Full Version: .OBJ & .STL limitations?

From: Sculpy [#1]
 11 Nov
To: ALL

Hello all
Can anyone explain to a complete noob how these two file formats will limit me if I want to manufacture jewellery compared to the hugely expensive other cad formats people normally use? I would also like to design other larger stuff to be manufactured with cnc or laser cutting. Is this going to be a problem with .OBJ & .STL?
Thanks

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From: Michael Gibson [#2]
 11 Nov
To: ALL

Hi Sculpy well both .obj and .stl are polygon file formats, where the model data is made up of a large number of little facets. That's a different type of data than the NURBS surfaces and solids that are stored in CAD file formats.

But CAD file formats aren't themselves hugely expensive you can export to both polygon file formats or CAD file formats out from MoI.

The type of data required can be different depending on the particular thing you're doing and there are even many variations within a certain field, like there's not only one way to do CNC milling, there are some programs that can do it from polygon data and other programs do it from CAD data. Then laser cutting is a different thing as well, that's often done from 2D curves.

You're talking about doing a lot of different possible things and different things will probably involve using different types of data and various other software. Each of these combinations with different software may involve using various file formats for translating your data over.

STL for example is not usually used as the main file format that your original model is saved in, it's typically generated only as needed to send the model data to a 3D printer in the form that it's expecting (in this case made up of a bunch of triangles).

When you're in the process of working with building your design with MoI you will want to save it in 3DM format, and only export to other formats when it's time to bring your data over to some other program.

I'm not sure if that answers your question or not though, maybe you will need to explain a bit more why you're focused on .stl and .obj formats in particular...

- Michael

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From: Sculpy [#3]
 11 Nov
To: ALL

Thanks. That's given me a better overview. The reason I was asking is because I have read DWG and DXF are the most common file formats for CAD designers and I don't want to be told later down the line "sorry, your file format is not compatible with our machinery, you will have to redesign your drawing using some other software"

I'm looking to become a designer/Inventor and want the ability to design anything from tiny jewellery findings to jumbo jets and have my ideas manufactured in casting shops or injection moulders for fast and cheap duplication.

I understand Moi is not going to have all the vast bells and whistles like other hugely expensive CAD programs out there that cost thousands but will Moi be flexible enough for my goals do you think? I simply cannot afford any other kind of CAD software even on subscription basis. At the moment its a choice between Sketchup and Moi and Sketchup is not suitable for small intricate items.

Regards

Sculpy

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From: Frenchy Pilou (PILOU) [#4]
 11 Nov
To: ALL

SketchUpMake (before you become a Pro) is free and receive very easily format SKP from Moi! ;) (for "unic" object)

Just a little thing if you want keep some arborescence of "multiple objects" from Moi to SketchUp prefere 3DS format export!
(3ds old format is limited in 65 000 Pts/segments/ faces...by object )

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From: Michael Gibson [#5]
 11 Nov
To: ALL

Hi Sculpy, well there's many different kinds of CAD designers, DWG and DXF formats are only really the most common for people using CAD for 2D drafting like so it replaces a drafting table for making 2D blueprints. There are so many varieties of CAD that the context matters a lot, like you might read in an architectural magazine that the most common formats are DWG and DXF but that means among architects.

re:
> I'm looking to become a designer/Inventor and want the ability to design anything from tiny jewellery findings to jumbo jets <....>

The problem here is that what you're talking about spans a whole lot of different industries, and each industry has its own particular specialized needs and software that is designed to meet those needs.

A Jumbo jet is made up of 6 million different parts and involves a large number of people working together on it. The process that requires is at a fundamental level just nothing at all like the process around doing a tiny jewelry piece.

You don't really want to use the Jumbo jet designing software to do the jewelry piece because it wouldn't be any fun having a fully staffed I.T. division working in your office doing all the database maintenance and TPS reports and what-not while you were just trying to draw some stuff... ;)

For choosing between MoI and SketchUp, I'd say MoI sounds like a better fit for you. SketchUp is very easy to use so it's great for beginners but it's also mainly designed to do boxy architectural shapes and builds everything out of polygons. So if you try to make a sphere for example it's not an exact sphere it will be a bunch of triangles just approximating a sphere. This could indeed come back to bite you if you want to take your model through a manufacturing process later that required accurate geometry. When you build something with CAD solids like in MoI you've got more bases covered as far as different file formats especially relating to manufacturing because you can generate a polygon format output from CAD solids if you need to but it's very difficult to do the reverse.

I can't guarantee that MoI will meet every single one of your future needs but it should be a good place for you to start!

- Michael

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From: Sculpy [#6]
 11 Nov
To: ALL

just what I wanted to here Michael. Thanks. Is there any way I can design jewellery with pave stone settings using Moi?

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From: Michael Gibson [#7]
 11 Nov
To: ALL

Hi Sculpy, it's possible to do pave stone settings using MoI's built in functions but it may be pretty labor intensive if you have a high number of them. So it kind of depends on the complexity of what you'd be trying to do.

To make it easier you would want some more specialized software that has tools specifically targeting that, like RhinoGold for example.

MoI itself is pretty general purpose, when software is more specialized for a single industry or purpose it can tend to make it easier to do that specific thing.

- Michael

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From: Frenchy Pilou (PILOU) [#8]
 11 Nov
To: ALL

<< SketchUp is very easy to use so it's great for beginners but it's also mainly designed to do boxy architectural shapes and builds everything out of polygons.

The boxy mode is now some avoid by some tricky plugins! ;)
So now SketchUp is also becoming a sort of Subdivision prog! (not so poweful than a real one but as it's so easy...;)
http://evilsoftwareempire.com/subd
http://evilsoftwareempire.com/vertex-tools

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From: Sculpy [#9]
 11 Nov
To: ALL

Just been watching Moi tutorials. This software is brilliant. Short of designing a space shuttle it should do all I need.
Thanks

Sculpy

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From: Michael Gibson [#10]
 11 Nov
To: ALL

Hi Pilou,

> The boxy mode is now some avoid by some tricky plugins! ;)
> So now SketchUp is also becoming a sort of Subdivision prog! (not so
> poweful than a real one but as it's so easy...;)

One of the things that makes SketchUp easy to use is that the main program UI has stayed focused on drawing lines on faces and using push / pull. That is cool that there's a plug-in that does sub-d smoothing but that type of modeling is very different from boxy line drawing push/pull modeling and so trying to use it for that is going to lose a lot of the easy to learn quality.

If you want to do sub-d modeling there are other programs out there that are focused just on that and have their entire UI tuned for doing that.

- Michael

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