New To CAD? No, but....

Jason -

I was not too keen on that "mindset" and "rut" thing.

I am perfectly well aware that an orthographic drawing seeks to represent a three-dimensional object as a set of views perpendicular to it, and you need those for actually making it.

I took up CAD knowing what it can give you, including isometric views very useful for visualising a complex shape, forming interpenetrations and developments, creating assembly-drawings, etc. I also know that it can help determine problems like clearances between moving parts - and that some makes have animating functions for those parts.

CAD does not make you a better designer, but it does ease drawing, if you can fathom how to use it. Manual isometric drawing is difficult, though not as difficult as the CAD version. On the other hand, it is far slower and can be very laborious thanks to having to plot oblique views of shapes that the computer calculates and displays in micro-seconds to very high accuracy.

The point is that using CAD introduces a vast and very deep additional skill even just to draw 2D views of relatively simple things; and uses concepts of its own that are not immediately obvious. And that is before you can start using it for any serious, real project.

It is not possible to write a manual that will cover all makes of CAD to a high level, but there are few if any real primers that teach you those generic CAD principles and controls. The instructions or 'Help' glossary for any given make simply tells you which button to press for what control, not what controls to select.

An expert CAD user can probably produce a fairly elaborate 3D drawing of a piece of machinery in a few hours - but if it takes hundreds of hours to learn how to do so, then it represents a loss, not gain, in valuable time.

Derek like Blowlamp I tend to use Alibre almost every day either for work or hobby and as you use it more things come quicker. I find it useful for work as many clients can't follow 2D drawings that well but a 3D image or interactive pdf that they can move about or zoom into gives them a good idea of what they will get for their money

Take that engine base I posted in the "big boy shootout" thread, probably an hour to do that including cores and core boxes then a bit of tweaking as other parts were tested in the assembly.

This is where it really comes into its own and saves time in the long run. As an example this engine uses a form of scotch yoke that is pivoted at one end. Scaling from the old etching gave some sizes for the parts but in practice it was found the crank thro was too big and had to be reduced so it did not hit the ends of the slot. Also the base was made a bit longer to get the conod to move equally either side of vertical.

How easily could you check things like that from 2D on a bit of paper without having to cut out bits of card and pivot them on pins. Then have to go back and cut another bit of card when you change a part. With the ability to animate e3D assemblies you can easily make a change and instantly see it's effect. here I am just holding my mouse on the end of the conrod and moving it in a circular motion. I can do that while viewing from any angle and a section through any part(s) is just a click away if I wanted to see something like a piston inside a cylinder and check it is not hitting the end covers.

Edited By JasonB on 06/05/2022 18:37:47

I don't think this thread is anything about wanting to learn about 3d CAD.

Martin.

Nigel's bald statement that CAD(of any sort) doesn't make you a better designer shows he really doesn't understand its value power.

Yes, there is a steep learning curve(just like being able to produce a presentable drawing of a part with pencil and paper) but once you've started up it the benefits become clear: you don't have to do all the extra stuff of drawing the features onto the other planes, because the computer does it automatically. Same applies to how far a hole needs to go; is it 34.76849mm or 45? Who cares - click All and it's all the way through/butted up to the next part, or your hard to draw 7 hole bolt pattern is cut into both parts complete with countersunk holes and threads. And they're the easy things, who wants to do the maths to add an angled hole tangential to a seemingly random curve. Again, the computer doesn't care, it just does it allowing your thoughts to be of the design, not the details.

Anyone who can confidently draw a real object by the traditional 2D representations ought to be able to fall into 3D CAD, as the hard part is often deciding which profile to sketch to get your initial solid - should you use the front because it's symmetrical, the side because it has the most/least features, the top because it joins to another part and you can use that to start with, or revolve your multi-feature spindle around the axis of the bearings it sits in? How about modelling your motor mounts directly off the motor you carefully aligned with the pulleys it drives.

And why the insistence that 2D workshop drawings are the end result? A folder full of pretty drawings is just another step like ringing round suppliers to find a decent price on the materials, not the final objective which is having a working part.

That's because he thinks in 2D drawings (as has been said here numerous times). Until people ditch 2D and realise that all the power is in the 3D model (and 2D drawings are a trivial fallout of that which can come along later but is best forgotten about at first) then learning solid modelling is difficult.

