Chamfer problem

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cehjan
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Chamfer problem

Post by cehjan »

Hi

I try to make a chamfer on the outer edges but without success. I don't know what the problem is, it seems to me that it shouldn't be a problem for FreeCAD.


OS: Windows 10 Version 2004
Word size of FreeCAD: 64-bit
Version: 0.20.1.29410 (Git)
Build type: Release
Branch: releases/FreeCAD-0-20
Hash: f5d13554ecc7a456fb6e970568ae5c74ba727563
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.3
Attachments
chamfer.jpg
chamfer.jpg (36.25 KiB) Viewed 1885 times
chamfer 1.jpg
chamfer 1.jpg (22.37 KiB) Viewed 1885 times
Spojnica.FCStd
(786.37 KiB) Downloaded 63 times
chrisb
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Re: Chamfer problem

Post by chrisb »

Your model looks perfect, all sketches are well done. (I would perhaps have modeled the first two features in a single pad, or would have used a carbon copy for the second poscket).
We have recently seen ssimilar fillets/chamfers fail. It's a problem with the geometric OCC kernel.
You can try to do the chamfer yourself with a subtractive sweep.
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chrisb
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Re: Chamfer problem

Post by chrisb »

A sweep works - almost:
SnipScreenshot-0dbc01.png
SnipScreenshot-0dbc01.png (19.61 KiB) Viewed 1854 times
It leaves a very tiny bit of material. You can try to move the section along the path or you can introduce a very short straight line (I guess that 20µm is enough).

Sorry, the file is too big to attach.
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chrisb
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Re: Chamfer problem

Post by chrisb »

A different corner transition did the trick. Please note that it now fails geometry check. So you should do this as the very last feature in the body. I removed all edges to reduce the size.
Attachments
Spojnica_cb.FCStd
(879.46 KiB) Downloaded 45 times
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cehjan
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Re: Chamfer problem

Post by cehjan »

If the circles R35mm (Sketch 001 and Sketch 002) do not touch the sides of the base feature everything is OK, i.e. if I change the diameters, 35mm to 32 in Pocket and Pocket 001 features, everything is fine and the chamfer is done quite nicely. Hmmmm
Attachments
chamfer OK.jpg
chamfer OK.jpg (40.61 KiB) Viewed 1846 times
Spojnica OK.FCStd
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chrisb
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Re: Chamfer problem

Post by chrisb »

That's a far better solution!
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user1234
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Re: Chamfer problem

Post by user1234 »

Works, when you use the refining option in the operation before the chamfer. The only issue is, that the geometry check says not ok on the intersection of the small hole. But to be honest, i ignore always such errors and never had a issue with that. Maybe when you make the hole after the chamfer, the error vanishes, but no warranty.


2022-09-08_21-45.png
2022-09-08_21-45.png (196.42 KiB) Viewed 1772 times

2022-09-08_21-50.png
2022-09-08_21-50.png (266.76 KiB) Viewed 1772 times


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user1234
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Shalmeneser
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Re: Chamfer problem

Post by Shalmeneser »

You should try to chamfer just after the 2nd pocket.
But it's impossible in your models due to coplanarity between the pockets and the pad.
Modifying this, Chamfer can works :
Attachments
Spojnica_SHALM.FCStd
(227.04 KiB) Downloaded 45 times
Capture du 2022-09-08 22-25-50.png
Capture du 2022-09-08 22-25-50.png (55.85 KiB) Viewed 1757 times
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cehjan
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Re: Chamfer problem

Post by cehjan »

Thank you User1234, I always forget to try to apply refine. It also works if I apply Refine only to the first 3 features.
Attachments
Spojnica refine.jpg
Spojnica refine.jpg (68.95 KiB) Viewed 1748 times
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cehjan
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Re: Chamfer problem

Post by cehjan »

Thank you Shalmeneserm. It works that way too, but generally Chamfer and Fillet are applied at the end and I'm not used to thinking about it in the middle of modeling a part.

Sorry for my English.
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