Any WIP?

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 From:  Spinner
57.1 

Hi guys,
Looks like a very neat little app developing here.
Only prob I'm having is it's like learning another language.
Peeking over someone's shoulder in WIP thread or a few tool use examples would help.
Sort of a common phrases in Nurbland booklet, would help many encountering nurbs for the first time through this enticing app.
I;ve noticed Michael useing simple construction examples to illuminate various posters on one aspect or the other.
Probably them that need it don't know what to ask and those who know think its too basic to post but a tips thread would help IMO.
Thanks Michael.
Cheers
Spinner

ps Looking forward to saveable, scaleable, background images.

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 From:  Frenchy Pilou (PILOU)
57.2 In reply to 57.1 
Why not try yourself the prog? With try / fealure
It's the best for explore a new product !
And this one is very easy and ergonomic:)

In speedy : use nurb is
Draw some curves for volumes 3D generating
You make after a boolean action (generaly a substraction) between these volumes 3D
That all :)
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 From:  Michael Gibson
57.3 In reply to 57.1 
Hi Spinner, yeah I know there is a lack of documentation right now which can be frustrating. I think that pretty soon I'm going to try and do a couple of those Camtasia screen captures which should help out.

Is there something in particular that you're trying to model that you are having a problem getting started with?

Maybe you can post a sketch or picture of something that you would like to model here and I can help you with some specific tips on how to get started, that would turn this into the type of WIP thread that you're asking about.

- Michael
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 From:  Spinner
57.4 In reply to 57.3 
Hi Michael,
Well one object I'm wanting to create atm is a metal casting with heaps of radiussed intersections. I think it can be broken down into bite size chunks and am having a go poly style but thought nurbs might be better.
So how would you come at this cast door? The hinge and wing nuts depicted are irrelevant.
cheers.
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 From:  Spinner
57.5 
Michael, et al.
While waiting for your comments on constructing the torp door, I've mucked about exploring a test object trying to break down an approach.
I don't understand why I can't seem to generate the back wall center, even though it was selected with the other bits that have spinned into surfaces.
Also I'm at a loss how to create the inner faces of the 4 pockets between my webbing? Ideally the webs should be radiussed on all intersections.
One thing for certain, I'm giving the radius tool a workout. So far its great.
Cheers
Spinner

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 From:  Michael Gibson
57.6 In reply to 57.5 
> I don't understand why I can't seem to generate the back wall
> center, even though it was selected with the other bits that
> have spinned into surfaces.

I'm not following this part, you may need to post the actual model file to clarify this question.


But if I understand your drawing correctly, I think you want to draw the entire outline with all sharp edges at corners, then use the extrude tool to extrude it out, and then fillet everything after that.

The key thing thing here is that if you extrude a shape that has other curves nested inside of it, those nested curves will be void areas inside the extruded solid. The other strategy thing is that if you're going to make a lot of little rounded edges it can be a lot easier to keep everything sharp and do all the rounds at once, rather than trying to build different sections at a time.

Drawing the curves involved quite a lot of different little steps. I've attached the model that shows things in various stages, I started by drawing an octogon, rotated it, drew several circles and then a bunch of lines for the little spokes, mirrored and rotate/copied some lines around and then trimmed the circles and spokes with each other to form the solid regions. Let me know if you want some more details on any of these steps, there is a lot of little fiddly parts to this.

Then I did an extrude to punch the shape up and leave holes for those inside regions. Then I selected the outside edges and filleted them with a larger radius, then I selected everything and did another fillet, you'll have to wait for a minute as it tries to do the same larger radius which produces a strange result on the little pieces, stay in fillet and enter a smaller radius, like 0.05, that was more appropriate for the size of the little spoke pieces. You would probably want to make the spokes a little larger if you wanted to do a larger radius.

Was this the type of result you were looking for? Let me know if you want any more info on any particular stage.

There may be some sloppy parts in this one, I did it kind of rushed. It's kind of a heavy model because of so many little roundy bits.

- Michael

EDITED: 16 Feb 2007 by MICHAEL GIBSON

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 From:  Spinner
57.7 In reply to 57.6 
Michael,
Thank you very much.
That's really helpfull.
I guess the poly mindset had me looking to create a 45 degree pie piece, followed by iterations. Easy to find oneself in a rut.
My earlier back wall prob has slightly mislead you. The door is solid with pockets rather than cutouts between the webbing. Armed with your example, I'll see if I can construct it again with that variation, myself, and probably be back with more queries shortly. lol Either way I'll return with my results etc. They might be of help to someone out there.

I'm at a loss with that prob though. I've attached an example. It shows two lines at 90 degrees end to end, radiussed. If I then revolve from one end I get the expected cup shape.
However if I double that geometry and revolve it 180 or 360 degrees around the center, one face isnt created. I confess to being a bit vague re the start n stop points, so it's probably user error again.

LOL It feels quite odd to be free of possable rtfm responses! Although I feel a little guilty to be consuming your time.
Thanks again!
Cheers
Spinner
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 From:  Michael Gibson
57.8 In reply to 57.7 
> The door is solid with pockets rather than cutouts between the webbing.

I see... It was a little hard to tell from the drawing.


> I guess the poly mindset had me looking to create a 45 degree pie piece, followed by iterations.