Actually it's difficult enough self-taught. By far the best way to learn is a full time teaching course. I'd venture to say that most if not all professionals have gone this route (I know I did) .... and it works. In 3 -5 days they will make you reasonably proficient.

I know that's difficult in the amateur milieu but are there really no community college courses available?

I dont decry or want to come all negative about 3d cad, it's used for drawings where I work.

They are very useful as others have said, to test a design, create easier to understand parts, how they fit together and their relationship with each other.

I really wanted to know how long in time does it take to become reasonably proficient? What spec PC or laptop? and then what choice of software?

Peter Greene mentions a course - all well and good if you can find one - I suspect the company supplying the cad package would run courses but no doubt expensive and maybe geared to more to the "professional".

I would love to have the time to learn 3d cad but not sure how useful it would be to me as I dont do a lot of design work but have great admiration for those that do !

Best wishes

Derek

There is a lot point-missing going on....

Martin ('Blowlamp' )  -

" I don't think this thread is anything about wanting to learn about 3d CAD. "

That's how it seems to have gone but -

- I have always said I did want to learn it..

The 3D function was partly why I bought it in the first place; naively thinking I could learn it.

.

Peter -

I am NOT stuck on 2D drawings and thinking in 2D as you and others allege!

I have to be realistic about what I can learn, and therefore how to use this model-engineering assistant to suit me - and you still need orthographic drawings in the workshop!

I do not believe CAD drawing makes you any better a designer than if you use manual drawing, because you still have to understand the engineering and its craft techniques.

CAD makes life easier by handling lots of very awkward calculations, removing some of the drudgery and risk of numerical mistakes. I know the highest-grade packages include things like stress and mass functions, and animation routines - but those are advanced features well beyond me.

CAD is still as much a tool as the lathe or milling-machine. Just as having a shiny new high-grade machine-tool and its operating-manual does not itself make you a first-rate machinist, no amount of drawing skill in any medium makes you a brilliant designer. I have even seen professional CAD drawings of parts details easy to draw but needlessly hard to make.

'

Some seem to think it impossible to draw a complicated machine in orthographic views only.

That is manifestly wrong. Many of us enjoy making models of highly-complex machines like main-line steam-locomotives and radial aero-engines. Their originals were designed and drawn almost all, even entirely, in 2D, orthographic form! Look at some of the old GA drawings for locomotives or power-stations: extremely highly-detailed layouts, from which the components and sub-assemblies were derived; and all by hand.

The fact if this being now feasible in 3D CAD does NOT mean no other way exists. The computer makes 3D images feasible, and in a far faster way, that is all.

.

Derek -

Hooray! You see the point about justification.

If I have to use only orthographic drawings it is simply because I cannot learn the 3D CAD I have spent so many hours trying to learn. All hours wasted.

And you are right. The only CAD course available publicly, are sold by the software publishers; dedicated to their programmes; and aimed at professionals so over several days at least, at industrial costs and probably a long way from one's home. I do not know if they offer Internet courses, but I expect they'd be still be pricey and nowadays assume a lot of prior knowledge anyway (professional conversion-courses).

Paul Tracy was selling TurboCAD courses. I don't know if he still does, but again probably for trade users.

Community college course? No. Those here in Dorset teach no engineering or science outside of any full-time trade courses.

Edited By Nigel Graham 2 on 07/05/2022 08:38:54

Edited By Nigel Graham 2 on 07/05/2022 08:39:26

How long does it take to become proficient? I'm teaching myself Solid Edge at the moment and have spent 30 hours on it so far. In that time I've cracked how to make individual parts and a moderately complicated Assembly (with sliding, rotation, a cam action, and fixed joints)

I already had a head-start because I know FreeCAD and Fusion360: they and Solid Edge have many similarities, That saved time but, but there are many detail differences and relearning is hard because old habits have to be broken.

Switching from 2D to 3D is particularly difficult: when 3D-CAD first appeared many draughtsmen fully competent at a drawing board were unable to cope. 2D design requires a different mindset from thinking in 3D: the two thought processes are a kind of inversion of each other. Some folk take to 3D like ducks to water, others fail to make progress because they misconceive how 3D modelling works and end up fighting it every step of the way.

