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Learning CAD with Alibre Atom3D

Discussion of the series starting in MEW 274

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Alibre Atom3D

Alibre Atom3D

Thanks to the generosity of Alibre, Model Engineers' Workshop Magazine is able to offer every reader of Model Engineers' Workshop a free six-month licence to Alibre Atom3D. Alongside this great opportunity, starting with issue 274 of Model Engineers' Workshop we are running a detailed tutorial series in the magazine. This page will be the 'hub' for links to example files, tutorials and more so make sure you drop in regularly to keep up to date!

JasonB12/03/2019 18:33:29
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Don't know about that. I started with Alibre PE which is basically what Atom is and then upgraded to Pro. Seem to be able to answer most questions here dispite being self taught.

You should be able to place anything where you want it on the screen which is known as a constraint. Post a screen shot of what you are trying to do and myself or David will put you right.

I have just looked through the first two parts of the series and I can not see anything there that is faded out and not usable. As far as I know the Atom trial is the full Atom package. Again if you can say what illustration you are referring two we can look into it.

Edited By JasonB on 12/03/2019 18:46:16

David Jupp12/03/2019 19:14:35
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Nigel Graham 2

Jason is correct - the MEW Atom3D trial is the full Atom3D. Yes there are additional tools available in Alibre Design Pro and Alibre Design Expert - quite a few of these just shortcut tasks that would be laborious (but possible) in Atom3D, some genuinely offer capabilities beyond Atom3D. Tools not available in Atom3D have generally been completely hidden from the user interface, so you'll never see them, rather than greyed out - this is deliberate to try to reduce confusion by seeing tools you can't use. It's possible a small number slipped through.

If you have difficulty with a specific task, just ask - we'll try to help. All 3D CAD is fairly complex software, so does take a degree of 'getting to grips with'. Some will pick things up quicker than others, there will be some that prefer to stick to 2D CAD or even drawing board - both of which are fine. Many ways to 'skin a cat' - go with whatever works for you.

Use of constraints, dimensions, or even 'Direct co-ordinate entry' are available in Atom3D to allow placement of anything you might create. None of these are restricted, so I don't understand the reference to this as a limitation. Fully accept that a pointer may be required to find some of these, or how best to use them.

Marketing e-mails; well why do you think anyone offers free trials? It's for several reasons, one of which is to get people's details and hopefully persuade some of them to buy. Also just raising awareness of the brand. Alibre is fully aware of GDPR, so just opt out if you don't want to receive the marketing e-mails - it won't affect your extended trial licence.

Nigel Graham 212/03/2019 23:39:37
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Thank you David.

The e-posts Alibre sends don't bother me too much, though their style is sometimes grating. I just delete them.

I realised very soon that Alibre would be no easier to learn than TurboCAD, even if I was mistaken thinking some tools had been switched off for the MEW course.

My problem was that Alibre was presented as a "model then draw" system. I recall a TurboCAD forum contributor stating TC is meant to be used in the same way, but I cannot learn its 3D side. I'd found similar with Fusion360. So I assume that all modern CAD programmes are much the same in intent if not methods.

3D CAD is extremely complex, and lacks useful manuals; but I want to make workshop drawings not brochure "paintings". However,I took up CAD partly for its facility to produce rotatable isometric assembly-drawings. Please don't get me wrong though: I respect the skill others master even for something as fairly simple as, say, the parting-tool holder that keeps flashing up in the side-bar ads. I can't play the piano, but I can still appreciate a Romantic-era concerto.

I made a mistake. I tried Alibre despite having already gone somewhere vague with TurboCAD: quite different but equally difficult. Worse, the MEW introductory course is straight into 3D CAD, which I'd already found too hard.

So on balance, I think it best to decide first if CAD is likely to be both feasible and helpful for you, and if so, to choose and learn just one make of CAD, to your own limit. If that limit is very modest, so be it, just accept and keep within it.

David Jupp13/03/2019 07:23:39
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The workshop drawings drop out with very little effort once you have done the 3D model - with even section views generated in seconds, all based on the 3D model. The really good bit is that if you change the model, the drawings update to reflect the changes.

