How to determine and design 2 arcs?

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ProApe
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Joined: Mon Sep 12, 2022 3:13 pm

How to determine and design 2 arcs?

Post by ProApe »

Hi,
I would like to design the object shown in the attached picture.
I have begun with a sketch but don't know
* how to determine the radius of both arcs
* how to draw the arcs. 3 points are requested but I have only 2 (the end of the lines)
Kind regards
ProApe
Attachments
20221002_110316_resized.jpg
20221002_110316_resized.jpg (456.18 KiB) Viewed 648 times
2 arcs.FCStd
(7.82 KiB) Downloaded 18 times
2 arcs.JPG
2 arcs.JPG (26.58 KiB) Viewed 650 times
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NewJoker
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Re: How to determine and design 2 arcs?

Post by NewJoker »

ProApe wrote: Sun Oct 02, 2022 10:58 am * how to draw the arcs. 3 points are requested but I have only 2 (the end of the lines)
You can draw the arcs using Sketcher Create3PointArc and then apply Sketcher ConstrainTangent between them and the lines to which they are attached. I attached the file with fully constrained sketch.

2 arcs drawn.FCStd
(8.43 KiB) Downloaded 18 times
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Shalmeneser
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Re: How to determine and design 2 arcs?

Post by Shalmeneser »

* Draw an arc with its vertex coincident with the lines (Sketcher_ConstrainCoincident)
* add tangency between the line and the arc : Sketcher_ConstrainTangent

no need for dimensions.
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2 arcs_SHALM.FCStd
(5.81 KiB) Downloaded 14 times
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Shalmeneser
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Re: How to determine and design 2 arcs?

Post by Shalmeneser »

@NewJoker : Tangency is missing twice.
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NewJoker
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Re: How to determine and design 2 arcs?

Post by NewJoker »

Shalmeneser wrote: Sun Oct 02, 2022 11:41 am @NewJoker : Tangency is missing twice.
Right, now it will be better:

2 arcs drawn 2.FCStd
(8.2 KiB) Downloaded 16 times
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Shalmeneser
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Re: How to determine and design 2 arcs?

Post by Shalmeneser »

:idea:
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2 arcs drawn 2_SHALM.FCStd
(6.72 KiB) Downloaded 13 times
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thomas-neemann
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Re: How to determine and design 2 arcs?

Post by thomas-neemann »

ProApe wrote: Sun Oct 02, 2022 10:58 am ...
here is a suggestion 1/2 minute (non-parametric draft /arch and part)

https://www.youtube.com/watch?v=SWrBDWnjETk

phpBB [video]

1446.FCStd
(4.33 KiB) Downloaded 13 times
Gruß Dipl.-Ing. (FH) Thomas Neemann

https://www.youtube.com/@thomasneemann5 ... ry=freecad
domad
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Re: How to determine and design 2 arcs?

Post by domad »

ProApe wrote: Sun Oct 02, 2022 10:58 am ....
Hello ProApe, greetings to the community!
One of the many other possibilities ....
Attachments
2 arcs drawn_domad.FCStd
(8.87 KiB) Downloaded 17 times
2 arcs drawn_domad.gif
2 arcs drawn_domad.gif (486.81 KiB) Viewed 495 times
ProApe
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Re: How to determine and design 2 arcs?

Post by ProApe »

Sorry, I had problems putting your numerous suggestions -for which I thank you very much- into practice. The GIF was very helpful (is there actually a way to control the playing of a GIF?). A video is of course even more practical, but I didn't recognise the method used in the video.
If I use the tool "Create an arc by its end points and a point along the arc" in the option "End points and rim point" at one of the two points and drag it over to the other I indeed get an arc with its central point, but how can I determine the correct arc diameter since I can move both and how can I fix them?

How can I change the appearance of the dimensions? I didn't find such a setting in the Preferences.
And where do I find a tool not to fix dimensions but simply measure dimensions?
heda
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Re: How to determine and design 2 arcs?

Post by heda »

based on your questions, it sounds like you have a misconception of how the sketcher works...

when you draw something (line, circle etc) in the sketcher there is no need to make this precise, actually it is more or less impossible to do...

you make it precise with adding constraints (like horizontal orientation, lengths, etc), also important is to make sure that points are connected (not visually on the screen, but that points have coincident constraint if they are supposed to be coincident).

maybe work through some of the basic sketcher tutorials on the wiki?
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