Constraints/Dimensions or No Constraints/Dimensions in 3D Modeling

Jasonb said:

The other thing I just picked up looking back through Pat's posts is that he takes a series of screen captures so he can go back and look up what dimensions were used on a sketch, this again is very unconventional and counterproductive as you would have to flick between the 3D CAD and the images. and in Pats case Autocad as well

Alibre and I'm sure Solid works has a much better way of doing it simply display the entered dimensions with the sketch, one image below has the dimensions toggled on the other off. So easy to see what dimensions were used when they are toggled on.

Click to expand...

I don't use the screencaptures to remember the dimensions.
You will note that almost none of the screencaps have dimensions, and I am not sure why or how some of them to, other than to say that I wanted to verify a distance without creating a driven dimension.
You can click on any shape, such as a circle, and read the dimensions from the dialog box on the left of the screen.

The reason for the screencaps is because during the progression of the model, the best method is not known, and so I basically and trying random things in order to get the model created and usable.

This can be a very long string of steps, and the order of the steps can also be critical to the success of the model.
My short term memory is very poor, and so I can flip through the screencaps to remember the order, and spot where I could change the order, or change the method, to produce a better outcome.

Sometimes I revisit a 3D design I did 10 years ago.
You think I can remember every step and sequence I did 10 years ago, 30 engine designs ago and 10,000 steps back?
No, not me; perhaps someone with a better memory can.

The screencaps can also give a quick overview of types of approaches to modeling, so one can compare and contrast approaches for similar designs and parts, and pick out the most effective method, such as creating flywheels, or other parts that are similar from engine to engine.
Looking at my screencaps, I can see that my methods have evolved over time, and continue to evolve.

The screencaps are not necessary for simple shapes.
For very complex models, with hundreds of steps, the screencaps have been invaluable.
I open the screencaps in file manager, with the view set to "extra large icons", and I can see many of the screencaps all at once, and easily navigate them and rediscover the sequence I have used.
Its a very powerful tool, but you will never read about this option in any book, and never see it here either unless mentioned by me.

So again, blanket statements don't apply to everyone, every model, or the range of complexity in models.
One really has to talk about specific models/applications.

You (Jason) are basically arguing semantics here, while overlooking some critical points I am trying to make.
I get your points. Do you get mine?

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ajoeiam said:

Hmmmmmmm - - - interesting - - - - - I find that I can't stand videos - - - - find they are a tremendous amount of waste time.
Webinars - - - - - most of them remind me of some of the poor profs that I had a few of at uni - - - - - took forever to get anything done.
Most of the hour long webinars could have been placed into about 4 pages of text and a few pages of graphs or pics or other visual aids.
Then I can get through those pages of text quickly - - - - with the webinar - - - - I've got to sit there for the whole bleeping time while the presenter farts around all too often trying to 'sound impressive' (and failing too much of the time).

Click to expand...

I thimpfks I have said this somewhere else. Stephen Pinker at MIT or Columbia says that the best speakers and writers are the middle middle class and lower middle class. The reason why is upper middle class peeps have been trained to speak in flowery language (and farts) and take an hour to say what could be said in one minute. (This is REALLY true.) They have been trained to thimpfk that this is the way to speak or write. But it turns out that people like us who have had to struggle to become or stay middle middle or work our way up, and we have had our hands dirty (yuk, I HATE greasy hands--I must be one of the HATERS we hear so much about these days) and we needs to get our point across quickly and also we don't have ti9me to waste listening to assholes say nothing. When I was a kid (last week) when I had my first computer, a TRS-80, I bought a magazine--this magazine came on a tape for the TOS (tape operating system) that the TRS-80 had. The tape would come with interesting programs on it. Games, information, programs of all types. One month, a 'politicians' speech generator came. It was one of the funniest programs as it was four syllable words strung together, grammatically correctly but saying absolutely NOTHING. Oddly, it SEEMED to be saying something.

I have heard MANY hours of meaningless blubber, as I take it you have. I learned to go talk to my professors before I ever took their classes.

Anyway, I still struggle often trying to get that one little piece of info that I know is in something I am reading or watching. With the internet/computer stuff we can jump ahead. With books we can rip out the worthless pages. I one time read Von Clauswitzes book "On War". It was the absolute KRAPPIEST book I ever read. I was so angry, in the end I burnt the piece of krap. One day I happened to read 'The art of War' by Sun Tsu. It said what clauswitless was trying to say but in a mere 39 paragraphs.

