Solid extrusions with Rhino

Well, this one is usually considered a basics in 3D modelling, but I'm having problems with constraining Rhino to do what I want it to do: a simple extrusion of a surface along a 3D curved rail.
The catch is - I need the result to be a solid, and the original surface to be perpendicular to the rail at any point. In other words, the defining surface has to follow the rail, not to have a fixed angular position in space.

The ExtrudeCrvAlongCrv command gives me this outcome (a circle extruded along a planar bezier curve):

which is not what I wanted.

It was such an easy task to perform with other software I had used in the past (Solidworks, UGS NX), and I was able create any 3D shape with those tools. Now I feel again like a little schoolboy learning the basic alphabet. Any suggestions about the proper (and quickest) way to do this task?

Cheers!

 

Sweep1 There are some options to control the orientation of the section to the rail in terms of twist.

 

Daiquiri I would use the rail command to get the surface I wanted, then cap the ends with a surface, then select all the surfaces and use the “create solid” command to finish off.

 

Sweep1 gives you the tube. Then you will need to Cap the open ends.

 

bhnautika beat me to it. And then CreateSolid

 

Thanks. I've tried it, this is the result:

Unfortunately the cross-sections appear to be randomly-oriented and non-perpendicular to the rail curve.

Another question related to solids - do you know if it is possible to assign a physical density to individual solid objects, in order to calculate both individual and overall mass?

 

Oh, my mistake!!!
The sections are not perpendicular to the rail because the original section was not perpendicular either.
Looks ok now - gentlemen, thanks a lot for the tip.

Remains the question about mass properties of solids...?

 

Actually the CreateSolid isn't always needed. A "solid" in Rhino is just a volume enclosed by a polysurface without any gaps. CreateSolid trims and joins surfaces and polysurfaces, and fills holes to create a single polysurface which encloses a volume.

If the polysurface already encloses the volume without holes then CreateSolid doesn't do anything that I see.

 

Not in basic Rhino that I'm aware of. I believe Orca (naval architecture add-on) has that capability but I'm not an Orca user.

 

That's a VERY bad news!
Means no possibility to automatically calculate either the mass or the CG location of the 3D object. A HUGE drawback for such a software imho, because it does calculate volumes of solids so it was really a piece of cake for software developers to insert the calculation of the mass, the CoG and the moment of inertia!

 

Rhino calculates the CG and moments of intertia of solids, VolumeCentroid and VolumeMoments. It doesn't have any built in functionality to multiply by density and sum the results. So far I've been copying and pasting into an Excel spreadsheet. I understand it's very feasible to write scripts to save the data to files, etc. An alternative is to purchase Orca.

Example of VolumeMoments results:

Volume = 1236.33671 (+/- 6.2e-06) cubic feet
Volume Centroid = 11.5122508,-16.2981011,-28.1365963 (+/- 3.1e-07,2e-07,3.2e-07)
Volume Moments:
First Moments
x: 14233.0183 (+/- 0.00031)
y: -20149.9407 (+/- 0.00015)
z: -34786.3069 (+/- 0.00022)
Second Moments
xx: 170386.549 (+/- 0.01)
yy: 373595.655 (+/- 0.01)
zz: 988213.197 (+/- 0.028)
Product Moments
xy: -231034.834 (+/- 0.011)
yz: 555384.79 (+/- 0.017)
zx: -400654.243 (+/- 0.017)
Volume Moments of Inertia about World Coordinate Axes
Ix: 1361808.85 (+/- 0.038)
Iy: 1158599.75 (+/- 0.038)
Iz: 543982.204 (+/- 0.021)
Volume Radii of Gyration about World Coordinate Axes
Rx: 33.1886582 (+/- 5.5e-07)
Ry: 30.6124672 (+/- 5.8e-07)
Rz: 20.9760623 (+/- 4.5e-07)
Volume Moments of Inertia about Centroid Coordinate Axes
Ix: 54634.8076 (+/- 0.001)
Iy: 15977.3971 (+/- 0.0012)
Iz: 51722.3568 (+/- 0.0015)
Volume Radii of Gyration about Centroid Coordinate Axes
Rx: 6.64762216 (+/- 7.9e-08)
Ry: 3.59488194 (+/- 1.4e-07)
Rz: 6.46801131 (+/- 1.1e-07)

 

Similar for surfaces, Rhino has the Area, AreaCentroid, and AreaMoments, commands. They are on the Analysis drop-down menu under the Mass Properties sub-menu, not under the Surface sub-menu. Likewise Volume, VolumeCentroid and Volume Moments are also under the MassProperties sub-menu.

Example of AreaMoments results:

Cumulative Area = 792.11509 (+/- 9.5e-05) square feet for 2 surfaces
Cumulative Area Centroid = 11.124368,-16.3553456,-28.1898576 (+/- 4.8e-06,4.5e-06,7e-06) for 2 surfaces
Cumulative Area Moments:
First Moments
x: 8811.7796 (+/- 0.0027)
y: -12955.3161 (+/- 0.002)
z: -22329.6116 (+/- 0.0029)
Second Moments
xx: 105049.33 (+/- 0.097)
yy: 251810.84 (+/- 0.14)
zz: 639398.34 (+/- 0.39)
Product Moments
xy: -143137.008 (+/- 0.12)
yz: 356091.71 (+/- 0.24)
zx: -248512.084 (+/- 0.2)
Area Moments of Inertia about World Coordinate Axes
Ix: 891209.17 (+/- 0.53)
Iy: 744447.66 (+/- 0.48)
Iz: 356860.16 (+/- 0.24)
Area Radii of Gyration about World Coordinate Axes
Rx: 33.542519 (+/- 1.2e-05)
Ry: 30.656526 (+/- 1.2e-05)
Rz: 21.225352 (+/- 8.4e-06)
Area Moments of Inertia about Centroid Coordinate Axes
Ix: 49851.9293 (+/- 0.0035)
Iy: 16953.612 (+/- 0.002)
Iz: 46946.0148 (+/- 0.0042)
Area Radii of Gyration about Centroid Coordinate Axes
Rx: 7.93317147 (+/- 7.6e-07)
Ry: 4.6263339 (+/- 5.5e-07)
Rz: 7.6984842 (+/- 8e-07)

 

Rhino also has the Hydrostatics command which calculates the primary quantities of interest for hydrostatics analysis. Those quantaties can then be used to calculate displacement, wetted area, immersion per unit change of displacment and so forth. With CG location added the various stability quantaties can be calculated. I have a spreadsheet I use, and also separately measure the cross-sectional area to use for prismatic, block and mid-section coefficients.

Example results of the Hydrostatics command:

Volume Displacement = 17.1316
Center of Buoyancy = 0.118631, 0.576582, 0.507369
Wetted Surface Area = 48.4074
Waterline Length = 14.6276
Maximum Waterline Beam = 3.63353
Water Plane Area = 35.2829
Center of Floatation = 0.0678755, 0.45833,0.8

 

Hi, sorry by rail tool do you mean rail revolve? i am having a similar issue.

I have a closed curve, (lets say an off circle) and a organic L curve that i want to 'pipe' in a sense..

Ive tried sweep1, sweep2, extrude along curve, rail revolve but can not work it out..

Essentially i want to just pipe a closed curve around another curve

 

Can you post a Rhino file with your "problematic" example?