I started with FreeCAD and wasted an enormous amount of time trying to make sense of the enormous number of different workbenches it provides. Didn't help that many older FreeCAD web tutorials were out-of-date and positively misleading because the developing software had moved on. (Outdated tutorials are a general problem on the internet: always check the tutorial matches what you have.) However, FreeCAD became much easier when I realised that almost all mechanical design is done in the Part Design Workbench, and the others can mostly be ignored. My Making a Start in FreeCAD thread is intended to get beginners going quickly by showing how the software is started, put in gear, and taken round a typical obstacle course.

In the good old days most ordinary personal computers weren't powerful enough to run CAD: too slow, not enough RAM, sluggish graphics, and second-rate screens etc. Today, almost any reasonably new computer has the grunt needed to run 3D CAD provided the models aren't too complicated. Worth getting a fast workstation with a powerful go-faster graphics card for professional use, but I do 3D CAD OK on a modest 5 year old laptop with an ordinary mouse. I recommend a big screen though, and two big screens would be nice! Not essential, but they minimise the amount of zooming and scrolling needed.

How useful CAD is depends on what you're doing:

• Many ordinary workshop jobs can be done on the back of an envelope.
• More complicated work makes sophisticated methods progressively worth the effort: moving from squared paper, via a drawing board to 2D-CAD. For simple stuff I prefer envelopes, but call on 2D-CAD a lot to check other people's plans, my own ideas, and to produce templates. I don't use squared paper much any more - 2D-CAD is better.
• 3D-CAD is a steeper learning curve, but knowing how to use it makes even mildly complicated 2D drawing obsolete. It's:
  • Essential for 3D-printing and probably CNC too.
  • A high-value time-saver for anything more than basic design work, either a stream of simple things, or any multi-part project.
  • Useful for visualising objects. Images can be made for publication, comparison or to help explain forum questions and answers.

I've always been interested in design, but it takes an age to develop with a calculator, drawings, and pinned cardboard prototype motions. 3D-CAD makes it possible for me to explore design as an interesting aspect of the hobby. Depends on how I feel: I enjoy hands-on making very much, but working at a computer is fun too, especially compared with my uncomfortable mid-winter workshop!

Dave

It's a mistake to think that 3D CAD is simply a faster way to produce drawings. In the 'good' old days models were often made to determine function and check for interferences. I recall seeing a photo of a tenth scale model of a ship engine room, in Model Engineer I think, to determine pipe runs and lengths. All done on the computer now. Complex curves can also be created which would be difficult, or impossible, to dimension on a 2D drawing. Professionally 2D drawings are less common, 3D models can contain tolerance and machining information for use by CNC machine shops.

Having said the above I still use 2D drawings in the workshop, at least for manual machining, and have been known to use 3D printed models to check functionality:

Ironically the 3D printed gear change mechanism worked a darn sight better than the ones made in metal.

Andrew

As mentioned in a previous thread on similar subject, it really does help with learning 3D CAD if you can get some personal tuition. It isn't always obvious which aspects of using CAD will cause the problems/frustrations - if in the same room as a tutor it's so much easier to ask a question, and it should be obvious to the tutor if anyone is struggling.

Videos can be good for learning specific operations, but can so easily gloss over or miss out the underlying basics - perhaps because it's 'obvious' to one who already knows. Videos are brilliant as a refresher for seldom used functions.

The major frustrations can be around finding how to access a particular function, or what input is expected, even what is the name of the function that I need, or how do I go back and edit the feature I just created (at the wrong size)... I also find routine Windows usage (not specific to CAD) can be as much of a block as the particular software.

As for time to learn, I used to run 2 day basic courses in Alibre Design. The course started with really simple stuff, it had a structure so that most of the main modules of the software were covered. Never more than 6 students in the class, so there was plenty of time to deal with questions. On a one to one basis, the material could probably be covered faster. The 2 day course aimed to get users from zero 3D experience to being comfortable working with the software. It gave students sufficient skills and knowledge to progress their own design work, it didn't by any means turn them into experts. An important point covered was how to get help in the future.