Each to his own. Not everyone will get on with the software, hopefully many will - even if only to get a better idea of whether 3D CAD is something they wish to take forward.

It was precisely the 'slow learning curve' problem that led to the 6 month extended trial for MEW readers. Many in the past has felt that 15-30 days trial just wasn't long enough to properly evaluate the software.

Nigel Graham 213/03/2019 11:04:43
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Thank you David.

15-30 days would be fine for a CAD expert to evaluate and review the programme. I would say it needs at least 6 months of very regular use to learn even fairly simple CAD from scratch.

I find what is lacking is any decent printed material. If you come to CAD cold from manual drawing, you are are faced with a huge knowledge gap. You understand making and using engineering items and their conventional plans, but CAD places an enormous extra skill gap between designing and making.

There is virtually nothing available to help you bridge that gap.

The software publishers assume formal, professional training in industry, so do not write manuals beyond ones like TurboCAD's pdf aide-memoire. They might produce training videos, but not everyone can learn from them. Further, the dedicated "manuals" assume you already understand CAD concepts as well as the engineering and draughting knowledge, and in depth.

Most big software firms duck responsibility by establishing "users' forums" and "[In]Frequently Asked Questions". Well, why not write decent instructions in the first place? Is there an Alibre book for example? (There isn't for TurboCAD.)

You can't just write "Select object X, click on Tool B". You need to know why Tool B, and crucially, what existing but hidden conditions in X are needed for B to work, such as mathematically rather than image-sight accuracy in joining and trimming, perhaps created much earlier,

I have two books that bravely try to convey the basic concepts. These, by D.A.G. Brown and by Neill Hughes, help, though I found the latter's "meter" for "metre" inexcusable and annoying. They explain some general CAD basics but still do not warn of the pitfalls. Like the CAD publishers, they assume you never make mistakes, and if it's in the computer it must be right. In fact CAD lets you unwittingly make those hidden mistakes I cited, because they do not stop the application itself; making the whole thing potentially an extremely frustrating waste.

So why the paucity of proper help in CAD? It's partly a commercial matter, but years of work and hobby experience has taught me that the world is full of experts in many fields, especially but not only IT, who understand it easily and almost instinctively, and cannot comprehend why mere mortals find it hard to learn. Instead they show what they can do and tell you it's easy (one reason I don't believe in "training videos", and displays of highly-detailed CAD engineering and architectural artwork discourage rather than encourage.

So why do I bother to use/waste hours of potential workshop time learning CAD?

I thought it might help my model-engineering!

Most model-engineers work from published plans so might never need to learn CAD except for its own interest or if they wish to send CAM files to materials suppliers - or indeed use CNC in their own workshops.

However, I am trying to build a large-scale miniature steam-wagon from no more than scraps of archive material, no castings, much "recycled" material. I have to design as I build - lots of traps and reversals. So I could see the advantages of CAD's drawing, editing and copying abilities.

I could not have known CAD is so difficult and frustrating. I had to abandon the 3D nightmare, and stick to relatively simple orthographic projections. Anyway making parts needs 2D elevations, not pictures. For model-engineering, isometrics are useful for assembly-drawings but not essential, and rendered pictures really show only an undoubtedly high but extra skill in making rendered pictures.

Would I use Alibre? Probably not now.

If starting from scratch, probably yes. It would have been sensible thanks to MEW's trial version and course. I have installed Alibre and I followed the first episode.

However, I've probably gone too far with TurboCAD to change now. It is a completely different method for the same task; I do not know if Alibre can take my existing TC drawings; and the Alibre + MEW, 3D-then-2D way, is wrong for me.

Colin Heseltine13/03/2019 11:46:10
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I have Turbocad 2018 pro and earlier versions but have really struggled to use it. I download added the trial AA3D and was able for follow the tutorials quite easily. I prefer the written notes in MEW and gave read through but not used as yet the trial design on the Alibre web site. This runs to a significant number of pages. I prefer written notes to videos that I have to keep stopping/starting/reversing. I want to be able to produce designs that can be 3D printed. Would also like to be able to produce plans for some bits I made for Cowells lathe and mill.

