[tobyaxis]

Oh, to have those parametric tools built into BobCad....that might make my heart go all-a-flutter.


Toby, those design tools sound awesome. And only $1600 for the package. That's not too shabby for that kind of power. Not that I have $1600 to spend, but it's a good deal.

What Burr said about being able to control the sweep is exactly what I was concerned about. I've been trying to adjust the curves to make them go more smoothly. Of course now the scroll part is something that really concerns me, because it's spiraling and concave at the same time.

Man, the stuff I miss when I leave my computer off for one evening!

Softwares I know of that will do this.
1) RHINO
2) Solidworks
3) UG
4) Pro/E
5) Catia

Unfortunately I was unable to do this in BCC V21 or Alibre. There is always a first time.

Is there a way you can get an accurate Point Cloud of this? There is still a chance that this could be done, but it will take a lot of time and Geometry to do it. Kind of like this Surface.

It starts here and you will have to look through a lot for all the details
http://www.cnczone.com/forums/showthread.php?t=11350

As a note I agree with the others that a Point Cloud would be one of the best ways to do this.

[DonW]

Also Don,
Was it you mentioning that the Backup wasnt working in V23??? I couldnt find the thread to respond to but thought I remembered it was you.

Burr

Wasn't me...

[BurrMan]

Don,
I slept on this last night and had a thought to add. Part of the issue is the geometry in the files you post is "Asymmetrical" and can xause this kind of "Buckling" in the centerlines like your seeing. Trying to run skins to remain symetrical across an asymetrical curve will certainly find the limitations of a geometry library.

I'm not sure what app your creating the geometry in but you could try to model it in "half" only, then mirror it over to get symmetry. Then you can easily check where they meet in the center for tangency, and surfacing will go much smoother.

I'm going to revisit this later today a bit, not that you want to keep spending time on it, but just as an exercise. I'll post back.

Burr

[DonW]

Ahh...but the crux of the matter is that it's not a symmetrical part/instrument. In fact, it's extremely assymetrical, and is supposed to be. Here's the actual outline of the top. I removed the points and scroll from the data I have showed thus far. The only thing I can think of to retain the recurve through the areas that I need it is to split out the section against the outline like I did on the bottom half. I may need to tweak that center cross-section chain in the one area to more closely match the curves on the side cross-section. Then I need to create some kind of "point cloud" or something to create the scroll area. As it is, I manipulated those two cross-sections so that they matched identically in that recurve area. The tough part is it gradually melts into no recurve up closer to the top. This is more of an "artistic" surface than a "technical" one. Lots of blending happening on the upper half, and as it goes into the scroll with the peak, and then winding around and dropping more radically back down to then blend into the rest of the top again.

[BurrMan]

Hi Don,
I must have slept to much!

I'll take back what I said about the asymmetry. I didnt mean that it should be equal sided but was reffering to the centerline curve versus the re-curve possibly being rotated a bit from each other, but also on revisit found I was wrong, so disregard the asymmetry comment.

I tried a bit of work on the bottom half. When you get time could you critic the results before I go further?

Burr

[Allen123]

Surfacing like this???

[BurrMan]

Don,
Here is the complete surface as I think you want the re-curve. Please look it over.

[BurrMan]

[quote=Allen123;566615]


Surfacing like this???


Hi Allen,
Thats a nice result! More of what Don has been after is the ability to control the suface "through it's path".

For instance, in the model you did there, Making that center ridge into a tangent curve and have it degrade and change specifically over the length, becomes difficult with only BobCad.

These are advanced surfacing techniques that require special toolsets and geometry libraries to handle things in certain way's. Even the Parasolids kernel is not quite geared for this.

[Allen123]

You are right, it would be nice to have those blending tools and more control the a simple skin.

With the skin you have to draw the wire frame as you want the surface to follow. Sometime this is harder than others.

I built this surface in about 15 mins start to finish. I would say it would be nice to control the blending better with out having to draw more sections and paths.

BobCAD does allow you to use more that 4 sections and paths. With this shape I have 3 sections and 2 paths. I think some programs call them rails and paths or something like that.

One I have the surface there really isn't any editing I can do other then going back and changing the wire frame and generating a new surface.

