3 point arc

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3 point arc

Postby 30tooo » Thu Jul 18, 2013 10:02 am

How can I draw a 3 point arc tangentially from an arc say.... on the left , down to a line and then tangentially to one on the right ? You can see (hopefully my previous attempt and you should see that the circle on the left is not tangential with the arc. All help gratefully received . Thank you .
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Re: 3 point arc

Postby 30tooo » Thu Jul 18, 2013 5:19 pm

If you look at my picture you will see a line atvthe bottom. The was another parallel to that. That is a restriction. I used 3 point arc but if you look close you will see it is not tangential to the left circle. I thought i might be able to snap tangentially , snap to object ( the line) and the tangentially to the right circle.

I hope i have explained that ok.

Thanks for the reply.
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Re: 3 point arc

Postby 30tooo » Fri Jul 19, 2013 9:53 am

Thanks for being patient Clive . Maybe this might help you understand .
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Re: 3 point arc

Postby 30tooo » Fri Jul 19, 2013 4:41 pm

Thats the badger......
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Re: 3 point arc

Postby Husky » Fri Jul 19, 2013 5:44 pm

30tooo wrote:I thought i might be able to snap tangentially , snap to object ( the line) and the tangentially to the right circle.

Unfortunately that isn't possible in the moment - but I know that the developers are working on it for one of the next updates :wink:
Right now you have to work with construction / help lines to solve this challenge. 8)
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Re: 3 point arc

Postby andrew » Wed Aug 07, 2013 5:20 pm

Yes, this should fit the bill.

BTW: The tool for this use case is called "3 Tangents" (not "Point, 2 Tangents"), I think the wrong tooltip might have been displayed in the screenshot above.
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Re: 3 point arc

Postby andrew » Wed Aug 07, 2013 5:56 pm

I see.. which point did you choose then? Is the exact point on the line given or another point? I thought the circle touches the two other circles as well as the line.
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Re: 3 point arc

Postby andrew » Thu Aug 08, 2013 10:55 am

clive wrote:I think Apollonius 'The Great Geometer' would have loved these circle tools.
Andrew you have done a fantastic job with these additional tools :D


Well, thanks :) It's a surprisingly complex problem. QCAD is using resizing and inversion to find the solutions.
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Re: 3 point arc

Postby Husky » Thu Aug 08, 2013 7:26 pm

clive wrote:Andrew you have done a fantastic job with these additional tools :D


WOW - what a circle tool set!!! I have absolutely to agree with Clive - that is an extraordinary tool-set.

@Andrew:
My honest respect and compliment to you!!! Thank you very much to make the "CAD life" so easy for everybody!
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