topic Re: AutoCAD 3D Constraints? in AutoCAD Forum

AutoCAD 3D Constraints?

Pertech-LLC — Tue, 31 Mar 2015 15:45:28 GMT

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?

Re: AutoCAD 3D Constraints?

JDMather — Tue, 31 Mar 2015 16:44:47 GMT

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)

Re: AutoCAD 3D Constraints?

BrianBenton — Tue, 31 Mar 2015 16:52:00 GMT

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.

Re: AutoCAD 3D Constraints?

nestly2 — Tue, 31 Mar 2015 17:16:53 GMT

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

Re: AutoCAD 3D Constraints?

JDMather — Tue, 31 Mar 2015 18:33:05 GMT

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

Re: AutoCAD 3D Constraints?

Pertech-LLC — Wed, 01 Apr 2015 12:56:58 GMT

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.

Re: AutoCAD 3D Constraints?

dgorsman — Wed, 01 Apr 2015 14:26:33 GMT

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.

Re: AutoCAD 3D Constraints?

CAD_Craig — Thu, 11 Jan 2018 12:29:25 GMT

@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

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

Re: AutoCAD 3D Constraints?

leeminardi — Thu, 11 Jan 2018 18:13:30 GMT

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

Re: AutoCAD 3D Constraints?

CAD_Craig — Fri, 12 Jan 2018 12:30:06 GMT

@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

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!

Re: AutoCAD 3D Constraints?

Anonymous — Mon, 20 Jan 2020 15:06:40 GMT

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Re: AutoCAD 3D Constraints?

mghvinjilia — Wed, 02 Jun 2021 10:43:27 GMT

Hello !

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

Thank you

Best Regards

Merab Ghvinjilia

Re: AutoCAD 3D Constraints?

leeminardi — Wed, 02 Jun 2021 12:18:54 GMT

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.