[DonW]

Burr, that looks about like the best I was able to achieve. Hard to say without being able to rotate it around. Not sure I got the recurve part right on the upper horizontal cross section, but it looks darn close, eh?

Allen, that's almost it, except that the outer section actually is an inclined plane up to that roundish button also. The inclined plane on the inside goes up/down much faster, and the surface between the peak and the two inclined planes is slightly convex like the recurve area. So what program did you do that in?

You guys are good...and please let me mention how much I appreciate all the help, if I haven't said it already.

[BurrMan]

Burr, that looks about like the best I was able to achieve. Hard to say without being able to rotate it around. Not sure I got the recurve part right on the upper horizontal cross section, but it looks darn close, eh?

Don,
With my last post there is also a BobCad file in V22 format posted as a zip. You could look at any angle you would like.

Burr

[BurrMan]

You are right, it would be nice to have those blending tools and more control the a simple skin.

With the skin you have to draw the wire frame as you want the surface to follow. Sometime this is harder than others.

Hey Allen,
Yes BobCad "CAN" do this but as you stated it would be difficult. Tedious at best.

I'm still trying to figure out BobCads surfacing tools to be able to define the "Rails" and "Paths". More learning.

Burr

[Allen123]

That was done in V23.

I really just did a quick version of it. Like I said it only took about 15 mins. If I had more that just a picture I am sure I could have done a better job.

That surface was done from wire frame in bobCAD with a skin.

I think to get really what you want, you'll need to create the base as a solid and create solid cutters to cut away from the base.

This is the only way to get the blend to nothing happen easily.

And just like burr said it can take a lot of work. You don't have to go gray over it, it's just understanding how to draw the wire frame and what surface features to use.

Just like the dome burr worked on,

[DonW]

Hey Burr, have you tried to extrude those surfaces into a solid by any chance? I tried, and failed miserably.

[DonW]

V23, eh? I've been somewhat reluctant to upgrade. I think part of what put me off was the sales guy, frankly. Also, I wish they would do what other companies do, and simply charge an annual maintenance fee which includes all upgrades and tech support for a year. I'd have no issue with that sort of thing. I have to do that with my accounting software every year, but they don't pitch it as a new version, it's simply their accounting software, and everyone who is using it and gets the fees gets new discs with each release of enhancements and new features and fixes. It's not treated as an old version vs a new version. It may be semantics, but it's how it comes across from the BCC folks. I don't think they intend for it to sound that way, but I think the sales folks give them that reputation.
Allen, is the surfacing in V23 better than in V22? All I got from the sales guy was how the CAM part was improved, and not the CAD/design part. Hey good folks at BCC, please feel free to step in here at any time...

[BurrMan]

Hey Burr, have you tried to extrude those surfaces into a solid by any chance? I tried, and failed miserably.

Hi Allen,
I did a quick extrusion test and stopped as the model is really not geared for it.

Trying to do NURBS work in a "Patch Manner" is really not the way to approach it to start. It will create all kinds of problems down the road. Some people like to work this way though, especially for the "Reverse Engineering" like this model is trying to acheive. So if he liked this surface result, he would have to continue down the "Patchwork" process to get his solid. It would only get harder from here.

You had already stated the answer with using solids created and Boolean operations to acheive the shape.

I'll look at the extrusion a bit later.

Burr

[BurrMan]

Hey Burr, have you tried to extrude those surfaces into a solid by any chance? I tried, and failed miserably.

Don,
Sorry to report that V22 failed for me also. I got the first 4 surfaces from the neck to go but the butt end had issues.

V23 did do the extrusion though, But that is not consolation for you, just a note that the software is getting better.

Burr



[EDIT] Mistakenly made my last reply to "Allen" when it should have been addressed to "Don".[EDIT]

[The One]

Hey Don,

Do these files depict what you are trying to do? If they do, I can share the "trade secret". If not, how do they vary from the results you are after?

Regards

[BurrMan]

Hey Don,

Do these files depict what you are trying to do? If they do, I can share the "trade secret". If not, how do they vary from the results you are after?

Regards

Wow The One,
I like those and would like to know the way you did them. THe surfaces seem much smother.

[Allen123]

A little skin action ?