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?

[etfrench]

I can't help very much because I haven't had any good experiences using the timeline.  Parametric modeling is the only thing I've seen that's useful.  I can't see any reason why that functionality can't be exposed in Direct Modeling mode.   Clicking on the Save icon will store the history if you really need to revert to an earlier version.

[Beyondforce]

Hi @Anonymous,

Direct vs Timline, they are both will get you the same results in their own way. Sometimes It has to do with what you are modeling, is it an assembly, a single part or an imported part.

You need to think about, what is it you are trying to create and test what works best for you in that scenario. You will hear opinions on both sides, but in the end, it is what works best for you.

As long as you follow and understand Fusion 360 basics rules like R.U.L.E #1, Delete vs Remove and few more, it doesn't matter if you are using Direct or Timeline.

Cheers / Ben
---------------------------------------------------------------------------------------------------------------------------
Did you find this reply helpful ? If so please use the Accept as Solution or Kudos button below.

Check out my YouTube channel: Fusion 360: Newbies+

[Anonymous]

Thanks for the replies,

one thing that I find misleading about direct modelling is that people perceive it to be history free but there is some history as you can use the undo function, surely that is an example of history?

I took on Keycreator with Fusion 360 yesterday, I followed one of their short videos and Fusion 360 more than held its own.

[Anonymous]

You can drag and drop things in the timeline so the history can be rearranged. 

[Anonymous]

I have not used the timeline myself but have read a few things about it, the part I struggle with is why would I need to rearrange the history when I can adjust things real time.

I admit my ignorance on the subject but it seems to me that history is pointless when you have direct capabilities.

The way I think about it is why does the program have to know where a feature was yesterday, it only needs to know where it is now when you have the capability to freely edit it.

[Beyondforce]

Forget about the rearranging part. The Timeline is a "Time Machine", you have the power to go back in time make a change and that will have an automatic effect on the rest of the model (depends on what you have changed).
If I'm not mistaken, when you pattern a part in Direct mode, the rest of the bodies doesn't have any relation to the original part. If you want to make a change to all the bodies, you will have to manually do that to all the bodies. Where in Timeline mode, you can go back in time make the change and it will replicate to the rest of the bodies. This is just one example!

[Anonymous]

If I have a pattern of holes and change one of the diameters or move one of them they all change automatically regardless if the hole being adjusted is the original.

When the dissolve function is used on that body or the body is turned into a component, all relationships are destroyed and each hole becomes independent.

[Beyondforce]

Spoiler

When the dissolve function is used on that body or the body is turned into a component, all relationships are destroyed and each hole becomes independent.

Which is why a lot of people like to work in Timline mode, especially when creating an assembly. You can go back and change anything anytime. Each mode has it's own drawback and it's up to you to decide, which mode (workflow) is best for you. 

Initially, Fusion 360 was built as a Direct modeling tool. But then a lot of people asked about the Timeline (History base modeling) so Autodesk decided to add the Timeline.

What I do think is missing, is a good Direct modeling documentation!

Cheers / Ben
---------------------------------------------------------------------------------------------------------------------------
Did you find this reply helpful ? If so please use the Accept as Solution or Kudos button below.

Check out my YouTube channel: Fusion 360: Newbies+

[Beyondforce]

I forgot to mention another thing... It is possible to combine Direct and History based modeling together. This way, you can enjoy both worlds at the same time, which is why Fusion 360 is So powerful!
https://knowledge.autodesk.com/support/fusion-360/learn-explore/caas/video/youtube/watch-v-xYyPpkyo4...

[Anonymous]

That's actually why I started this thread, to see if there is any benefit in using both modes or using just the history based set-up.

I have started a thread like this on a couple of forums and have yet to see a solid example of how history benefits a user when we have DM capability.

As I said above I can edit patterns and every feature in the pattern will update just like the history based side does.

[Beyondforce]

Maybe @jeff_strater have a document which list the advantages and disadvantages of each mode?

Ben

[O.Tan]

Technically, from a mechanical point of view, direct modelling solves a lot of issues inherited from history based model, however they're some scenarios where history does better and to be fair, it also depends on how capable is the CAD modelling engine at "solving" these issue (on deciding should you model this part in history or direct).

Here's a simple example:

Example A

1. The picture above is done in TL, I wanted to create a box with a step in the middle and for it to be repeated 3 times (so in my timeline the sequence is, extrude surface from sketch 1 & 2 > pattern body > join body into one (same steps as Example B).

2. If I want to edit the pattern, let say increase for 3 to 5 for example, I can do it with relative ease, just double click on the pattern tool and it'll auto update.

