Loft command on hand cast help ! /ty



Hi there guys I want to make a arm cast but I’m beginner , I got a model arm …I used the contour command and I got the curves , when I use the loft command I got some weird things - I’m not sure this is the right command to use , any suggestions?!

thank you ! Alex

(David Cockey) #2

The Loft command works in a very simple way. It connects the corresponding points on each curve. It is not intelligent and does not know where to add holes.

Can you post the curves? Click on the vertical arrow icon in the tool bar above where you type your post.

Also you said you used the Contour command to get the curves. What did you use the Contour command on?


armes.3dm (1.6 MB)

I used Contour command on a mesh I downloaded from web / is on arm layer




hi alex, you can draw a curve with InterpCrvOnSrf for example directly on the loft where you want that hole. or you put a flat curve very close to this position, see that its not bigger than the corresponding surface and use pull, it will project it onto the surface. you can of course also take your curves.

if you have the curve you need in position select it and trimm a hole into the the loft. after that you model further wit lofts and join those two shapes and use FilletEdge with option chain. you may have to play with FilletEdge a bit it also depends on the quality of 2nd the loft

here just a crude example to show that this is possible, already connected the 2 lofts.

another option is to connect the 2 opposing lofts with BlendSrf when they are distant from each other after you cut a hole into the first loft of course and then join.


Hey thank you Richard , is there a way to recreate or make a polysurface to a surface?!

I want this polysurf arm to be a surface

arm1.3dm (4.0 MB)

(David Cockey) #7

For a polysurface such as your example there is no simple way to change the polysurface into a single surface. I assume your polysurface was the result of the MeshToNURB command. The results of that command are usually not very useful.

One method to create a surface from a mesh is to first create a set of curves on the mesh. Contour and, Section are the easiest way to create the curves. Curves can be drawn on the mesh. Use InterpCrv with the vertex OSnap on to get the shape of the desired curve, then use Pull to pull the curve onto the mesh. Sometimes it is useful to create a temporary set of planes and/or surface and Intersect with temporary surfaces or planes with the mesh. The location and arrangement of the curves will depend on the shape of the mesh and how the surfaces will be created. So knowledge of how to create surfaces using curves is needed.

The curves created directly from the mesh will actually by polylines with straight segments. Smooth curves, are needed to create smooth surfaces. FitCrv, Rebuild, RebuildCrvNonuniform can be used to change the polylines into smooth curves.

Once the set of curves is finished the surface or surfaces can be created. Sometimes a single surface is not desirable or even possible so a polysurface will be needed, However the polysurface will have only a few surfaces compared to the results of MeshToNURB. Commands for creating surfaces from curves include Loft, EdgeSrf, Sweep1, Sweep2 and NetworkSrf. Each has requirements on the arrangement of curves.


Thank you so much David ,I will try to do it as you told me !

best regards


hey Alex i think i found a better solution. if you trim the hole into the surface and loft that thumb further then use the surface edge of the hole for the thumb loft, it then gives you the option to choose match start tangent which will smoothly translate it into the thumb and no need for blend then.


Hi there Richard I’m sorry I quote you , by mistake !
Well yap thank you , I tried so many ways … this shit is giving me a headache …I post another topic in grasshooper maybe I can create that voronoi patern on a polysurface !

thx anyway for your time and effort !

(Ali Dlg3) #11

Hello! I’m having problems trying to loft the surfaces
I’m also making an arm cast, I used the loft command but I had to do it one curve at a time and now I have a series of polysurfaces that make the scan, but its not a complete surface and gh can’t select it

If anyone can help me :frowning: please


(Wim Dekeyser) #12

In the context of getting help with Rhino, a picture doesn’t really say anything at all.
I’m not sure why you had to do one curve at a time…

I found a 3dm file in a post that you deleted in another thread. Hope it’s the same one.
cast-wd.3dm (3.2 MB)

(Ali Dlg3) #13

I did one curve at a time because when I tried to do it all in the same time the loft didn’t follow all the curves, it just game me a surface between the first and the last one. Im not sure what I am doing wrong


I would handle this with three surfaces. Then trim and blend the thumb into the hand section.


Is there tiqs on how to arrange curves where they cross each other?
Just making sure tangency or curvature
of curves won’t garantee a continuous surface.

In your example where the red curves meet the blue, around the wrist area.
How do you set up the curves so cleanly?


Those are just the surface edges and seams. No curves showing.
I typically start with section curves. Then rebuild. I’ll then split the mesh into manageable sections to be used as projection bases within VSR. Then I can suck my surfaces to the mesh sections. Up the degree and point edit. Until a get an acceptable deviation result.

(Ali Dlg3) #17

Thank you so much! I will try your aproach :slight_smile: