Dogbone dressup problem (again)

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Giulio Buccini
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Dogbone dressup problem (again)

Post by Giulio Buccini »

Hello,

after making a specular copy of my bracket (against the vertical axis) I casually discovered that the dogbone-dressup now ignore one corner. :o
Any idea on how to fix this?
Selection_7694.jpg
Selection_7694.jpg (52.14 KiB) Viewed 2184 times
P.S.
I have already increased the geometry accuracy as suggested here.



--------------------------------------------------------------
OS: Ubuntu 16.04.7 LTS (XFCE/xfce)
Word size of FreeCAD: 64-bit
Version: 0.20.26720 (Git) AppImage
Build type: Release
Branch: (HEAD detached at 7bca26e)
Hash: 7bca26e7c14d4d43374ff7e0c8582735b249cbfd
Python version: 3.9.9
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.3
Locale: English/United States (en_US)
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dogbone test.FCStd
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Giulio Buccini
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Location: Munich - Gemany

Re: Dogbone dressup problem (again)

Post by Giulio Buccini »

As I said above, on the original bracket the dogbone operation is working flawlessly (see attached file).
I'm lost...
Attachments
dogbone test - working.FCStd
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Giulio Buccini
Posts: 541
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Location: Munich - Gemany

Re: Dogbone dressup problem (again)

Post by Giulio Buccini »

Just a curiosity: by turning off the cutter-compensation and zeroing any offset on the toolpath, the dogbone magically appears in the ignored corner (see images below).
Unfortunately, any other combination of the two params above makes the dogbone to disappear again. :(
.
.
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Selection_7695.jpg
Selection_7695.jpg (30.45 KiB) Viewed 2144 times
Selection_7696.jpg
Selection_7696.jpg (38.64 KiB) Viewed 2144 times
Giulio Buccini
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Re: Dogbone dressup problem (again)

Post by Giulio Buccini »

I spent all night trying to make the dogbone appearing in that corner. No way.
At 3:00 A.M: my wife kicked me in the ass and forced me to go to bed... :D

Any clue?
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sliptonic
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Re: Dogbone dressup problem (again)

Post by sliptonic »

I suspect the dogbone is getting confused by this little segment. The length is suspiciously less than half the cutter radius. Can you refine the model to make it longer or make it go away?
2022-01-17_12-42.png
2022-01-17_12-42.png (23.64 KiB) Viewed 2006 times
Giulio Buccini
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Re: Dogbone dressup problem (again)

Post by Giulio Buccini »

Ehmmm... that little straight segment was added by following your suggestion in another thread.
As you explained, the dogbone dressup works well only when the corner does not contains curves/arcs (i.e. G1 movement only).

This bracket is just a specular copy of the original one. I applied a simple mirror operation against the YZ plane, then I applied the "Simple Copy" command of the Part WB to obtain an independent object.

So, the matter is

dogbone-dressup op works well on the original bracket,
dogbone-dressup does not work on the specular copy.
Giulio Buccini
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Re: Dogbone dressup problem (again)

Post by Giulio Buccini »

Here below the problem.
On the left there is the original bracket, on the right the mirrored one:
Selection_7698.jpg
Selection_7698.jpg (86.17 KiB) Viewed 1971 times
A detailed view of the original bracket. The dogbone is correctly calculated thanks to that little straight side:
Selection_7699.jpg
Selection_7699.jpg (27.59 KiB) Viewed 1971 times
herbk
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Re: Dogbone dressup problem (again)

Post by herbk »

Hi Giulio,

several times i got it work if i turn the part a little but (1° or less) at similar cases.
In other cases a simple copy or refinement brought the solution.
Gruß Herbert
Giulio Buccini
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Re: Dogbone dressup problem (again)

Post by Giulio Buccini »

Hello herbk,

I tried to rotate the bracket of one degree. Same result.

I think there is bug/glitch in the code...
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sliptonic
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Re: Dogbone dressup problem (again)

Post by sliptonic »

Giulio Buccini wrote: Mon Jan 17, 2022 7:32 pm Ehmmm... that little straight segment was added by following your suggestion in another thread.
As you explained, the dogbone dressup works well only when the corner does not contains curves/arcs (i.e. G1 movement only).
Correct. That is a limitation of the current dogbone.

If you inspect the gcode you'll see that it's too short. With offsetting, it becomes a G2 going into a G1. So no bone.
2022-01-17_16-40.png
2022-01-17_16-40.png (220.93 KiB) Viewed 1905 times
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