AutoCAD 3D Constraints?

[Pertech-LLC]

OK first off, I know the bare bones basics in the 3D world, so feel free to elaborate on any answers.

My basic question I can't seem to find an answer to is; Are constraints of any sort possible in plain ACAD 3D?

Long version: I have a basic design need to lay out something similar to a steering system, with 2 pivot point idler arms & a connecting bar. I'd like to lay out some sort of constraint where I can pivot one of the idlers & watch the path of the connecting rod & the other arm. (See drawing1). This basic design could be done easily in 2D & save time. However, it gets more complicated when you change the angle of one of the pivots (See drawing2), which is the case for my actual project (along with playing with varying idler arm lengths).

A method of specifying that I want a fixed distance between two 3d points, while being able to specify each objects pivot axis would be perfect, but I can't seem to find much searching. I realize I may be asking a bit much of the base ACAD software with this one, but does anyone have a work around for this scenario?

[JDMather · Accepted solution]

I think I would look at something like Autodesk Inventor for this project.

A colleague of mine wrote a paper on doing some thing like this in AutoCAD, but it is quite advanced.  I don't think it could be understood outside of classroom instruction.

You could also investigate Fusion 360.

Students can get Inventor or Fusion for free here http://www.autodesk.com/edcommunity

and

Fusion 360 is free to most other users as well.  (check the qualifications for free use)

[BrianBenton · Accepted solution]

The short answer is no. AutoCAD constraints are only for 2D applications.

That being said, some people have found that they sometimes work in 3D circumstances. You really have to jump through hoops to get it to work. 

You will find they are not powerful enough for what you are trying to do. I would agree with JD in the other post that you might want to take a look at Fusion for this project.

[nestly2]

Single plane like your first example is no problem, but once an AutoCAD constraint is applied, it can't be further constrained to move in the Z axis

[JDMather]

I can get you in touch with someone who knows how to do this if you are interested in a training class.

[Pertech-LLC]

I'm not sure any of those cover what I'm needing either, the odd pivot axis on each arm being the catch. I've looked into some basic scripting to get some motion, but it's all based on a single pivot axis. I have yet to find anything done with that method that pivots on an odd axis like that. May be possible with some lisp work, but that seems it would be limited to a custom lisp for each potential design.

I'm not so much looking for the animation as I am using it as a design tool, the seeing it move isn't as important as the quick reference of what happens when I change the length of one arm or angle of pivot, which coming from a usual 2D environment constraints were the first thing to come to mind.

[dgorsman]

Wouldn't necessarily be a custom routine for each design - it should be possible to sufficiently genericize the functionality that it can be re-used.  Quite a bit of work, though, and probably easier with dotNET.

[CAD_Craig]

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@nestly2 wrote:

Single plane like your first example is no problem, but once an AutoCAD constraint is applied, it can't be further constrained to move in the Z axis

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I need to do something almost exactly like this. Can anyone tell me how this was done?

[leeminardi]

Here's a tutorial I just put together to show the steps in creating and animating a 4-bar linkage using block, parametrics and a little vlisp.  

https://youtu.be/Y4VAJ5mNnng

[CAD_Craig]

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@leeminardi wrote:

Here's a tutorial I just put together to show the steps in creating and animating a 4-bar linkage using block, parametrics and a little vlisp.  

https://youtu.be/Y4VAJ5mNnng

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I watched the video and it did end up helping me. I hadn't thought of using a block with both 2d and 3d elements in it to drive the constraints. Thanks for posting it!

[Anonymous]

كيف يتم تفعيل القيود على الاجسام ثلاثية الابعاد

[mghvinjilia]

Hello !  

How I can draw 3d spline to have minimum distance between lines 5 unit ( for instance )  

Thank you 

Best Regards 

Merab Ghvinjilia 

[leeminardi]

Could you provide more information about the requirements?  Are the lines positioned randomly in 3D?  A sample drawing with a potential solution would be helpful.