Using surfaces or solids ?

[EddyVE]

This may sound like a stupid question, but for modelling, when should one use surfaces instead of solids?
So far, I have always used only solids.
I am a machine designer and most parts are not really complex. I have always been able to do what I needed to do by using solids.

Are there things you can do with surfaces that you can't do with solids? Or better: for what purposes do you use surfaces?

Kind regards
Eddy

 

[raedbenz]

hi.....using solids for easy(not complecated) models is good.but if u want to design a complex shapes such a car body or pcmouse etc...it is better to use surfaces and some times u mustmno other choice...


i hope that is informative

 

[rcamp]

I use surfaces extensively in modeling even simple assemblies. They are a powerful tool.


The main advantage comes from the fact that you can model 3d volumetric parts, yet they don't have to be formal parts, so they are not ever included in BOM's. For this reason you can use them


As base features for individual parts to pull common data from


Skeletons to control size and locations


Tools to control the allotment of space and clearance


Incorporate other "meta" type data that you don't want to be visible (at least not in the default viewing mode). For instance you can create volumes in your part that are an exact reperesentation of the form that has to be machined in mating components to accomodate it. The manufacturing data / machining volumeis then store within the actual part itself.

 

[EddyVE]

So it seems like there is more to surfaces than I thought.
I really should check them out.
Thanks for your help, guys !

Kind regards

 

[[-Skint-]]

Hi EddyVE,


I am new to pro-e, only been using it on & off for about 3 months now ( but my total time using is more like 5 hours per week for 3 months

I have started using surfaces and I am completely self-taught, dont be put off if your unsure about them, there are plenty of tutorials and guides that you can find online.


I am doing ok, but slow progress.

 

[appinmi]

We are a manufacturing house. We never create our own models. We create process models from customer's blue prints. We start with the "stock" material and. to simulate the machining process, everything is done with "cuts". If we were to allways use solid cuts, sometimes we would have to add material back onto the part.When machining, you can never add material to the part so we use surfaces, then merge them together, and use the merged surfaces as our cut. That way we are never trying to "add material" back onto the part.

 

[AHA-D]

We are a manufacturing house. We never create our own models. We create process models from customer's blue prints. We start with the "stock" material and. to simulate the machining process, everything is done with "cuts". If we were to allways use solid cuts, sometimes we would have to add material back onto the part.When machining, you can never add material to the part so we use surfaces, then merge them together, and use the merged surfaces as our cut. That way we are never trying to "add material" back onto the part.

I understand that no milling or turning can add material. But I fail to see how a cut can add material. Am I missing something ?


(I design turned components on a regular base. I do use revolved protrusions to add material but that's in order to create controllable features, the final product needs to be turned with realistic equipment - and that's the designers responsibility)


Alex

 

[appinmi]

We do a lot of 3D surfacing. If you design a cut at the base of the surfaces, if there are any protrussions, such as bosses, you will then have to create a protrussion on the model that puts the bosses back in. We create a surface with capped ends at the base of the cut. Then create the bosses as surfaces, merge together, and use these merged surfaces to create the cut.


Another example was something that happenedto us. We roughed out a part, leaving .030 stock all around, sent the part to heat treat, and then finished the part when it came back. To our amazement, the fillets did not clean up, because when we modeled the finish cuts, we did a CUT and then created the fillets using a ROUND. Since the finish cut left a square corner along the trajectory, putting a ROUND in to create the fillet was easy and didn't show any problems. When we went back and remodeled it, we changed the solid cut into a surface. Then added a ROUND to the surface, and then made the cut. We were surprised the this cut showed that the rough cut gouged into the fillet. So now we never create any features that will add material to the model.

 

[ndk]

Is it possible to model this one just only using solid command?

View attachment 2015

 

[AHA-D]

Is it possible to model this one just only using solid command?

Yes : copy external geometry

Alex

 

[raedbenz]

hi mr AHA-D....


i would like to know how we copy external geometry....??? if u know any tutorial explains that, plz tell me where can i find it...


thanks

 

[Jacoolo]

basicaly if one want to model a simple shape than solid is optimal way to go. Surfaces are also fine but everyone has to have in mind that solids are next step forward from surfaces.


Yeah, I know, I can hearit right now - "What this guy is talking, solids are better than surfaces???, #$!!@##!!!"


But let`s look closer


So, if You choose surfaces You have to make to steps : create surfaces and than merge them. Solid features make it at once. Think about that!