Colin

David Jupp13/03/2019 15:29:05
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Nigel - it MIGHT be practicable to use work done in TC as a basis for Atom3D files. From you comments I believe that all your previous work is in 2D - this could probably be exported as DXF or DWG (I've never used TC), then imported into Atom3D and used to generate sketch profiles for 3D work. This video covers the basic method - the video shows Alibre Design rather than Atom3D, but the process would work in the same way. It can sometimes be quicker and simpler to just start over though - all depends on the individual case.

I did write a short article on the basics of 3D CAD for MEW some while back (not sure which issue) - this thread would get a bit long if I repeated that here. At the very basic level, 3D CAD moves 2D profiles through 3D space to define 3D features. A feature can either add material to or subtract material from the model. The movement of a profile might be along a straight line, in a circle, or some more complex path.

Building simple features one upon another allows complex parts to be modelled - in some ways it's similar to fabricating a real world part - joining 'lumps' together and cutting / drilling / filing material away. Forget the 'drawings' until later in the process - though having ran courses, I know that some people struggle to change their workflow.

As for the mathematical accuracy of joining trimming - yes profiles have to be 'closed' for most operations, but at least the software analyses this and can point out where the problems are. Lots of problems start because users create one complex sketch (like a finished 2D drawing), where a number simpler ones spread over several features would be much easier to create, and to edit if changes are needed afterwards.

Neil Wyatt13/03/2019 15:46:38
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Each to their own!

I find Atom3D much faster than TurboCAD and did not take long to be doing things faster in Atom. Yes they are extremely different in approach and this means there are still some things I would do in TurboCAD. The big advantage is that Atom3D is parametric and includes access to an object tree, Turbocad Deluxe isn't so you can't revise your designs so easily.

Some say that 2D drawing ruins you for 3D. If you try to do 3D from a 2D persepective you just end up trying to make every object as a 2D outline and then projecting it up into 2D and get rather frustrated rather fast.

To get the best out of 3D you need to visualise the solids making up your objects and how they interact. The turret above was made from a series of reference planes on which I 'built' various parts to add or subtract the features of the final object. This made it easy to adjust the gross proportions by just moving the planes.

Neil

SillyOldDuffer13/03/2019 17:55:10
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I empathise with Nigel, but I'm pretty sure he's the problem, not the the tools he's struggling with. Not deliberately or because he's stupid, exactly the opposite!

Here's the problem: drawing a 3 dimensional object in 2 dimensions requires a rather complicated set of mental gymnastics. How to make the translation was painfully learned when we were young and, because it seems so normal we've forgotten how difficult it was. Now Nigel is trying to invert an entire mental process: he has to tell a computer how to represent a 3D object directly, and the way it's done isn't natural to him.

In this kind of learning situation there's severe danger that the brain will seize on previous ways of doing things and expect them to work. When they don't, we get frustrated and become convinced that the new thing is somehow wrong. The effect is corrosive: who said it's better to strangle a new-born than to suffer frustration?

The issue is akin to trying to learn a new language where some words make sense, but most of the grammar and syntax is alien. It's hard. I suspect Nigel has been trying TurboCAD, Fusion, and now Alibre in hope of finding a CAD package that matches his world view. This is likely to cause even more confusion because they are different as well as mismatched to him.

The painful cure is to follow the instructions for using new software exactly making no assumptions whatever. Short of a mentor, the MEW tutorial is just what's needed. Don't expect any of it to work as you expect, adapt and obey. Don't skip ahead, don't rebel. The process is like learning to ride a bicycle - suddenly the new learning makes sense and you're off.

Like anything else, not everyone is good at relearning. No way will I ever learn German. It's why youngsters with zero life experience can work smart phones while poor old grandad fumes because they don't understand tape measures. I've had many run-ins with stuff I just don't get. Sometimes it's best to walk away. Life's too short for masochism...

Dave

Nigel Graham 214/03/2019 00:29:02
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Errr, thank you SiilyOldDuffer but with great respect I can't quite understand what you mean, beyond your having totally misrepresented me!

