Direct vs History based modelling

[Anonymous]

There is another thread going with this sort of conversation but that thread is more to do with history based modelling than direct modelling.

I find this topic very interesting and have had this conversation a number of times with no real conclusion.

I would be forever grateful if somebody could give an example of how history based modelling is needed from a mechanical engineering point of view.

Ideally what I would like is a solid example, such as if a person was designing a mechanical device how changing something downstream would not be possible with direct modelling, or some other example please?

[cekuhnen]

@O.Tan

To keep it short and simple, History Based modelling works best when the user have an end goal of how the final product should look like. For e.g.: this cabinet has 4 partitions and etc., reason being that a properly modelled part will allow a seamless update from upstream to downstream,
but for those who isn't sure how they would like the final product to look like or from a mechanical engineer perspective, they're more interested to model a part that'll solve the issues they encounter, then having to care about modelling it the correct way, Direct Based Modelling will be better.

I fully disagree. We only use timeline. Even the engineers.

Maine reasons I use timeline:

design exploration - don't know about how things will look

design adjustment - after exploring  design things might have to change

Generative ability - I can drive and automate so many steps DM cannot time saver)

obviously as I stated few times you need to know your craft to use it well. 

[PhilProcarioJr]

@cekuhnen

"So if something fails it is not the softwares fault but because the user simply did use it not in a way he should. Period!"

This couldn't be farther from the truth, case in point if your modifications cause ANY impossible geometry cases you just broke all dependent downstream features and I don't care how much experience you have. I have 18 years experience using Solidworks everyday and still manage to break features doing what should be simple changes. I guess I don't know what I'm doing or we can agree to disagree on this one.

Timeline only works with simple geometry. I wont argue that the timeline is great for a lot of things, but it's not as great as people would like to make it out to be.

@jeff_strater

Other players in the CAD field have it working.

When I said it's not that complicated what I meant was it can't be any harder then Fusions cloud system or simulation....I never meant that statement to mean it would be a trivial task to implement, but more so it can be done as others have done it already.

It's just my 2 cents, doesn't mean its right it's just my opinion based on what I know and my experiences with other software...

[cekuhnen]

@Beyondforce Yeah I agree.

I find both modes very useful with what they can do. I really also do not mind having a dump DM feature in the timeline.

switching between modes is not elegant but well not really hard to understand either - and while not elegant it makes however logically sense.

in interface design ( ihave a lot of experience in that) you have to make often a compromise specifically when you deal with opposite things

Having my main background in surface modelers such as rhino alias Cobalt I don't see any problem with the timeline. In alias it is a pain

to see how things are done and influence each their. Cobalt and SolidThinking show a design tree wach is like the timeline.

fusion however allows me in addition to capture more things such as move rotate and I can even make a parametric copy as a feature

which is why I rather call this generative than parametric modeling.

I agree with phill that the timeline is harder to use well - however this I should not because of the timeline but because man 3D is not easy.

A DM mode that can capture features would be also pretty sweet as I enjoy DM modeling and with interactive abilities then this would be great.

but to be hones I rather for th edesign work we do and for teaching go with the timeline because in the long run it is more useful.

The only difference between SolidThinking and fusion in my workflow is that in ST or such I can just 3D sketch an der freely move my sketches.

in fusion I have to create sketc planes first which will require sketches first and this is from my point of the view th only dramatic downside.

but that also appalies to inventor and such. NX can offer both but not for the same price fusion is at. Do no this forget that.

I have converted many people in my environment to use Fusion and while it has downsides do other apps not have that? Something that I should so easy in fusion

is a lot harder again in alias. I found there is no perfect tool. And they hit the same issue with fusion as well but then looking back still stay with fusion for obvious reasons.

While it does not have everything however after adjusting my workflow it offers to nearly most needs a solution.

[cekuhnen]

@PhilProcarioJr

Obviously everything can break. There can be many reasons. But using parametric tools the wrong way breaking a relationship is an often cause.

Sometimes I still have to restart if that happens.

I am also not against DM that is smart like what you guys talk about in NX. 

That however is less just only direct modeling anymore.

And I cannot imagine that that system has no problems either or limitations.

Siemens for sure did not do this in 2 weeks and they for sure also don't give their software for free to hobby

users students and charge a small fee compared to other apps to commercial users.

I am not saying that you are wrong phill. I am in 3D since 16 years myself so I am not new. The idea of a smart DM sounds delicious.

but that is just not what fusion focuses on. They use a traditional feature history with some cool added tools on top that makes it more

attractive to me that pure ALias or pure ST.

and unlike SW or others that show features vertical they use the width of a screen - so I might even disagree with Jeff stating that Fusion does

a traditional thing here.

I found that after years with cad each system as ups and downs and even something like a history based system can have great advantages.

there is just no perfect solution fitting all needs. You have to choose.

when SW came out everybody was scream that finally designers and engineers work on the same. Well no - not everywhere and in some cases the old

way of starting with a surface modeler and then using the model to Add the 3D part in a solid modeler is still used and practiced for many practical reasons 

even while this workflow feels highly out dated.