I think that one of the strategy parts that you're not used to is relying more on doing patterns with curves first, before constructing surfaces.

If you have recognizable 2D curve elements in the design, it is usually worthwhile to focus on creating those curves mostly first and build from there. This is one of the major strengths of NURBS modeling - if you have something resembling a blueprint you have a lot of power to create the blueprint exactly by drawing and trimming curves with each other.


So for doing pockets instead of holes, take the same curves and instead of extruding them all together at once, do all the inside ones first (to select all the inside ones, do a window select to grab everything and then click once on the outside one to deselect it, leaving just the inside ones selected).

This will generate a bunch of separate solid sections. Take these and go to the front view and drag them up away from the base plane. then select the outer section by itself, extrude it up so that it is halfway penetrating through those other pieces. You may now want to select the bottom curves (do this by going to the front view, and doing a window selection from the left to the right that just captures the bottom of the shape - going from left to right captures only what is strictly inside the selection window, going from right to left will show a dashed window border and will capture anything that intersects the window in any way, not only those things that are strictly contained). Hide these curves because they will get in the way a little bit. Then select the base piece, do Boolean / Difference, then select the smaller pieces. This will cut all those pieces as indents into the big piece. Now you can go in there and fillet the edges. Let me know if this doesn't make sense.


> However if I double that geometry and revolve it 180 or 360 degrees around the
> center, one face isnt created.

Yes, I understand what you mean now. Creating it from the center in that manner creates a type of surface that is squished to a single point inside its middle and sort of folded over on itself. MoI is not going to like this kind of a surface, it will generally cause problems. This is not an uncommon problem with revolve, I need to build some helper stuff into Revolve to automatically trim and throw away half of the shape in this case to help you out. But in the meantime when you do a revolve, you should have the shape you're revolving strictly to one side of the revolve axis, not in the center of a shape like you had.

It's a little hard to describe why the revolve from the center of a shape is bad, but imagine if you only revolved it by 30 degrees or so, you would have a single surface that looked like two pieces touching at a point in the center - having the surface squished in the middle of it like this is not good.


> I confess to being a bit vague re the start n stop points, so it's probably user error again.

It can be important to be precise when you're constructing things, because you'll often want pieces to join up with one another. So be careful with just eyeballing things, it can cause problems later on if you're doing a more detailed construction.


> Although I feel a little guilty to be consuming your time.

Don't worry too much about that, I need an excuse to model things and time spent on the forum is actually very efficient for me because it hopefully helps other people at the same time.

- Michael
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 From:  Spinner
57.9 In reply to 57.8 
Michael,

> I confess to being a bit vague re the start n stop points, so it's probably user error again.

It can be important to be precise when you're constructing things, because you'll often want pieces to join up with one another. So be careful with just eyeballing things, it can cause problems later on if you're doing a more detailed construction.
------------------

In the interest of getting the info out here and my own understanding,
I meant a bit vague in comprehension, rather than execution. As an ex-draftsman, accuracy is ingrained. lol
Intuitively I expect to tell it what to revolve (selection) how far to revolve (degrees in text input) and what axis to revolve on. I'm not clear on how the start and stop points are used to define that axis, especially for the cases it seems designed for, where that axis isnt perpendicular or parallel to the active view window. I'd guess its related to the way an angle is defined but haven't explored enough for the penny to drop. I've successfuly used them to revolve by drawing two points on an axis but what I've inputted by the random distance I chose between them is anybody's guess.

I'm painfully aware of breaking the injunction to keep one's mouth shut and risk appearing stupid, rather than openning it and thus remove all doubt. However, its a good cause and at the least all the experienced nurbists get a good chuckle.

Cheers
Spinner
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 From:  Michael Gibson
57.10 In reply to 57.9 
> As an ex-draftsman,

Ah, somehow I had jumped to an assumption that you were coming from a non-NURBS background because of using different modeling techniques such as the stuff called "subdivision surfaces". I shouldn't jump to assumptions about people's backgrounds so quickly.

It's actually quite valuable for me to find out about different things that you find confusing. Hearing about that stuff is how I learn what areas tend to confuse people and can help give ideas on how to improve things in the future.

So when you pick a revolve axis, the distance between the points you pick is not used for anything, the important parts are the location of the base point, and then the _direction_ that is formed between it and the second point. It would probably be better shown graphically as an infinite construction line instead of a line segment.

Think of the axis that you draw as a line that is the pivot pin of a door hinge, where the revolved shape will be created along the way the hinge swings. It doesn't matter if you have a one inch tall hinge, or a five inch tall hinge, they both make a swing in the same direction if they have the same pivot pin. Does that make sense? Let me know if that still doesn't make sense.

The distance you pick can be important to some operations, but not for revolve.

- Michael
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 From:  Spinner
57.11 In reply to 57.10 
Thats exactly how I used it, so a success for intuitive interface!

re ex-draftsman,
Nope, you were correct on the total lack of nurbs experience.
I hail from the dark ages, when draftsmen drew on paper with pen and ink, engineers used punch cards on big clunky mainframes and all the apples in the office were in lunch boxes. LOL
To a large degree, I'm a good test for Clueless meets MoI. So I'll keep posting and hope its of use.
Cheers
Spinner
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