Learning CAD

hiya every one,

now that things are progressing I need to move onto the next workshop tool project. this is the CNC milling capability.

obviously the key part is drawing the part in the first place. this seems to be an obstacle for me. although I am not a computer biff, I am struggling to learn how to use design software to do the job. I can design on paper easily 3D and 2D just not on the computer.

so here is the question,

what is the easiest software to learn and that can be used to draw 3D models for cnc milling.

an example is track plates for my digger.

cheers guys.

becky

I don't like complicated CAD systems either, so the two CAD programs that I use are ViaCAD 2d/3d and MoI. Both are very powerful for the money whilst being straightforward to use. I would say MoI can be easier and more productive when talking about pure 3D modelling, but I think ViaCAD is more productive for producing good 2D drawings with dimensions etc. I use the strengths of them both to help me achieve my goals.

Martin.

I have been using Alibre (now Geomagic) for a number of years to produce 3D models for CNC work and also 2D drawings. I use Meshcam for producing 3D toolpaths and Sheetcam (UK program) for 2D toolpaths.

have a look at my album for some of the results.

Eric

Do you need the cad work for cnc or just to produce drawings?

I ask because I have spent 30years cnc programming from g-codes to the latest conversational programming systems. The worst systems are the cad-cam programs - I can have a machine cutting metal by programming on the machine long before the cad-cam has even scratched it's digital chin.

If you know the shape you want and the path of the cutter, then just punch in the numbers. The best cad-cam packages are mega-expensive and still have you watching the damned thing cutting fresh air most of the time.

Waiting to be shot down.......

trevor

OK Trevor I'll oblige

I have a small 3D part here and it's 64,000 lines long taking in all the fillets etc

I don't think I have that long to live if I have to put that in by hand.

LOL, thanks John.

But most jobs aren't 3d die sinking or complex profiles. For modelmakers the shapes are quite simple and programming on the machine gets the programmer a feel for the machine that a cad-cam does'nt give....also you have a pretty good idea where the tool is about to go next......

Trevor

Easiest to learn... that will depend as much on you as the software. There is a learning curve to all these - so if you have access to help from someone, then whatever package they use might be a good answer.

Otherwise, take a look at some free training videos for various packages..

Do you just want to draw single parts, or do designs involving assemblies?

Do you need to be able to import files from other people or from manufacturers? (import/export may be limited on some systems - you may well need to get your files into your CAM software).

Will you need to produce 2D drawings from your 3D designs? (not all systems offer this).

Prices vary enormously, both for purchase and then for ongoing maintenance subscription (if you want to keep the software up to date or get help if it fails).

Can you afford the time and money for a training course ? (If they are available).

You can get free time limited trials of many products - though without access to training videos or some help from a friend, it might still be an uphill task to learn anything useful during the trial period, you'll need to put quite a bit of effort and time in.

I have a connection to a Geomagic (Alibre) reseller, so my advice may well be biased - I think the points I've made are generally valid though when trying to choose a system.

Yes but Becky did ask for 3D cad and her example is quite a complex 3D model, something that you can't just plug in the numbers.

And in all due respect you state you have 30 years experience, Becky has none, so without any training or being with someone to watch how they work plugging in numbers isn't going to work stood in your little shed all alone.

I would say a track link for an excavator is quite complex 3D items

I never got on that well with 2D, prefering to use the drawing board but about a year ago bought Alibre PE and have been very happy with it. You can get a free trial if you visit their site.

J

There are some nice MoI tutorials here that give a flavour of its use. **LINK**

Martin.

There is a free 3D CAD available on RS Components website. There are also some quite respectable packages available free to students.

Quite a lot of threads on CAD packages on this and other forums with good and bad advice. However I notice lots of posts mention a package or two they are using and you find they cost more than a decent milling machine even though the post is being made on an essentially hobby forum.

Draftsight seems to be the most popular 2D genuinely free as opposed to short trial freeware. It might be a start.

Edited By Bazyle on 25/10/2013 14:15:10

During the course of my main career I did many thousands of "drawing board" drawings. It was later that I obtained 2D drafting software and learned how to use it. Now I employ 3D design extensively. I have 2two 2D design programs that I would not dream of using nowadays. There are many benefits of 3D, Visualization being a big factor and not least....you get your 2D working drawings for free!