[PhilProcarioJr]

@cekuhnen

The whole point of this thread was what is the difference between Timeline and DM and what can the Timeline offer that DM doesn't.

In my posts I tried to make it clear that both have their uses and both are valuable, that one is not necessarily better then the other.

It was mentioned that you can do so much more with the Timeline, so I gave my opinion based on my experiences.

The fact is that for every one thing someone can tell me benefits from a Timeline I can give a benefit that DM has that Timeline doesn't.

So in the end which one wins? Answer is simple neither because both have their uses just different cases.

The real question is what is your goal with this model, only then can you get a good accurate answer.

This is like the whole which is better Mac or PC debate...another useless waste of time because the answer is based on what you need to do with "said" computer, but people don't say what they want to do they just ask the vague question that can't accurately be answered.

It came up that other software offers better DM then Fusion so I chimed in that I too would like better DM tools, that is what the ideastation and the forums are for is it not?

The fact of whether or not competing software costs more is irrelevant.

Case in point isn't all other simulation and CAM software on the market more expensive then Fusion?

So people that ask for better tools in those ares shouldn't even bring it up because the features they want from other software is more expensive?

It's an opinionated discussion about wants, needs, and peoples views...there is no wrong answer here.

Stating things like they are facts, when in truth they are opinions doesn't help the discussion.

Stating things like "Period!" is the same as stating it as fact when in reality it was your opinion.

I have a lot of respect for you and you definitely have skill as a designer, but It doesn't help anyone stating opinions as facts.

The reality is there is not one person on the face of this planet that can design a complex part with a timeline and not break something going back and making a bunch of changes, and I don't care how much experience you have.

We are human beings and in no way will ever be able to account for every possible problem when designing something, besides what fun would CAD be if you never had to figure anything out and everyone could do it?

Cheers

[Anonymous]

Your reply is exactly what I was looking for Jeff, thanks for taking the time, and thanks to all the very experienced CAD professionals for their input.

There are a couple of things I would like people to comment on.

The first is would I be correct in saying that DM is ideal for the light CAD user and parametric modelling is ideal for larger projects.

For instance a small tool room using Fusion 360 for jigs, fixtures and basic mechanical design would find DM more productive?

The second concerns hardware, I freely admit my ignorance on the subject but my perception is that DM is far lighter on resources than parametric modelling?

[Beyondforce]

Interesting conversation guys, it started almost to sounds like a "pissing contest" 😉

The two modes can be used separately or combined. Now, when to use either modes and how, is up to the user.

While one person sees an Apple another person sees a fruit salad or a juice. What I'm trying to say, these are all tools and how to use them depends on your personal skills and creativity.

If you read @jeff_strater post between the line, you can see that there is a bigger picture. This bigger picture is Autodesk's business strategy. What is their strategy?, no body knows except them and for the obvious reason, they are not going to share it with the world.

Another thing is, I have noticed from many of the tutorials out there, no body talks about the planning fase before the execution. If you don't have a good plan, there is a good change you'll end up with all kinds of problems along the way. That is one of the reason that many new beginners are strangling with Fusion. One thing is to know what are the different tools/modes are doing, and another thing, is to know what tool to use and when!

Ben.

[PhilProcarioJr]

@Anonymous

"The first is would I be correct in saying that DM is ideal for the light CAD user and parametric modelling is ideal for larger projects.

For instance a small tool room using Fusion 360 for jigs, fixtures and basic mechanical design would find DM more productive?"

Yes and no, The answer to that question depends on who you are and how you model and the needs from that model. For fixtures and basic mechanical design parametric modeling really shines. Whether or not it is more productive depends on how many revisions your model will go through and if you need different designs based off of one master design. If it's a one off that needs little to no changes DM probably would be faster but if it needs different changes or variations Parametric would be way faster.

"The second concerns hardware, I freely admit my ignorance on the subject but my perception is that DM is far lighter on resources than parametric modelling?"

DM is definitely lighter on resources.

[PhilProcarioJr]

@Beyondforce

There is a definite need for tutorials on design intent, because without it your going to end up with a mess.....

[daniel_lyall]

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@PhilProcarioJr wrote:

@Beyondforce

There is a definite need for tutorials on design intent, because without it your going to end up with a mess.....

---

This is the one thing new user get caught on, I had a lot of bad models until I worked out who to goto for answers that's 6 people who if they post some where, I will look at what they post, so I can learn how to use fusion.

@PhilProcarioJr I have to agree with @cekuhnen when it comes to furniture DM is the wrong way to go. For a quick mock up yer DM is fine, the final item nup.

Why is DM wrong no parameters no linking Parameters, no capture position and you have many things the same size be it a hole or whatever they need the parameters.

same goes with framing one shed sketch can =  Many, why parameters and being able to move stuff in the timeline and in the drawing, and this again For a quick mock up yer DM is fine.

