Getting crazy with a polar array

Hello I am trying to correct a file to print in 3D (expensive material).

I made a test and I think has an error. I checked the file and there is a mistake that apparently comes from a place I can not find.
That is what i did:

  1. Find the center of my position.
  2. Place my model.
  3. Arrayed the model in a polar position from the center ( 4 pieces ).
  4. Then I ‘bridge’ those pieces with a cilinder.
  5. HERE THE PROBLEM: The cylinder does not match with the edges of my polar arrayed modules.

Please find attached print screens + file.

rhino forum.3dm (1.3 MB)

Thanks so much

The problem is that your original object is just a tiny bit inaccurate. The box part, spherical surface part and the cylinder part do not share the exact same centerline, they are off by 0.001 to 0.002 mm. Just enough to cause what you’re seeing. You need to adjust your original part so that the centerlines coincide, and then your polar array should work exactly…


Yes I am trying to solvce it… I re did the green piece again centering everything with ‘align command’ still happening the same…I think i am tired I will keep trying …the circles on the piece look totally centered…
this is becoming strange.

Failing.3dm (17.1 MB)
Hi I am since 5 hours…I re did the model …
I can not believe this is happening. A draw a line…I put the middle snap…put the point there
array polar…the objects keep being off…i really dont understand.

please if someone can help me

Hi Bruno - that file looks correct to me - what is wrong with the array?


Is not…if you check the boxes are not aligned. Just draw a line from one vertex to the other and you will see the line will not match with the exact same vertex in the box infront.


Hi Bruno - well, ArrayPolar is fine as far as I can see, it looks like your objects are not perfectly symmetrical on the center of the array.


well my object is 46 mm and the center of my array is at 23, so I do not understand what is wrong.
If my object is a perfect cube and then my center is the middle of that cube …when I array them …they are not facing each other in the same position ?

Hi Bruno -

if you are only measuring whole millimeters, the array is perfect - if I understand the problem you’re reporting though, the discrepancy is .003 mm after the array - so if that matters, then you need to align the cubes more precisely - as far as I can see the cube on the right is out of alignment with the array center by about .0015 - if you move it that distance in +Y, I think your problem goes away.


If the cube is perfect and the center is perfect. The un-alignment…where does it comes from ?

Maybe I do not understand the problem but, if I DupEdge an edge of the right hand cube:

and Mirror it on the marked line, it does not line up on the other side of the cube, by about .003:



This is what I meant when I said

You will need to reconstruct your original object so that all parts - cylinder, sphere and box - are exactly on the same centerline. Then the polar array will line up perfectly - assuming the array center point is also exactly on the object centerline…


Right. @Bruno_Suraski Make it perfecter!


@Bruno_Suraski Use the End, Mid, Quad and Center OSnaps to find locations when modeling and aligning.

I did it all again…worked. I a new file.

Thanks everybody for the patience