DIY Reflector

Hello all,

I'm just some random college student and part time gadgeteer. This isnt
exactly astronomy related, but its something you guys more than anyone
else will have experience with, i imagine.

I need to craft my own reflector. Now, its ellipsoidal, not parabollic,
and its very very deep, unlike the parabolics you guys use. But still,
I was wondering if anyone had ideas for how to get started crafting my
own reflector. Just to disclaimer this, I'm looking to try and get 18 -
24 inches diagonal, and have it be at least a foot and a half deep.
Like I said, deep.

I've considered metalworking/smithing a reflector (ugg... could never be
acurate enough), casting it (and learning how to cast for a year or two
first), electro plating it (nasty chemicals, no doubt, with crude
homemade pulse modulation systems and having to do trial by fire to
empiracally re-devise electro plating), and hydro forming it (And
welding together a hydroforming chamber to do so). Of course, the silly
part is all these require having some sort of appropriate form to start
with, metalworking aside. At least with casting it only has to be a
foam form! But electroforming and hydroforming both require a big huge
metal form to form over.

Now, I really am not sure what exactly I'm supposed to ask... I know
this has to sound rediculous, but I'm happy spending another three or
four years learning how to do this. If anyone has any ideas at all for
how I can start making my own deep ellipsoidal reflector, your
assistance would be greatly appreciated.

Thanks
Matt

If anyone has any ideas at all for
how I can start making my own deep ellipsoidal reflector, your
assistance would be greatly appreciated.

that's a weird one ;-)
How about spinning up some resin while it sets, then figuring from
there ?
jc



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Myren wrote:

Hello all,

I'm just some random college student and part time gadgeteer. This isnt
exactly astronomy related, but its something you guys more than anyone
else will have experience with, i imagine.

I need to craft my own reflector. Now, its ellipsoidal, not parabollic,
and its very very deep, unlike the parabolics you guys use. But still,
I was wondering if anyone had ideas for how to get started crafting my
own reflector. Just to disclaimer this, I'm looking to try and get 18 -
24 inches diagonal, and have it be at least a foot and a half deep. Like
I said, deep.

How good a figure do you need? What wavelengths are you interested in?

Myren wrote:

Hello all,

I'm just some random college student and part time gadgeteer. This isnt
exactly astronomy related, but its something you guys more than anyone
else will have experience with, i imagine.

I need to craft my own reflector. Now, its ellipsoidal, not parabollic,
and its very very deep, unlike the parabolics you guys use. But still,
I was wondering if anyone had ideas for how to get started crafting my
own reflector. Just to disclaimer this, I'm looking to try and get 18 -
24 inches diagonal, and have it be at least a foot and a half deep. Like
I said, deep.

I've considered metalworking/smithing a reflector (ugg... could never be
acurate enough), casting it (and learning how to cast for a year or two
first), electro plating it (nasty chemicals, no doubt, with crude
homemade pulse modulation systems and having to do trial by fire to
empiracally re-devise electro plating), and hydro forming it (And
welding together a hydroforming chamber to do so). Of course, the silly
part is all these require having some sort of appropriate form to start
with, metalworking aside. At least with casting it only has to be a
foam form! But electroforming and hydroforming both require a big huge
metal form to form over.

Now, I really am not sure what exactly I'm supposed to ask... I know
this has to sound rediculous, but I'm happy spending another three or
four years learning how to do this. If anyone has any ideas at all for
how I can start making my own deep ellipsoidal reflector, your
assistance would be greatly appreciated.

Thanks
Matt


For the coolest method of forming metal, I like this method:

http://www.metalwebnews.com/howto/ex...e-forming.html

I could do that kind of work for free, if someone would let me!

Dave

Myren wrote:

Hello all,

I'm just some random college student and part time gadgeteer. This isnt
exactly astronomy related, but its something you guys more than anyone
else will have experience with, i imagine.

I need to craft my own reflector. Now, its ellipsoidal, not parabollic,
and its very very deep, unlike the parabolics you guys use. But still,
I was wondering if anyone had ideas for how to get started crafting my
own reflector. Just to disclaimer this, I'm looking to try and get 18 -
24 inches diagonal, and have it be at least a foot and a half deep.
Like I said, deep.

If you spin a vat of fluid the balance of centrigual force and gravity
makes the surface take on a parabolic shape. I think if you spun
something like melted wax and then let it harden as it spun, you
would get a paraboloid. Suitable for a form, maybe for the reflector
if you can somehow coat metal onto it.

But you want an ellipsoid. I wa thinking maybe if you layered
the material, denser at the top, perhaps, but I think the density
factors out in the balance of centrifugal/gravity. Make a two
speed vat? Spin the top more slowly(slower?) than the bottom?
Or somehow spin it in concentric rings of varying speed?

Tom Clarke