JWST mirror.

[Chriske]

Just started building a full scale model of JWST's mirror.
It will be the show-piece of our next open door at our observatory mid September.
Yep, that thing is 6.5m high...

Now that I come to think of it, I should not use the word 'scale' but rather 'copy'...😄

[Chriske]

First test were very disappointing.
Using 3mm plywood resulted in very bad  surface quality, Even after applying a few coats of varnish.
The idea was (after varnishing and sanding) to add a layer of (high)glossy gold vinyl.

So now plan 'B' is to use sheets of acryl. Acryl has a very flat surface. Did already a small test and it looks promising.

 

[PeterStudz]

This sounds great! 
 

Something like acrylic is probably a better solution. The only way that I’ve found/know for simply sealing wood like plywood for a smooth and non-porous surface goes back to my model airplane days. This involved sticking down tissue paper to the plywood and sealing it with cellulose sanding sealer. Then sanding it down, applying more sealer, sanding… repeat, until you got a smooth surface. The result is waterproof too. 

Works on something very porous like balsa wood too. Of course to get something shinny smooth requires some effort with the sanding. However, I used it quite recently to seal and smooth the edges of 18mm plywood for my Dob base and EQ platform. Worked a treat and easier/better than edging with something like veneer. 
 

Anyway, good luck. I look forward to seeing this when it’s finished!

[Owmuchonomy]

That is some project.  We have a fortunate coincidence in that our Planetarium dome is 6.5m in diameter.  We have an animation which resolves into a full scale image of the JWST primary and secondary mirror onto the dome.  This usually creates some gasps across the audience when they grasp the unfolded size.  We also have the kitchen splash back in black and gold hexagonal ceramic tiles to resemble the JWST mirror in space.

[Chriske]

On 12/06/2024 at 12:55, Owmuchonomy said:

We have an animation which resolves into a full scale image of the JWST primary and secondary mirror onto the dome.  This usually creates some gasps across the audience when they grasp the unfolded size.

Wooow...! Nice idea...!👍