Perfect Ellipse?
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=13852
Printed Date: 05.Sep.2026 at 02:23
Topic: Perfect Ellipse?
Posted By: dery
Subject: Perfect Ellipse?
Date Posted: 29.May.2023 at 19:34
|
Can someone please tell me what is perfect ellipse and how do I draw it in AutoCAD 2014? Thanks
|
Replies:
Posted By: TECH 011
Date Posted: 30.May.2023 at 08:18
| I also want to know the answee |
Posted By: Vladimir Michl
Date Posted: 30.May.2023 at 08:26
|
Perfect true (B-rep) ellipse can be created with the [CMD]ELLIPSE[/CMD] command (with the [VAR]PELLIPSE[/VAR] setting kept on 0). ------------- Vladimir Michl (moderator) https://www.linkedin.com/in/vmichl/" rel="nofollow - LinkedIn , Autodesk Expert Elite |
Posted By: dery
Date Posted: 30.May.2023 at 11:30
| What is perfect ellipse? Can anyone show me easy example of how to construct perfect ellipse using technical drawing method in AutoCAD? |
Posted By: Kent Cooper
Date Posted: 30.May.2023 at 14:37
|
dery wrote: Can anyone show me easy example of how to construct perfect ellipse using technical drawing method in AutoCAD? Use the ELLIPSE command [with the PELLIPSE System Variable set to 0]. If you want to do it with the electronic equivalent of manual drafting techniques, using something like a compass, you can't make it a true elliptical shape, because the curvature of an ellipse is of constantly changing radius, so there's nowhere to put the compass point. If PELLIPSE is set to 1, it makes an approximation with 16 arc segments, which is pretty close [and was the only way, and that System Variable did not exist, in early versions before the ELLIPSE command made a real elliptical shape].
|
Posted By: dery
Date Posted: 30.May.2023 at 15:26
| What is the difference between a perfect ellipse and regular ellipse? |
Posted By: philippe JOSEPH
Date Posted: 31.May.2023 at 08:00
|
Hello dery and Kent, in fact the actual ellipse command is very good within the limitation of it being with facets but very precise anyway. Before AutoCAD R13 of year 1995 ! the R 12 release had effectively not so precise ellispses and as R12 was the first software coming in my work company this lead to a funny exchange between an old but reliable engineer with "only" his polish method calculator and an young with no experience contractor unable to draw "perfect" ellipses with the R12, only given the OK with the R13 release. Dery, up to what level of perfection do you want to go ? I once complained about the unprecise helix drawn by AutoCAD and a german guy gave me a program to draw it correctly because the AutoCAD one was 200 mm apart ( only at the extremities ) for a 10 m radius.
|
Posted By: dery
Date Posted: 31.May.2023 at 10:37
Why do you ask "Dery, up to what level of perfection do you want to go ?"? I have no idea what you're talking about. |
philippe JOSEPH wrote:Posted By: philippe JOSEPH
Date Posted: 31.May.2023 at 11:07
| Dery, how much precise must be your ellipse and for what use do you want a perfect ellipse ? |
Posted By: dery
Date Posted: 31.May.2023 at 20:33
Does perfect ellipse availble in precise and unprecise? If so, I choose precise. Please show me how to construct perfect ellipse using technical drawing method in AutoCAD.
|
Posted By: dery
Date Posted: 02.Jun.2023 at 13:47
|
Why no reply? Please answer my questions. |
Posted By: Vladimir Michl
Date Posted: 02.Jun.2023 at 13:52
|
There is no "more perfect" ellipse in AutoCAD than the perfect ellipse created with the ELLIPSE command. ------------- Vladimir Michl (moderator) https://www.linkedin.com/in/vmichl/" rel="nofollow - LinkedIn , Autodesk Expert Elite |
Posted By: Kent Cooper
Date Posted: 02.Jun.2023 at 14:39
|
>> Please show me how to construct perfect ellipse using technical drawing method in AutoCAD. << Maybe we need to know exactly what you mean by "technical drawing method," if that means something other than what I discussed in my earlier reply. A question: whatever you mean by that, is there a reason you need to do it that way, rather than to use the built-in command, which makes a more perfect one than you will ever be able to do by other methods? Turn SNAP on at some large-enough value that you can pick on exactly the same locations, and draw an Ellipse using the ELLIPSE command with PELLIPSE set to 0, and again at the same locations with PELLIPSE set to 1, then Zoom in and you'll see the difference between a precise one [the Ellipse object] and a pretty close approximation [the Polyline object]. Is that approximation close enough to "perfect" for you?
|