When I am tryi9njg to relax watching nutlix, trying to find something that is not infantile, adolescent, pedantic, juvenile and so on, something that is adult. I might watch a few minute of the crap then look for something else. Then sometimes I find a good program being self addicted to their sukcess (the successfull sukcess fool sux from a cesspool), they either run out of ideas or they start stretching the story to enable themselves to last longer on their sukcessful run. Occassionally one finds a really good show that simply ends when it is time (Breaking Bread, Grimm, maybe even the 15 season Supernatural, the original Swedish trio of The Girl Who . . . ). How many Harry Potter spinoffs are there that just plain suk?

I have taken to watching foreign movies and series now because they are so different from American stuff usually. I'm waiting for the next "Grimm" as it had humour, phantasy, danger, etc., etc.

I also find many machining utub vids to be too long with the peeps yapping and yapping. the very best ones, do the machining, edit it properly and talk with over editing the speech. How many times has someone filmed something being machined to show 3-4, 5, 6 minutes of one operationl. I mean, come on, why not film the grass growing and show that for a couple hours? I have nothing better to do than to watch something like that. Maybe they would get an oscar. Most peeps who watch some of that are machinists and we don't need to see the "grass grow"--I see the "grass grow" on my own machines. I want to see the setups and the end result not hours of the same thing.

I stopped watching TV quite a few years ago when I got rid of cable.
Cable had become one giant infomercial.
Originally, cable did not have commercials (are you old enough to remember that?).

Books are very tedious for me to read, basically because they can generally be condensed into a few pages, and relate the same message.

In college, I use to scan the books before the class started, and basically get an idea of every concept that was going to get taught.

I am trying to hang in there on ytube and watch my casting buddy's work, but ytube is really going full-crazy on the inserted advertisements.
First is was an ad at the beginning, then two ads at the beginning, and then an ad or two mixed in.
Now it is two ads ever 60 seconds or so. I am going to have to abandon my buddy on ytube.
Ytube in just unwatchable these days, with the motherload of KOR-style videos (that would be King of Random for those not in the know).

And the cover pictures on the videos are comicbook stuff, like an elephant jumping on top of a lion who is chasing a dinasoar.
Total detachment from reality.

And the talking heads are endless on ytube.
I was watching one talking head machinist video one time, and LOL he said, and I quote exactly:

"I ran into one of my followers at a show the other day, and he came up to me and said 'I love your videos, but you talk to much'.
I said 'No I don't', and he said 'YES YOU DO' "

And indeed he did talk like some sort of windup toy that runs forever.

Nextflix went super-woke a while back.
We actually had Netflix for a while, but it was so full of BS videos that we had to ditch it.
Netflix was running some sort of woke contest, trying to out-woke each other.

And I use to attended each session of any class I took in college on the first day, to find the best teacher, and then transfer into his or her class.
The difference between a good and bad teacher often meant the difference between passing and failing.

Vimeo has videos without commercials, but has a relatively limited offering.

And I like foreign movies, and they are the only movie I would consider watching these days, since there is a change they won't be totally full of woke stuff, and have an acutal interesting storyline.

My TRS-80 is a few feet away from me as we speak.
I remember connecting it to the TV and running basic programs and games like it was yesterday.
That was some radical sci-fi stuff back then.

I still have an IBM PC with dual 12" floppy disks, and no hard drive.

My wife had one of the first portable IBM-PC clone computers, which was the Compact.
This was considered extremely hi-tek for the day.
That sucker was heavy though (not my photos below).
Mice had not been invented yet back in the day.









Edit 02:

As far as writing and speeches, the Gettysburg address comes to mind.
Edward Everett spoke for two hours, followed by Lincoln saying 271 words.
Less is more as they say.

.

So Pat when you say "I don't dimension anything in 3D CAD" what you are really saying is "I don't use Solidworks Auto dimension feature but I do manually enter dimensions".

Quite a bit different and could well confuse a lot of people.

Same with your recent comment "I don't use the screencaptures to remember the dimensions." yet you started off this thread by saying "The idea behind the papertrail is to help me remember how I got from the beginning of the model to the end, and also to capture dimensions in the dialog box on the left of the screen, so I can quickly see what dimension I used for any sketch"

GreenTwin said:

In Solidworks, you can toggle on and off "auto-dimension" I think, but check me on that.
I never use auto-dimension, because I don't want to enable driven dimensions.