When You use surfaces You often put the same dimension in model twice. I know that many poeple do not care about that, but when it comes to make a drawing YOu canonly hear Argghhh.... why here it is so many dimensions!!!


Surfaces and solids togheter create mixed modeling. This approachcan generates problem with dmu, data exchange and so on.


So when use what? These are may thoughts:


*If it si a plastic duck or toy with strange shape, choose surfaces,


*if it is a cast model, engine pieace, but not so complicated, choose solid.


*if it is a cast model but very complicated one- surfaces, even copmlex assembly approach, with cores, reference models and so on is a good choise


*choose surfaces for cavities, cores with complicated shapeetc


*choose surfaces to create references at top of model for inner geometry, if You model casting models, than remove inner geomby solidify, the outer geom make by solid


well it does not fulfill the topic but I hope it will help

 

[AHA-D]

hi mr AHA-D....


i would like to know how we copy external geometry....??? if u know any tutorial explains that, plz tell me where can i find it...


thanks

Sorry for misleading you, but that was only a joke in response to the unrealistic question of doing difficult things in one move. You can in effect copy a model in another file and use this in an associative way to do other things. Copying external geometry is one feature, all of the work is of course in the other file (which will be more than one feature ...).


Alex

 

[dougr]

"I understand that no milling or turning can add material."


NS....


"When You use surfaces You often put the same dimension in model twice."


Why ???


What-on-Earth is a "solid cut" ???
Edited by: dougr

 

[dougr]

basicaly if one want to model a simple shape than solid is optimal way to go. Surfaces are also fine but everyone has to have in mind that solids are next step forward from surfaces.


Yeah, I know, I can hearit right now - "What this guy is talking, solids are better than surfaces???, #$!!@##!!!"


But let`s look closer

You guys are not getting it.


Surfaces are construction features in the same manner as datum-curves are. (Am sure most of us have used datum-curves to aid feature construction).


Ultimately you ALWAYS WANT solids...


PS


Viewing surfaces to be only useful for complicated shapes is very narrow, one extremely useful technique for surfaces is that of creating "bounded volumes".


Am sure you guys are smart enough to figure what a bounded volume is..


My modelling would be impossible without the use of surfaces for two basic reasons:


"boundary blends" (or styles)


"bounded volumes"
Edited by: dougr

 

[dougr]

Is it possible to model this one just only using solid command?

View attachment 2027

I'd say not, ultimately you'd want to use boundary blend and/or style features.


Blend commands for solids aretoo inflexible. (planar sections, identical section entity #)
Edited by: dougr

 

[Zaki]

Hi Guys


According to my thinking and observations, solids are better than surfaces. Why?? Every modeling and machining software (cad/cam) is adapting now solid modeling methods, why?? think about it. Like MasterCAM, Delcam and other surface based modeling softwares. I know that surface modeling is the base of CAD/CAM softwares. When the softwares developed first time so all those adopted surface modeling, but as the time is going these all getting improvement further and further, and adopting sollid modeling techniques. Now the main modeling aim these days ( as like proe) is to get final solid model. surfaces are just supporting the hard to model features to get required results and nothing. No one is modeling these days in total surfaces but to get a solid model finally. Surfaces has zero thickness. How could u determine the volume analysis.


There is a lot of flaws in total surface modeling, and a lot of benefits in solid modeling. U can check by ur self.

 

[dougr]

Hi Guys


According to my thinking and observations, solids are better than surfaces. Why??

Like I said you ALWAYS want solids as an end result, surface features much like datum-curves should only be viewed for construction purposes..

 

[jeff4136]

> solids are better than surfaces


Wearen't talking about two different "things", just two different methods of creating the same thing; usually a manifold solid b-rep. Solid modeling methods are just another way of creating a b-rep. They are widely used because macros do a lot of the work transparently making it simpler, quickerand manifold volume rep checks keep users from getting themselves in trouble.


> ALWAYS want a solid


Why? All you want is the topological / geometric rep. A close shell will serve just as well for most purposes, all purposes if you associate a density parameter to it and can represent voids if they exist. The notions of surface vs. solid exist only in software developers methods; i.e. you have to use different operations on a "solid" vs. a "surface".


An often overlooked reason to use surface features vs. solid features is performance. If a solid feature creates surfaces that areconsumed by the associated boolean operation they are useless overhead.


Use the feature that is most efficient for the purpose.

 

[rmatija]

Hi guys


I think the best way is combination of both


All go not only with solids, or its very hard work.


Best regards