Embedding part into another

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scampy
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Joined: Wed Jun 07, 2023 5:02 pm

Embedding part into another

Post by scampy »

New to the forum and to FreeCad (or CAD in general for that matter) so be gentile :D

Without going into to too much detail, I've been asked to help a friend out as the chap who used to do some CAD work for him on his hobby stuff has now retired (it was his full time job a well as a hobby). So I've received the FreeCad file, and been tasked with making and adding a new component to it.

The component is basically a tube 1.7mm tall with a 0.3mm cylinder of the same radius as the inner radius of the tube so one end of the tube is capped off, so basically a U shape part. These two components were joined so they formed the component I need.

Now to the problem. When I insert that U shape part into the existing freecad design the existing part that appears inside the tube, rather than the tube displacing material in that area. Hopefully the attached image helps explain things. The part I have made is green, it sinks into the existing part that is grey, but leaves material around the original hole in the grey part which I've coloured in red
issue.png
issue.png (78.18 KiB) Viewed 1508 times
If I try selecting both the part I created and the existing part and then try any of the cut or join options via the Part menu I get an error stating that the computing result failed with an error : "Mesh.feature" object has no attribute "shape" with an option to continue (which makes everything disappear) or abort.

Can anyone advise what I need to to to remove the red cylinder section that gets formed when I position the new part into the existing component. I'm assuming the chap who made the original part up did so by combining lots of smaller parts in some way. The icon under the combo view tree is green and looks bit of film in an S pattern
icons.jpg
icons.jpg (32.03 KiB) Viewed 1508 times
I've pixelated the description as my friend wants to keep the description of the item being modelled out of the public domain, and in the scheme of things is not relevant to the issue. The Spure is the grey part in the main image and the bearing holder is the capped off tube I've created

Hope someone can explain in laymans terms how to resolve this

thanks in advance

Malcolm
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Roy_043
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Re: Embedding part into another

Post by Roy_043 »

scampy
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Re: Embedding part into another

Post by scampy »

Thanks for the link.

The first par runs through OK, but on converting to solid I get this error

11:37:05 Recompute failed! Please check report view.
11:38:41 Traceback (most recent call last):
File "<string>", line 2, in <module>
<class 'Part.OCCError'>: Shape is not a shell

So I'm guessing there are holes or missing parts in the original design, which given it was designed by someone else will take some digging to locate and fix
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Roy_043
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Re: Embedding part into another

Post by Roy_043 »

scampy
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Re: Embedding part into another

Post by scampy »

Thanks once again.

I've tried splitting and then merging... still no joy. I've tried making a shape and then converting to solid for just the part I need, but whilst that didn't complain I couldn't then modify that part for some reason (and it still looked mapped with lots of triangles / wireframe).

My skills are not up to remaking the complete model (only installed the program the other day and have never done CAD stuff before other than doing a tech drawing O level many moons ago !) so I think my mate will have to fix this in the real world by physically drilling a hole !!

Thanks once again for the pointers
scampy
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Re: Embedding part into another

Post by scampy »

Ok tried a further time. I used the Mesh tool to split to components, selected the component I want to make a hole in and converted to a shape and then to a solid - that worked

So I created a cylinder to the size required and then positioned it in the newly converted solid where the hole needs to be, I then selected the new solid part first, then holding CTRL down selected the cylinder - both were now green. From the parts menu I selected the cut out and then after a few seconds it fell over with the error message attached, which might as well be in Klingon for what sense it makes. Clicking continue makes both parts vanish.
error.png
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scampy
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Re: Embedding part into another

Post by scampy »

Sorted - I refined the shape first and then it worked !

Its going to be a PITA to do that for all the parts that need the hole enlarging !! - but its a work around
scampy
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Re: Embedding part into another

Post by scampy »

Moving on from this, whilst I've managed to resolve this by following the suggestions and splitting the STL into individual components and then just working on the component that needs changing, is there a way to stop the application replicating things.

For example, once the split has been accomplished I select the part I want to work on and create a shape from the mesh. It lists the shape in the tree, but creates this as new part / entity, which using the transform function can be moved. If I then convert the shape to a solid it does the same, and using transform having selected the solid in the tree, that too can be moved. If I go a stage further and refine the solid, I get yet another entry in the tree, which again can be moved using the transform option.

My logic (can't help the way my brain is wired) is when an action is done, its done on that part, and not by creating a new part by that process, ie the part is actually converted into a shape, which then gets made a solid so you are only working on the one part and not three or four iterations, all of which then need to be deleted once I have the final refined solid to work on.

Having finally made the changes I needed, then replicated my modified part four times as required, and with all stages of the transformation process deleted from the tree I selected all and exported as an new STL file, which when viewed had rouge copies of the part i modified floating unattached to the model. The model in freeCad didn't show anything, and nothing in the tree was hidden. I resoled this by selecting blocks of parts and exporting to STL until I had a model with no rouge parts floating around. Strangely under the tree I had all the parts highlighted for inclusion - so no Idea where it was picking up the deleted parts form !

Any pointers or explanations as to why it does this, and is there a way of having the software work on one part rather then duplicating it as part of the various processes ?

Thanks

Malcolm
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Roy_043
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Re: Embedding part into another

Post by Roy_043 »

scampy wrote: Fri Jun 09, 2023 6:07 pm Any pointers or explanations as to why it does this
It's called parametric design and this is what FreeCAD is all about. To create a non-parametic object you can use Part_SimpleCopy.
scampy
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Re: Embedding part into another

Post by scampy »

Thanks once again... I'll give that a try. As I said I'm new to all this so excuse my ignorance.

One thing I'm struggling with is cutting multiple holes in a part that already had one hole cut.

I did all the conversion to solid, made a cylinder the size of the hole I needed, and duplicated it, then placed both where needed. I selected the main part and first cylinder and the hole was cut. It created a 'cut' part which again was moveable. Placing the second cylinder into this part called cut and repeating the process to cut results in the main part disappearing irrespective of the order the two parts were selected.

Advice please
two holes.png
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