Boolean subtraction fails w/ drafted lettering

Is there a workaround in V6 to subtract drafted (3-5deg) solid lettering from a polysurface? Boolean, apparently, doesn’t like drafted lettering…no draft - no problem.

Hello- impossible to say with out at least one example in a Rhino file.


draft-lettering.3dm (957.9 KB)

Hello- the objects are a bit messy - font curves are notoriously messy for surfacing purposes but one thing you can do short of making clean ‘proper’ curves is this

Starting w the “R”, get that original surface - or the curves but I do not see that here - and DupBorder
Delete the surface.
SimplifyCrv the border curves and then make a new surface with PlanarSrf.

Extrude that, then `MergeAllCoplanarFaces’ and work with thar result for your Boolean operation.
Any luck?

here’s a version with cleaned up curves -
draft-lettering_Cleaner.3dm (806.4 KB)

(I did run MergeAllCoplanarFaces after extruding)


BINGO! Worked for the single letter. Now, can I do the commands on groups or must it be single entities?
If I fillet all bottom edges will that mess the flow, if not at what point do I fillet? All of this workflow is to make incised/debossed lettering on jewelry models that will decrease the likelihood of investment breakout during burnout and casting . Can’t read your response file in V6

Hello - I replaced the file with a V6 one above, but editingh seemed a bit glitchy so I am not sure it updated.
In general for the best results, I would make clean curves and not use the fonts’ curves directly whereever possible. I would fillet, if I undestand you, before extruding - you should extrude the curves to a height only sligtly more than the depth of the cuts - the taller it gets, the messier it can get.


Thank you, Pascal. Very, very helpful. In something of the same vein, could a line drawing, (only lines, no shading) be made into a very small volume polysurface and be incised using Bsubtract? I got the “vectorize” plugin to try this except with larger type and began wondering about an engraving effect.

Hello - in V7 yes - up to a point as far as precision goes - here is an example as V6 file - the command in V7 is MultiPipe.

DrawingToVolume.3dm (2.4 MB)


Downloaded V 7 Maybe an upgrade in near future. Does 7 have a “new features” tab?

Hi Frank -

It looks like it does, yes:


Thank you I downloaded the evaluation copy and I’m working with it now

Assuming text on a curve is too involved in Rhino, what is the best format to import curved text in and what selection options are to be checked? Most likely exporting from Corel Draw, which has an wide array of export options.

Hi Frank -

Grasshopper has the Text on Surface component, but, yes, that might better/easier in Corel Draw.

I’d probably try with PDF, SVG, or DXF.

So, importing an svg from Corel, creating surfaces, extruding, and then experimental subtraction from a solid rectangle produces this. The top surface of the rect. disappears…why? Only the “O & L” and the small cylinder were extruded. Trial version of R7, but it does the same in R6

In the same vein, why do the subtractions (“L” & a cylinder) show in wireframe and not in perspective rendered? Have exported as .stl and the subtractions are not in the .stl

Hi Frank -

As Pascal mentioned a couple of times earlier in this thread, don’t use the fonts’ curves directly.
These are bound to have issues.
If you post the 3dm or svg file, we can take a closer look at what’s going on.

Wim, Here are 3 diff imports in R6. All came in as curves. Surprised they all imported diff. sizes.??Worked with the “L” in all 3. SimplifyCrv seems to have no effect. Tried to apply the work flow Pascal outlined.
Liberty-end-plate.3dm (1.3 MB)

Guess I don’t know how to export as surfaces from Corel in any of the 3 formats.

Hello- as predicted these are junky curves - if you zoom in close enough there is stuff like this

that one is here -

there are others. Use IntersectSelf to mark locations to check - strictly speaking they do not self intrsect but within tolerance.
That little segment is 3.3655719016250032e-06 units long…

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So, Pascal,
I guess if my electron microscope wasn’t out for repairs I might have detected what you’ve pointed out.
A. All true type fonts have these line quirks?
B. Are the junky curves inherent in some fonts and not others?
C. Has anyone had the need to write something that would examine each letter and make corrections via batch?
D. Any way to use any of the export/import formats and bring in clean surfaces that can be bordered with clean curves?
E. Why doesn’t SimplyfyCrv work like it sounds, at least not in R6?
F. Does R7 make any improvements over R6 in this area?