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Constraints in AutoCAD

10/11/2011 10:15 AM

I want to draw a circular object in autocad then when I rotate it the object will move in the X plane (like if I were to roll a ball across the floor). Either that or when I move the object in the X plane I would like the ojbect to rotate again as if it were rolling.

Any ideas on how to do this would be great.

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#1

Re: Constraints in AutoCAD

10/11/2011 12:06 PM

Are you attempting to make an animation using AutoCAD? There is much Superior software if this is the case.

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#2

Re: Constraints in AutoCAD

10/11/2011 3:39 PM

AutoCAD is bundled with Inventor, Autodesk's 3D solid modeller. Inventor will do what you want, and WAY more.

If you've got AutoCAD on your desktop, chances are you've got Inventor too. Talk with your I.T. department if you don't. You'll NEVER go back to 2D.

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#3

Re: Constraints in AutoCAD

10/11/2011 3:54 PM

Thanks for the replys. I do have inventor and I know it is possible to do this on inventor but often I just want to run a few ideas by people and it is way easier to take the existing 2d model and make changes. By being able to do this I can save a lot of time.

It seems like such a simple thing to do but then you look at the constraints and think how the hell do you apply them to do this?

FYI the technology I'm looking at is ball valves and in some designs the ball rotates and stays in the same lateral translation, in other cases as the ball rotates the ball also translates.

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#4
In reply to #3

Re: Constraints in AutoCAD

10/11/2011 4:16 PM

Is the ball spherical and smooth? If so, why bother with the rotation bit? Or am I missing something that would be obvious to another valve guy?

I am heavily biased toward 3D. There might be more up-front work, but a well designed and constrained assembly allows multiple design iterations in a relatively short period of time. Animations become a snap if you've constrained your parts with that in mind. Add Vault into the mix and you can have a new design, documentation included, in just minutes.

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#5
In reply to #3

Re: Constraints in AutoCAD

10/11/2011 11:37 PM

If you think such a simulation is easier in 2D Autocad than in Inventor then you haven't received adequate training in Inventor.

I've done hundreds of simulations and "what-if's" in Inventor with groups of people and rarely had anyone question what was on the screen. With Autocad I've often had to explain to people what they were seeing.

Linear and rotational constraints are much easier to manipulate and animate in Inventor, and the ability to simultaneously rotate, pan, and zoom the screen in 3D is invaluable.

But, then, that's not what you came here asking about. And, to be honest, I can't answer your question as I've only used Autocad to do simple dxf editing for the last several years.

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#6

Re: Constraints in AutoCAD

10/12/2011 12:54 AM

You are basically in the wrong application - use Inventor [then you can extract the drawing files to autocad, if drawings are required]

These days, most model [Inventor] then extract .

You can go the other way - as you are asking. I.e. draw in autocad then import to Inventor, and animate. But it's more 'died in the wool' drafting approach than 'productive', given the state of 'modeling art'.

This approach of model then extract also applies to Pro-E, but not so much for Solidworks, which is great for modeling, but the drawing side still sucks.

However all 3 will interface with CNC, largely obviating the need for 'hard copy' drawings - which was the autocad 'edge' - back then.

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#7

Re: Constraints in AutoCAD

10/12/2011 2:39 AM

Thanks again for all the replies. I know I need more training in Inventor, the problem is just time, we are short staffed, have many projects backing up and we have thousands of parts and assemblies already drawn in Autocad but not Inventor. The draughting dept is also snowed under so this isn't something I would ask them to do.

I applied constraints to one assembly to show how the ball in a valve rotated when other parts moved and someone asked me the other day how I did it. The problem with the valve he was asking about is that the position of the ball moves as it is rotating. The ball is spherical but has parts cut out of it and it is vital to be able to see these parts.

One day the draughting team will get round to modelling the assembly in Inventor but until then I was hoping for an easy way to apply constraints to the already drawn assembly in Autocad.

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#8

Re: Constraints in AutoCAD

10/12/2011 3:05 AM

MACA, remember way back when (if you're old enough) when we all used blue-line blue prints? Drafting boards, t-squares and different hardness pencil leads for different line thicknesses? Then along came that fancy computer drawing stuff that some companies started trying to push? Who needs that? We had ALLLL our drawing libraries done by hand. All those parts. All those drawings. Who has time to learn computer drawing? And how will we ever make the transition, while all of our thousands of parts are drawn on vellum? Just don't have the time to learn. Much faster to just hand draw it and get it out to the shop.

Well, you must realize that you are at that very same point again. Yes, it takes time to learn. Takes a bit of investment, for programs and for lessons and practice time. Yes some drawing will be late. For now.

But like it or not, the industry really has moved forward. We all had to make those very same investments and lost time, and the frustration of learning the new programs. The solid modeling programs. And in the end, eventually and forever after, drawings and changes/revisions and presentations are just sooo much faster and clearer and more efficient. It's just the way it is. I've been there. I feel your pain, and I held out for the same reasons that you are justifying it. But the world moves forward and hold outs really do get left behind and suffer for it. And... you already actually own the program. First expensive step is done. All you need now is professional instruction (so you don't learn counter-productive bad habits that many self-taught people force upon themselves), and practice time.

