Proper way to create a sketch? (Office Arguement)

[AnchorChain]

Please help me to argue my case regarding the "Correct" way to create and maintain a sketch for a part.  I have a fair amount of 3D experience and have always been told to fully constrain my sketches.  Here at work we have someone new to 3D and new to Inventor with no formal training learning to use the software. When he creates a sketch he'll dimension it out until it gets "too cluttered" for him and then he deletes all of the dimensions.  When I come behind him to edit a part none of his sketches are dimensioned.  I asked him how he modifies sketches if he needs to, he said he re-dimensions it, changes the dimension, then deletes it again.

Is this just a preference on my part due to my formal software training, or could this cause major issues down the road?  Aside from the double work being done to re-dimension every one of his sketches just to change a dimension or two.

We're just now beginning the migration from the 2D world into 3D and I want to make sure all of the new work being done in 3D is done correctly now, and all "bad habits" are corrected now to make our lives a little easier later.

[Curtis_Waguespack]

Hi AnchorChain,

Here is what I recommend:

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

[JDMather]

Have this person read this document

http://home.pct.edu/~jmather/skillsusa%20university.pdf

and attach one of their files here.

Based on my experience there will be real problems with the file (not just good geometry with the dimensions removed - but real problems).

Someone working like this would never be able to keep up with the rest of my class and would fail the class.  They are too slow and inefficient and costing the company money.

Edit:  there is more to constraining a sketch then simply to fully constrain and dimension. 
A lot of times intellegent use of symmetry about the origin presents savings down the road as well.

[jeanchile]

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@AnchorChain wrote:

When he creates a sketch he'll dimension it out until it gets "too cluttered" for him and then he deletes all of the dimensions.  When I come behind him to edit a part none of his sketches are dimensioned.  I asked him how he modifies sketches if he needs to, he said he re-dimensions it, changes the dimension, then deletes it again.

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If your co-worker worked for me he would be handed a box and his last pay-check. He would then be reminded of the NDA and CNTC he signed when he was hired and reminded where the door was in case he forgot.

[Edit: if this sounds a little harsh it's because he would certainly have been given the tools to do his job correctly if he was hired without them. We take training and education seriously here.]

[AnchorChain]

Curtis - That link will be very useful to him to help him see that he doesn't have to do everything in a single sketch like he's been doing.

JDMather - Since the person I'm dealing with here is the VP of the company he should love to hear that!

Knowing this guy the way I do he's going to fight this until he sees something that says "you must fully constrain sketches with dimensions".  Otherwise, it's one persons opinion on how it should be done, to him.  By the way he sees the inferred constraints, endpoint to endpoint, etc, as enough that adding and leaving the dimensions is not required.  I told him it's going to bite him big time but rolled off his back.

[AnchorChain]

jeanchile - see my reply to JDMather in post 5.

I do understand what you're saying.

[jeanchile]

For the record, I'm just a nobody, but JD is a highly respected instructor of all things CAD and Curtis literally wrote the book on Inventor (Mastering Inventor series).

Taken together that absolutely is the "you must fully constrain sketches" thing you are looking for. Just show him this thread. Dimensions aren't the only thing used to constrain sketches (usually the last thing actually) and like Curtis and JD are showing, if his sketches are getting too busy, he's doing it wrong.

Good Luck.

[JDMather]

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@AnchorChain wrote:

JDMather - Since the person I'm dealing with here is the VP of the company he should love to hear that!

Knowing this guy the way I do he's going to fight this until he sees something that says "you must fully constrain sketches with dimensions".  ...

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There is nothing that requires "you must fully constrain sketches with dimensions". 

There are plenty of 3D CAD programs that don't even use parametric constraints/dimensions.

The point is that it is costing time (and money) to not use these tools.

...and going back and erasing all dimensions - that is like the boss taking bills out of his pocket and burning them.

Not too intellegent in my opinion.

I have run into plenty of people who think their "free modeling" techniques are faster.

All of my fastest, best quality producers are evidence that this doesn't hold water.

[jeanchile]

We have a rule here at my company:

"Don't take an opportunity to learn something and turn it into an opportunity to cost the company money."

