpt or Stitch to turn the surfaces into solid.
Many thanks!

Thanks for the idea - I haven't really used surfaces outside of sculpting away solids but this sounds like it will do the right job. It also sounds like it will give me the ability to produce a tube with a wall thickness instead of the solid I have currently produced. I'll get experimenting with these functions once I've run some software updates.

Re: Two perpendicular lofts greet and 'corners' erroneously overhang

S_May — Sat, 30 Dec 2017 09:25:58 GMT

Hello everybody,

The topic is too complex, I do not think that everything can be clarified with one word.

Practice creates masters...

a happy 2018 to all