So if you are struggling to get started, I'd suggest try to get some time with somebody (patient) who is already familiar with the software you are trying to learn. Being in front of the same computer is best, but a web conference with screen share can work OK in shorter sessions.

These days most demos, or training on specific CAD functions that I do, use web conference (on cost and time grounds). A colleague (who does more design work than me) still runs the 2 day in-person courses - location and price are typically problematic for non-business users.

I'm not seeing any intention of you wanting to learn. I think you want to make the point that 3d CAD is too hard for you to grasp.

I've suggested MoI and you have offered no feedback one way or the other.

What is the point of this thread you have started?

Martin.

Nigel,

There is a lot of good stuff on here, however, I think you are approaching 3D CAD with the wrong mindset, let me explain.

I was in a similar position to you. I had come through learning to use a 2D CAD package, gaining a reasonable 2D proficiency, enough for what I needed to use CAD for. I had been using 2D CAD for about 25 years.

When I retired bought a 3D printer for a specific task which it did admirably but then started to think, what if I could design stuff and print it myself.

At the time MEW started the 3D CAD series with Alibre Atom3D so I took the free trial and started on it. It was an absolute disaster despite me following the tutorial in MEW. I kept tying myself in knots because of all of the 2D experience I had. Then I had a lightbulb moment when I read somewhere that said words to the effect of "forget everything you have learned about drawing and think that you are trying to machine a lump of metal and what you would do to it". Then it all started to make sense.

I find when making a 3D CAD drawing that you are either adding or taking away material with a positive or negative extrusion and make sure you are doing it on the right plane. You have to make a number of sketches, one for each separate machining process you are performing on the part you are producing before the positive or negative extrusion.

I would not profess to be an expert, in fact, I am far from that, but I have been able to produce everything I have set out to do so far, maybe not in the most elegant way but at least it has always worked.

I have no commercial interest in Alibre or know anyone connected with it but I find that it is simple to use once you have grabbed that first fundamental that it is nothing like 2D CAD and it is just about making a sketch, extruding it into a shape then adding or subtracting other extrusions to it via other sketches. It really is so simple - I think you are overcomplicating it and are taking all of your 2D experience into producing a complex drawing rather than using simple sketches to make a complex object.

Others may disagree with my views. I almost gave up with 3D but now find it useful and straightforward, but what is most important, it is satisfying and rewarding when you produce something.

Steve

er ... OK.

Edited By Peter Greene 🇨🇦 on 07/05/2022 17:55:34

I hope the drawings below, produced in TurboCAD 19 Deluxe, help explain my points.

I hope too, no-one thinks I do not realise the value of CAD. I do, but while most people use by their choice and own approach to how they - not it - design what they make, my choice is limited by how to use it, not by why.

'

Martin -

I am sorry but you are mistaken here:

" I'm not seeing any intention of you wanting to learn. "

Wrong. I have every intention of wanting to learn - I already knew what CAD offers; but I had not realised it is so hard to become sufficiently proficient! If I had known that in advance, I would not have bought it.. Anyway, is it wrong to be honest and admit failure?

' ' '

The pictures represents my level after hundreds of hours' trying to teach myself what many others must find easy to learn to high level, in much less time.

'

My original question was from my trying SolidEdge (CE) as an alternative to TurboCAD. I knew if I made reasonable progress, there are people here and in my club to offer help. It seems few in model-engineering use TurboCAD, but I have just updated my edition to TurboCAD 2021-x64. Siemens web-site offering SolidEdge tutorial videos deterred me with terms like "synchronous" in describing the videos supposedly for beginners. It implies needing much existing CAD knowledge, suggesting the material is for professional users moving from other makes. I had hit a wall of unintended technical exclusivity.

'

The drawings: Of my 4"-scale steam wagon chassis essentially as it is now, minus the enclosed vertical engine not yet made but which will stand behind the boiler and between the crew seats. I have omitted the seats and the chimney, for some reason, though I have made them. The flywheel shows as the green circle in the elevation.'

The orthographic colours are by Layers; which I find help differentiate sub-assemblies, and too see details under them.

The bunkers proved very difficult to draw as open-topped boxes with floors. The yellow block is of course the water-tank, sheet brass. The two chassis rails are of heavy channel-section; drawn by Extruding rectangles into cuboids for thickness / depth, Assembling and Adding them into cohesive units. Since the chassis necks inwards for the steering, making one rail needed nine cuboids!

