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Author Topic: CAD, level of difficulty  (Read 3132 times)

rezdis

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CAD, level of difficulty
« on: December 07, 2012, 12:04:41 AM »
 
Quick Question
I?m considering taking a class on CAD and I?m wondering how difficult of a program it is to use compared to something like Photoshop. Does anyone have experience working with CAD programs that could help?
 

digitalman2112

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Re: CAD, level of difficulty
« Reply #1 on: December 07, 2012, 05:59:49 AM »
I think photoshop / photo editing software is a good comparison. Photoshop is designed to give the end user amazing capabilities - and this means a TON of options, 5 different ways to solve the same problem, a huge menu and tool selection, etc. The learning curve can be quite steep. For someone that had never edited photos, I wouldn't likely recommend Photoshop unless they REALLY wanted to jump in and spend a lot of time learning - or they wanted to use it professionally.

CAD software is the same way - there are simple packages, and powerful packages - generally, if you want power, you give up simplicity. With CAD, it really depends on what you are drawing - there are packages optimized for architecture, for mechanical design, for 2D, for 3D, etc. We are seeing the emergence now of programs like TinkerCad that are targeting 3D printing.

My experience with CAD is very dated. I suspect the expertise at the lab is divided between 2D / mechanical work (people like Dave W.) and 3D work for simulation / gaming / 3D printing (People like Tom, Chris, Tony, Pat).  We also have a lot of people that do vector work for laser cutting (which has a strong similarity to CAD) using illustrator or inkscape. (Talk to any of the people hovering around the laser...)

As for classes, if you like self-directed learning using video - check out lynda.com - if they have what you want, it is expensive, but if you have lots of time, it is a great resource for diving in and learning a LOT in a very short time (at your own pace)




Matt

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Re: CAD, level of difficulty
« Reply #2 on: December 07, 2012, 09:37:35 AM »
What are you looking to do with the resulting CAD? If it's 3D modeling for the sake of printing or photo-realistic rendering then there are some tools that are more free-form and less mechanical than pure CAD software packages. These are more intuitive to use and are closer to modeling with clay or sketching. ZBrush is a great example of this type of software. (Take a look at some of the tutorial videos on Youtube, it's a neat piece of software)


If you want to produce output files for CNC machining or laser cutting then a traditional CAD package is probably the easiest thing. It is possible to do this type of design in other vector drawing packages like Illustrator or Inkscape but holding real-world dimensional accuracy is kind of a secondary consideration with those packages. They are designed to create vector art which can be scaled on demand.


If you want to get started with a powerful CAD package that still has a modest learning curve to get started I would download RhinoCAD. The full versions are fairly expensive (not as far as CAD packages go, but still several hundred dollars). However if you're a student they have a reasonable price for the student edition. Also, the trial version is fully functional and is only limited by the number of saves you can make (25 I think).


The best advice I can give is to start thinking about how the objects you want to design are physically made. Most CAD objects are designed using combinations of two things: Boolean material operations and extrusions/sweeps.


To work with boolean material operations you need to start seeing the big, primitive shapes that make up the object you are trying to design.Then merge those shapes together and cut them away to achieve the desired result. Shapes can be joined together (three spheres in the right places with the right proportions will give you a convincing mickey mouse head when joined into a single solid). Or you can use the shapes to "cut away" material from another shape (using a cylinder to cut a hole through some other shape so it can have a bolt through it or so it can slide on to a handle).


Sweeps and extrusions are where you start to get some of your more interesting organic shapes. Generally these operations involve taking some shape (may be something you sketch free-hand or even a primitive geometry like a circle or sphere) and sweeping them along some path while leaving "trails" behind you. Picture a typical flower vase. You can sketch what you want the cross section to look like as a simple 2D curve. Then when you sweep that shape around a fixed axis in a circular path you get a vase shape. this is very similar to how vases are really made on a pottery wheel. Your hand provides the contour/shape and the rotating wheel does the "sweep" to produce the 3D shape. Extrusions are just sweeps along a straight linear path. This does things like turning circles into cylinders, rectangles into cuboids, or a complex cross section into something like an 80/20 aluminum extrusion.


