Extrude outwards or inwards around a central point

Is there a command in Rhino or a way in grasshopper to extrude a 3D curve outwards or inwards.

I wanted to do a toothed disk like this one.

Found a way but still believe there’s an easier way or some Grashopper magic (a multidirectional outwards vector or a vector pointing to a center point?)

What I did was to draw a circle, divide by 36, sublimate and rotate the points 5° and move the odd set up 2mm, then connect all the dots, offset the resulting curve, sweep2 along the two curves and extrude the resulting surface…
Second solution that worked was to create one tooth ans polar array.

check out

shall the notches / cuts stay the same depth?
then you will need another workflow:
_extrudeCrv in a horizontal direction, then
_setPt (x and y) to the center.

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Thank you. Exactly what I was looking for.
Do you know of there is a way to do the same from inside out?

Right…that makes sense…

sorry, it doesn’t make sense, i was thinking of a custom c# grasshopper script i made

Now I see what you mean with same high.
It doesn’t matter for my project but I still would love to understand.

Can you explain which points you set center xy?

I tried to cut a hole and thought I’d get a new set of surface points on the inner brim but it’s still a single point in the middle.

if _extrudeCrvToPoint does not fit:


with a custom direction (horizontal)
make sure to set
_useExtrusion Polysurface
_creaseSplitting Disable
_explode the object-type extrusion


… x and y to 0,0,0 in this case

inside out

if you want “inside out” - you can
_extendSrf with Merge=No
instead of splitting

_split or _trim

split by isocurve or by a additional cutting curve