Putting the bits together used both Assemble tools and co-ordinate sums - I know the latter should not be necessary; and I saw SE does not show a grid and co-ordinates, by default.'

I probably used "primitive" (library) cylinders for the boiler, smokebox, the differential with its chain-sprocket (not the true shape of the modified BMC unit, nor the sprocket teeth); rear axle, wheels. '
The front axle is really an I-beam. Each wheel is really a pair of dished, rose-pierced steel plates in a thick wooden rim and shrunk-on steel tyre. The radius-arms, springs and Ackermann steering are also fitted but like the wheel details, too difficult to show in 3D. I don't yet know where the chain and 2-speed gears will lie in the chassis: a typical task for the 2D drawing.'

(Shrunk-on: 30 minutes in the oven at Gas Mark 9, then wiv' a big 'ammer! Many Edwardian factory staff photos include a bloke with a sledgehammer.) '

I did not make it from many drawings, certainly no CAD ones. I made these drawings from it. Perhaps that will explain that I am the designer - sort of - not the pencil or computer. Although the 3D picture has no practical value, these two drawings represent firstly, what I have already "designed" and made, and secondly, my level of skill with CAD.

I wanted taking up CAD to facilitate the project, with me still as designer ! All my mistakes, revisions and re-makings are by me. The software won't necessarily stop that, but might help me make the revisions and corrections before wasting more metal and electricity in the shed.

Once again, your approach is causing your problems. We keep saying that you need someone to show how any of your parts could be produced using a program you already have.

As we showed in a previous thread, your chassis rails are not nine separate operations each, but two simple, editable sketches and another editable procedure. Then you create a mirror of it for the other side. That makes you the designer, with the computer as a tool.

Coordinates are another deadly trap: let the computer use the features on the parts to position/align/join them. You won't assemble the real thing by moving the boiler back 30.56583mm and up 23.9 from the front crossmember and ground, but shift it until the mounting holes line up.

The elevations you need(I would prefer want, but I suspect we work differently) are then taken from the model because it already has ALL of the information. You can create as many as you need, showing the whole machine, separate parts or how sub-assemblies relate to each other. Again, that's being the designer.

Your 3D model is the CAD equivalent of a back of an envelope sketch, which is then used to start the design and figure out how you're going to do it - the traditional drawings of complex parts weren't created by just grabbing paper and pencil and drawing away. A considerable amount of training, practise, experience and thought was used first.

I have to agree with Nicholas Wheeler above, in that it appears that your basic approach is flawed. I find the drawing in your last post extremely crowded and difficult to read, possibly exaggerated by the scale. However, to prove, at least to myself, a relative newcomer to Alibre Atom, that a reasonable stab at it could be made, I devoted a whole half-hour to drawing up the following to illustrate how it could be done:

From the top, the shape of the chassis side rails, offset from the centreline by the appropriate dimension. (I had to guestimate the values, of course.) Next row: the cross-section of the rails, then sweep the cross-section along the side rail shape and then mirror about the centreline.

Third and forth rows, the cross members. That's the individual parts. Make an assembly and using constraints, align the parts to form the complete chassis, thus:

In this way it is possible to build up the whole model from the separate parts as you would in real life. Rightly, or wrongly, I have got the impression that you are trying to produce the 3D model all in one go from an orthographic projection. Correct me if I've got the wrong end of the stick..

Sorry to have taken up so much space. I really am trying to help.

John

Edit: Just noticed that I've missed a crossmember out - but you get the idea,

Edited By John Hinkley on 08/05/2022 14:33:44

Hi Nigel,

When I started with 3D cad 3-ish years ago it took me months to get something worth the effort. I was using FreeCAD then and managed to produce this model of an Austin 7 engine block.

The next image is a "cut away" view of the block internals, internals I might add that play no part in the casting process. My mistake to include them in the design. I am learning!

And then I 3D printed it using an Ender 3.

The 3D prints will be used as patterns to cast the parts in aluminium, I can't cast iron with my set up. If you have no strong need for 3D, don't bother with it. Stick to 2D if it suits your needs. There is no way I could have produced these models without 3D cad.

