Ooops! ‘Bye ‘Bye Alibre Atom

[Nigel Graham 2Participant @nigelgraham2]

 

Probably three to four hours to draw this, one of the crank-end cylinder covers for my steam-wagon engine. This in TurboCAD as it was too difficult in Alibre.

 

These covers are a matched pair. I am making the engine as a twin simple-expansion unit as the boiler pressure is too low for compounding, I have been advised; though camouflaged by making the prominent top covers to different diameters!

 

I don’t know why the gland/guide-bar boss does not seem to join the disc, even though I had not “Added” the two parts. Other CAD systems seem to put obvious “glue lines” on their equivalents. I might have had the work-plane in the wrong place. The drawing also shows the piston-rod hole as not going right through, and I could not correct that – possibly also a work-plane error. Work-planes, the surfaces on which each feature is built akin to selecting a facet or plane in Alibre, are one of TurboCAD 3D’s most difficult aspects.

I may make the real covers in two parts anyway, screwed and sealed together then finish-machined, to save metal and machining. That will depend partly on my metal stocks!

 

I have discovered at last how to derive elevation drawings from TurboCAD 3D models but still not how to scale and dimension them (though dimensioning is easy in TC’s 2D mode). I will have to print the derived orthographic form, and annotate it manually.

 

The curved faces are as smooth as TurboCAD’s simplest “rendering” stage allows. TurboCAD offers near-photographic imaging but that needs a very powerful computer. Try it on my PC and the poor thing overloads and closes the programme without even asking about saving the file!

[JasonBModerator @jasonb]

Honestly I think you would have been better off spending 3 1/2 hours more in the workshop progressing the build and the last half hour drawing that part on paper if it is taking you that long after all these years to get a CAD drawing that is still not right and not even in 3D.

It should be a couple of minutes work in something like Alibre but I fear you are not going to reach those levels of proficiency so if the wagon is ever going to see a chance of being complete then stick with what you know and forget the CAD and spend the time making swarf.

 

[Nigel Graham 2Participant @nigelgraham2]

I’ve a better idea, Jason.

I take your point but unlike most model-engineering I am not following readily-available original or model-design drawings, let alone examining the full-size subjects. The project has also suffered from “external” pressures including two workshop moves (oh, with house-moves.)

No original drawings exist, the wagons are long extinct although a full-size replica has been built. Not many were built, the Hindley company collapsed not long after WW1 and was not taken over.

I have some photographs of that replica, but not seen it physically. It was built to commission and I know the builder had to do as I am, design from assumptions and the same scanty, 1908 publicity and trade-review photographs.

 

To have any chance of this thing working at all – never been certain – I need design as well as build it as well as I can, so need draw some areas of it properly. This lack of drawings is why much work now is correcting or working round unforeseeable problems by mistakes a long time ago.

Enough exists to be its own drawing: measure, rough sketch, make to fit. Revise if necessary. Even the Injector Bracket is 1 v.2, Water-pipe 2.0, suspended from Boiler Mounting Cap 2 v.2, three parts never drawn; for example.

I don’t want to keep replacing parts. Metal, electricity and time are too precious. I make any formal drawing in the evenings, or perhaps in the mornings, losing less potential workshop time than taken by optional extras like shopping and eating.

I can use CAD enough for very simple parts in 3D, and general-arrangements, assemblies and difficult parts in 2D. This includes the crankshaft, and I need also replace the cylinder-block I made too many years ago.

 

I don’t know why your phrase “…. and not even in 3D”.

Why is 3D considered so important? Alibre &c use a 3D model to form the elevations holding the manufacturing information, but the CAD model only represents the finished thing.

So better than abandoning CAD altogether, use it mainly in 2D mode.

I have not yet investigated if Alibre is suitable for that. TurboCAD offers a full 2D / 3D choice although intended primarily for 3D-based work. The 3D option is still there: optional, if I can learn it.

[duncan webster 1Participant @duncanwebster1]

Perhaps it’s time for Nigel to stop banging his head against a brick wall. Having been involved in design engineering for all my working life, I fully recognise the potential of 3D CAD, but we managed without it for many years. I’ve tried and failed to learn 3D several times, I get on quite well then after a pause to do other things I’m back where I started. Masterpieces like the Merlin and early jet engines were designed in 2D with paper and pencil, but it would have been easier in 2D CAD and easier still in 3D. What guarantees failure is trying to learn 2 or more different programs at the same time. They do the same things, but in different ways. I find learning from Utube particularly difficult, often in heavily accented English, either going too fast or too slow, and not addressing the particular issue I’m struggling with. #2 son is a 3D CAD wizard, but his teaching skills are no better than mine.

[JasonBModerator @jasonb]

I can use CAD enough for very simple parts in 3D, and general-arrangements, assemblies and difficult parts in 2D. This includes the crankshaft, and I need also replace the cylinder-block I made too many years ago.

I don’t know why your phrase “…. and not even in 3D”.

I’m sorry Nigel whatever that simple cover was drawn with be it 2D or 3D Turbocad it’s errors show it was done by someone who in your own words does know why lines are missing so you still after 5 years posting here can’t produce a simple part in CAD. That is why sitting down and producing detailed paper drawings is probably the better option if you have only got that far in 5 years there is little chance of producing the general arrangement drawings in CAD that will be of much help in construction.

As I said it’s a fairly simple part that should only take a few mins to model and another couple to arrange the dimensions on a 2D Drawing, quick example here

 

[David JuppParticipant @davidjupp51506]

Nigel

Whilst it is possible to work directly in the 2D Drawing workspace of Atom3D, I strongly discourage that.  Not only will you find it inefficient, you’ll hit all kinds of other problems, simply because that is not what it intended for.

The whole philosophy is based on modelling 3D parts / assemblies, from which any required 2D views can be derived.

[Nigel Graham 2Participant @nigelgraham2]

Thankyou David. I did think that may be the case, though its rubric does mention 2D drawing.

Jason – my problem with that drawing was not that it was in CAD as such, but in 3D CAD. I could have drawn it in 2D format and a lot more easily, but wanted to be able to draw it in 3D.

That was in TurboCAD, whose work-plane system is perhaps the hardest part.

I found the most difficult aspect of Alibre was its Assembly routines, usually failing on wrong orientations and “over-constrained” errors I could not correct.

On balance, both make’s 3D model systems are as difficult as each other; but on the whole TurboCAD’s 2D mode is considerably easier than either are in 3D.

No matter how well I manage the tutorial exercises, when I try to use CAD, especially in 3D, for the real purposes I’ve bought it for, I fail because they never help you understand it. Discrete exercises do not tell you why this way and not that, where you can go wrong, how to avoid the mistakes and how to correct them (beyond immediate “Undo” or complete re-start).

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Duncan –

There is considerable peer pressure to use only CAD, and only 3D CAD at that; and I do recognise if you can use it well enough, it does make drawing anything far quicker and arguably easier than by hand. And you don’t end up with a carpet full of graphited, granulated rubber.  Nevertheless buying it is a huge gamble, a costly mistake in time and money if you can’t learn it.

However, though it is more in total volume to learn, I’ve not found carrying two different makes of CAD itself a problem. I use whatever is the easier for the given task and only bought Alibre Atom because it appeared simpler to learn than the very much more powerful TurboCAD – but I also use rough sketches on paper, and are they any less prone to errors?

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