[Solved] Odd occurance when creating circle 2 points

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jamby
Full Member
Posts: 55
Joined: Fri Jun 24, 2016 2:41 pm

[Solved] Odd occurance when creating circle 2 points

Post by jamby » Sun Nov 03, 2019 6:41 pm

Hi

Versions
QCAD version: 3.18.1.0
Date: Oct 4 2017
Qt version: 5.8.0
Compiler version: gcc 4.8.1
Build Date: Oct 4 2017
Revision: 24e23aa782cf917916212eb27798f35ce96f9248

Architecture: x86_64
OS: Linux
OS version: Centos 7
Vacuum-hood.third.dxf
(102.41 KiB) Downloaded 346 times
Screenshot from 2019-11-03 09-30-51.png
Screenshot from 2019-11-03 09-30-51.png (9.45 KiB) Viewed 3333 times
When drawing a Circle 2p from the center on the left hand circle (0,0) out the upper line at 60 deg, it fails to find the intersect of the line and the two circles along the line. When it reaches the small circle at the end of the line it finds the intersect and end points but displays a circle outward from those points. Similar problem coming back from the end of the line to the two circles.

Parts of this drawing were created in this model and others, the large arc on the right and the two lines extending from there to the left were brought in as a polyline by copy with reference from another model here they were exploded twice and then the part of the polyline that was in the same area as the 2.6" dia. circle were deleted.

This issue has been present in all of the derived models from the first.
Thanks

Jim
Last edited by jamby on Wed Nov 06, 2019 5:48 am, edited 1 time in total.

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Husky
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Posts: 4935
Joined: Wed May 11, 2011 9:25 am
Location: USA

Re: Odd occurance when creating circle 2 points

Post by Husky » Sun Nov 03, 2019 8:39 pm

Hi Jim,
jamby wrote:
Sun Nov 03, 2019 6:41 pm
This issue has been present in all of the derived models from the first.
it is not really a CAD issue - the tool has not all required information.
If you start a 2P line in the center of the circle and restrict it with 60 degrees you cant tell the tool where the intersection is with a snap. You could use auxiliary lines but that would also be an over kill ...
Snap to end horizontal line - fails because the end isn't the end below 60 degrees.
Snap to intersection - how to determine the intersection,
Lengths of 60 degree line - hmmm, what is the accurate lengths ...

Long story short: In cases like this one it would be the easiest way to create a "non fitting" (to short / to long) line and trim it afterward with "Trim Both". That gives you an perfect intersection of both lines.

Husky-2019.11.03-02.png
Husky-2019.11.03-02.png (64.62 KiB) Viewed 3325 times

Husky-2019.11.03-03.png
Husky-2019.11.03-03.png (64.29 KiB) Viewed 3325 times

IMPORTANT note!
Your drawing has 3D information what makes me thinking it wasn't entirely created in QCAD. That is a recipe for trouble. To make sure that everything works in QCAD as expected flatten the drawing below Menu/Misc/Modify/Flatten drawing to 2D :wink:
Work smart, not hard: QCad Pro
Win10/64, QcadPro, QcadCam version: Current.
If a thread is considered as "solved" please change the title of the first post to "[solved] Title..."

CVH
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Posts: 3416
Joined: Wed Sep 27, 2017 4:17 pm

Re: Odd occurance when creating circle 2 points

Post by CVH » Mon Nov 04, 2019 12:09 am

Indeed: Z is not zero is the issue here.
Husky wrote:
Sun Nov 03, 2019 8:39 pm
IMPORTANT note!
Your drawing has 3D information what makes me thinking it wasn't entirely created in QCAD. That is a recipe for trouble. To make sure that everything works in QCAD as expected flatten the drawing below Menu/Misc/Modify/Flatten drawing to 2D :wink:
Screenshot_rev.png
Screenshot_rev.png (11.51 KiB) Viewed 3320 times
The green intersections will be found correctly when 2D.
The circle added at the intersection of the two lines is not a circle 2P.
This is a Circle Center, Point. (Red)
But that doesn't matter here.

To draw a Circle Center Point with as reference the far intersection of the two lines (Orange):

Draw / Circle / Center, Point CI
Select centerpoint.
Change snap to Intersection Manual SY.
Select both lines that intersect. (Yellow)

Intersection Manual is not an auto snapper.

Regards,
CVH

jamby
Full Member
Posts: 55
Joined: Fri Jun 24, 2016 2:41 pm

Re: Odd occurance when creating circle 2 points

Post by jamby » Mon Nov 04, 2019 12:41 am

Wow
Who'd a thunk.... Yes using flatten (took awhile to find even with the map) all was good. Not sure if this was the same line of models that I read in a set of points from a file but that's the only thing I can think of that might have introduced a not 2D element. The file was X.xx,Y.yy but who knows.

This is the final outcome I was looking for on the finished profile.
Screenshot11-03 15-35-35.png
Screenshot11-03 15-35-35.png (4.07 KiB) Viewed 3315 times

Thanks again
Jim

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