It is critical for users to understand the difference between driven dimensions and non-driven dimensions.

.

Click to expand...

I do understand driven dimensions, do you? I

I don't think there is any way to avoid driven dimensions as they are part of the sketch which is driven by other factors such as sizes entered (in dialogue boxes in your case) and the only way they will alter is to change the factors driving them.

Two simple examples of driven dimensions in this image, Alibre puts driven dimensions in brackets so it's easy to tell them apart from non driven ones.

First the circle. I sketched the circle and entered 30mm diameter, I then made a pie cut by sketching two a bit of the circle away. You can see that the 15mm length of the pie cut is in brackets as that is DRIVEN by the diameter and only way to change that would be to alter the diameter value.

Second is a right angled triangle with the length of one edge entered and an angle entered any other length or angle will be driven as that is DRIVEN by pythagorus eg the entered line length and angle.

So you can't avoid Driven dimensions but you can drive them.

Jasonb said:

So Pat when you say "I don't dimension anything in 3D CAD" what you are really saying is "I don't use Solidworks Auto dimension feature but I do manually enter dimensions".

Quite a bit different and could well confuse a lot of people.

Click to expand...

Yes that is a bit confusing.

You can add dimensions (I am defining "add dimensions" as pushing the "smart dimension button") either in your "part" files, in your "assembly" files, or in your "drawing" files.
These are three separate file types that Solidworks has.

I very seldom use the smart dimension button in a "part" sketch, unless I need to check some distance between two lines.
If I insert a smart dimension, and check something in a "part" file, then I erase that dimension.
I would not intentially leave a smart dimension in any sketch in any part file.

When I create a drawing file, I drag and drop a part onto the screen, and drag out the various views.
Then I use the smart dimension button to dimension the 2D drawings that have been created, because otherwise you cannot use the drawings for anything.

In assembly files, I don't recall ever using the smart dimension button in one of those files.

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Jasonb said:

Same with your recent comment "I don't use the screencaptures to remember the dimensions." yet you started off this thread by saying "The idea behind the papertrail is to help me remember how I got from the beginning of the model to the end, and also to capture dimensions in the dialog box on the left of the screen, so I can quickly see what dimension I used for any sketch"

Click to expand...

You are confusing dimensions created by pressing the "smart dimension button" with the dimensional value that shows up in the dialog box on the left of the screen when you draw a shape such as a circle.

One is pushing a button to create two leaders, arrowheads, and a number, and the other is a value in the database that does not appear on the screen as a normal dimension.

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Jasonb said:

I do understand driven dimensions, do you? I

Click to expand...

Well, that would be a topic of debate.
Do I understand all of the nuances of all the features and commands of Solidworks?
Obviously not. Does anybody? Brian Rupnow maybe, or Rob Wilson.

There is a lot to what you can do with a smart dimension, and that is a lengthy topic.

Here is a video of some things you can do.

Much the same as what I just posted.

Also at about 7.30 a very good example of why you constrain the various parts that make up the sketch and relate then to each other.

In my "part" files, I don't push the "smart dimension" button for any reason to add driving or driven dimensions, and I have never done that unless it was a brief temporary check that got erased.

If you can get added value out of using the "smart dimension" button, and programming all of those features, more power to you.

That is not what I do, and it is totally unnecessary to do that in a part file for an engine part.

That is what I have said before, but I repeat it because there seems to be confusion.

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Jasonb said:

Also at about 7.30 a very good example of why you constrain the various parts that make up the sketch and relate then to each other.

Click to expand...

But as I mentioned, I don't do any extra steps to constrain anything in the sketch, and I don't add any relations either by doing extra steps.
The program creates some relations automatically, but I don't add those after I draw the sketch, and I don't change those if the program happens to create the relation automatically.

.

I think much of it relates to how you want your sketch to act if you happen to change something.

Should a person automate what happens when you change a sketch, or leave things bare-bones?
Personal choice I guess.

A person could use whatever features they feel they can leverage in their favor.

I keep it as simple as possible, with the fewest number of steps possible, or at least attempt to do that.
Less is more for me.
More may be more for others.

.

GreenTwin said:

I stopped watching TV quite a few years ago when I got rid of cable.
Cable had become one giant infomercial.
Originally, cable did not have commercials (are you old enough to remember that?).