I am not blaming the software either.

I have no idea what you mean by "world view" but I tried all 3 CAD programmes - plus AutoCAD 2000 - to see what I would find the best for me.

Neill - Sorry, but your comments about "parametric", "object trees" etc are over my head. I think they are for advanced users.

Your second paragraph does not apply to me. I am used to orthographic drawings by default and am not trying to "project" them anywhere; but I use isometric as an auxiliary tool.

David - I tried to import a TurboCAD file into Alibre, to see if it's possible. I found Alibre does not read TCW files.

I appreciate that CAD generates "solids" from planar figures, but in different ways giving the same shapes with very different internal characters and reactions.

It took me a long time to realise why I could not draw a simple cross-section. Apart from the term not being used anyway, the programme did NOT tell me why I could not make it work.

Those last two observations refer to TurboCAD, but I am not convinced any CAD programme would be any better.

I understand the notion of drawing a model by adding geometrical objects to each other, but 3D uses many ways to do so, and it is by no means obvious which to use and which not, how and why. Anyway, an orthographic drawings is also a set of objects stuck together. The only difference is in using a single work-plane.

Alibre, TurboCAD and Fusion360 essentially do the same things though in different ways. Fusion initially looked simpler than TC but I found it's about the same level of difficulty. It also seems to force the 3D-then-2D route as Alibre does.

TC offers you the 2D/3D choice from the start, if you do not need to draw in 3D. Orthographic-only is still difficult but at least avoids its 3D's incomprehensible morass of combinations and permutations of multiple "solid" generators, work-planes and co-ordinate systems. I don't know, but suspect Alibre and F360 will have comparable systems, as they all do fundamentally the same things.

Following a series to make a specific drawing of some specific, fairly simple example teaches you how to draw that example; but whilst useful you need far more than that to use CAD properly and usefully even for similarly simple items.

A video only shows you an expert demonstrating the software.

My requirements are simple:

1) A CAD programme that helps me to design and draw particular engineering items so I can make them.

2) Isometric: perhaps useful for clarifying awkward shapes and assemblies, but not essential.

3) The programme being reasonably easy and intuitive; with proper operating information available (some hope).

Rendered pictures merely add add a huge extra burden of skills, knowledge and work to the process.

Being able to make a prettily-coloured model is not itself a reason for doing so.. By corollary, recognising the limits of own abilities are a reason for not attempting that. I cannot learn how to make 3D CAD pictures, but I do not need to anyway, and do not see the why Alibre wants me to use a roundabout way to make the real drawings. I want to make metal things, not "paintings".

I have explained why I cannot change to Alibre now. I am perfectly well aware these programmes all differ significantly in how you use them, and there is no point in abandoning one I know enough to create admittedly-rough drawings, and start all over again with another!

Further, I now have quite a number of TurboCAD drawings, but Alibre does not recognise their file-types so cannot open them. I investigated this only today.

It seems I've found a gulf of understanding besides that already between CAD and me, but also between my CAD needs and others' preferences in using it.

JasonB14/03/2019 06:59:42
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Posted by Nigel Graham 2 on 14/03/2019 00:29:02:

David - I tried to import a TurboCAD file into Alibre, to see if it's possible. I found Alibre does not read TCW files.

I don't think we can help you. Even with written instructions which you say you prefer you just can't read them. Look again at what David wrote. :

Nigel - it MIGHT be practicable to use work done in TC as a basis for Atom3D files. From you comments I believe that all your previous work is in 2D - this could probably be exported as DXF or DWG then imported into Atom3D

No mention of importing or opening Turbocad files.

Neil Wyatt14/03/2019 09:08:02
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Posted by Nigel Graham 2 on 14/03/2019 00:29:02:

Neill - Sorry, but your comments about "parametric", "object trees" etc are over my head. I think they are for advanced users.

Your second paragraph does not apply to me. I am used to orthographic drawings by default and am not trying to "project" them anywhere; but I use isometric as an auxiliary tool.