The disability stuff I do TL all day why every person is different. 

If I need to do a breaket for a motor it does not matter they have a standard sizing.

If what you are doing fulls into a standard sizing it does not matter.

IF we give examples of where DM and TL are strong, this will help all manly the noobs.

There are a lot of things where it does not matter at all.

[cekuhnen]

The first is would I be correct in saying that DM is ideal for the light CAD user and parametric modelling is ideal for larger projects.

For instance a small tool room using Fusion 360 for jigs, fixtures and basic mechanical design would find DM more productive?

A very feature rich design will always be slow. No matter if the project is large or the single design is just complex. 

True - as I explain with your second question with DM it will be faster - but you have no interactive ability to adjust design later

or better explore your design.

My reason why I am against DM is that my work is not mechanical (box sphere cylinder shapes) but is often very organic or uses a lot of splines and curves

to split a part, to run a surface along and such. With DM you really need to know what you want to do (blueprint) to build it when your work is more organic.

One has to also understand that based on what you want to build certain DM or parametric can be a choice based on the shapes and surfaces and how you later

want to adjust and explore it.

The second concerns hardware, I freely admit my ignorance on the subject but my perception is that DM is far lighter on resources than parametric modelling?

Advantage of DM is that features are not refreshed. With complex designs I can sometimes experience wait times of seconds when features have to be recalculated.

Specifically when you do something at the beginning of the timeline Fusion will run through all added features.

But that is just a given.

2 ways to help

1. Rule number one - use components because if you change something in the timeline of a component Fusion only updates that timeline set of features.

2. hard edge model as much as possible - add filets later when needed and the design is done. fillets can be very slow if you have many, One design I worked on had 350 edges to filet.

3. use building blocks and then array them. pattern tool is amazing because instead of filleting 350 edges I later used just one object fillet it and then circular array it. much faster and less work

[cekuhnen]

@Beyondforce

"Another thing is, I have noticed from many of the tutorials out there, no body talks about the planning fase before the execution."

That is because I expect somebody to have that when looking into Fusion or 3D or watching my video.

I tackle that workflow and how to approach it in my design classes.

[Beyondforce]

@cekuhnen,

Unfortunately, Common Sense is not that common!

It's like reaching your destination. Which way will it be best to take and what type of transportation (tools) shell I use. People are different, Some have a natural talent, some are fast learners and some you have to explane everything. I'm sure, you are seeing those students in your class all the time.

Ben.

[cekuhnen]

@Beyondforce Yeah I deal with different learning styles and skill levels on a weekly basis 😉 quite a challenge!

[Beyondforce]

@cekuhnen, I have been in the IT servie industry for more than 15 years. I want to think that I have seen it all, but the surprises are never ending 😉

There is this funny test, to see how Out Of the Box and creative people are. Bring a Wood Stick to the first day at class and ask the students what do they see. But don't forget to make you own list as well 😉

[daniel_lyall]

@Beyondforce That's all down to the teacher to adapt, It does not matter what learning style someone is.

A person who teaches is ever bad at what they do and teaching is the easy way.

They don't like the job but love to teach it.

They love all aspects of what they do and want to pass it on.

Guess where at @cekuhnen fulls into, don't it's the last one I am a visual learner he teaches me stuff all the time and that's the hardest one to teach.

[cekuhnen]

@daniel_lyall

Ah what please?

"

A person who teaches is ever bad at what they do and teaching is the easy way.

They don't like the job but love to teach it.

"

With respect - I quite disagree that if you teach you don't cut it in the real world.

The reason I teach besides working in the field is because I like learning and I enjoy mentoring.

If you want to prosper in a university landscape you also have to do both anyway to stay up to-date as a requirement by the university

through keeping an active research, gallery, or project record.

[daniel_lyall]

@cekuhnen I know teachers who are crap at the job but teach and are bad at that, I had one until they got fired they moved to another education provider and are about to be fired.

some depending on what it is don't like doing the job but can teach it very well.

Then we get people like you who love the job and can teach it to anyone and love doing that.

I have learnt A lot from you I am a visual learner what is the hardest to teach.

@cekuhnen you're in the good side of teaching you do it, you do it very well, and you pass it on, not everyone is like this

[cekuhnen]

@daniel_lyall I think part can be blamed on how educators are funded in the US.

A lot of educational services or universities find recently adjuncts very attractive but what can you expect from a person teaching a course for 3 grand a semester.

Fortunately those for profit trash degree factories are gone.

But funding in edu has to change or the problem can just get worse - but there are always bad apples somewhere - in edu as well as business.

how did blackberry otherwise run itself against a wall ...

[daniel_lyall]

We had the same thing here, It went from bums on seats to pass rate  under 55% pass no funding over 55% to 75% 2/3 funding over 75% full funding, a couple 00 education providers shut there doors the next day after the rules were changed.

Teaching is hardwork