Drawing board v CAD

Neil In 84 years that's the first time I've come across ' conflate ' ( Had to consult dictionary )

Roy

Neil

It may well be that its just as easy to draw an impossible to make part on paper in 2D as it is to produce one on the screen in 3D. But its a darn sight easier to see the impossible nature in 2D as, generally, you are working from a "tools eye" viewpoint. In practice most folk with more than a modicum of experience in reduce to 2D visualisation and drawing thereof almost automatically avoid the impossible pitfalls on any given view. Unless the part is far more complex than folk like us are likely to handle.

For us 2D drawing impossibles are usually related to work holding and machining sequence rather than absolute impossibilities. Usually due to not properly visualising the assembly aspects where each view is perfectly practical. Sections can be important there. I'm as guilty as any for flying shy of doing sections to better illustrate access problems. Case in point was last "bitch job from hell", an aluminium replacement for an unobtanium plastic base / pivot part for a glass shower screen. Had I done an extra couple of sections I'd have realised that my proposed machining sequence was very poor and made life far easier for myself by doing things a different way.

With 3D its much easier to end up with impossible having produced an overall shape that looks fine but could only be done by clever casting, multicore plastic moulding or 3D printing. 3D drawn objects are inevitably more complex than 2D views and are flattened out into a pseudo perspective view on the monitor. So you need to track rotation of a pseudo perspective representation of a complex object to verify if it can be made. Lot harder than verifying a 2D drawing. Much more likely that you will see what you thought you'd drawn not what you actually have drawn. Which is easy enough in 2D despite greater simplicity.

Clive

Possibly the first time I've every typed it

Neil

Brian,

I am surprised. Although my two versions of DesignCad are both old (1999 & 2007 respectively) I've yet to find something that I could do in v 17.2 that I cannot do in the earlier version. Of course, it may be that I haven't yet had to do something particularly difficult. I agree that v17.2 for example, added some extra facilities which made some tasks easier, but as far as I can remember, nothing that I couldn't find a way round in the older version. In fact, in some respects, the older version was actually easier to use, and when I bought v.17.2, I was somewhat disappointed as the leap in facilities was not as great as I had expected. All of which makes me think that for me, there is no real advantage in upgrading any further.

Regards,

Peter G. Shaw

You're assuming you can't see 3D objects as 2D projections.

It's two clicks for me to look at my object in any projecting I want from a choice of 14, so I can see the same as any of the six 2D elevations with the option of dimetric and isometric as well.

That means I can do any check I could do in 2D or on paper AND I can also 'orbit' my object and look from any direction and do trial assemblies to check they will fit together.

I'v just decided to scrap a part made largely by cut and try combined with back of an envelope (actually the little chalkboard on my workshop door), but i sued 3D CAD to get the basic shape. The scrapping was because after I machined out a 'scar' left by the 4-jaw one section was left too thin. No design process would have told me to make it overlength to avoid marking surfaces I don't want to machine - only common sense could have done that!

Neil

As a late starter with computers and for me the long slog learning Turbo cad have found it so useful.

I started with a very basic computer given to me by a student then had to upgrade to be able to use the early Turbo cad program I played with 3D but for me 2D was adequate.

Have a bit more modern cad program but the early version seemed easier to use

Read D.A.G. Browns Cad for model engineers to start with you don't have to spend a lot for an old cad program for what I was doing.

Regards my flash steamer things are not looking good for me to compete again as health problems don't suit wading in water and walking far.

Shame as when right it's capable of 130 mph plus as certain laps have proved.

Time is in short supply and hope my latest project gets running at end of the year.

That's the thing with all aspects of engineering the old brain cells are kept working.

Edited By Windy on 18/03/2018 21:38:02

Not only can you produce projected views (plan,elevation, isometric, etc from a 3D model), you can also produce 2D and 3D sections with a couple of clicks.

3D CAD models are extremely accurate and can calculate the centre of gravity and mass of an object. 2D drawings from 3D models can be automatically or manually dimensioned to 8 or more decimal points (eg. 0.00000001mm).

Most models are parametric, meaning that the size of a model is controlled by the size of the dimension. By changing the size of a dimension on a part, the model is automatically updated and every instance of that part in every assembly model and drawing that references it is also updated, saving heaps of work updating associated drawings.

Paul

Neil

I know you can turn 3D objects into 2D projections with is a great help but seeing is a lot different to creating. Especially if you have numerous choices of projection angle and style. Far too easy to see what you think you drew rather than what you actually drew. Its also very easy to choose a favourable view or projection angle rather than the one that demonstrates impossibility. Ultimately you still have to be able to fuse everything together in your minds eye. Which is no trivial skill for something relatively complex.

It doesn't help that 3D usually involves more complex things than 2D. From the inevitably time limited Model Engineers perspective the biggest issue with 3D is the amount of stuff you need to be familiar with before you can sensibly get started and the even larger amount you need to understand before you can be pretty sure you aren't making errors. 2D is much simpler and more forgiving in that respect. Especially as its quite reasonable to sort with something very simple, maybe a pattern of holes with odd spacings needing to be converted into co-rdiantes for milling on the mill, and build from there.

