topic Re: Symmetry and helper lines in Inventor Forum

Symmetry and helper lines

Anonymous — Wed, 23 Sep 2015 14:12:24 GMT

Hi,

I recently switched from FreeCAD to Autodesk Inventor and I'm having a few problems.

In a 2D sketch, How do I make two points symmetrical with respect to an axis? I want to use x,y or z-axis but I can only seem to click on lines that I created, and not on the axes of the coordinate system. This was possible in FreeCAD and I don't understand why it isn't in Inventor.

Also, is there a way to create a "helper line" in a 2D sketch that will be used in constraints (to make two points symmetrical around this axis) but will have no other function? In FreeCAD this was possible by toggling the line's visibility.

Thanks in advance!

Simon

Re: Symmetry and helper lines

Frank-Oosterwaal — Wed, 23 Sep 2015 14:17:35 GMT

Everything your asking for is possible.

If you add the sketch you are making then we can show you.

Re: Symmetry and helper lines

ampster40 — Wed, 23 Sep 2015 14:35:02 GMT

within the sketch environment, utilize something called "Project Geometry" and click on any work feature (axis or plane) or even entities from other sketches, in order to be able to use them in the current sketch. After that, there is a symmetrical constraint that could be used but your sketch may have to be modified slightly in order to use it. Provide the .ipt file as an example would help us help you.

Re: Symmetry and helper lines

Anonymous — Wed, 23 Sep 2015 14:36:01 GMT

Consider this 2d sketch that I attached for instance.

I want to have the lock-shaped thing symmetric to the X-axis. I can achieve this by using the horizontal constraint by clicking on the center of the top arc first and then on the origin of the coordinate system. But I want to be able to achieve this with the symmetry constraint as well, the one that looks like [ | ] in the constraint menu. I click on two points but then cannot select the x-axis as symmetric line.

Same for the worker lines. Right now I have a distance of 19.5mm set between the centers of both arcs. But what I really wanted to do was create 2 helper lines that are tangent to these arcs at top and bottom and have the distance between these be 33mm (which automatically makes the distance between the centers of the arcs 19.5mm). I can create these lines but how do I tell Inventor that these are only helper lines?

Re: Symmetry and helper lines

mcgyvr — Wed, 23 Sep 2015 14:44:23 GMT

http://knowledge.autodesk.com/support/inventor-products/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/Inventor-Help/files/GUID-0949DF69-9B9A-4C8D-A3EB-022CFCAC2A8D-htm.html

axes cannot be selected.. Need to use "construction lines" (aka helper as you call them)

and here is where you turn on construction lines..

Re: Symmetry and helper lines

Anonymous — Wed, 23 Sep 2015 14:40:11 GMT

I just tried the Project Geometry but I'm not able to click on the axes of the coordinate system.

Re: Symmetry and helper lines

Anonymous — Wed, 23 Sep 2015 14:42:44 GMT

Thank you, but the problem is that I cannot click on the symmetric axis that I want, which is one of the axes of the coordinate system.

Re: Symmetry and helper lines

mcgyvr — Wed, 23 Sep 2015 14:48:54 GMT

@Anonymous wrote:

Thank you, but the problem is that I cannot click on the symmetric axis that I want, which is one of the axes of the coordinate system.

edited my post after you posted.. you cannot use origin axes for symmetry lines..

BUT.. simply using a vertical constraint on the centerpoint of one of the arcs will accomplish the same goal...

Re: Symmetry and helper lines

Anonymous — Wed, 23 Sep 2015 14:55:19 GMT

Yes, I know I can solve the problem now. But say that the sketch consisted only of those two lines connecting the two arcs, but the arcs were not actually there. How would I make those symmetrical to the vertical axis in that case?

Re: Symmetry and helper lines

swalton — Wed, 23 Sep 2015 14:57:43 GMT

Make sure you are clicking on the plains and/or axis shown in the origin folder, not the triad shown in the graphics window, when you use the project geometry too

Re: Symmetry and helper lines

Anonymous — Wed, 23 Sep 2015 15:04:35 GMT

@swalton: Thank you so much, that was my problem. Before, I clicked on the axis in the graphical window. It works now!

Then my only other question remains: how do I create helper lines in my 2D sketch? I mean I can use the origin axes now as a symmetry axes but how do I create a symmetry axis of my own and tell Inventor that it is an external geometry (used for constraining my sketch) and is no part of the actual sketch?

Re: Symmetry and helper lines

Anonymous — Wed, 23 Sep 2015 15:06:50 GMT

@mcgyvr: Thank you, this construction line is exactly what I was looking for!

Thank you so much everybody, this thread can be closed!

Re: Symmetry and helper lines

swalton — Wed, 23 Sep 2015 15:10:47 GMT

You can mark the thread as solved by pressing the "Accept as Solution" button for any/all replies that showed you how to answer your question.