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Anthony
Posts: 387
Registered: ‎10-03-2011
Message 1 of 10 (270 Views)

Frustration with constraints

270 Views, 9 Replies
10-14-2011 09:47 AM

Being new to Inventor I am still unconvinced by the necessity for the huge amount needed for constraining sketches in Inventor, what is the best and most importantly easiest method of constraining a simple sketch ?

Anthony Goodwin ~ Cad Manager/Senior Designer
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cbenner
Posts: 3,176
Registered: ‎04-06-2010
Message 2 of 10 (264 Views)

Re: Frustration with constraints

10-14-2011 09:55 AM in reply to: Anthony

For the best answer, I recommend posting the version of Inventor you are using, and perhaps a screen shot of the sketch in question, or even the part file so others can look at it.  What kind of training have you had?  Look up user JDMather and see if you can get to the tutorials in his signature, very helpful to new users.

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ampster
Posts: 1,129
Registered: ‎07-26-2005
Message 3 of 10 (254 Views)

Re: Frustration with constraints

10-14-2011 10:02 AM in reply to: Anthony

Fully Constrain your sketches and get into the habit of doing so.  There might be an instance where you can get by without constraining a certain portion of your sketch, but it will be minimal if at all.

 

Look at it this way, in order for Inventor to understand your design concept - and to be able to handle even the slightest change - Inventor needs to know your intentions. Leaving something unconstrained tells Inventor you basically don't care what it does with it.

 

If you do not constrain sketches, Inventor may provide undesirable results if/when something changes or is added to the design later on.

 

HTH

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ampster
Posts: 1,129
Registered: ‎07-26-2005
Message 4 of 10 (249 Views)

Re: Frustration with constraints

10-14-2011 10:08 AM in reply to: ampster

let me add to that...

 

My job entails answering the phone when something isn't working right.  I'd say roughly 90% of those issues seem to come from under-constrained sketches.

 

After they have sent me their files, I start at the top of the feature list and diagnose every sketch, feature, constraint, etc.  After applying a few constraints or dimensions to under-constrained entities, the issue is usually resolved.

 

Things I see are symetrical geometry for example - or rather that was the design intent, are usually off the center point or center work planes by just a hair or two.  Applying dimensions and constraints to center the geometry works practically all the time.

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JDMather
Posts: 26,282
Registered: ‎04-20-2006
Message 5 of 10 (244 Views)

Re: Frustration with constraints

10-14-2011 10:21 AM in reply to: Anthony

Anthony wrote:

I am still unconvinced by the necessity


I have see zero, zip, nil evidence that not fully constraining sketches is any faster than constraining sketches.
In fact, all the evidence I have seen is just the opposite.

Virtually all of the fastest and best designers I have taught - fully constrain their sketches (OK, there are relatively rare times when it isn't necessary - but that is for experienced users - not beginners.)  Beginners should definately fully constrain.

 

And, now read this carefully, and then read it again - once you learn how to use Inventor you don't even add many constraints yourself - Inventor does it for you automatically in the background.

Missing dimensions?  Send to the shop floor and see how far that gets you.
Oddball dimensions?  See above.  You will quickly loose all credibility that is tough to gain back.  The shop floor guys will go out of their way to show what an idiot you are.  Do good work and they will point out your mistakes to you (rather than the boss) to help you improve the design and not even say anything to the boss.

 

You might start by reading this document http://home.pct.edu/~jmather/skillsusa%20university.pdf

then come back here in a year and review your post.

Please mark this response as "Accept as Solution" if it answers your question.
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Valued Mentor
jclaidler
Posts: 512
Registered: ‎10-29-2009
Message 6 of 10 (227 Views)

Re: Frustration with constraints

10-14-2011 11:01 AM in reply to: JDMather

Best advice... fully constrain all sketches.  First use 'geometric' constraints, then 'dimensional'.

 

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mcgyvr
Posts: 6,720
Registered: ‎12-01-2004
Message 7 of 10 (225 Views)

Re: Frustration with constraints

10-14-2011 11:03 AM in reply to: JDMather

JDMather wrote
Oddball dimensions?  See above.  You will quickly loose all credibility that is tough to gain back.  The shop floor guys will go out of their way to show what an idiot you are.  Do good work and they will point out your mistakes to you (rather than the boss) to help you improve the design and not even say anything to the boss.

Ain't that the truth..

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rjay75
Posts: 315
Registered: ‎04-14-2005
Message 8 of 10 (225 Views)

Re: Frustration with constraints

10-14-2011 11:05 AM in reply to: Anthony

The best method is to fully contrain your sketches. To help with that and to make it easier make sure Contraint Inference and Persistance is turned on.

 

Especially because you're just starting out believe everyone when they say fully contraining is sketches is the way to go. You can get really unpredictable results that are very difficult to resolve later on.

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Curtis_Waguespack
Posts: 2,811
Registered: ‎03-08-2006
Message 9 of 10 (205 Views)

Re: Frustration with constraints

10-14-2011 11:39 AM in reply to: Anthony

Hi Anthony,

 In addition to the other replies, this might be of interest:

http://inventortrenches.blogspot.com/2011/03/inventor-101-simple-fully-constrained.html

 

I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com



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JDMather
Posts: 26,282
Registered: ‎04-20-2006
Message 10 of 10 (190 Views)

Re: Frustration with constraints

10-14-2011 12:05 PM in reply to: Anthony

Take this challenge - post some parts you have already created (don't go back and clean them up).

Let's see what others could offer as techniques that would add design intent value to your technique.

Please mark this response as "Accept as Solution" if it answers your question.
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