3D Offset Tool Difficulties...

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R23D
Posts: 135
Joined: Sat Jan 25, 2020 5:23 am

3D Offset Tool Difficulties...

Post by R23D »

OS: Windows 10 (10.0)
Word size of FreeCAD: 64-bit
Version: 2022.430.26244 +4758 (Git)
Build type: Release
Branch: LinkDaily
Hash: b024b876480a533018fdc702145e9e38f8c54ba6
Python version: 3.9.12
Qt version: 5.12.9
Coin version: 4.0.1
OCC version: 7.5.3
Locale: English/Australia (en_AU)

I need to create a 3D offset of my part in the part workbench and it doesn't work. Every time I try, I get this error message: 23:53:08 <Exception> TopoShapeEx.cpp(3498): Null shape 23:53:08 Recompute failed! Please check report view.

It doesn't seem to matter what parameters I set.

I have checked the part geometry and no errors were found.

When I try to do the same in the following standard version of Freecad, I get no error messages but the view does not update and when I try to complete the action, the program crashes.

So, it doesn't seem to work in either version.

Any help greatly appreciated. :)

OS: Windows 10 (10.0)
Word size of FreeCAD: 64-bit
Version: 0.20.25645 (Git)
Build type: Release
Branch: master
Hash: 37d9757399b4c2ec30318eb88d7cd7c508246345
Python version: 3.8.10
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.2
Locale: English/Australia (en_AU)
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NewJoker
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Re: 3D Offset Tool Difficulties...

Post by NewJoker »

Can you share the file ?
R23D
Posts: 135
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Re: 3D Offset Tool Difficulties...

Post by R23D »

Sure. :) Sorry. Some of the Booleans are a little haphazard due to reworking and design changes. I think I also have one of the fillets mislabelled. :roll:
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heda
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Re: 3D Offset Tool Difficulties...

Post by heda »

hm, 3d-offset of what? the whole body?

btw, ever considered sketches for some of this? works just fine in part wb as well.
R23D
Posts: 135
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Re: 3D Offset Tool Difficulties...

Post by R23D »

If I do sketches I have to define constraints. Some of the other parts of this are based on sketches. This is just a small part of the model. Yes, the whole body.
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Shalmeneser
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Re: 3D Offset Tool Difficulties...

Post by Shalmeneser »

:idea:
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R23D
Posts: 135
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Re: 3D Offset Tool Difficulties...

Post by R23D »

Ok. You've remade it (minus 1 fillet) in the part design workbench in a way in which you prefer to model. Uhm... thanks? You still can't create a 3D offset from it. I've just tried. It doesn't work. If you can make one please share the secret. :)
heda
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Re: 3D Offset Tool Difficulties...

Post by heda »

don't get why you would want to 3d offset a whole body if you have modelled it yourself, why not just do it to the desired dims.

that aside
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generally, fc chokes on degenerated topology, and situations like this (amongst others) will create that.
in other words, imho not worth spending your time to try to get it to work - because it won't out of the box.

if you are hell-bent on doing it, you will have to offset face by face (or chunks of faces that do offset) and cut/reshape/join those offset surfs to become a watertight shell that can be made into a solid.

here are three individual face offset, well actually the fillet adjacent to the planar face will not 3d offset unless one joins it with the planar...
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reducing number of fillets before you offset, and add them after to the rebuilt offet solid will probably make things easier...
R23D
Posts: 135
Joined: Sat Jan 25, 2020 5:23 am

Re: 3D Offset Tool Difficulties...

Post by R23D »

So, it won't work because my fillets are very close together? I'm not sure if that is what you are saying. Is that what you are saying? Why is it always the fillets? lol There IS space between them. I wasn't aware one had to leave a specified amount. What would that amount be?

I AM kind of hell bent on doing it because it's not about making or not making something 'the right size'. If I wanted it bigger, as you quite rightly pointed out, I would either have made it bigger or used the scale tool (which works). An offset of a shape is not the same thing mathematically as scaling, except for certain simple shapes. Like, a cube, for example, would look the same after scaling or offsetting.

I need multiple instances of an offset of this part of the model to use as negative space in order to render my model as a 'print in place' mechanism.
heda
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Re: 3D Offset Tool Difficulties...

Post by heda »

fillets are complicated things, also for the big commercial ones, but they have spent more time on coding workarounds for specific situations 8-) which hides the complexity for the user.
might not only be fillets in this case, but as said, it will choke on any degenerated topology (whatever type or situation it is).

really up to you if you want to row upstreams or downstreams.

why not make a parametrized "template model"?
hook that up to a spreadsheet (the model itself is not overly complicated as such, you could even choose to do part, or all, of the "offset math" in that spreadsheet)
and for each version just enter the parameters in the spreadsheet (or an offset value if you choose to do all math in the spreadsheet), make a snapshot of that size with a simple copy that you can use for anything you want.
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