Books are very tedious for me to read, basically because they can generally be condensed into a few pages, and relate the same message.

In college, I use to scan the books before the class started, and basically get an idea of every concept that was going to get taught.

I am trying to hang in there on ytube and watch my casting buddy's work, but ytube is really going full-crazy on the inserted advertisements.
First is was an ad at the beginning, then two ads at the beginning, and then an ad or two mixed in.
Now it is two ads ever 60 seconds or so. I am going to have to abandon my buddy on ytube.
Ytube in just unwatchable these days, with the motherload of KOR-style videos (that would be King of Random for those not in the know).

And the cover pictures on the videos are comicbook stuff, like an elephant jumping on top of a lion who is chasing a dinasoar.
Total detachment from reality.

And the talking heads are endless on ytube.
I was watching one talking head machinist video one time, and LOL he said, and I quote exactly:

"I ran into one of my followers at a show the other day, and he came up to me and said 'I love your videos, but you talk to much'.
I said 'No I don't', and he said 'YES YOU DO' "

And indeed he did talk like some sort of windup toy that runs forever.

Nextflix went super-woke a while back.
We actually had Netflix for a while, but it was so full of BS videos that we had to ditch it.
Netflix was running some sort of woke contest, trying to out-woke each other.

And I use to attended each session of any class I took in college on the first day, to find the best teacher, and then transfer into his or her class.
The difference between a good and bad teacher often meant the difference between passing and failing.

Vimeo has videos without commercials, but has a relatively limited offering.

And I like foreign movies, and they are the only movie I would consider watching these days, since there is a change they won't be totally full of woke stuff, and have an acutal interesting storyline.

My TRS-80 is a few feet away from me as we speak.
I remember connecting it to the TV and running basic programs and games like it was yesterday.
That was some radical sci-fi stuff back then.

I still have an IBM PC with dual 12" floppy disks, and no hard drive.

My wife had one of the first portable IBM-PC clone computers, which was the Compact.
This was considered extremely hi-tek for the day.
That sucker was heavy though (not my photos below).
Mice had not been invented yet back in the day.



View attachment 141528View attachment 141529





Edit 02:

As far as writing and speeches, the Gettysburg address comes to mind.
Edward Everett spoke for two hours, followed by Lincoln saying 271 words.
Less is more as they say.

.

Click to expand...

You can block adverts, but if I find some utub vid I like, I download it THEN watcdh it.

What the hell is 'woke' anyway? some new kiddy crap pretending to adult?
I stopt watching tv in my early 20s (last week). And it was for the same reason you did --too many ads.

I think a significant part of the confusion is the fact that the word "dimension" is being used in two very different ways. Pat, you may be thinking of dimensions primarily as the values that are shown next to a drawing or sketch (please correct me if I am wrong!). You create a circle of a certain size, located on the origin, but you do not bother to have the CAD program add the written "dimensions" that indicate what that size is. And indeed, you never need to do so for the sake of 3d CAD modeling. The size has been set; that is all that matters. Whether or not you see a description of that size (a "dimension") is a matter of convenience, not necessity.

But for JasonB and others (and again, please correct me if I am wrong!), "dimension" refers to that initial setting of the size of the circle. If you don't set that, then the circle could be of any indeterminate size, and almost certainly your parts won't fit together. Confusingly, this use of "dimension" does not preclude the other use; one still chooses whether or not to add "dimensions" to the resulting drawings.

I hope I am not putting words in anyone's mouth, and beg forgiveness for attempting to speak for any of you. But maybe, possibly, this is why this has been such a difficult issue - we are using the same word to mean very different things.

That's how I see it Andy. A dimension is entering a length, diameter, radius, etc in the sketch which sets two dimensions and then the final entering of the amount to extrude which is the third dimension to define a 3D shape after all isn't that what 3D stand for three dimensional.

Even if I choose not to have those entered amounts visible while sketching and extruding the part they are still there in the system and are what the system will use when finally producing 2D working drawings otherwise it would not know the value that comes up on the drawing

Jasonb said:

That's how I see it Andy. A dimension is entering a length, diameter, radius, etc in the sketch which sets two dimensions and then the final entering of the amount to extrude which is the third dimension to define a 3D shape after all isn't that what 3D stand for three dimensional.