:

I understand the notion of drawing a model by adding geometrical objects to each other, but 3D uses many ways to do so, and it is by no means obvious which to use and which not, how and why. Anyway, an orthographic drawings is also a set of objects stuck together. The only difference is in using a single work-plane.

Hi Nigel,

I realise those things don't mean a lot - but if you were to work through the tutorials, they might make sense.

I think you demonstrate my second paragraph is exactly the issue, although perhaps I shoudl have said 'extrude' rather than 'project'. With an orthographic projection you have to develop drawings by taking shapes in one plane into another. This means when you change to 3D you tend to try and draw the part up in the same way, drawing one view and extruding it, and as this is the simplest way of making a 3D part and systems all start with it you tend to start there -and get stuck there.

3D is far more than producing an isometric view of your part.

You might well produce simple objects in 3D by working from three planes, but for any complexity you will end up with many planes, allowing you to do things like interpolating shapes to get compound curves in 3D, projecting features off other features, rotating parts and sweeping parts along lines. Having been taught traditional drawing anything beyond the 'angled cut through a cone' approach gets pretty complex from an orthographic perspective.

It sounds to me like you are entirely comfortable, and probably rather competent, working with 2D.

| I cannot learn how to make 3D CAD pictures, but I do not need to anyway, and do not see the why Alibre
| wants me to use a roundabout way to make the real drawings. I want to make metal things, not "paintings"

I think this is the basic issue - by definition Atom3D is primarily for 3D modelling, but allows you to produce 2D drawings if required.

As you just want 2D drawings you really are better off using a package that is 2D led or allows you to work in a predominantly 2D environment - TurboCAD is probably better for this approach.

Neil

David Jupp14/03/2019 09:34:12
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I'd say that there is significant benefit of using something like Atom3D even if you only want 2D drawings - it's often faster than a pure 2D approach once you get the hang of things, especially if you need cross section views, enlarged detail views, isometrics etc. Also when the design evolves/changes, the 2D drawings update automatically.

The vast majority of commercial users of Alibre produce 2D drawings for manufacture of their designs.

SillyOldDuffer14/03/2019 10:37:54
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Posted by Nigel Graham 2 on 14/03/2019 00:29:02:

Errr, thank you SiilyOldDuffer but with great respect I can't quite understand what you mean, beyond your having totally misrepresented me!

I am not blaming the software either.

I have no idea what you mean by "world view" but I tried all 3 CAD programmes - plus AutoCAD 2000 - to see what I would find the best for me.

...

Hi Nigel, apologies if I've misunderstood you, but what you've been saying in the thread rather suggests the opposite. I'm trying to help, not criticise.

'World View' can be found on Wikipedia. I mean it in the sense of 'the fundamental cognitive orientation of an individual'. Briefly, our understanding of the world and the things in it is built on the sum of our individual experiences. Most of the time building on experience works extremely well, but it can cause severe problems when previous experience is inappropriate to a new situation. The way I run my life in South West England would need radical revision if I was stranded on a desert island!

What I'm getting from your posts is a strong belief that 3D CAD software should operate as you imagine it. At root your approach to drawing is orthographic, I guess for good historic reasons. Unfortunately none of the 3D packages take that approach. An orthographic mind-set has you swimming against the tide. Your search for a 3D CAD package in tune with your requirements may be doomed to failure - I don't know of one.

You're not alone; when 2D CAD first appeared quite a few professional draughtsmen couldn't cope with it. Not because they were incompetent, or because 2D CAD was outrageously difficult, but because their old drawing board skills had to be unlearned. In the next generation others came unstuck unlearning 2D and learning 3D CAD. Not had any success breaking bad habits myself, even though my doctor has carefully explained all the nasty consequences of my life-style.

If you want to persist with 3D CAD, I suggest:

  1. Ignore all previous experience. (This is really hard to do.)
  2. Do not make any assumptions about how the software behaves.
  3. Concentrate on one package only.
  4. Start at the beginning and patiently master the basics. (Hard to be patient!)
  5. Do not skip steps or jump ahead.