These are just some basic examples, they get much more complicated going forward but you can still produce some very decent CAD models just with these basic techniques. I would be glad to sit down with you at some point and work through a few of these using my copy of Rhino if you just want to get a feel for it.


-Matt
« Last Edit: December 07, 2012, 09:41:25 AM by Matt »

Hybridsix

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Re: CAD, level of difficulty
« Reply #3 on: December 07, 2012, 04:42:43 PM »
Without being quite as beautiful or descriptive as armstrom's writing, I use two, free, cross platform CAD programs now on a fairly regular basis, both for work and for lab-related things.


Draftsight - 2D Cad
This is a decent entry level CAD program, free for most users, that will perform many functions like standard Autodesk AutoCAD - so easy to move from one to another, command wise. Commands are entered either by typing, or using the mouse to click tools and points on the image, to edit values. Good for creating files for the laser.


FreeCAD - Parametric 3d Modeling
While far from perfect, this 3d modeling program is opensouce, and based on several other open-source CAD programs such as pycad and openscad, but with a more user friendly and intuitive work space  As mentioned, you can either start with primitives and build up that way, or start with "sketches" and create shapes to extrude, revolve, or sweeping those 2d lines along a path. I've been using this program exclusively so far to work on things for the FamiRocket project (as slow as I am) its kind of been helping me to learn the software. With this one, commands are not typed like in Draftsight or AutoCAD, they are more GUI/Menu/Folder based for parts and tools. The big advantage of using this for 3d work is that any change you make, can be changed later down the line without going back a whole bunch of steps (i.e. changing the hole size in a complex part) Good for 3d printing, routing, etc.


These programs may not be perfect, but they're what i've chosen to follow at this point, mainly due to cost, and cross-platform availability.

rezdis

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Re: CAD, level of difficulty
« Reply #4 on: December 07, 2012, 09:13:10 PM »
 So I looked at the course description and it says the class is structured around MasterCam.
 

rezdis

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Re: CAD, level of difficulty
« Reply #5 on: December 07, 2012, 09:21:31 PM »
 And there apparently there is a sequel class where we use Auto CAD.
 

P47

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Re: CAD, level of difficulty
« Reply #6 on: December 07, 2012, 09:36:47 PM »
That almost sounds backward. MasterCam then Autocad. I think it should actually be Autocad -> MasterCam.
 
Autocad CAD-Computer Aided Drafting and Design, is a program used to create 3D models and/or assemblies for production, .
 
MasterCam CAM-Computer Aided Manufacturing, is software used to take the model and/or assembly you made in Autocad and create toolpaths for production machines ie: mills, printers, lathes, etc, .
 
Personally I think it would be more productive as far as learning would be to take an Autocad class first and then take the MasterCam class. Either way, CAD/CAM is a great toolset to know. If you want to create production models and/or assemblies and cam them out for production, then that's a great class to take.
 
On the other hand, if you want to create more organic and fun characters I'd recommend a polygonal modeling program like Silo and Cheetah3D.
« Last Edit: December 08, 2012, 10:51:23 AM by P47 »

jdbugman

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Re: CAD, level of difficulty
« Reply #7 on: December 08, 2012, 09:55:04 AM »
I just got alibre design. It was 200 $ and it is a scaled down auto cad. I picked it up and was able to make objects that I could send to the 3d printers.  Also they have a 30 trial. If you are trying to make a part and you need specific dimensions then this is a great easy program. It really depends on what you are doing.

Simply7

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Re: CAD, level of difficulty
« Reply #8 on: December 08, 2012, 02:45:54 PM »
I just picked up alibre as well looking to use it for design work. They had a black friday sale.