Draftsight is only 2D so it can't produce the 3D models becky wants.

ViaCAD 2d/3d is presently on offer at $64.99 while MoI is $295 or $89 from Novedge if you are a student or have a teacher friend/relative.

Martin.

The key points for CAD software, IMO, are the following:

• Parametric design
• IGES output, STL is not good enough unless you are only 3D printing
• Printable drawing output, with the ability to put multiple views and sections on a single page
• DXF import, for reusing existing drawings

Parametric design means you can drive whole designs from a single measurement if you are careful. For example I created a design for a heart-shaped cam, which can be changed for different cam throws by editing a single number. The whole part then updates correctly to maintain the correct proportions.

I also use Alibre. I haven't upgraded since they renamed to Geomagic, as I don't see any new features that would make the cost worthwhile. It has all the features I've mentioned above, even if the DXF import is a little hacky.

What you won't get with Alibre is great integration with CAM, unfortunately. What I mean by this is, if you do go and change a part, you will have to resign yourself to recreating the CAM project you used the first time around. It isn't a major issue for me, but it would be terrible for industry production workflow.

I also suggest getting hold of the 30 day Geomagic demo, and trying out the 2D sketching capability. Extrude some simple parts from sketches, then move on to more advanced work.

Draftsight is free, and well worth trying out. It is NOT 3D however, which could be seen as either a plus in terms of being simpler to use, or a minus in terms of functionality.

I personally would not use Sketchup or Rhino, as they aren't focused on CAD work, but people do, and that can work for them.

Unfortunately this is the state of CAD/CAM right now. It's only recently that there has even been usable 2D CAD for free or within reach of the hobbyist. CAM is even further behind.

Edited By Luke Graham on 25/10/2013 14:34:18

Well.

I use Sketch up for 3D.and various post processors for 3d print..Skein forge claims to process for milling..never proven..

hate( at first ) sketchup..but getting the hang of it I think.

early cad was awful..(80's)..later autodesk got useful...not just part drawings but design drawing..bur never 3d in anger..

look at autodesk line of not for profit..123 rings a bell..

3D cad can be very frustrating..since it looks so similar to 2d but isn't..[ my experience]..

try free ones..you will need to try until you find one that works for you

Unless things have changed then I don't think Sketchup is capable of drawing true arcs or circles. I believe they are actually made up of many straight lines to represent these curves and so aren't really suitable for engineering purposes, in my opinion.

Martin.

Why not try OpenSCAD? It's 3D, parametric and open source, so you can download it and try it for free! Have a look at openscad.org?

Or another one is FreeCAD - also parametric and open source, found at http://www.freecadweb.org/ and  with a nicer interface perhaps?

Chris

Edited By Chris Parsons on 25/10/2013 20:36:57

Edited By Chris Parsons on 25/10/2013 20:43:38

Martin, that sounds like the sort of thing I know as a "polyline". It is a curve made up from lots of tiny straight lines from point to point.

3D is relatively easy to learn as long as you stop thinking in 2d and start thinking as if the part was in your head or you were actually making it on a machine. Most of them (3D cad systems) are parametric, so the approach is to get the basic shape "sketched" in rough and then add dimensions to fix it in space. Try thinking of how you would start out making a "thingy". You would start by knowing that it needed to be "roughly" four inch long and half an inch thick so you start with a rectangle and add these dimensions. You then need a slot at one end and this is done with a slot shaped sketch (rectangle drawn on the starting face of the thingy) with dimensions added to fix the slot size and position from the end etc. You then think, I need a bolt hole at the other end to attach the thingy to the wotsit - so you use the whole tool to add the correct type of hole by selecting the starting face for the hole and inserting a location point with some fixing dimensions. You then realise that it is too short to reach the end of the wotsit, so you edit the four inch dimension and type six inch instead and the whole thing now looks like it will fit. Save the part, drop into a drawing frame (and if you are lucky it will be able to add the dimensions for you) and print it out. Chances are, the thingy will fit a treat and you have saved a load of time and agro making and moding it!

The alternative would be to keep the thingy you have imagined in your head and try to do all that while measuring and making little fag packet sketches in the time-honoured way - and then making another when you realise it was two inches short or making posh sketches in 2D (but you can't just change the size from four to six inches without a load of messing about).

Mark