Even if I choose not to have those entered amounts visible while sketching and extruding the part they are still there in the system and are what the system will use when finally producing 2D working drawings otherwise it would not know the value that comes up on the drawing

Click to expand...

I have never used SolidWorks, but based on Pat's descriptions of his process, I wonder if "setting the size" of a part works somewhat differently than it does in some other 3d CAD programs. In FreeCAD, when I draw a rectangle and want to set its size, I click on a side and click on the "vertical height" constraint and enter a number - and it shows up in the sketch just like a "dimension" would show up on a 2d drawing. But it sounds like in SW, perhaps one pulls up a dialog box and sets various size parameters there, which do not necessarily show up on the sketch. The size is there, constraining the sketch, but no "dimension" shows up unless a setting is enabled.

The more I think about it, the more I wonder if it would be helpful for the CAD world to adopt something like "size" and "position" when talking about constraining the shape and position of an object, and save "dimension" for the "printed" numbers that are intended only to communicate that size / position.

awake said:

I think a significant part of the confusion is the fact that the word "dimension" is being used in two very different ways. Pat, you may be thinking of dimensions primarily as the values that are shown next to a drawing or sketch (please correct me if I am wrong!). You create a circle of a certain size, located on the origin, but you do not bother to have the CAD program add the written "dimensions" that indicate what that size is. And indeed, you never need to do so for the sake of 3d CAD modeling. The size has been set; that is all that matters. Whether or not you see a description of that size (a "dimension") is a matter of convenience, not necessity.

But for JasonB and others (and again, please correct me if I am wrong!), "dimension" refers to that initial setting of the size of the circle. If you don't set that, then the circle could be of any indeterminate size, and almost certainly your parts won't fit together. Confusingly, this use of "dimension" does not preclude the other use; one still chooses whether or not to add "dimensions" to the resulting drawings.

I hope I am not putting words in anyone's mouth, and beg forgiveness for attempting to speak for any of you. But maybe, possibly, this is why this has been such a difficult issue - we are using the same word to mean very different things.

Click to expand...

Andy-

Yes, you are correct.
Jason is using the word "dimension" to describe a value in a database.

The traditional definition of "dimension" goes back to manual drawings, which is how I did all my drawings when I got out of school.
There were no CAD programs that ran on personal computers in 1985, or they were in their infancy, and so we hand drew every drawing.
So you drew the building or equipment, and then dimensioned it with leaders, arrowheads and text to show how big it was.

Today, there are a lot of terms, and they may not be consistent from program to program, and certainly are not consistently understood by everyone doing 3D or even 2D work.

And then you get into driven and driving dimensions, etc. and the confusion gets worse.

And relations can be confusing too, along with having separate "parts", "assembly" and "drawing" files.

It is still worth the converstation in my opinion because I get a better understanding of 3D by comparing notes with folks like JasonB.
JasonB has a lot of good ideas, and so you can bet I pay close attention to what he says.

I think others perhaps learn from following the conversation, tedious though it may be at times.

.

Jasonb said:

That's how I see it Andy. A dimension is entering a length, diameter, radius, etc in the sketch which sets two dimensions and then the final entering of the amount to extrude which is the third dimension to define a 3D shape after all isn't that what 3D stand for three dimensional.

Even if I choose not to have those entered amounts visible while sketching and extruding the part they are still there in the system and are what the system will use when finally producing 2D working drawings otherwise it would not know the value that comes up on the drawing

Click to expand...

It would be better if Jason called the database number a "value", and a dimension is what is displayed on the screen to reflect that database value.

That is what it really is in my opinion.

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awake said:

The size is there, constraining the sketch, but no "dimension" shows up unless a setting is enabled.

Click to expand...

I think you are using the wrong terminology.

The values in the database define the line, ie: start point, end point, length, angle, but they do not constrain the line to vertical, horizontal, parallel, concentric, etc.
The contraints typically are set manually, unless your program does some of it like Solidworks where it can set a vertical or horizontal constrain on its own.

You guys are mixing and matching terms, which is what makes it so confusing.

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awake said:

The more I think about it, the more I wonder if it would be helpful for the CAD world to adopt something like "size" and "position" when talking about constraining the shape and position of an object, and save "dimension" for the "printed" numbers that are intended only to communicate that size / position.

Click to expand...

It all goes back to some "value" that is stored in a computer memory chip register.

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