topic Re: Problems with Loft and Join in Fusion Design, Validate & Document Forum

Problems with Loft and Join

susan458 — Fri, 09 Jul 2021 15:13:51 GMT

Some times I can do this and other times I can't - would love to know where I am going wrong.

When I try and join the second loft to the first I get an error message, and I don't understand the message!

Have attached an image of the error message and the drawing

Betreff: Problems with Loft and Join

mango.freund — Fri, 09 Jul 2021 16:44:37 GMT

Hello @susan458 don't make your life harder than it needs to be. greetings mango

Re: Problems with Loft and Join

jeff_strater — Fri, 09 Jul 2021 17:21:45 GMT

@susan458 - branched forms are hard. The error message, I agree is not informative. I suspect the problem is that, on the second loft, the geometry is very nearly identical to geometry from the first loft, near the shared profile. Joining geometry that is nearly the same is a problem for the geometry engine. You can see this by creating your second loft as a new body and just selecting both, or changing the color of one:

there are likely ways to approach this that will work better. I'll see if I can come up with something. @mango.freund 's approach is one way, but that only works if this is truly a pattern.

Re: Problems with Loft and Join

jeff_strater — Fri, 09 Jul 2021 17:30:03 GMT

here is one way. Not 100% sure it is the geometry you want. Basic idea is to add a profile so that you just create one body for the part that overlaps:

then, do each branch as a separate body loft:

and, finally, combine them all together:

model is attached

Betreff: Problems with Loft and Join

mango.freund — Fri, 09 Jul 2021 19:22:59 GMT

hi @susan458in the end, because all colleagues had the same problems with combining and the final form as you need them. the foot end is conical - so be it. greetings mango

Re: Problems with Loft and Join

susan458 — Tue, 13 Jul 2021 13:26:08 GMT

Many thanks for all the replies, not a solution but now realise it may not be possible and won't waste any more time trying to get it to work. Have just used strait loft and this works very well, and I think looks better!

@mango.freund I am needing to shell this to create three pipes joining into one, for reasons I don't understand I can't combine them to form one body and as such can't shell. If I try to shell them as separate bodies the single end remains blocked.

Re: Problems with Loft and Join

mango.freund — Tue, 13 Jul 2021 13:40:38 GMT

Re: Problems with Loft and Join

jeff_strater — Tue, 13 Jul 2021 14:07:06 GMT

@susan458 - can you describe what you mean by "strait loft" here? Thanks.

"Have just used strait loft and this works very well"

Re: Problems with Loft and Join

TrippyLighting — Tue, 13 Jul 2021 16:18:26 GMT

There is at least one thing no one has commented on yet.
There is no need for 3D sketches for this design. You only would need three sketches. On each for the loft end and start profiles and if did not want to connect those directly without a center line ( I assuming that's what you meant with "straight loft" ) then you need one sketch for the center line the loft is going to follow. All of these sketches should be 2D sketches.

Re: Problems with Loft and Join

TheCADWhisperer — Tue, 13 Jul 2021 16:29:38 GMT

@susan458 wrote:
... now realize it may not be possible and won't waste any more time trying to get it to work.

I'll wager that there is a simple solution.

Q1. Do you have a picture of something similar that already exists in the real world?

Q2. Is there a portion of this geometry that is supposed to be a mathematical cone?

Q3. Is there a portion of this geometry that is supposed to be a mathematical cylinder?

Q4. What manufacturing process will be used to create the real world part?

Re: Problems with Loft and Join

TrippyLighting — Tue, 13 Jul 2021 16:49:43 GMT

Here is a screencast what I mean with 2D sketches only. Dimensions were chosen arbitrarily. Also, sometimes it is not necessary to have a rail if you want some curved lofts.

Re: Problems with Loft and Join

susan458 — Thu, 22 Jul 2021 08:31:51 GMT

Many thanks for all the replies, all very informative and helpful, esp the video