What is meant by ellipses with degree (please see below image for more detail) and how do you draw it?

Hello dery, please find an example of ellipses with degree.In fact an ellipse is a circle that you look on its side with a certain angle ( degree ).If you have an angle of 0� you will only see a line, if you have an angle of 90� you will see the circle.I hope this will be self explanatory because I'm at home without AutoCAD.

Dery, what you see on the picture are old drawing plastic parts to be used on the drawing board.If you want to draw your examples you can do it in 3D or draw a circle and do some "angled projection". 

philippe JOSEPH2018-08-27 17:40:31

dery wrote:  What is meant by ellipses with degree (please see below image for more detail) and how do you draw it? That is what is represented by the Rotation option in the Ellipse command, except that you should subtract their number from 90 degrees [i.e. use 65 where they show 25]: ELLIPSESpecify axis endpoint of ellipse or [Arc/Center]: {picked a point}Specify other endpoint of axis: {picked a point}Specify distance to other axis or [Rotation]: RSpecify rotation around major axis: 45 {or whatever}
Kent Cooper2018-08-28 00:32:28

And the next step is your AutoCAD drawing 2D or 3D + flatten.

Kent COOPER, I have uploaded the AutoCAD file : ELLIPSES WITH DEGREE.dwg in the CAD/BIM Blocks library because I'm trying to draw the cubes and the ellipses.For the ellipses your methods looks appropriate to the case but I'm not abble to draw the cubes in 2D ( dimensions x , y  , z in relation with the angles defined in the 3 figures ). Can you help ? I have tried to draw it in 3D with the concept define in the test :Figure 11.47 . Angle size determines viewpoint of object but it doesn't work vith the command viewpoint.Dery have you fixed your drawing problem because not me.
philippe JOSEPH2018-08-31 08:12:21

Obviously the 10-degrees-up-on-one-side and 40-degrees-up-on-the-other in the original left-most image don't mean the same thing as the "From the X Axis" and "From the XY Plane" angles in your VPOINT dialog box images.  I'm not sure how to translate between them, but it certainly would involve some potentially complex trigonometry. But I now question the legitimacy of the original image.  I did manage a fully-2D way to get a 55-degree- and two 25-degree-rotation Ellipses to sit cleanly in Lines representing a "cube" with those 10- and 40-degree base-side angles.  But I'm reluctant to describe how, because if all was legitimate, the Ellipses that touch shared "cube" edges should touch them in the same place, but they don't -- their touching points are a [not huge but] meaningful distance apart.  I suspect that for those nice round-number base-side angles of 10 and 40 degrees, the true "rotation" or "degree" of those Ellipses would not really be their nice clean 55 and 25 degrees.  Do you know where those numbers come from, i.e. how the rotations are derived from the base-side angles?  It would take me some pondering to figure what they should really be, and maybe I'll find time to try to figure that out later....

That turns out to be the case -- the true "rotation" or "degree" of the Ellipse on the left face of the left-most image [with the base-side angled up at 10 degrees], that they show as 55 degrees, would in reality be a hair over 57 degrees.
Likewise the one on the top face of their middle image.Kent Cooper2018-09-10 21:20:37

Hello Kent, thanks for the effort to explain this for me and Dery.Unfortunately I'm not enough good at maths for you and from all the years that I did use informatics I know, because I have used the drawing board and then the computer and again the drawing board, etc... again till 1995 the beginning of the "all computer era" for me that when you use a computer you loose the ability of "thinking" or at least how to use a hand calulator.My actual problem is to solve dery's exercise and of course if I have enough time I will do some "hand viewpoint test" to point to the right direction and drawn in 3D and then flatshot the result but :I would be interesting to realize it "directly" in 2D and this will only be possible if I can drawn these cubes in 2D and then try and draw these ellipses with degrees that wil have to touch the sides of the 2D cubes.I know how to draw "by hand" 2D or 3D" automaticaly with the computer" isometric views but not these 3D "special point of views", can you help me ( and Dery if he still want )? 
philippe JOSEPH2018-09-10 21:38:59

