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Multi-part assembly drawing

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Nigel Graham 207/05/2021 22:58:26
1525 forum posts
20 photos

Nicholas -

I don't agree orthographic elevations are automatically confusing. I take your point about Fusion labelling the views but you can do that in 2D or 3D, on screen or on paper.

That's not the difficult part. Your tool-grinder table would be little harder to understand in a standard orthographic form than in your rendered illustration.

I do agree some of the more advanced manual drawing techniques such as oblique views and isometric circles are not straightforward, as I recall from a full GCE A-Level Technical Drawing course; but CAD introduces its own difficulties and concepts. It is very different, giving more contrast than comparison.

Where CAD really scores over manual drawing is firstly in cutting the donkey-work of repeated assemblies and secondly in its generators for those advanced techniques, but I would not say learning to operate it to that level any easier - the skills are different, that's all. I accept though it is also influenced by how easy you find it to understand complex software of any sort.

The snag I found was that of limited CAD-basics training materials better than "training" videos demonstrating specific editions. Fortunately my copy of TurboCAD came with a primer, to TurboCAD yes, but written as step-by-step exercises as a pdf "book", not a video.

'

.For a simple example of that advantage:

Half an hour ago I was designing some special unions; entailing comparing hexagonal, octagonal and duodecagonal outlines of the same diameters. (I want the nuts to be discreet as well as compact.)

The Polygon tool in an orthographic drawing made this very rapid and straightforward. Whilst easy manually, it would have been a slow process; in 3D CAD it would have been more difficult, added extra steps, looked pretty but not been any more informative.

'

Peter -

My comment about scaling came from the printer-setting menus I find. They seem all to work as dividers, down to 1:1; of large objects. I could not see how to enlarge the image to scale and without the dimensions following suit, so for example scaling up by 10 would print something 0.1" wide, 1" wide and dimensioned as 1" wide.

Nicholas Wheeler 108/05/2021 00:34:11
603 forum posts
44 photos
Posted by Nigel Graham 2 on 07/05/2021 22:58:26:

The snag I found was that of limited CAD-basics training materials better than "training" videos demonstrating specific editions. Fortunately my copy of TurboCAD came with a primer, to TurboCAD yes, but written as step-by-step exercises as a pdf "book", not a video.

'

.For a simple example of that advantage:

Half an hour ago I was designing some special unions; entailing comparing hexagonal, octagonal and duodecagonal outlines of the same diameters. (I want the nuts to be discreet as well as compact.)

The Polygon tool in an orthographic drawing made this very rapid and straightforward. Whilst easy manually, it would have been a slow process; in 3D CAD it would have been more difficult, added extra steps, looked pretty but not been any more informative.

I have the printed guides IMSI published for TurboCad for both 2&3D. They're typical of such software 'manuals' in that they only really make sense when you know how to use the damn thing. I gave up on Turbocad several years ago, so they're useless to me and you are welcome to them if you want.

Any 3D Cad will draw your polygons just as easily. One extra step - extruding them to be solids - would add the thickness for your aesthetic comparison.

The grinder I showed is intended to be compact and made out of simple sections with as little work as I could get away with. The spindle is mostly from published drawings. None of the things I've shown have had any visual finishing applied to them as it requires lots of faffing about with lighting, shadows and other artistic judgements that are of no use or interest me.

I don't care about parts; finished assemblies are what matter. Drawings, 3D models, sectional views, combinations of all of those or even scratchings on a dirt floor are just as much steps on the way to that as rooting through a pile of stock then milling the curved slots for a tilt 'mechanism.' It's all just work that should be done in as an efficient way as possible.

Nigel Graham 208/05/2021 10:06:49
1525 forum posts
20 photos

Thank you for your offer Nicholas.

I would find them very helpful - which the on-line "Help" manual is not, to any great extent. Though I managed to create from a copy of its contents pages, a proper, alphabetical, printable index via 'Word' and 'Excel' .)

I think I already have IMSI's guides, or at least links to them, but as you say they do demand already knowing CAD principles - and it's ;lacking that which is my biggest stumbling block.

However I found two primers on the TEE Publishing list. D.A.G. Brown's is fairly old and looks dated by its cover photo of a 1990s-style computer, but still helpful in introducing 2D drawing. The other, by Neill Hughes, is modern and concentrates much more on 3D rendering - though not on how to spell "metre" - but of course neither can cover specific makes of any CAD package and they admit that. Brown probably used AutoCAD; Hughes' examples might be in Fusion, Alibre, SolidWorks - he lists quite a number of CAD publishers.

'

I think I know why my drawn bunkers have glass floors. I forgot the basic extrusion is only of the polyline, so that needs to be filled to be opaque. I have since remembered finding that in a 3D geological diagram for a caving-club magazine article. One stratum was "missing", but once I filled its foundation polyline, even though "white", it appeared.

