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Comments
And where the design office is largely affects its core role.
You can be in an office designing factories or steel framing largely removed from the machine shop.
Or within arms reach of the CNC, cutters and welders.
Two years ago I was tasked with setting up a design office in our company. (60 staff total)
We have no CNC or lathes and any drawings were previously on Publisher. Yes... Publisher.
I was to be producing steel assembly and fabrication designs + Roto moulded products and moulds.
Lots of variation.
I trialled Inventor for one of our projects a multi hull Kayak/Catamaran.
The parametric design experience was something to behold. And in the end stifling so
we purchased SolidEdge ST6 and could then operate in either Parametric or Synchronous at any time on any model part.
When I was on the (1 day) training course I asked the guys at SE if I should primarily use the ST mode or stay in PAR.
They advised as we had no heritage CAD history and our office was starting fresh, just go for it in ST.
I have to say it's been brilliant.
Parametric has it's place but ST or what you are calling Direct modelling is brilliant.
About the only time I use Parametric is when one of the plugins requires it. Eg when adding working Gears from a gear generator plugin.
Being able to have mix and match of Parametric and Synchronous Technology within designs is excellent.
I don't dream of converting a highly disciplined parametric CAD user over to be 90% Direct overnight.
Or expect machine workshop integrated workflows to change quickly either.
Having a well constrained database driven directly editable model is a reality already. It is how I work now.
It is not like using the paint brush in Photoshop.
It is still dimensioned and constrainable CAD.
When all the other players either have or are introducing direct modelling I am at a loss to understand why Onshape have only done the minimum necessary to be able to edit imported geometry. With all the potential of Onshape to overcome collaboration issues I find the lack of DM perplexing to say the least.
Would appreciate some serious comment from the Onshape guys.
Looked at some youtube videos last night and bumped into this, don't know how it's related to DM but this is what I would like to see in Onshape assembly:
It would be really nice to use cad for testing how things work, not just trying to replicate something on screen that you already know 'in real world'.
Parametric is everything when months, even years, later a mod deep in the design ripples outward.
One of the great banes of CAD has been the attitude that because everybody else does it then so should we. This has lead to some amazing bloat in some mainstream products.
Keep It Simple Smart.
There are lots of terms flying around this thread, but for what it's worth, I think of Direct Edit or DM as free-form pushing and pulling of surfaces without any constraints involved. History based, to me, is what people would refer to as parametric. Synchronous Tech is unique at the moment and is really neither of these as I understand it. @KiwiLee has mentioned it is still constrainable CAD. @Charles is right. Keep it as simple as it should be. We don't want Onshape to rush into something because we are a little too impatient - I don't think they would either. Onshape is filling out the History based methods at the moment. The direct edit tools are helpful as they are now. Something like Synchronous Tech, if it's worthwhile, would be another tool in the arsenal.
Yes
Yes
Yes
Yes
Yes
Note: I can only comment for SolidEdge Synchronous.
Here's another thing; lets say you're doing dimension optimization based on FEA results. In parametric if you are optimizing an early feature it must regenerate the entire model/assembly to change the dimension. In DM, the edit is far quicker. Sometimes on the order of 5-10 seconds quicker. So for parts with longer history trees the difference in time for a dimension optimization can be 30s in DM and 600s in PM.
I was hoping you could expand on this. I have found that with Parametric models, you better have your relationships 'programmed' just right, otherwise an early change has a big chance of blowing the whole thing up on recompute.
In DM, you can change an early feature without changing anything else. That's the power of it. So in your example, DM is actually a better tool in my experience.
PM: You program a recipe that creates a part. If you need to make a change, you throw your model in reverse, make the change, and throw it into drive and pray.
DM: You make a part. If you need to make a change, you change the part.
That said, there are certain things that PM does waaay better like sweeps. You can make sweeps in DM, but it often just turns into a surface that is difficult to change. This is more a limitation of software development, not a limitation of DM.
It's one thing to take something which is already well understood, like chain, and create rules to make it behave as we know it should. It's not trivial, and it's rather useful.
But it's quite another thing to be able to invent a new jointed assembly, based on (say) a hunch, and to be able to preview how the parts would interact without having to make a (real world) study model. *
So I disagree with the person posting the video, who qualified the physics he demonstrated in Crea as perhaps being limited in usefulness.
* Of course, 3dcad already said the same thing, just more concisely ...
Nobody seems to disagree that constraints are a good thing. Geometric constraints are good. equations are good. You want behaviors, you want dimension designs etc... Right now Onshape uses constraints in a history based approach.