I'm not sure how to get a 3D view to be from the right direction that Flattening it will result in the desired base-edge angles, either.  If I think of something, I'll write back.In 2D construction, the "problem" in the drawing file of the dimensions of the edges has a solution for a specific degree-of-rotation of the top-of-cube Ellipse.  The one on the "left" face, in the left-most image in the initial message here, is (because the other two have their Ellipses rotated at the same "degree") a rhombus, so 50 units is appropriate there.  And because it's a rhombus, you can build the appropriate Ellipse pretty easily [for the moment, consider only that left face]:Make an Ellipse using the corners of the rhombus for the axis endpoints [the dashed-line larger green one], put a Line across the middle of the face [yellow], and SCALE the Ellipse down, about its CENter, using the Reference option with the two magenta points as the Reference distance [MIDpoint and APParent-intersection], and the end of the yellow Line as the new distance.  Either of those Ellipses will give you its axis aspect ratio in the (assoc 40) entry in its entity data -- the real rotation of it is the angle whose sine is that number [included in the next image]. That image also shows one way of easily making the other two sides, also as rhombi, as a true isometric version would be, making their Ellipses equally easy to draw in the same way [blue].  BUT in the original image, the Ellipses on the top faces of the cubes all have their major axis horizontal, which the above does not.  For that, the desired degree of rotation of the Ellipse affects the edge dimension along the 40-degree sides.  Determining that involves drawing an Ellipse with its major axis horizontal, and the desired rotation, Rotating copies of that appropriately so that drawing bounding boxes around them [the dashed grey below -- I have a routine to do that] and Rotating those back gives edges parallel to the "cube" edges, then some Moving and Scaling [with Reference option] to get them in the right positions and sizes, and the far-side cube edges in the right places. I'll upload the CAD file that both these images came from -- same place and same file name with -2 added at the end.

OK kent you have done an incredible job !If I understand your first question about the way to find the right 3D view giving the desired angles I was about to give a try by aproximate ( and numerous ) tests with the command viewpoint "From the X Axis" and "From the XY Plane" angles.Anyway I will have to read and read again your explanations to do my tests, thanks again.And the dimensions noted 50 on your first image ( maybe taken and modified from my AutoCAD file ) will have to change conformably to the Figure 11.47 given firstly by Dery.I have noticed the arrival of your new AutoCAD file in the CAD/BIM Blocks and will take a good look at it tomorrow.

So, is there any step-by-step explanation with some images?I still don't understand what you're talking about. 

Hello Dery and Kent, the subject is re-drawing your 3 figures 11.47.I don't know how to determine the 3 lengthes of the cube in 2D so I'm trying to do it in 3D with the command viewpoint and then flatshot it to get the 3 different lengthes and the 3 didfferent ellipses ( with angle ).Then it will be possible to determine the angles of the 3 ellipses if I suceed in doing it because any change in the preset "from X axis" + " from XY plane " change the 2 angles.

Here is a spreadsheet that helps create a view of a 3d object with specified angles off a baseline.  I noticed that the VPOINT command does not allow for a particularly tight tolerance.  The spreadsheet also sets up a vector to be used with the more capable DVIEW command.  "Copy" the excel data within the border, Invoke the "POints" sub option of DVIEW command, then paste to the command line.The Excel File is here at Autodesk 360:https://autode.sk/2p0VELQI've uploaded the DWG in this image into this sites Blocks area.  

Hello Seant, I have seen at a first glance the arrival of your AutoCAD file in the CAD/BOM Blocks.Thanks a lot, can you explain eventually your method to set the viewpoint correctly ?

As soon as my original message gets past "Pending Approval", I think all will become clear.l

Hello Seant, thanks again, unfortunatly I'm not understanding your "Pending Approval" but it's like this.Dery and Kent, I have uploaded a new file : ELLIPSES WITH DEGREE-01.dwg based on Seant's 3D AutoCAD file that are giving the real values of the famous angles 25� , 25� and 55�.At first I did set "manually" my 3D viewpoint with the values of Seant's file but it was not perfect Alpha 9.979...£ and Beta 40.009...£ so I simply copy/paste Seant's viewport into my own file and it was 100% OK.Seant, so I presume that the settings "from X axis and from XY plane" are not set manually but informatically..........
philippe JOSEPH2018-09-14 08:04:47

Though, it has been in the "Pending Approval" state for over 24 hours. Maybe it has met with disapproval.  It contains a link to an Excel file on my Autodesk 360 account.  Is there a preferred method of presenting non DWG files?

Hello again Seant, I would be happy to have your explanation Excel file but I don't know how to get it so I won't have to stay poor , uggly and ignorant ( joke ).

Maybe give this a shot.  There has been a space added between every character.h t t p s : / / a u t o d e . s k / 2 p 0 V E L Q

It looks like that will not work.  Posting to this forum is not very user friendly.

My first post to this thread (#14) is now visible.

[QUOTE=dery]So, is there any step-by-step explanation with some images?....[/QUOTE]
 I just uploaded ELLIPSES_WITH_DEGREE-3 [in the same Mechanical/Other category], explaining how I drew the left instance in the original image, purely in 2D construction.

[QUOTE=Kent Cooper][QUOTE=dery]So, is there any step-by-step explanation with some images?....[/QUOTE]
 I just uploaded ELLIPSES_WITH_DEGREE-3 [in the same Mechanical/Other category], explaining how I drew the left instance in the original image, purely in 2D construction.[/QUOTE]
Where I should download it?Can you show me the link?