'

I agree the drawings should be done as efficiently as possible - same as the physical making - but the ways I use TuboCAD are very inefficient because. I can't grasp how to use it properly. However, I find I can't make things from pictures I still need dimensioned elevation drawings for the workshop.

I like Hemingway's approach with their kits (that's how I recognised your T&C Grinder!), and I saw the same at work. The assembly drawings are in 3D but the parts drawings are orthographic, some with small renderings in the corners to help you visualise them.

There was a superb example on the TC Forum galley a while back, of 3D CAD at its best by a kitchen-fitter who uses TurboCAD professionally to create images to help his customers in discussing their wishes. One or two other users carped at the near-photographic scene's very slightly unreal lighting, which I thought a bit mean of them. He'd even included a realistic bowl of fruit on the otherwise-empty work-top. (Do empty worktops exist ?)

I would like to be able to draw rendered models properly. Luckily, 2D assembly and parts-drawings are much more useful for me. The extra work and difficulty in 3D would not return information I cannot put in a dimensioned orthographic far more directly and easily, and which shows the real outlines, distances, etc. for building the physical thing.

'

Received wisdom, or dogma, in many quarters equates can with must; and this appears given by modern CAD packages. You can use them to make sophisticated 3D illustrations before anything else, but I see must only for specific cases as with that kitchen designer's contract-negotiating images.

These two examples of my attempts show what I mean:

The first illustrates the difference between lift and force pumps, to help in discussing with a friend-in-caving which type to make for a particular cave-exploring project. We had made one to drain a pool filling a passage to the roof, yielding superb discoveries beyond. This is also for a specific pool for which we need assess the appropriate pump type - and which I cannot view for myself. I don't know if this will happen, but those sections only show the principles and have no workshop value. The foot-valve by the way, is a thin rubber diaphragm.

The basic sketch of my steam-wagon, is merely an academic exercise. I am preparing orthographic drawings to help me locate the various units in the chassis, and design them. This 3D rendering also has no engineering value, even if I could add the missing details. I would still need dimensioned elevations I can draw directly.

:pump principles 3d attempt.jpg

vehicle ga 3d attempt.jpg

Tomfilery08/05/2021 10:22:55
131 forum posts
4 photos

Nigel

Picking up on your comment to Peter:-

"My comment about scaling came from the printer-setting menus I find. They seem all to work as dividers, down to 1:1; of large objects. I could not see how to enlarge the image to scale and without the dimensions following suit, so for example scaling up by 10 would print something 0.1" wide, 1" wide and dimensioned as 1" wide."

Turbocad will do what you want, but you have to know how! You can insert a "Viewport" in your Model and open a "View" in a paper space which links to the model. When setting up the "Viewport" (and the "View" - so be careful you can put magnification, or reduction, factors in both) you can tell TC to make the items in the "Paper" space as large, or small, as you want. TC links the dimensions to the "Viewport" and displays dimensions in the "View" as per the full size version, irrespective of the magnification/ reduction.

Of course, this can sometimes work against you, e.g. when you draw an object full size and want the paper space item to show scaled down dimensions for model building purposes. In that case, it is possible to break the link with the Model space item and so show the dimensions in scale size. Using this technique you could draw an item full size and then produce Paper spaces for multiple scales.

Oh, and one other point - if using a Viewport any changes you make in the Model space within the Viewport are automatically reflected in the individual, or multiple, paper spaces.

I suggest you might need to investigate further.

Regards Tom

Nicholas Wheeler 108/05/2021 12:41:09
603 forum posts
44 photos
Posted by Nigel Graham 2 on 08/05/2021 10:06:49:

Thank you for your offer Nicholas.

I would find them very helpful - which the on-line "Help" manual is not, to any great extent. Though I managed to create from a copy of its contents pages, a proper, alphabetical, printable index via 'Word' and 'Excel' .)

I think I already have IMSI's guides, or at least links to them, but as you say they do demand already knowing CAD principles - and it's ;lacking that which is my biggest stumbling block.

However I found two primers on the TEE Publishing list. D.A.G. Brown's is fairly old and looks dated by its cover photo of a 1990s-style computer, but still helpful in introducing 2D drawing. The other, by Neill Hughes, is modern and concentrates much more on 3D rendering - though not on how to spell "metre" - but of course neither can cover specific makes of any CAD package and they admit that. Brown probably used AutoCAD; Hughes' examples might be in Fusion, Alibre, SolidWorks - he lists quite a number of CAD publishers.

I like Hemingway's approach with their kits (that's how I recognised your T&C Grinder!), and I saw the same at work. The assembly drawings are in 3D but the parts drawings are orthographic, some with small renderings in the corners to help you visualise them.

