Complicated offset surface-how to make solid?


The surface I started with is a little complex. It has been offset but unfortunately it glitches when I select ‘solid’ under the offset surface command. Does anyone have suggestions for how I can cap the space between the offset surfaces? Cap doesn’t work because it covers the interior and I am just trying to make a thick enough wall to print.

Thank you!



you might try to _Loft the pairs of edges or use _Sweep2 with a line connecting the original and the offsetted surface at a corner. It would be helpful if you can post your surface or show a picture of it, though.



Let me try and I will post results either way. Thank you.


Unfortunately those commands didn’t work with the form as it is now. Here is a picture. Let me know if you have ideas for troubleshooting


Hi Petra,

can you post the surfaces ? (use _Export in Rhino and then click on the “upload” button when replying to this post, to attach the file)



Block letteringpiece.3dm (575.8 KB)

Here it is.


Since your offset surfaces are extremely crappy, I would recommend that you not try whipping this dead horse and just abandoned these surfaces and create new ones.

In the enclosed file I used the section command to create section curves from the offset surfaces and then deleted the offset surfaces. I then used loft command to create new surfaces from the curves. I lofted one surface for each lobe using the rebuild option in loft. I then extended the surfaces and trimmed and joined.
Block letteringpieceX.3dm (674.2 KB)


Hi Petra,

there are some foldovers in your surfaces which prevent you from getting a clean result.

I would redo all surfaces by removing them and start with cleaning up the curves. You might just use _DupEdge on the upper open borders, then project them to the CPlane using _ProjectToCPlane.

For the cleanup of the curves, its a bit tedious but since it can be mirrored its worth it. I did this for the upper and lower borders and just _Rebuild curve by curve with the required pointcount after exploding them and used _BlendCrv to get the corners slightly better. Since the upper and lower curves are planar, the final cap surfaces can be built using _PlanarSrf. The rim surfaces where built using the _Loft command…using pairs of the upper and lower shape curves.

Block letteringpiece.3dm (934.6 KB)

Note that above is just a quick example, i’ve not looked much for deviation between the old curves.



Thank you, I’ll do my best to digest and regurgitate that information in the 3D. As you may have guessed, Rhino is very new to me. Not even sure yet what makes a ‘crappy’ curve-as in what I may have done or not done from the beginning that contributed to these challenges. Tx!


After repairing the curves, offsetting the curve wouldn’t work. Here is the result. hmm,Might be doing something wrong. Wouldn’t mind remaking the curve altogether but don’t know how to change my process to make a better one…Block letteringpiece2.3dm (5.9 MB)


if there is any way that you can post the original curves you created or took as a foundation then please do so, dont take any further steps till this one essential step is not done. you have to clean this up right from the bases. the whole thing just becomes worse otherwise, all tricks and help is for nothing if you dont get this straight first.

and another thing which i noticed pretty often, which also can make you computer slow even though its super fast and new and whatever, but if you keep working in rendered mode and you have a large amount of those pieces lying around on your cplane then no wonder its tough to work on :slight_smile: switch to shaded for the sake of your poor GPU and CPU and most probably your patience :smiley:

back to your curves.


hey Richardz, just now getting back to the forum. Yes, there are lots of newb issues here. Here are the original curves. Maybe should have rebuilt??

Block letteringhelp.3dm (98.2 KB)


how did you produce the curves? traced them of some drawings? maybe it would be easier to redraw them again in future knowing that you should end up with smooth curves so using less points may be better. also for hard edges you can draw piece by piece and join it after that. that will also be the method of rebuilding them now. and i will also very slightly change (smoothen) the geometry along the procedure. so if you are not ok with that and really need your bumpy curves then we have to rethink it.

i can see you resulted the upper curve through a simple 2d scale and moved it along the z axis. that might work later on, but first we have to clean up the initial curve. if there is no other way and redrawing is no option, we can first trim the lower curve. you can mirror and join them later. that is just that we dont have do do the same work twice.

i also saw that you have some interruptions those all have to be rejoined and delete the conjunction point.

anyway first explode the remaining half rejoin the parts which should remain one continuous curve and use Rebuild.

between the hard edges you can select the round leafy parts and use Fair a couple of times just keep hitting the space bar till it has an acceptable continuity

after that you can use FitCrv. for the best results through the entire build up i used the following settings
you can still play with it but it resulted in few but accurate points. i also lowered the degree to 2.

on this one below there is plenty to do

this will smooth out using Fair again a couple of times till its good enough for you.

here again in particular you have to rejoin those and delete the connection edit point it will result in one continuos curve do that with all interruptions. after that use Fair and FitCrv. also use fair and fit curve on the straighter parts between the hard edges.

do that till you have all parts reworked and rejoin the whole side mirror it join scale and move along z as you did before. then offset each curve the upper and the lower. the inner ones can be done with loft the outer ones i had to use sweep 2 to get something acceptable. then you can use cap to cap the outer surface select the inner and trim the middle part of and join all together to one solid volume.

here you go the finished file so far it could be done maybe a bit better but its usable for sure.

Block letteringhelp new.3dm (3.1 MB)

Offset simply ignored / SimplifyCrv


I don’t see mentioned above is to select the curve and do Edit>Control Points>Control Points On.

That will show the complexity of your curves. In general, Rhino works better when your curves are less complex. You can see here that some of your curves are very dense relative to others, even where the shape is similar.

You might want to try the Rebuild or RebuildCrvNonUniform commands on them to simplify.

One of the things you do not indicate is how flexible you are with your shapes. How precisely do they need to match what you have?

Some of your leaves come to points while others have curves at the end. If you can you might want to try bringing them all to a point.

Another alternative is to use the Fillet command to use arcs to round your curves.

Another command you might find useful is FAIR in conjunction with Analyze>Curvature>Curvature Graph On. The latter will give a graphical indication of changes in your curves. You can use the FAIR command to smooth waves out of your curves. The curvature graph will show how your progressing with that.

If you FAIR the curves then rebuild you can get a simpler curve than a rebuild without a FAIR.

Here you have a curve that waves (that may be what you want but if not . . . . )

After fair:

(Pascal Golay) #15

@Petra_Winnwalker, did you get the help you need here?



Yes, thank you. Very helpful. It sounds like one thing I should have done right away is rebuild the curves.