[skippy]

I'm not new to CAD (2D) but I am new to 3D CAD and have been trying to learn Rhino5 over the last few weeks. I have an evaluation copy at the moment and will buy the full version in the next week or so. I have decided to run with Rhino for various reasons: 1) I have a Romer 9ft digitizing arm which will plug directly into Rhino and 2) after much reading over the last year I have realised that it's the best program for my needs (surface modeling, as opposed to solid modeling). Certainly there's lots to learn and my brain isn't getting any younger.

(1) I'm wondering if there's anyone who's familiar with Rhino who wouldn't mind answering (by email) a dumb question or two along the way. I'm watching all the video tutorials on the net so the questions won't be many (i.e. no pestering) but they may seem dumb such as the following:

(2) I draw a surface (organic curve) and I want to remove a section of it so (in perspective viewport) I do a vertical line then "surface" then "extrude curve", "straight" but it always goes in the wrong direction. What do I have to do to make it go in the direction of the other plane? Change the C.Plane each time?
Thanks for your help.

[awerby]

It sounds like you're trying to extrude in the wrong viewport. Rhino is particular about that, and even if you've shifted the view, it will still only allow actions in relationship to the original view. So, for instance, if you're working in a top view, it won't allow you to drag something perpedicularly through the flat surface you're looking down on. You'd need to shift to a side view for that.

If you're trying to remove a section from a surface you're looking down on from the top, draw a curve in the top viewpoint that delineates the cutout you want to make. Then shift to a front view and invoke the ExtrudeCrv command; you should be able to drag the extruded surface vertically through the original surface, then split it using the extruded surface as a cutting object.

Andrew Werby
www.computersculpture.com

[skippy]

Thanks for your reply Andrew,
I went back just now and reproduced what I was doing. I drew a 20 x 20 x 20 cube zeroed at the XYZ then I tried to take an angle cut off the bottom of the cube. (my original shape wasn't a cube) The only way to get the angle that I wanted was to select the right view port and do a straight curve that starts at Y-3Z3 (front) and finishes (at the rear) at X20Y20Z0. I then shift to all view ports and find that in top view the line is diagonal, i.e. it starts at X0Y-3Z3 and ends at X20Y20Z0. No problem I thought, I'll just do a line in plan view to where I want it to start from then use Osnap for my straight curve then extrude it. So in plan view I do a line from X0Y-3Z3 to the right to X20Y-3 but when I look at it in perspective and front views the right side of the line goes to X20Y-3Z0. No problem, I'll do a vertical line 3 high in front view to get to where I want to go. No, not good either. In perspective I see that the line which starts at X20Y-3Z0, ends at X20Y0Z3 instead of X20Y-3Z3. The solution is probably very simple but what it is, I don't know.
Thanks

[skippy]

I've tried five time to do an edit on the above post but it just sits there thinking about so here's my edit in a new post:
Thanks for your reply Andrew,
You were right about the viewports as I went back just now and reproduced what I was doing and it worked perfectly. What I forgot to mention in the above is the drama I had just getting the straight curve to extrude from as described here:

I drew a 20 x 20 x 20 cube zeroed at the XYZ then I tried to take an angle cut off the bottom of the cube. (my original shape wasn't a cube) The only way to get the angle that I wanted was to select the right view port and do a straight curve that starts at Y-3Z3 (front) and finishes (at the rear) at X20Y20Z0. I then shift to all view ports and find that in top view the line is diagonal, i.e. it starts at X0Y-3Z3 and ends at X20Y20Z0. No problem I thought, I'll just do a line in plan view to where I want it to start from then use Osnap for my straight curve then extrude it. So in plan view I do a line from X0Y-3Z3 to the right to X20Y-3 but when I look at it in perspective and front views the right side of the line goes to X20Y-3Z0. No problem, I'll do a vertical line 3 high in front view to get to where I want to go. No, not good either. In perspective I see that the line which starts at X20Y-3Z0, ends at X20Y0Z3 instead of X20Y-3Z3. The solution is probably very simple but what it is, I don't know.
Thanks

[awerby]

I'm afraid I can't quite follow all that, but if you have specific coordinates you want to hit, then make a point at each one of them, typing them in instead of trying to click on them. Then turn on the Point O-snap and use the Line command to connect them with straight lines. Once you've got the lines where you want them, then extrude the lines into surfaces. If you don't want to extrude them in one of the orthogonal directions, then you either can extrude and then rotate the surface before splitting, or set up a new construction plane that's tilted at the correct angle and then extrude.

Andrew Werby
www.computersculpture.com

[skippy]

Sorry Andrew, I should have done more jpg's and less explanation. I did a cube and wanted to take a cut off the bottom of it (line then extrude to make a cutting plane) What I wanted to achieve for the line was as per test2.jpg so I selected right view port and draw my line as per test1.jpg. I then looked at the perspective view port and see a diagonal line (see line AB in test.jpg), then I did lines BC and CD just to try to get to the second point of the first line (point B in test2.jpg) and as you can see, each time it went where I don't want it to. I've since figured it out. What I just found out is that I should work with "Planar" (in the status bar) almost permanently selected otherwise the lines jump from plane to plane as per the jpg in my first post.

[EHNisja]

Skippy, here's a quick tip for you. If you want to trim off the bottom of the cube as shown in your first image all you need to do is select the line in that view and trim. There is no need to make it a plane.

As for making a plane in desired direction, use the "direction" switch in the command line to force the surface to go the direction that you want. It can be any vector.

[Treeline]

Skippy, I just saw this.
For your specific question in this thread, you might want to immerse yourself in the use of ALL of the CPlane commands.
This video link doesn't cover all of the CPlane uses, but it should give you an idea of how valuable and time saving it can be.

Edit: Well, sorry. I didn't know that this forum stripped out youtube links.

You're on your own.

[honestak]

Don't forget in Rhino 5 you can just use the gumball for extruding operations. just pick the axis you want to extrude and hold CTRL then move either the appropriate distance or enter distance via the keyboard. you can always cap surface afterwards

[skippy]

Thanks for your answers guys. I only just this minute got notifications that there were answers (seems that my notification settings changed all by themselves from "instant" to "whenever"). I've come a long way since I posted this and am doing quite complicated surfaces these days (thanks largely to great tutorials on youtube) however I must admit that I still don't have a good grasp of all the uses of the different construction planes even though I've always have a reasonable understanding of 3D space and geometry in general. I'll continue this reply later as I have to go out now.
Thanks

[Treeline]

I've got many years of 2D drawing and only went 3D when I wanted to start milling. I think what all of us share who might have some previous CAD experience but not much in 3D isn't so much the use of the many commands for operations, but the single difficulty of trying to wrap our heads around the whole concept of drawing in 3D and learning to think differently in 3D.

[skippy]

Back again
EHNisja: I've since learnt the one about trimming using a line and "apparent intersections" however I didn't know about "direction" switch in the command line. Thanks for both tips.
Honestak: Re the gumball, I thought I knew most of its functions but I didn’t know that one so thanks.
Treeline: Any chance you could send that link to my pm or to my email? Thanks
philwmcintosh at gmail dot com

[ger21]

Edit: Well, sorry. I didn't know that this forum stripped out youtube links.

It doesn't. There are hundreds of YouTube videos posted in the forums here.

[Treeline]

It doesn't. There are hundreds of YouTube videos posted in the forums here.

Well, I tried it twice and both times the link wasn't there when I reposted.

I guess it must be me.