I'm currently looking at Fusion 360 (again) 'cos I really should get that CNC Tag going after 12 years! Basically getting nowhere because its all silly arty crafty curves 'n stuff tutorials. No sensible manual to cherry pick what I need out of it to actually poxy do something.

Clive.

Clive, perhaps this may help.

Agreed that F360 learning is a bit hit and miss but it may be that you have not discovered the route to the more conventional 'user manual' style teaching area.

With F360 open on your screen, click the 'Help' question mark and select 'Learn Fusion 360'. This opens a page in your web browser.

That page has a series of short video tutorials which although they demonstrate a few principles, don't answer the kind of questions most of us would ask. However, at the bottom of the table on the LHS of the screen is an option 'See all Fusion 360 learning".

Click that link and you are taken to another web page that is laid out very much more like a user manual and with links in each category that branch into further depths.

You may have already been there and found it unsatisfactory, but others may not have discovered it, so perhaps useful to have noted it in this thread.

Another route which is also useful is to use keyword searches having entered into the 'Community Forum' area, again under the question mark, top right in the application banner. A lot of information via that route, plus you can ask specific questions and usually get a prompt answer.

Edited By Swarf Maker on 18/03/2018 23:48:50

Anyone who doubts the ability of Fusion 360 to produce really good quality, buildable models should look at the recent work of 'Crueby' on the MEM (Medel Engine Maker) Website where he has two comprehensive build threads.

'Lombard Hauler Engine' completed **LINK**

and his current work in progress 'Chris' Marion Steam Shovel' **LINK**

If you look at the easrly stages the two projects you will see the quality of the drawings he has made and from which works.

My understanding is that he learned Fusion 360 from scratch to build the Lombard, which you can see steaming and running in the last of his posts on that topic.

We all work in our own way and old habits die hard, but those who have looked over the hill to see the sunny new uplands are having a great time. Like a lot of things in life we form opinions without actually experiencing the issue. I took up CAD and CNC around seven years ago without any prior experience with either, and yes, I did struggle but once the penny dropped I was away, after 51 years as a model engineer I was reborn making things that I considered beyond my skills. As a previous contributor mentioned it taxes your brain thus keeping it active and most of all very enjoyable, which after all said and done why we participate in this wonderful hobby.

Go on have a look you won’t regret it

Mike

I started many years ago on a drawing board as an apprentice in the Marconi DO School, but some considerable years later picked up a cheap copy of TurboCAD on a visit to the US. I updated that a few times but always struggled with it in 3D. 2D - pretty good, but never quite got to grips with its 3D capabilities. From what I have seen in demos at exhibitions, this does seem to have improved a lot from my version. One area that I always struggled with in TCAD was making changes. I often ended up deleting and redrawing as being quicker than editing. Again, this might well have improved in current versions.

Then I discovered first of all OnShape, then Fusion 360 which I now use. A lot. Its ability to visualise in 3D (like picking up an object and rotating it in your hand), "change history" (go back and edit a dimension and all the follow-on changes automagically happen - if you've created your drawing properly), parameterise key dimensions to make easy changes - all these speed drawing and reduce errors. For me, anyway. I'm currently redrawing in F360 the Don Young Black 5 drawings (very much for personal use only, I hasten to add). One driver for this was the odd comment in the "build manual" that builders had found an error in a stretcher that caused a clash with the tender wheels. The 3D model shows this clearly, allows me to use sectional views to take dimensions for modifying parts, etc. I could do this with 2D, but given the list of "this then that" dimensional dependencies between wheel flange and stretcher, it would be an error-prone pain to do - which is presumably why DY didn't notice it in the first place. Just one example.

One very important point about using 3D CAD - and especially with a parametric, time-line and constraint-based system like F360 - is to understand some of the underlying principles that make it very different to drawing in 2D. It is much less like drawing and much more like modelling, with the spin-off benefit of allowing you to create drawings from your model. Unless you understand some of these principles, you are never going to get the best out of it.

However, I do accept that a lot depends on your own abilities. Some people (talk to a good architect, for example) have the ability to visualise in 3D in a way that I cannot even understand. They can probably stitch together a 3D visualisation of a set of drawings but many of us cannot. Horses for courses - I find F360, if not intuitive, then at least easy to use after a bit of practice and the combination of visualisation plus producing a variety of drawings for workshop use works for me. And, generally, I can visualise parts for the purposes of holding and machining (even if I then forget and leave out a vital step...)

I am also an enthusiastic user of Vectric Vcarve - great CAD/CAM tool for 2D working, which I use a lot in conjunction with a CNC router for woodwork. Unlike F360, it provides the minimum of well-chosen drawing tools that meet the large majority of needs.

Back-of-the-enveiope works for me as well, sometimes!

Swarf Maker

Thanks for those suggestions. Looks like that may be a better way for me than going via the videos on the main Fusion 360 site. We shall see. As usual formal course based learning needs more connected time than I really have. I can see I'm gonna need some more printer cartridges!