The Alibre Tutorial running in MEW coupled with the ability to ask questions in this thread is a golden opportunity.

My 'world-view' leads me to believe that there isn't a CAD package that meets Nigel's requirements. I could be wrong! Can anyone else suggest one?

Dave

Steve Skelton 114/03/2019 10:49:58
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Here's my experience for what it's worth.

I tried to use the package based on my AutoCAD 2D experience and fell flat on my face.

I then read the tutorials and had a lightbulb moment.

I found I had to forget everything I had learnt about 2D CAD and drawing board draughting and imagine I was trying to make the item from a solid block or adding to it in a solid block as if I was machining it (or welding on to it). I then found it made sense.

I am not suggesting I am proficient at using the package but if I think in terms of adding or taking away material then I seem to be able to do what I want.

Not sure if others are with this??

Steve

Nigel Graham 214/03/2019 11:02:44
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Thankyou Jason.

Yes, I did read the verb "might", and I did try other file types including ones with the magic letters 'DW', but without success. Given the very long list of possibilities though, it would be very easy to miss the one that might work..

Neill - I did spot your accidental use of "project" but wasn't quite sure what it ought have been.

I'm familiar with the "extrude" principle, as it's a basic one in TurboCAD 3D too. TC though gives several different ways of producing a "solid" - extruding from a planar figure, and editing a "primitive" ready-made object being perhaps the main ones; and I spent lot of time experimenting with them.

I never reached the advanced levels of "sweeps" and the like, but I found even with those two basic actions the properties of the generated solids and their reactions to editing tools differ markedly, with no clear rhyme, reason, pattern or manual instructions to help you choose the right type where both will give the same figure (mainly cuboids and cylinders). I assumed this will be common to all 3D CAD packages, because they have to perform essentially the same calculations and routines behind the presentation.

The MEW example works because all such decision-making has been done for you, so if you follow the instructions carefully you end up with a prettily-coloured picture of scribing-block already designed, without you really understanding how. It's a rote technique, valuable as a primer, but if Alibre has the same subtleties as TurboCAD and no doubt "others available", a rote primer won't guarantee future success with your own designs.

I still have the drawing of the scribing-block's base from Part One - I even succeeded in enlarging its diameter and recessing its underside so a real version would be more stable.

[That's as far as I reached. I had bought the magazine in Smiths, and took out a subscription (itself not as simple as it had seemed) to start with the next issue, but I think it jumped one. I have not yet verified edition numbers but the Alibre series appeared to refer to things not in Part One.]

I do realise advanced CAD skills can let you make images that would be horrendously difficult to draw manually; but that can be a trap, as the components would become horrendously difficult to make on an ordinary lathe and milling-machine with normal model-engineering skills.

Don't forget our own projects as model-engineers are either new to our own design and can use modern design practices, or are replicas of machines built in the days of exquisite draughtsmanship by pencil, T-square and set-square. Either way they have to suit our own workshops and craft abilities.

Having said that, I do know a lot of model-engineers now are using small CNC milling-machines and 3D-printers, so provided they still ensure the design suits the machine, the problem of physical difficulty is reduced somewhat.

(I recall seeing my first CNC mill in the factory where I was a storekeeper. One of the work-pieces for which it was intended was carved out of a big aluminium-alloy slab. The first attempt revealed it too large for the machine, which itself was sizeable; so while that batch was milled conventionally the drawing-office re-designed the part to fit the CNC mill! Pencil and paper designs, too.)

You still need to understand both Design and CAD. They are separate. The latter is extremely difficult, and exists to express the former as images.

JasonB14/03/2019 11:11:03
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Posted by Nigel Graham 2 on 14/03/2019 00:29:02:

My requirements are simple:

1) A CAD programme that helps me to design and draw particular engineering items so I can make them.

Can you show us an example of what you want to draw, just a link to a photo or drawing or post a photo or screen shot of the sort of thing you want to draw. maybe if you can see it being drawn in a 3D package you will get a better idea of whats involved.

Nigel Graham 214/03/2019 11:59:40
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To SillyOld Duffer.

I'm afraid you are reading too much into my motives and needs.

