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Complicated Arc Construction

Printed From: CAD Forum
Category: EN
Forum Name: AutoCAD
Forum Description: Discussion about AutoCAD and AutoCAD LT, viewers, DWG and DXF formats, Design Review, AutoCAD web, Drive, add-ons
URL: https://www.cadforum.cz/forum_en/forum_posts.asp?TID=13947
Printed Date: 13.Jun.2026 at 15:22


Topic: Complicated Arc Construction
Posted By: dery
Subject: Complicated Arc Construction
Date Posted: 02.Feb.2024 at 20:03
How do you draw by technical drawing/mechanical drafting theory using AutoCAD 2014,
the R2690 arc that tangent to R30 circle at point A,
and tangent to R2100 arc at point B,
and the R2100 arc is tangent to 3£ line?
Thank you


Replies:
Posted By: Kent Cooper
Date Posted: 02.Feb.2024 at 22:20
Is the curve from A toward B supposed to have a starting direction of 0 degrees, that is, be tangent to the little R30 Arc at its quadrant point, that is, is the center point of the R2690 Arc direction above A?  If so, draw a Circle from that center point using A for the radius, then draw a Circle using the Tangent-Tangent-Radius option, tangent to the first Circle in the vicinity of B and to the 3-degree Line, at the 2100 radius.  Trim appropriately. Whether B will end up 90 units below the one Line remains to be seen -- it may not be possible for all dimensions and radii and tangencies to be correct at the same time.

Posted By: philippe JOSEPH
Date Posted: 03.Feb.2024 at 06:52
Hello Dery and kent, I see parametric constraints shown on your image, this should solve "all" your "problems".
Kent, your explanations won't fullfill the expectations of Dery as he wants a figured out ( on AutoCAD ) step by step drawing like I did on the previous discussion : How to Draw Arc with Known 3 Parameters.
Dery, as a student you should invetigate more on those "simples" geometric exercises.

Posted By: dery
Date Posted: 03.Feb.2024 at 09:18
Originally posted by Kent Cooper Kent Cooper wrote:

Is the curve from A toward B supposed to have a starting direction of 0 degrees, that is, be tangent to the little R30 Arc at its quadrant point, that is, is the center point of the R2690 Arc direction above A?  If so, draw a Circle from that center point using A for the radius, then draw a Circle using the Tangent-Tangent-Radius option, tangent to the first Circle in the vicinity of B and to the 3-degree Line, at the 2100 radius.  Trim appropriately. Whether B will end up 90 units below the one Line remains to be seen -- it may not be possible for all dimensions and radii and tangencies to be correct at the same time.


Hi Mr. Cooper, could you show me by image please.


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