I guess I'm not alone in having come into CAD by the pragmatic route of needing to draw something to make it. But by their very nature 3D systems have to be design first then make (almost) anything within reason so the whole thing has to be much more complicated. Folks like me who pretty much go from vague visualisation and perhaps a few paper scratches direct to 2D drawn parts struggle with the formalities of doing a right design first. Doesn't help that much of what I do is repair parts, modifications or make something that does ... to fit this. So the design is pretty much a given making direct to 2D easy. Its getting on board with the formal design process that's difficult because I'm used to a starting point pretty close to where Fusion breaks out the completed design down to 2D parts drawings for manufacturing. Skimming through the tutorials its almost scary how much folks like me have learned to just carry in their heads as they go. Its almost impossible to remember how little I managed with 2D CAD (MacDraw actually) first time round 30 years back and how hard that was.

But paying £1,000 for another upgrade of VectorWorks when Apple system upgrades break what i have isn't attractive and I do want to get this CNC thingy going so I'll have to find a way. Once I find the right mouse hole to wiggle in through hardest part will probably be the what "I'm used to" mindset (I can do this much faster in VectorWorks). As ever a month or three past the Eureka moment I shall wonder what the fuss was about.

Clive.

.

For me, it depends on what I'm doing as to what drawing system I use.

For initial ideas I usually make freehand pencil sketches on the back of old computer printout sheets.

For making individual metal parts, perhaps to replace a broken part of a machine, I use 2D CAD (Draftsight) which I finnd quick and easy to use having used Autocad on and off since release 1.4 in the early 1980s.

For a part to be 3D printed or a simple assembly of parts I turn to Onshape, chiefly because it will work under Linux. It does full parametric modelling, however gets a bit slow for large files.

I've been trying to get to grips with Fusion 360 but as I have to reboot the computer into Windows 10 and then wait for an eternity for it to configure all its updates and reboot before I can do anything I don't often bother.

Russell

I agree with Larry, never had much use for drawing boards and certainly do not want to have to learn cad at 73, much too busy making things using my head for the design process.

I may be old fashioned, but the worl seem to have gone totally electronic without many hands on skills being valued.

A recent servay found that the only jobs likely to survive the oncoming robotics would be the skilled Hans on fettling ones, that repaired and things, as not all things are throw away yet.

Wouldnt be without my iMac, iPhone and iPad though.

The trouble with 2D cad is it ruins you for 3D cad.

If you try and make 3D objects in the same way as you do on paper - thinking it all our in one plane then projecting it into 3D you won't get far.

3D design is best approached like machining, creating primitive, simple shapes that you fuse, intersect and subtract from each other to get more complex shapes.

And when you are creating 2D drawings from 3D models and assemblies, generally you are extracting and presenting the info you need to machine the parts. Simply ensuring that every feature is fully defined isn't enough. You need to think about the machining processes and sequence so that the various dimensions shown are what you need when standing at the machine. Otherwise you end up going back to the computer to redimension the relevant feature part way through the job. Eventually you get the drawing creation more or less right the first time.

Some of the 2D drawing stuff goes away with CNC but you still need to think about how you will hold and machine the part, ideally before you even start modelling it in any detail. It's still perfectly possible to design stuff that is almost impossible to produce or simply more complex and fussy than it need be.

Murray

I would not go back from 2D CAD to a drawing board for all the tea in China. I'm trying to get #2 son to teach me 3D but he is about as patient with me as I was with him when trying to teach him maths when he was at school. Not very, we both work on the 'I can do it so it must be easy' principle. I'll get there. The beauty of CAD isn't just drawing stuff, it's when you want to make it say 5mm longer. With a pencil you have to rub it out and draw it again, with CAD you just click the stretch icon tell it how far and which direction and bingo, 2 seconds and it's done. If you want to know where the centre of a fillet radius is just ask, with paper and pencil it was a bit of trigonometry. Want one opposite hand, just click mirror, and so on ad infinitum.

Edited By duncan webster on 20/03/2018 15:40:52

I used to use a drawing board, I actually started at home aged about 7 my grandad taught me, he worked for BEA as an engineer, we used to build model aircraft control line initially and later radio control.

I got into Autocad very early about 1987 on 8086 with Co pro, but had been using CATIA on a Sun system prior to this, I later bought Autocad 10 for home use in about 1989, I still have all the books and discs in the original box, it cost a fortune at the time.

Over the years I've probably used most cad systems, I've seen loads of draftsmen struggle, especially early on, modern 3D modelling systems are a world away from the old stuff and are now true design tools, but only if you know how to use one without thinking about it, by that I mean its native to you, in that you instinctively know what to do to create the feature you want, if you have to look for a method, ie consult the help system, or search through the menu system for some feature, your still learning and are not yet proficient with the tool, it could also be you have the wrong software for the job in hand, organics are still the most difficult thing to design in cad, but its getting better all the time, I've used Faro arms clay modelling software, Sense 3D, but its expensive, we had a play with Zbrush at work looks really good we may will buy a seat if we think it will get some use.

Shaun