If it takes you twice as long to complete a task but you made an investment in yourself, and by default the production value of the company, then do it. This guy is doubling the time it takes to do something for no benefit. he's actively constraining the elements and then going the "extra" step of negating the benefit. He needs to learn to do this correctly in order to save the company money. As one of the executive staff he should know this.

You may be right that there is nothing stating you "have" to do it... unless you work for my company then there certainly is. My adivce to the OP would be to make sure anyone using IV as his company knows they "have" to do it.

[JDMather]

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@Anonymous wrote:

Not too intellegent in my opinion.

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errr, guess that demonstrates my lack of intelligence.

Not too intelligent in my opinion.

[SeanFarr]

I admittedly was one of those guys that modeled a part with many features and a single sketch(tons of dimensions). It didn't take me too long to realize that it was wrong and time well wasted. One of the greatest advantages of using Inventor is the ability to edit or re-use models. If a model is done correctly you can edit it's original size and shape with minimal re-work. Try editing a model that was made with one sketch and 20+ dimensions, it will result in errors upon errors.

Good Luck with the battle! haha

[cbenner]

IMHO,

One other thing that truly bothers me to fits of ranting and raving, is sketches that are not constrained logically about the origin planes.  Example, when I edit some of our old pipe fittings, and find a FLANGE, basically a big disk with holes in it, where the base sketch center point is 6 " or more from the origin plane intersection!  That can casue problems down the road as well.

An intelligent, simple as possible and fully constrained sketch saves more time that it takes to create, though you may not see it until you go to make changes later.

[QuasiMojo]

Maybe showing the power of the parameters list, or linked parameters will help drive the concept home.  I'm in R&D; consequently, parts change quite frequently as everyone figures out how something needs to work.  Sometimes we have dimensions coupled to external models.  Using parameter driven modeling (e.g., many parts linked to a spreadsheet) in an invaluable method for updating a design in a timely manner.  I frequently have equation-based parameter sets so I don't have to go back into every part and change each mod one at a time.  Of course, you miss some that way, too.  Anyhow, if you don't have fully constrained and thoughtfully dimensioned sketches, you cannot take advantage of this flexibility.  You might as well be doing it on a drafting board.

[gsmith9810]

It is also possible that the individual referred to by the OP (VP or not) is making an assumption about doing it the first time v. re-doing it or editing AFTER an ECO makes its way into the process? Certainly when things are fresh in your mind, you might be able to make a case for his workflow but not after you (or somebody other than you) has to back into the model and make changes.

[MikahB]

I'm basically a self-taught Inventor user and I make my living using primarily Inventor.

With Inventor, like most things in my life, I learn like the cavemen did - I make a mistake, get burned, then try find a better way that burns less - or not at all.  That method of learning has developed in me an almost obsessive need to fully constrain.  I seek symmetry at all costs and exploit it.  I reference all things to the Origin using as few dimensions as possible.  I hate green lines and occasionally hiss at them involuntarily like a frightened cat.

You can choose to argue with your co-worker or not, but take it from somebody who's spent many hours REDOING what had already been done once because he thought well-constrained sketches were for nerds.  Well constrained sketches are for people who need to be efficient and make money.  Unconstrained sketches are for hacks and wannabes.

[GSE_Dan_A]

Simple way to prove this person wrong...

A good ol fashioned MODEL-OFF!

You vs Him in a battle of 3D modelling! Come up with a challenge that consists of modeling up a part(or assemblty) and then having to resize/alter the part.  First one to complete the challenge wins!  Your Boss can be the only onlooker to ensure he won't be publically humiliated.  When your boss sees how long it has taken to modify a sketch or two and update the part/ assembly, it will be clear as day why it is important to fully constrain, dimension and organize sketches!

[KobusE]

I read this post and must admit that I agree with all the replies thus far.  If this guy started working for me, he will only last past the company induction.  I have a few golden rules for my modellers and one of them being that sketches have to be constrained and dimensioned.  As JD mentioned, unconstrained undimensioned sketches can have huge impacts on a model.

Another rule we have is to work as efficiently as possible, and redimensioning everytime you need to change something simply goes against the grain of that.  As he is supposed to be one of the persons looking after the wellbeing of the company the bottom line and anything affecting it should talk louder than any manual stating "thou shalt constrain sketches".

I wish you luck with this but definitely don't envy you.

Kobus