[Please Move] [Solved] Part Fusion (Join Walled Objects) Cannot determine type of null shape

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namezero111111
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[Please Move] [Solved] Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by namezero111111 »

Dear FreeCAD folks,

I just started using FreeCAD and am trying to join a pipe into a body and am getting the error "Cannot determine type of null shape".
The console also logs "Input shape is null"

I am trying to join Part->Body with Part->Pipe and then put the Connect into the "Part" object.

I am unsure what causes the error, but I think it must be related to the shape binder?
The dependency graph shows this as the only connection.

Any help is appreciated.
dep.jpg
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Attachments
Dust Shoe.FCStd
(78.55 KiB) Downloaded 67 times
Last edited by namezero111111 on Fri May 07, 2021 6:06 am, edited 3 times in total.
chrisb
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Re: Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by chrisb »

Which is the path, which is the section?
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namezero111111
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Re: Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by namezero111111 »

I want to make a fusion so that the pipe cuts a hole into the top part (Body "Pipe" cuts into body "Body")

However, all boolean operations fail with this error apparently.
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adrianinsaval
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Re: Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by adrianinsaval »

can you share your file or a screenshot of it?
namezero111111
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Re: [Please Move] Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by namezero111111 »

Hello; the file is attached to the original post. I have asked to move the topic to the appropriate forum.

Here is a screenshot.
Capture.JPG
Capture.JPG (50.94 KiB) Viewed 3113 times
EDIT:

I resolved this after the posting the screenshot and reading this post :
"Body" did not have a "tip" set. If you look closely, there is a green icon next to it now, and the fusion works:
Capture.JPG
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solution.JPG
solution.JPG (11.83 KiB) Viewed 3110 times
chrisb
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Re: Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by chrisb »

namezero111111 wrote: Thu May 06, 2021 2:22 pm I want to make a fusion so that the pipe cuts a hole into the top part (Body "Pipe" cuts into body "Body")
This is probably a precision issue. And my guess is, that it is not what you really want: Looking from the top ...
Snip macro screenshot-f558b8.png
Snip macro screenshot-f558b8.png (16.37 KiB) Viewed 3102 times
... I see a small burr around the pipe.

Only looking at the issue here I would say you should model all of this in one body, but I guess you want the pipe as a separate part too. In that case my first try would be to make it exact by modeling the pipe with two features: a tube made from a sketch like Middle001 and a loft. If it doesn't work, then make the diameter of the tube 1µ bigger than it should be.
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chrisb
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Re: [Please Move] [Solved] Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by chrisb »

Another idea: Make the number of edges equal, at least in Start001 and Middle001. That is highly recommended to keep lofts better under control. I will give it a try.
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namezero111111
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Re: [Please Move] [Solved] Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by namezero111111 »

Having the number of edges not equal is true; I don't know why this works.

You make a good point about rounding errors, too. I have tried moving it lower or higher without result.

However, I have found the root problem was related to the tip of "Body"! (see above).
chrisb
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Re: [Please Move] [Solved] Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by chrisb »

I have seen that there is another problem with the loft: You have to make inner and outer loops in the sketches in the same sequence. This is not the case in your model. No time left now, will return later.
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chrisb
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Re: [Please Move] [Solved] Part Fusion (Join Walled Objects) Cannot determine type of null shape

Post by chrisb »

I wasn't successfull yet. However, I attach my model here, so others don't have to go through the same failures again. My model avoids coincidences currently very clearly and still fails.

My next try would be to replace the loft with a revolve. But that would change the smooth transition.
Attachments
DustShoe_cb.FCStd
(64.71 KiB) Downloaded 64 times
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