I am trying to design things I can make with my workshop and abilities. I am not in the plans business, nor making brochures. I don't really believe in phrases like "world view", either.

I can see the point of 3D CAD images, and I know CAD anyway requires a new approach of its own, beyond manual draughting.

Vicarious experience at work showed me the advantages of CAD, and I bought TurboCAD. It was the only genuine CAD package available to the amateur at the time - only a few years ago .

I sampled Fusion360 (like Alibre, 3D-model-then-draw) - gritting my teeth at its "in your face" presentation - and AutoCAD 2000 (2D-only I think). SolidWorks is not intended for amateurs. Of various low-budget or "free" CAD packages on-line, those not devoid of engineering-drawing facilities anyway were heavily-stripped "student" or "trial" editions of costly industrial software.

After a monumental struggle I can make good-enough-for-me orthographic drawings, and very, very simple 3D images; but much further is beyond me, including accurately placing and linking multiple 3D elements. (For simple cases and symmetrical elements, I calculate their co-ordinates, but that is slow, error-prone, poor practice.) I will have to live without 3D CAD despite having hoped originally to be able to use that facility.

So I tried Alibre, hoping it might be easier to learn than TurboCAD despite doing the same things. I think I missed an edition of MEW so that won't help, and so far only have the scribing-block base from Part 1 of the series. Given all this, it is not logical to start completely anew on a very different make of CAD with a 3D-first approach.

Nigel Graham 214/03/2019 14:01:45
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JasonB

According to the e-posted notification you invited me to send an example, but I can't see the invitation here.

Never mind, thank you for the invitation.

I don't know if I can take you up on that, I'm afraid, but the machine I am trying to design is the enclosed, inverted-vertical compound engine for a 4"-scale Hindley steam-wagon.

It took me a long time to find a way to design it, irrespective of how to draw it, with no original drawings known. I have now found a proven miniature engine design as a template for the motion-work's geometry; and have started to draw the assembly and parts.

So far, I have drawn the crankshaft from scratch. I'd already part-machined the cylinders so have drawn them from their measurements, and presently I am designing and drawing the engine case.

Geometrically, so far this is a fairly easy set of rectangles and circles, and all in 2D mode.

I had drawn the crankshaft and even started trying to draw the engine's GA, both in 3D. I found both were long and laborious tasks; but the latter soon proved impossible.

I found out how to place that first version of the shaft on the TurboCAD forum gallery as a first 3D attempt, in outline only. Another user kindly coloured it for me! It looks pretty but that's about all.

As a last straw, after my becoming disheartened by a beautiful Alibre rendering of a marine engine on a recent ME or MEW cover, the TurboCAD User's Forum log-on no longer works, at least from my computer. So far IMSI has been unable to repair it, and it prevents my seeking help.

JasonB14/03/2019 16:21:25
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Much like producing the 2D drawings first attempting a general arrangement as the first step is kind of the opposite to how you use the 3D programs. The following are some examples from an engine that I am working on at the moment for which I only have a couple of photos one of which is this

guadeloupemill13076.jpg

Started with a basic fag packet hand sketch just to get a few basic proportions

dsc03564.jpg

From that I went straight to alibre and started drawing individual parts starting with the base, then as each part is drawn it is placed into a 3D assembly. I will then flit back and forth drawing and adding new parts and tweaking and altering those already sketched to get the fit, proportions etc that I want.

This is the screen shot of what parts I have drawn so far, just basically coloured to indicate material no nee dfor fancy renderings at this stage.

parts.jpg

And this is the assembly. What you can't do if you draw it as a set of 2D elevations is rotate the crank and see how the piston rod and cross head move or move the whole assemby around to look at it from any angle. Or if i change any one of those parts it will automatically update the assembly this is the parametric part.ass2.jpg

From there it is just a few clicks to produce the GA drawings complete with an isometric and this drawing will automatically update with every change or additional part added.

ga.jpg

As I said earlier I'm just a self taught user, not even an engineer and just picked it up by watching a few videos and having a go. That's about 2hrs work at the most on that engine so far

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