Making a shape like the JWST's mirror

[micheus]

At Discord, an user asked for a way to make a shape like the JWST mirrors.
Despite other simple approaches, I come with this one intending to show the use of Magnet with Move, as well as the use of Put On [RMB] to create the "array".

[ivla]

Wow, great!

Also it's possible to use Deform - Inflate(RMB) in vertex selection mode instead of Magnet Move - by using a reference object.
Reference center point marked by orange color, radius point is in center of deformed plane (I selected four vertices around it), inflate value - 100%.

[sciroccorics]

Hello guys,

Nice little model. I guess that the easiest way would be to use the 'GeoDome' primitive. Here is a 6-step making-of :

• Step 1 : Create a 'GeoDome' primitive at resolution 6 / View along Z to get image in Figure 1
  
• Step 2 : Select all vertices and apply a Bevel of 0.072 to create 350 hexagons and 12 pentagons
  
• Step 3 : Select 1 hexagon that is equidistant from its 3 neighboring pentagons / Hit I (= select similar faces) then + and + (select 2 layers of neighbors) to get 20 patterns of 19 hexagons, arranged like the James Webb Space Telescope.
  
• Step 4 : Apply Shell Extrude Normal 0.02 and delete initial GeoDome to get 20 telescope mirrors pointing towards the origin
  
• Step 5 : Apply Explode Uniform -200% to make all the mirrors facing outer space, which is more useful for a telescope
  
• Step 6 : Put the Earth at the origin, and you've got your 20 orbiting telescopes, much better than the NASA ;-)
  

[micheus]

Nice entries guys! Thanks for sharing.

I liked you approach sciroccorics. It will create a more accurate curvature.

[sciroccorics]

Thanks Micheus,

I liked the problem that you opened in your OP, so a spend some time to find my own solution. I didn't know that there is a Discord channel dedicated to Wings, I should subscribe.

The parameter 0.072 for the bevel is a bit empirical, theoretically it should be 50% of the edge length, but we don't have a proportional bevel operator in Wings. Note also that, as it is the case in the real mirror built for the JWST, there are only 6 true regular hexagons among the 18 (actually my model has 7 regular hexagons as it includes the central one) : if all 18 hexagons were regular, the whole mirror would be flat which is not very interesting for a telescope

[ivla]

It will create a more accurate curvature.

To be exact, JWST' main mirror is parabolic, not a spherical.
So your approach can give a more accurate result 

BTW, many thanks for hint about "Put on(RMB)".

[ivla]

My version of JWST mirror modelling process (orange is a selection color here)

Make 3-sided cylinder


Split three upper edges to halves and connect new vertices


Select two side faces and mirror on it


Select this edge and dissolve it


Select face and mirror on it


Select central vertice and center the object ("move absolute" to x=0.0 z=0.0 with "move object" checked)


Duplicate object to get an appropriate form as shown above in this thread ("Put on[RMB]" or "duplicate radial")


Make another object to define the mirror curvature


Select one vertice in center of one of objects


Twice extend a selection (press "+") and select all similar vertices ("i")


Deform - Inflate[RMB]




Press "Tab" and input "100"


Select vertices on rear side, then Deform - Inflate[RMB]


Done.


Now you can weld objects as you need.