topic Re: Rotate on user created Plane in AutoCAD Forum

Rotate on user created Plane

Drewpan — Fri, 27 Aug 2021 07:08:30 GMT

Hi All,

How do I rotate an object about a user created plane?

3dRotate aligns the three rotation axis about the WCS even if I am using UCS.

Rotate3d also seems to use the WCS axes even in UCS.

I have created a Plane between two parts of my drawing and the origin (0,0,0).

I want to align a part between those two points and the origin at a specific angle, and then

rotate the same part below the Plane at a very specific angle.

The specific example is like this.

Line 1 extends from the Origin to a point 126 degrees and one unit. Polar (1, 126)

Line 2 extends from the Origin to a point 126 degrees and one unit. Polar (1, -126)

Line 3 extends from the Origin along 0 degrees one unit Polar (1,0)

This creates an angle of 108 degrees between Line 1 and Line 2 and will become a

regular Pentagon.

All of these lines are initially zero elevation above the Z Plane.

Line 3 is then rotated about the Origin 31.717 degrees up into the Z Plane. So that one end is the Origin

and the other end is in Z Space.

By doing these rotations, the angle between L1 and L3 (and L2 and L3) on the Plane created by L1, Origin, L3

is 120 degrees. This will create a Regular Hexagon later.

L4 is positioned from the Origin to 180 and one unit Polar (1,180). This is exactly half way between L1 and L2

and then will be rotated -10.135 degrees below the XY Plane into Z Space.

That is the easy bit.

I now need to draw L5 which must be at 60 degrees relative to L1 and L3, and then further rotated

perpendicular to the Plane L1, Origin, L3 to form an angle from the Origin of 11.992 degrees towards

the XY Plane.

L6 is much the same except on the other side, 60 degrees relative to L2 and L3, and then further rotated

perpendicular to the Plane L2, Origin, L3 to form an angle from the Origin of 11.992 degrees towards

the XY Plane.

I have attached a drawing file. For reference:

L1 Light Blue Correct Position and Angle

L2 Dark Blue Correct Position and Angle

L3 Green Correct Position and Angle

L4 Yellow Correct Position and Angle

L5 Red Not yet positioned correctly. Should be 1/2 way between L1 and L3 but not at 11.992 to Plane.

L6 Red Not yet positioned correctly. Should be 1/2 way between L2 and L3 but not at 11.992 to Plane.

The Drawing is a Prototype part for a Bracket so that I can demonstrate I can build the finished Object,

then I will use it as a template to design the actual Bracket.

It has taken a VERY long time to get all of the angles worked out and the thing is a nightmare to actually

try to draw as it is symetrical and causes optical illusions when drawing 3D on a 2D screen. Hence the

colour coded Struts to try to reduce this.

Any help is much appreciated. If I can get this working and draw the finished Object then I am almost

finished the Project.

Thanks in advance.

Andrew

Re: Rotate on user created Plane

tramber — Fri, 27 Aug 2021 08:47:05 GMT

Sorry not to have the time yet to explore your dwg further but :

How do I rotate an object about a user created plane?

My answer would be : use ROTATE ! the 2D version !

Experienced as i am, i beleive that your exercice is not complicated at all.

You may have to use the ALIGN command sometimes too but not particulary in this case i guess.

This is a basic answer.

To practice half angles, don't forget to use the bissectrice option of the _Xline command.

Re: Rotate on user created Plane

tramber — Fri, 27 Aug 2021 08:56:24 GMT

Last but not least, did you know that you can write geodesical coordinates ? Cylindar or spherical ?

@0<113,100 (cylinder)

@0<113<123 (sphere)

see that link for exemple

Re: Rotate on user created Plane

Drewpan — Fri, 27 Aug 2021 12:23:56 GMT

Hi,

I think you have missed the point.

I am not trying to do a simple rotation of a part in 2D space. I am trying to do a two axis rotation on a

plane that is neither the WCS or the UCS. I am not trying to simply turn the part about itself.

What I want to do in effect is to align the 3-axis rotation ball from the rotate3D command with the

part I wish to rotate and the Plane that is defined by the two other parts, and then rotate this part

to a very precise angle. We are talking degrees to three decimal places - that is quite precise. It is

also required as when matched with Struts of similarly precise ratios, the shape can be scaled to 100

times original size. I would not call 31.717 degrees a very intuitive angle but when applied to a part,

another part rotated 126 degrees on the XY plane it creates an angle of exactly 120 between those parts.

