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Brackets and Varicad - Alex Belits
Brackets and Varicad
I have made the drawings of my brackets in a 3D CAD, in particular, Varicad 9.0-1.1. I have never done any serious 3D work before, and brackets happen to have a rather convoluted geometry, however certainly some of Varicad's idiosyncrasy contributed to making this work more difficult than how it should be.

First and foremost, yes, the tree representation of the shape is a good idea, this is why everyone does it. However the complete lack of a tree editor, and the only function defined on a tree being "explode" that also happens to not distinguish between added and subtracted shapes (leave alone, order of them in the branches) often turns a shape into Humpty Dumpty. Yes, Undo will put it together again, but how about being able to edit things while they are separated, and re-assemble? To be fair, there is a function that edits a single leaf, the problem is, when the shape is assembled there is no way to find most of them. Even explode->mark->assemble->edit-marked would be good, but where the heck is it? How about collapsing branches when I remove the pieces instead of just telling me that I can't remove something, leaving the only option to explode, and then manually re-assemble, going back to the Humpty Dumpty problem?

Second, fillet function does not work if the authors' idea of its position in the tree contradicts with how other pieces (including cutouts) are positioned around it. Very unintuitive -- in fact, it doesn't look rational either because I can't predict which fillet will work and which one won't. On the other hand, same effect can be done in most of the cases through the Extrude tool, and that one happens to work perfectly, and allows re-editing of the shape and length. But how would I know until I am in the middle of editing?

Third, it's very nice to have the unrolling function, after all brackets are made of sheet metal, and having them automatically unrolled with sheet thickness taken into account can be very helpful. It would be nicer if the selection of sequence of surfaces to unroll was not designed to be done with a sniper rifle. In fact, I am not sure if sniper rifle would help, but the precision of my mouse didn't seem to be adequate at all.

Fourth, Varicad seems to be of two opinions about the validity of some shapes. I mean, it draws them, displays them, sees no collisions in its collisions check function, but then if I want to export it to IGES (that it won't be able to read), or run a renderer, it calls something called "3D kernel Antares", that promptly tells me that it doesn't like a shape, and won't render it. The same shape is happily rotating in the editor, in all its OpenGLness, and nothing indicates that it can be wrong, but call the renderer, and it produces an error without any explanation. Press Undo few times, and it will return to the condition where everything is ok, and subsequent editing usually produces a perfectly valid, for both internal renderer and that "Antares" result. Weird.

Other than that, Varicad works well, and if a 3D newbie such as myself managed to make parts drawings in it, it probably is pretty usable as long as the user knows what to check for and what to avoid. Its object placement and editing, various kinds of extrusion-based shape creation (including loft/coil/helix and editing of them while in the combined shape) is quite nice, and I had no problems with it while making those complex bent brackets. However in 2D it's far behind Qcad2.

There was a new version released recently, maybe they have fixed some of those problems, however I haven't seen it yet.

Current Mood: accomplished accomplished

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abelits From: abelits Date: May 14th, 2004 08:10 pm (UTC) (Link)
Today the drawings were received and checked at the metal shop -- Solidworks read IGES files without any problems, and it happened that fillets had to be removed, to allow Solidworks do its own unrolling. After that everything worked.
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