 Example B

1. This time, I did the same thing but it's fully done in DM, I did the same steps as well but notice in the 2nd and 3rd picture is once I "joined" the bodies, my "pattern" feature disappeared and I no longer able to easily add more patterns

2. To fix it, say pattern from 3-5 is that I'll have to pull the surface and then "pattern" the step.

Now, I know this isn't the best example but what I wanted to point out is, if you have the option of using Direct or History in the same environment (like the videos I linked in the other thread), rule of thumb is, if somehow you need to do some fancy pattern stuffs (and based on your experience, you know the CAD software will not play well with these particular pattern in Direct Modelling), then working in History is the better bet, but for most situation, Direct is much faster and easier and for most edits you don't need History. 

[PhilProcarioJr]

@O.Tan

I think the questions and views being raised by everyone in both threads are off.

Asking which is better is like saying:

Which is better a Mac or a PC....

I have extensive experience in both DM and Timeline modeling so the answer is simple.

If the CAD app is properly developed neither is better they are just different ways to an end goal.

Now in the case of Fusion the timeline is better because they stopped developing DM before all needed functionality was implemented.

There are direct modelers out there that allow you to "Go Back" and change whatever you want whenever you want...Fusion doesn't.

Some direct modelers offer way more control over creating/editing models then Fusion does with the timeline even.....

Just my 2 cents...

[O.Tan]

Yeah, I'm aware of that. And I don't see the issue of asking for a better modelling environment in Fusion for the future, as they're people asking for better sculpting tool and etc etc.

[PhilProcarioJr]

@Beyondforce

"Initially, Fusion 360 was built as a Direct modeling tool. But then a lot of people asked about the Timeline (History base modeling) so Autodesk decided to add the Timeline."

Actually from what @jeff_strater told me the reason they added the timeline is because there were limitations on what could be done with direct modeling and the timeline was added to address those limitations.

He didn't elaborate on what those limitations were.

Personally I would like to see a hybrid modeling approach like @O.Tan posted where you don't need to switch, the software just knows what to do based on the tools you are using.

The switching is so cumbersome at the moment and switching back and forth make Fusion very unstable ATM.

[Beyondforce]

Well... tomato tomatar, I'm sure they didn't added the timeline just because people asked for it, but there were some other considerations.
If you ask me, I think they should mix them together like the other CAD software you have mentioned before.
I haven't used Direct modeling yet, mostly because I like the timeline and there aren't good documentation for the Direct modeling. No Direct modeling documentation tells me, that Autodesk don't care about it. Maybe they are planning on discharging it soon!

[PhilProcarioJr]

@Beyondforce

I very seriously doubt they will ever ditch the direct modeling environment simply because they plan to add more mesh editing and CAD integration. Getting rid of the direct modeling environment would add a crap load of overhead to the mesh integration and manipulation. It would just be a very bad move on their part, but who knows.

Direct modeling environment has it's uses just like T-Splines have theirs. What it all boils down to is what your model is going to be used for and how it may need to be future manipulated.

If there is no needed design intent then direct modeling is very powerful and if direct modeling is implemented correctly then changes become even easier then "going back in time". The true question for businesses is who do they employ future out of the box designers and engineers or old school I hate change designers and engineers. If the answer is the later then timeline history based modeling is their answer. 

I keep hearing people say that the timeline is so powerful because you can go back and edit a sketch or feature and have everything downstream auto update. I'm sorry but that whole line is a load of crap. 9 times out of 10 changes made to upstream sketches and features breaks most of the model going downstream unless you spend 20x more time prefiguring everything out. Your playing the what-if game when designing. So you spend a ton of time solving all the what-ifs to have a solid stable model. Now I fully understand that for simple designs History is great but if your model gets very complex you can throw that out the window, thus the need for both.

Just my 2 cents...

[Beyondforce]

@PhilProcarioJr,

I'm partially agree with you. I'm just doing a simple math. When was the last time they have done something to the Direct modeling (any update lately?) and how come there are no documentation (I guess it's not important!).

In regards to the Timeline, as you probably notice so far, many people are lacking the basic Fusion 360 knowledge. There is a learning curve that a lot of people are trying to skip!

I understand their eagerness to start bulding and creating models, but they don't take the time to learn the program. Not only that, in my YouTube channel I'm trying to do my best to show people techniques and that there are many ways to achieve the same goal, and before you decide which way to go for, you should also consider the big picture. One thing I can't teach people, is how to think out of the box 😉 

That's also why it's so difficult for me sometimes to help people in the forum. Should I just show a person how to do what he is asking for or Should I stop him right there and try to explain why he should stop and learn the basics first. - I have a feeling, that you know what I mean.

Anyhow, I think people should do what ever works best for them (Direct or History) as long as they follow the basic rules!

Ben.

[PhilProcarioJr]

The thing that really gets me is having a direct modeling environment work in a parametric way is actually not that hard to achieve. 

All they need to do is have constraints for features, I know this because other CAD apps have implemented this already and it works beautifully.

I'm not going to drop competitor's names but some have it and it really is a faster, more efficient and better way to work...