Sure history based modeling is good for family of parts and similar but different designs and many other benefits already stated in this thread. But is more basic than that.
I think the fundamental power of history based design is that it breaks down a very complex problem into smaller manageable chunks. Anyone who has ever used a non-history based modeler is familiar with one message. 'failed to calculate". When you don't have a history you are asking for the system to do all kinds of things that border on impossible. Non-history based systems simply fail a lot. Just look a basic 3D model with fillets. For a history based system its a simple problem, but for a non history based system its a very complex problem, even for a simple shape.
Also to use a non-history based systems means to throw away sketch driven design... Since by definition having a sketch that drives a feature is called "history". And the ability to tweak a sketch and have the model update is great for conceptual design. being able to make many many changes in predictable, iterative manor is what history based design rocks at.
Non-history based systems simply put all the burden on the human to do all the work. As Kevin clearly showed in his stats. It takes more work to build things in Non-history based tools, because you are doing all the work all the selections all the transforms everything. A lot more selections. a lot more manual interactions... There is no design intent...
You cannot just magically make a imported 3D part smart. Trust me.. I have seen a lot of attempts. (several I personally worked on and shown in videos on this thread). Yes you can add constraints to a non-history based part.. The challenge is what constraints do you add? All you have to do is look at auto dimension tools in 2D sketches. Been around for a long time. And the problem is there are just too many different possible solutions... And that in single 2D sketch... how hard to you think it is to do on a entire 3D model? the analogy that is fairly accurate is "Nailing jello to a tree"
So the act of adding constraints to a 3D model is a manual process. Handled very well using tools like move face. These are great for manipulating in a more "direct" way.... You will see more cool stuff in Onshape as time goes on. But I think the 20 year old discussion of history vs non-history has been already been decided by the market...
The market has chosen history based modeling.
Joe
That said, and as Joe said, there is no denying that using a feature list (or history) is a very powerful and very well proven way to define and modify manufacturing designs.
The practical input of Onshape users in the forum has been very helpful to us in prioritizing future work. And the way the community has been helping newcomers has been awesome. Thanks!
http://youtu.be/amI0JZRso-c
Joe
I'm sure it's not that easy but I agree with @Jon Banquer that even though history based modeling might be better way than non-history, things should still develop towards full support for non-native models. But currently opening a model without history needs basically almost same work as starting from scratch to convert into native format with history.
I also agree with @Joe Dunne "power of history based design is that it breaks down a very complex problem into smaller manageable chunks". It makes things easier when you can concentrate to one little thing at a time and knowing you can change parameters afterwards to adjust if needed.
And very much agree with @Dave C that arguing about DM vs. PM isn't getting us anywhere. This is the only thread with negative tension in comments and a lot of down votes in comments which is pretty rare in other conversations.
Everybody would probably just like to have better, simpler, flexible and responsive 3d modeler to handle different type of work to be done effectively. Onshape development has been so fast, yet still well planned with robust features (very few bugs) that I'm confirmed they are able to brings us something better than any of existing cad systems.
Edit: And I appreciate very much the fact that great number of Onshape people are here with us in the forum discussing about the development.
So how about we move on here and focus on getting Onshape able to truly model parts as well as the other established systems can.
I will disagree that the market has decided on parametric. Aside from SE:Synch I haven't seen a DM tool worth using and it's changing drastically every year. There is a lot of development left here.
Having a 3d part with 3d dimensions that behaves appropriately is quite addictive. I've never seen this in PM! Although, I don't see why you couldn't do it.
DM is like building with Legos. PM is like baking a cake.
Sometimes it's best to have a plan, sometimes you're trying to use CAD to create a plan. PM and DM both only work really well for one of these. They have their uses.
I built full cut lists off the BOM. Loved how the dimension data can be manipulated. Named etc. And drives the part and BOM.
Im not massively experienced with the pattern / mirror but I have used it in large Trailer design where components were mirrored.
But as those were then unique parts I needed unique SAP numbers anyway so took the easy save out and rename within the assembly.
Our shop floor has no CNC's so all parts need drawings too. No problem and it's all live and relative to the parts.
It's working like this that got me excited about CAD again.
Those Yes was for KeyCreator.
Thanks Joe Dunne & Dave C for eventually clarifying Onshape's position on 'Direct' modelling. For the record I don't happen to agree with much of what you said.
In response to 3dcad's comment 'This is the only thread with negative tension in comments'. May have something to do with the importance of this issue to a lot of people.
Do you have any news about my small challenge ?
Because you keep saying it is possible to build part's families with ST but I'm still waiting
Maybe you didn't found solutions ? ^^
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