Lee

Thank you for your help:

Nicholas -

Finding a tutor is the hard part! Short of very expensive courses a long way from home and not feasible for me.

TC does not use the term "sketch", and in the edition I used at least, those cranked channels can only by built up by adding separate entities. All ways came down to that approach. Thinking about it, I probably assembled only one length of channel from 3 cuboids, then made copies for the other 3 parallel to an axis.

The central portion being cranked meant I could only build it up separately from three rectangles, starting with a line joining the corresponding vertices on the parallel sections - which in turn can only be set by entering grid offsets. Using rotation would have entailed calculating the angle, but probably not accurately enough to work (i.e. pixel-on-pixel).

From a straight section of channel it was easy to rotate a copy of appropriate length by 90º, then copy that, to make the three cross-members. (One is in the cranked portion, its ends angled to suit, to support the back of the boiler, footplates and eventually the engine. No. 2 is just ahead of the back axle, No.3 across the rear end.)

As you say, the second longitudinal was a mirror-copy, and that was straightforward.

I know you are supposed to let the computer do the calculations but TC allows co-ordinate moves; and I use them when I should not, for assembling entities to each other. That is because I find TC's 3D assembly methods so hard. Simply mating two vertices is fairly easy, but otherwise needs fiendishly difficult "Reference Point" manipulations. (I don't know if other CAD systems use Reference-points: an object's RP is by default the centre of the plane area or of space the object occupies but can be moved to, typically, a 3D object's surface to give an assembly snap-point not on a vertex. )

Using co-ordinate and distance entries lets you place easily, objects at points not fully identified by others. For example, the cylinder representing the differential on that representing the axle: assemble the diff co-axially to the end of the axle, then enter the appropriate dimension to push it along the shaft. If you can't move the RP to help you do that, the only option is co-ordinate sums - but I do know TC hopes you don't need do that!

(When I tried using SolidEdge, I managed to drawn a concentric rectangle and circle, but found nothing to place the circle or copies of it elsewhere at set distances within the rectangle. I noticed too that the rectangle was a set of separate lines, not a closed polygon. And that in 2D!)

'

John -

Ah, well, that shows how radially different are Alibre Atom and TurboCAD!

You show the Alibre version of TC's "Model Space" - the drawing area - is a planes-frame floating in an infinite nothingness. Solid Edge seems similar. TurboCAD lets you display a grid instead, optionally inch or metric, to which you can set the drawing - using the Grid Snap, I normally put the major centre-lines on the main axes. In 3D your default view is "looking down " obliquely on the grid, in its (x, y) directions.

I could not see how you produced that channel cross-section; nor how you produced it along the full length, bends and all.

TurboCAD has a "Sweep" command, but I have never used it, and do not know what it is for. It is sometimes mentioned in the Users' Forum Gallery by users describing how they made some exquisite 3D image; and appears called "Rail Sweep" - hardly intuitive!

The drawing looks crowded because it is greatly shrunk to fit here; and contains many centre-lines and dimensions that do not show as such. However, I did not produce the 3D image from that. I don't think that is possible (in TC) anyway, and I drew it entirely from new.

Anyway, I would want the opposite - producing the orthographic workshop drawings from the 3D model. I think TurboCAD does offer that, but I don't know how.

Lee-

That is very impressive! 3D printing and CNC machining are obviously beyond me, and beyond my means, but I admire what can be done with them.

2D suits most of my needs, and is necessary for the workshop drawings, but I had wanted to be able to use 3D CAD mainly for assembly-drawings; and at least I have that option.

I have used 3D CAD for a non-engineering task: the diagrams for a caving-club journal article I wrote, explaining the nature of geological faults. I had to use only black-and-white, with hatching, to represent strata; and one part puzzled me for a while. In white-only, it kept appearing as a cavity. Once I realised I had to "colour" it white, it worked fine.

I made a video using rectangles to create a simple symetric version of a chassis similar to yours, without needing to mirror anything.

It uses the sweep tool that you haven't tried yet.

Martin.

Edited By blowlamp on 08/05/2022 23:08:11

I've also had a go at your bunkers. Started with a rectangle and shaped it to suit. Extruded, then Shelled to leave an open top container. Finally Mirrored to make a pair.

Martin.