Sorry I didn't answer your actual question, it's just that your reasoning not to use Inventor brought back a lot of memories of exactly the same things I remember I was saying a while back.

I apologize for lecturing. Just trying some tough love on a familiar problem Now I'm finished

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#9

Re: Constraints in AutoCAD

10/12/2011 5:25 AM

I have to agree with the consensus here, it will be easier & more realistic in Inventor. We, like you, have a large legacy (10,000 drawings) in 2D but we now find it much quicker to re-create them in Inventor rather than working in 2D.

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#10

Re: Constraints in AutoCAD

10/12/2011 5:56 AM

I agree totally with the comments made already. The problem is that I work for a company which employs 5000 people in 51 different countries and this is not my choice. The switch to Inventor is happening but in my day to day work I mostly work with 2d drawings on Autocad because that is what the drawings are on.

There is no way my boss would give me the time to draw these assemblies in Inventor (partly because the draughting dept are supposed to be doing it) and this is just a one off problem which I was asked.

Along with a collegue I built and animated a complete assembly in Inventor last year but I do not have time to keep my skills honed in Inventor because in my job I use it so little. If you don't use it you loose it.

Anyway, back to the original problem, it seems either nobody knows or nobody would ever try to do this. Its actually not a serious problem because there are many ways to skin a cat and we have the info we need from the 2d drawing it was more a question of "if its easily achievable does anyone know how?"

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#11
In reply to #10

Re: Constraints in AutoCAD

10/12/2011 10:19 AM

"if its easily achievable does anyone know how?"

Tutorial on How to Import a 2D AutoCAD Drawing Into an Inventor Drawing

By Matt Scheer, eHow Contributor

AutoDesk Inventor is a three dimensional graphical editing program. Similar to AutoCAD, Inventor is used for creating detailed designs of buildings, machines and more in three and two dimensions. Inventor lets you import two-dimensional data

assets from AutoCAD into an Inventor drawing or a new file, then edit the data without any artifacts or dropped points and paths. This feature is especially useful for turning a two-dimensional drawing in AutoCAD into a complex three-dimensional design in Inventor, where it can be prototyped or run through mock simulations.

Difficulty:Moderately Easy

Instructions

    • 1 Click on the "File" button, then the "Open" button in AutoDesk Inventor.
    • 2 Search for the AutoCAD file you wish to import into AutoDesk and select it. Do not yet press the "Open" button.
    • 3 Change the file type to DWG and press the red "Options" button. Turn on the "Constrained End Points" option to ensure all of your endpoints are imported correctly into the AutoDesk file. Click the "Open" button.

Read more: Tutorial on How to Import a 2D AutoCAD Drawing Into an Inventor Drawing | eHow.com http://www.ehow.com/how_6646852_tutorial-autocad-drawing-inventor-drawing.html#ixzz1aZpNMlYA

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#12
In reply to #10

Re: Constraints in AutoCAD

10/12/2011 10:30 AM

I understand your plight, I was once there myself. I can't offer you a suggestion on how to deal with your problem using AutoCAD since I use Inventor exclusively, and how been for over 10 years. But I will say that you can pick away at your 2D legacy data as time and project scheduling permits. As time goes on, you'll get faster and faster. Once you have an impressive assembly and animation all ready to go [and tested for functionality!], let your boss have a look at it.

I'm curious, why is your drafting department doing the modelling? Shouldn't you be?

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#15
In reply to #12

Re: Constraints in AutoCAD

10/12/2011 3:32 PM

We are under instruction that all cad work, be that AutoCAD or Inventor, is to be done through the draughting team. My days are spent doing calcs, writing documents, investigating failures etc. I would be the first to agree that this isn't the best setup but there is a major shortage of engineers here and we are very understaffed. I don't work on new design so I very rarely use Inventor. Thinking about it the last time I used it was on a one day Inventor course about this time last year.

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#14
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Re: Constraints in AutoCAD

10/12/2011 3:29 PM

My comments were under the presumption that you had some control over what programs are used and what training is received. But for someone in your position, obviously there is not a lot you can do other than make reccommendations... which I know often fall on deaf ears.

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#13

Re: Constraints in AutoCAD

10/12/2011 1:24 PM

I personally have not tried animation of a 2D model. But, if you refer to your autocad reference books and review "navigating in walk mode", this sems to be what you were describing. The book also covers saving the path as a movie file. Once again, not up my alley. Not all out there is 3D. I am working with an end user, they are not even up to speed in autocad 10. The 3D model and drawing files, had to be dumbed down for autocad 2007, which supports their operating software.

good luck

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#16

Re: Constraints in AutoCAD

10/13/2011 10:44 PM

Are you saying that the object doesn't rotate on its axis, but rotates around some point off centre to the axis of the ball?

If this is what you have, do you just need to change the "anchor" point or whatever it may be called. If you can make the anchor or base point in the centre of the ball, then when you rotate the object, it will rotate on its axis, & not move away from where it should sit?

Hope this may help or at least point you in a direction to address your problem.

I understand about companies, resources, existing systems...

It not at all helpful when all you get is "No, use this system!"

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