Alibre Design A Power Guide For Beginners And Intermediate Users

[Aila Gilb]

Progressto the point I can now produce orthogonal drawings adequate for my own workshop use, though there are still areas beyond me, like Layers and TurboCAD's complicated 'Viewport' for transferring drawings from their 'Model Space' to 'Paper Space' for printing.

I think Layers allow advance formatting of different line-types, dimension styles etc., and DAG Brown's CAD primer (in the Workshop Practice series) suggests using them to repeat sub-assemblies from place to place. I have to format everything individually.

For printing I just copy and paste the drawing, reducing it as necessary; but there is a peculiarity with TurboCAD's scaling system. It allows scales from 1:1 up, as its Users' Forum gallery shows with exquisitely-rendered pictures of big things, but not vice-versa. So you can draw very small components, but I can't see any way to print them enlarged by definite scales with correct dimensions. It also has multiple printer menus, some lacking ISO- 'A' paper sizes.

What I do like about TurboCAD is it allows you to draw in two dimensions directly, unlike Fusion and Alibre. This is just as well: workshop drawings need to be orthogonal, and the 3D mode is beyond me!

Likewise if it does not have A sizes you should be able to create a custom size and save it. Printing a drawing that was laid out on US letter size to A4 and distort it if you don't get your printer settings right.

Although printing directly from model space sort-of works, that is not the way it's designed to be used. What you do is to manipulate your view of model space by zooming and panning. If in 3D mode you can also rotate as required.Once you can see the model, or part of model, that you want to print, you then use the Create View command to define the boundary of the view with a rectangle. (Advanced users can create shaped boundaries.) When you're satisfied with the boundary you hit Enter to be presented with a little menu where you can accept the default name (something like View-1) or create your own. At that point you have created your viewport.

You then switch to paper space by clicking the next tab along from the model tab at the bottom left of the window. It's usually called Layout-1 or Paper-1. You are then presented with a window containing a blank page of the default page size and orientation. If you then click FilePage setup you will be presented with a little window where you can choose the page size and orientation you want. Actually, you can can choose paper size and the drawing sheet size because you can tile a large drawing sheet with paper sheets, but usually you keep them the same, with the same orientation.

Once you have a paper space layout that you like (A4 portrait, say) you press enter, select the Insert Viewport command, and define a rectangle (any size you like) on the paper to receive your viewport. Once you've chosen the name of the view you want, click Goto and then Close and it will appear in the rectangle.

You can change the size of the rectangle by selecting it and dragging the sides.The scaling default is to fill the boundary rectangle with the defined viewport, but you can choose you own scaling by right-clicking the rectangle and choosing PropertiesViewport. From the window displayed, you can select what layers are to be shown in the view, and what the current scaling is. If you check the Fixed box you can select from a range of scales, or define your own. You can add as many different views as you like, but usually you just want one per page.Its up to you.

Layers are common to most 2D drawing packages, and they can be set-up with different line weights, line styles, colours and Fonts etc. I use layers to separate construction lines, outline and hidden detail, dimensions, headings, notes, trace images, and centre-lines etc. Layers behave exactly like transparent overlays, and they can be turned on or off as needed. No need to delete construction lines, just hide them by turning off their layer. Likewise I can print drawings with or without dimensions and text, and ignore or include doodles as needed.

Printing a technical drawing by cut and paste is naughty because doing so discards the drawing's intrinsic accuracy. Cut and paste is for Office Workers, not Engineers. Any decent technical package will scale prints to whatever is needed, and on dimensionally stable paper the result will be trustworthy. If I want an A0 drawing, my local print shop will do it while I wait.

May I suggest Nigel's drawing adventures are because he's using the wrong tools! Fusion and Alibre are both 3D design tools, not really suitable for conventional 2D drawing. Turbo-CAD seems more 2D, it it too is a 3D tool. 3D packages use simple 2D editors to develop 3D objects. In these, a 2D square might be extruded into a 3D block, and then other features are added by drawing new 2D features on any of the blocks faces, and then extruding or cutting with them. 3D models are built from basic sketches and rarely exist as a single 2D drawing. When a conventional 2D drawing is needed for workshop use, it's projected by the software from the 3D model. Or it generated G-Code to drive a machine tool directly. Producing a simple 2D drawing from Fusion without going through the entire 3D process is really difficult, maybe impossible.

If the 3D design process doesn't match Nigel's workflow, the tools he's using are doomed to confuse and fail him. Doesn't matter how much they cost, or how wonderful they are, or how much time has been invested. If they don't work for you, try something else!

Although I like 3D (Fusion & FreeCAD), I also value QCAD because it's a good 2D package, and I need 2D too. For 2D work like plans, templates, checking other peoples drawings, and developing ideas QCAD kicks the poo out of Fusion. Not because Fusion is rubbish but because QCAD is specifically designed to do 2D drawings; it's a brilliant electronic drawing board for doing the pen and pencil Technical Drawing I was taught aged 14. It's valuable, and if Fusion were taken away tomorrow, I could do everything I need in the way of design with QCAD as a conventional draughtsman.

Give QCAD (or similar 2D package) a go Nigel. I think it's a better match to what you need. None of these things are dead easy to use from the get go; they all need to be understood. I think 3D is unusually challenging because the approach inverts the way 2D drawing is done. The inversion makes it much easier to develop 3D objects, but it also makes 3D tools much harder to grasp. Much of what they do felt counter-intuitive to me and then I suddenly 'got it', like learning to ride a bike.

I cannot make the Layers work: I have no idea why. This gives me a problem, in that turning a set of entities into a Group puts it in a default Layer not intended for object outlines, and it cannot be edited without breaking it apart again.

You delete construction-lines in TC not by the Delete key, but a distinct Clear command; but that is no problem. Often my construction-lines are temporary copies or extensions of outline entities, as a speedy and accurate method for the specific object.

I realise the inherent accuracy of a CAD drawing can be arithmetically far higher than I can machine the physical objects, but I have not found the printed Paper Space image losing that accuracy a problem, provided transferring the image has not changed the dimensions given in Model Space.

However, I will try to use the Viewport system! It also seems to answer an apparent difficulty in scaling a small object so the printed image is enlarged rather than reduced: the image menus' minimum is 1:1.

One problem is that there seems almost no decent books that help you understand CAD principles before you battle with a specific "make" of CAD. I have found only two, and have both; by D.A.G. Brown and Neill Hughes respectively. They help to a point. Brown's is the more useful for learning basic CAD skills although its cover photo looks very dated. I felt the Hughes book (whose British publisher spells "metre" and "-ise" as "meter" and "-ize"&nbsp, is more a demonstration of 3D-modelling by an expert, than an aid to learning to use CAD.

I was attracted to CAD partly because although I was never involved with the drawing-office at work, I observed the possibilities for 3D assembly and layout drawings; as well as facilitating any drawings by for example, readily and accurately copying repeated details. TC's 'Copy' is one of its easiest and most useful tools!

Changing to another programme? Well, I did try that with Alibre but realised it was an unwise move. Even if I stick to 2D draughting though, I think I have gone far enough with TurboCAD for it to be better to stick with it, in the vague hope of cracking some of its harder features, rather than starting all over again. Also of course, I retain the option of 3D if one day I risk trying it again.

I never use construction lines and rarely use a viewport (though it is particularly useful if you want to scale down a drawing (in model space) you have drawn full size to build a model in a different scale, or want to rescale an existing model to something else).

To reduce the scale of an image in a viewport simply enter the scale you want i.e. 1:19.05 (for 16mm/ft). Getting dimensions in the viewport to appear as scale dimensions is a little involved, but readily doable.

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