My problem with all software manuals is that they're written by people who know how to use the software, and for whom just having the picture on the screen/ability to send files/whatever is their end result. You and I want that representation for practical purposes(although I think our personal requirements show the difference between your technical training and my pick it up as I go along experiences), to send a well formatted 1000page document to someone on the other side of the world who needs it, or to have an entire CD and photo collection on a memory stick to be used in all devices that are available to us.

I have both books you mentioned, and the WPS one is typical of any 22year old computer book - it's so dated to be almost useless, unlike the similar ones on technical drawing or gears that were largely fixed subjects when they were written. If you don't have Hughes book, then I would suggest it is exactly the primer(good description) you need to illustrate the principles you're struggling with. The fork jig and pedal crank are particularly good.

If I'm honest the engine was an academic exercise as I don't have the patience for all the repeated parts, the skills to make tiny fuel injectors or facilities to cast the block, head, manifold and throttle bodies. It uses defined parameter, lots of joints and other techniques to prove to myself that I now have a reasonable grasp of how to use the program. To get to that stage, I've been modelling every part I've made recently. Often that was after finishing them.

I lack the artistic abilities to create worthwhile renders. And I have better uses for spending time proving that again. All of these pictures are straight from the design space, with materials defined to better represent the parts. Fusion suggests that the engine will weigh 3.3Kg....

The grinder is a different matter, as I have a real use for such a thing. You noticed the table is heavily influenced by the Worden, and the grinding head follows common practice. It's in a third iteration that I will build at some point soon. The previous attempts were far bigger(it has to live on a top shelf), chunkier, more complex and had various conflicts that are now worked out. I couldn't have done any of that without the 3D CAD. It's also intended to be very easy to make; the table and tilting mechanism are ideal candidates for laser cutting especially as I would have to buy the material, and the slide rails are standard parts. An evenings simple work(a number of tapped holes along parallel lines is pretty simple, right?) would have that assembly working. The spindle from the WPS book is the only tricky part, and that's only because it needs to be made well. The belt guard is to be 3D printed as it produces a better part in less time than I could make in sheetmetal. Embossing my name into it is a whimsical touch that wouldn't be feasible any other way. I won't be buying any of the kits, because if I spent that sort of money I would expect to take it out of the box, plug it in and start using it.

Nigel Graham 209/05/2021 23:09:55
1525 forum posts
20 photos

Tom -

I hit the same snag earlier this evening. My first attempt to fit a drawing to an A4 sheet shrank the promised Viewport to playing-card size despite my care with all the settings. I don't know how I did it, but my next attempt approached the quoted 1:1 scale, though still undersize . At least the numbers on the dimensions are as intended - I have know them reflect the shrunken copy.

Essentially I cannot make the system do as I set in those umpteen printing menus.

'

Nicholas -

I like your grinder design. Your comment about price made me look up Hemingway's present price for the 'Worden' kit, and while I agree nearly £400 is not cheap (the motor alone would be a sizeable part of the cost) I don't think you'd find a comparable machine made commercially for that price. There is or was one, resembling a model lunar lander, available for just sharpening vertical-milling cutters, but costing some £800+. I have recently completed the 'Worde,' but I can't recall what I paid, having bought the kit some 4 or 5 years ago now.  

Oh, you know what you mean about manuals etc. being written by people who think we all know the software as well as they do. Indeed, I would say the same about a lot of the software itself I have encountered, at work, from official bodies and in my hobbies. Some of it is downright obstructive.

'

I do have both of those books. I think I bought them together, from the TEE Publishing stand at Alexandra Palace a couple of years or so ago now. (2 or 3 BC...)

I would not dismiss DAG Brown's book out of hand. 3D CAD was probably unavailable when he wrote it, at least for amateur users; but CAD generally has advanced by developing new concepts and functions, not by replacing its basics. I have found it very useful - e.g. it helped me understand a little bit about Layers.

Brown wrote his book as a model-engineer for model-engineers when CAD was just becoming available to us; but since he subsequently designed a range of fine-scale model fittings, no doubt now uses up-to-date 2D and 3D software. Incidentally, the packaging of my copy of TurboCAD is decorated with 3D-drawn images of a bogie and manifold for a miniature steam-locomotive.

Neill Hughes' book leaps that two score years gap by showing what is possible now; but I regard his as complementary to the earlier, not replacement.

Yet I found Hughes more disheartening than encouraging. I have the book front of me now, and though I am allowing for the author using a very different "make" of CAD (and annoying spellings), he still plunges into the deep end in some areas. He seemed to have written for those embarking on a formal apprenticeship or further-education course with a heavy emphasis on CAD/CAM design and production.

Hughes makes the interesting point that orthographic drawing is still very important even at professional levels.

Edited By Nigel Graham 2 on 09/05/2021 23:33:09

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