Basic Attachment Tutorial

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hmk
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Solved: Model croaks

Post by hmk »

I followed the tutorial, but when I make the last pocket operation with the FinalSketch sketch, my model falls apart. I did a Part_CheckGeometry before applying the pocket operation and it gives me no errors. After pocketing, the check tells me this:
Screenshot from 2021-01-27 11-52-43.png
Screenshot from 2021-01-27 11-52-43.png (41.76 KiB) Viewed 3698 times
Is there a chance to fix this? (I am asking to learn something in general, I am less interest in fixing this particular problem.)

I am also wondering, did I do something wrong or is this something that can happen once in a while? After all, many geometry is exactly at the "seams" of other geometry. Would it be more robust to make the triangle sketches bigger so that they extent over the base geometry?

Edit: I found the problem, I had 4 lines in the FinalSketch sketch, probably introduced by a mirror operation! :oops: Note to self: First learn the basics before trying to be extra-smart... Still wondering, would an experienced user have guessed something like this from the checker's error message?
pd-tutorial-attachment.FCStd
(23.34 KiB) Downloaded 91 times
Bance
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Re: Basic Attachment Tutorial

Post by Bance »

You couldn't have been following very closely since there are no mirror ops in the tutorial :lol:

There is no need to mirror anything, the attachment can be adapted to suit the sketch drawn in any orientation. I used specifics only so as to demonstrate certain features. As stated in the text, this example could for the most part be modeled using Std planes and offsets far more quickly.

As to your editing of the tutorial itself, there is no need to apologise or ask for permission. Thank you for correcting the 'typos.' Some of the other edits have been reversed though, specifically the use of a label in functions (see https://wiki.freecadweb.org/Object_name/en.)

I also enhanced the reference to 'Carbon Copy,' since somebody is bound to confuse similar with 'the same.'

The extra verbiage, I would not deem necessary, however the wiki is read by many for whom english is not their first language, and if it aids understanding I'm perfectly happy to let it stand. :)
hmk
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Re: Basic Attachment Tutorial

Post by hmk »

Bance wrote: Wed Jan 27, 2021 2:57 pm As to your editing of the tutorial itself, there is no need to apologise or ask for permission. Thank you for correcting the 'typos.' Some of the other edits have been reversed though, specifically the use of a label in functions (see https://wiki.freecadweb.org/Object_name/en.)
I am glad I did not cause offense! And for the label: I learned something -- sorry for the hassle in undoing it.

BTW, since it's not really a beginners tutorial the following is probably obvious for most, but could perhaps be added at the conclusions:
- you could do the 3 triangles and pocket operations in any order and arrive at the same result
- your approach helps (greatly?) with the topological naming problem, but references can still break when the sketch (line that carries the attachment) is modified (this has been already mentioned by someone else in the another thread)
- with your setup width and height can be modified without breaking the model (width<length keeps all faces intact, only their geometry changes, I think)

Congrats on a great tutorial!
garya
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Location: Ovando, MT, USA

Re: Basic Attachment Tutorial

Post by garya »

Comment:
The tutorial mentions avoiding attaching to generated geometry, and cites planes and lines as examples. It would be helpful if it also mentioned vertices/points.
manos
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Re: Basic Attachment Tutorial

Post by manos »

Bance thanks for your very useful Tutorial.
It took some time to me to understand that :Normal to edge" means that the attached object wil become normal to the SELECTED edge at the reference object. By the way what geometrical element of the attached object will be normal to the selected edge at the reference ?

At first glance it seems to me that you use the attachment with different way than described at WIKI:part attachment.
E.g. Map Mode is not mentioned at Wiki page at all.
Any way your tutorial helped me so much.
Bance wrote: Thu Dec 10, 2020 10:32 pm ... The attachment modes are a little tricky to visualise at first. I'm going to do some work on the Part attachment wiki page, hopefully I can work out a way to graphically describe the various modes.
Now on we have the tutorial, what about your plans about " graphically describe the various modes." ? I look forward to see at last some screenshots.
Thanks again
Bance
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Re: Basic Attachment Tutorial

Post by Bance »

manos wrote: Sat May 29, 2021 9:55 amBy the way what geometrical element of the attached object will be normal to the selected edge at the reference ?
That would be the objects origin, this means that for a primitive object it is somewhat arbitrary. This is emphasised in the tutorial.
manos wrote: Sat May 29, 2021 9:55 am At first glance it seems to me that you use the attachment with different way than described at WIKI:part attachment.
How so?
manos wrote: Sat May 29, 2021 9:55 am E.g. Map Mode is not mentioned at Wiki page at all.
You are quite right they are in fact documented on their own appropriate page. See Data
There should probably be a cross-link included on both pages.
manos wrote: Sat May 29, 2021 9:55 am graphically describe the various modes.
This has proved a little more difficult, some of the other attachment modes depend on the amount of definition supplied. So for instance a partially defined mode may be sufficient in some cases but would not necessarily match the fully defined mode.

I'm glad the tutorial helped, please don't hesitate to ask. :D
manos
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Re: Basic Attachment Tutorial

Post by manos »

Bance thanks for your response.
Bance wrote: Sat May 29, 2021 11:39 am
That would be the objects origin, this means that for a primitive object it is somewhat arbitrary. This is emphasised in the tutorial.
Really it is empasized at the tutorial but i hoped that some simple-clear cases would exist.

For example after the attachment of Isosceles Sketch:
We open the Tree and we select IsoscelesSketch. Then we look at the Data tab of ComboView. We see that Support= BaseSketch. EDge3 , Map Mode=NormalToEdge, Attachments etc. In other words we do not have any clue about the plane at which the IsoscelesSketch ia placed any more. Or we have ?
manos
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Location: Greece

Re: Basic Attachment Tutorial

Post by manos »

manos wrote: Sat May 29, 2021 6:19 pm
... after the attachment of Isosceles Sketch:
We open the Tree and we select IsoscelesSketch. Then we look at the Data tab of ComboView. We see that Support= BaseSketch. EDge3 , Map Mode=NormalToEdge, Attachments etc. In other words we do not have any clue about the plane at which the IsoscelesSketch ia placed any more. Or we have ?
I have not found any answer to the question yet: At which plane the IsoscelesSketch is placed after the attachment.
Any help welcomed.
Bance
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Re: Basic Attachment Tutorial

Post by Bance »

You can tell by looking at the placement, It is parallel to YZ plane and offset by 115mm and 70mm from Std Origin.
manos
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Re: Basic Attachment Tutorial

Post by manos »

Thanks Bance. I have to read the tutorial again
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