While I may only be a Student, I have been doing this Project for months and I am quite up to scratch with

commands like 3dalign. In fact this is the command I am using to actually build my Geodesic Sphere from

the part I am trying to design.

Maybe if you spend a little time playing with the attached file you will see what I am trying to achieve.

Cheers

Andrew

Re: Rotate on user created Plane

leeminardi — Fri, 27 Aug 2021 14:25:04 GMT

Is this a continuation of this thread you created back in April?

I would encourage you to add some illustrations when stating your goals. For example, what does:

"L5 Red Not yet positioned correctly. Should be 1/2 way between L1 and L3 but not at 11.992 to Plane." mean. L1 and L3 are cylinders. Do you mean 1/2 way on a plane defined by points 1, 2, and 3?

Looking at your task :

I now need to draw L5 which must be at 60 degrees relative to L1 and L3, and then further rotated

perpendicular to the Plane L1, Origin, L3 to form an angle from the Origin of 11.992 degrees towards

the XY Plane.

By " 60 degrees relative to L1 and L3," do you mean that the 60° should be measured on a plane defined by a point on line L1, the World origin (0,0,0), and a point on line L3? If so, just define a UCS with those 3 points. The axis line of rotation for the 11.992° angle would be perpendicular to the angle bisector of L1, L3 and pass though the origin.

I prefer Rotate3d to 3drotate. You are incorrect in stating "Rotate3d also seems to use the WCS axes even in UCS." The "2 points" option lets you define the rotation axis at any 3D orientation.

[Object/Last/View/Xaxis/Yaxis/Zaxis/2points]:

You might have better success in getting a satisfactory answer by posting a single geometric construction question with a labeled drawing and a clear definition of the constraints and goal.

Check out the Windows 10 Snipping Tool if you are not familiar with it. If necessary, copy and paste the image into Paint to annotate it.

Good luck.

Re: Rotate on user created Plane

Drewpan — Sat, 28 Aug 2021 01:11:45 GMT

Hi Lee,

Yes this is related to my post in April but I am a lot more advanced than when I was then.

Calculating all of the Polar co-ordinates was just too hard so I tried another direction.

My explanation in the post was my attempt to logically explain what I was trying to do

in regards to the drawing I posted with it. All of the parts are in the correct orientation

except the Red ones. All of the parts pass through the origin.

The User Plane I am referring to is as your picture shows 1-2-3. The Red parts must be

at 60 degrees from the parts marked 1 and 3 on that Plane. The part must then be rotated

perpendicular to that Plane 11.992 degrees "down" towards the XY Plane.

Maybe I don't understand UCS as well as I thought. I will try your suggestion and use

Rotate3d after I reread about UCS.

One of the reasons I post here is that it helps crystalise my thoughts as I have to try to

explain it so that others understand. This in turn helps me get my head around what I

am attempting to do. I also get some answers and suggestions.

I have been thinking about the problem since I posted and have a few ideas about how

to make it work. I use both 3drotate and Rotate3d depending on what I am doing and

how my drawings are orientated. I find 3Drotate more intuitive because it is visual but

I also see how Rotate3d is more powerful. I just have to work out how to make it work

in this instance.

This Project has taught me more about AutoCAD commands than any tutorial or CAD course.

I am frequently searching for commands to do what I need and reading manual pages often

points me to more commands that help.

Thanks for your answer.

Cheers

Andrew

Re: Rotate on user created Plane

Drewpan — Sun, 29 Aug 2021 05:56:56 GMT

Hi,

Through your suggestions and a little further research into how some commands work I think I

have finally cracked it.

I stumbled upon an AutoCAD Blog that mentioned 3Drotate and how to re-align the Gizmos.

If you click the centre point of the Gizmo it gives you the option to line up with Object.

This allowed me to set the Plane with UCS then realign the Gizmos so that they worked as they

would in the WCS. I have built the basic Pentagon and Hexagon frame using my connector and

it is working so far. I just have to create the "caps" made of triangles with the correct angles

and see if they fit. They should but we will see.

Thanks for your help.

Cheers

Andrew