Dery you can find the AutoCAD file in the CAD/BIM Blocks library here in the site.Take a look on the top left of your screen and you will find it under : CADForum Home , CAD Discussion , Tips & Tricks , Downloads , CAD/BIM Blocks and here you are...By the way "1" There are a LOT of very interesting AutoCAD files there and with a search by names you will find nearly everything that you want.By the way "2" Have you done your searches and tests on the subject that is suposed to be a student's home work ?



philippe JOSEPH2018-09-15 07:21:22

[QUOTE=dery ....Where I should download it? Can you show me the link?[/QUOTE]Also, right in the home page, as of today it's still recent enough that you'll find it in the "New CAD Blocks" box.  Once it passes out of there, the CAD/BIM Blocks item on the left has categories -- go to AutoCAD DWG Blocks / Mechanical / Other.

Kent Cooper2018-09-17 15:19:48

Hello Kent, I have uploaded an updated file : ELLIPSES WITH DEGREE-01B.dwg showing the 2 cubes elaborated by you in pure 2D and me a flatshot of a 3D solid and it shows a little difference in the X dimension ( the other Y and Z being = 50 ).See at the bottom right of the file.In fact all the discussion is about these X , Y , Z dimensions...

[QUOTE=philippe JOSEPH].... the 2 cubes elaborated by you in pure 2D and me a flatshot of a 3D solid and it shows a little difference in the X dimension ( the other Y and Z being = 50 ). ...[/QUOTE]
 That's because the 20- or 25-degree "rotation" of the Ellipses on the top and right faces of my drawn-all-in-2D "cubes" are arbitrary round-figure approximations that look sort of close to what the real appearance would be.  Your Flatshot version, coming from a real 3D cube viewed at the right angle to get the 10- and 40-degree angles for the base edges, results in a true rotation of those Ellipses of about 22.622 degrees.  Presumably if I went through the process using that, instead of the approximated 20 or 25, it would match yours on the other edge length.

Hello everybody, I just found this in my old pictures :

Hi guys, I have a problem opening the CAD/BIM blocks you already uploaded using my AutoCAD2014.Are you sure that you already save the file so that it can be opened using AutoCAD2014?It cannot be opened using my AutoCAD2014.Please help me.

Hello Dery, tomorrow I can save it as AutoCAD 2010 instead of my AutoCAD 2017 that we have recently changed.

It's alright. Now I can open them using my AutoCAD 2014.However, there is still one problem, the text is missing.As I can see of these CAD/BIM Blocks you uploaded, this is not a step-by-step instruction, I don't understand.Can you please upload another CAD/BIM Blocks with a step-by-step instructions?Thank you.

dery2018-09-30 14:53:48

Dery, on my files the text color is green as you can see on the thumbnails, try and change your screen color if green.The basis of the studies is the very first 3 schemes and I have done a study based on a 3D cube in the model space and then try to open viewports in the layout space to "look like" the 3 schemes.I have "almost" suceeded but with a very poor precision, and Kent COOPER did an other "2D only" study on how to draw the ellipses inside the shapes.Then SEANT gave us the good "point of view" to apply to the viewport ( scheme 1 ) so I did that and did a FLATSHOT to have the cube with the 2 correct angles 10 degree and 40 degree as the basis was the 2D drawing.At this time "we" have the first schemme OK and only SEANT can give us the good viewport settings for the 2 others but as it's based on an EXCEL file difficult to send "we" don't have the 2 others.Hope this will help, if not tell us.

philippe JOSEPH2018-09-30 16:50:14

Dery, a/the "step by step" method is explained on Kent COOPER's file ELLIPSES_WITH_DEGREE-01.dwg 14 sept 2018.

[QUOTE=philippe JOSEPH]Dery, a/the "step by step" method is explained on Kent COOPER's file ELLIPSES_WITH_DEGREE-01.dwg 14 sept 2018.[/QUOTE]
 [Actually, the step-by-step is in the one called ELLIPSES_WITH_DEGREE-3.]

I'm so sorry Kent, yes it is in ELLIPSES_WITH_DEGREE-3.

[QUOTE=philippe JOSEPH]. . . .At this time "we" have the first schemme OK and only SEANT can give us the good viewport settings for the 2 others but as it's based on an EXCEL file difficult to send "we" don't have the 2 others. . . .

[/QUOTE] A link to the Excel spreadsheet is in the 4th post on page 2 (my first post in this thread).  Are you not able to download and/or open that file?  

Also so sorry Seant, I just didn't see your post.Now I have the EXCEL file and I will use it to elaborate the 2 other drawings with the other angles so that I will be abble to get the X,Y,Z dimensions of the cube that I'm not abble to draw in those non isometric points of view.

I just took a look at the 2 other drawings and.......Maybe it's possible to draw them easily with a "simple" 2D projection between 2 views because the other angles are equals..............
philippe JOSEPH2018-10-01 20:21:55

Seant, I have open your EXCEL file and set it to the 2 other schemmes but I don't know where to copy/paste the 2 angles as I don't fint the sub option POints.

philippe JOSEPH2018-10-02 08:07:23

[CMD]DVIEW[/CMD] The POints sub option is part of the DVIEW command.  Depending on the language version of AutoCAD, the command may need to be called with a "." prefix.  If need be try:.DVIEW