Wanted offset aluminium reflectors

[William Moore]

I am in USA and like to mess with solar cookers, might say it is an obsession. The best reflectors are as stated in the heading. Seems that over here they rarely use aluminium so I have done all my design work with powder coated steel reflectors using foil tape for good reflection. It is messy, too much light scattering. AL polishes well, if you can get the powder coat off first. Prefer 100cm, approximately. Have found one dish I have found is 200 cm, hardly portable but will certainly sterilise lots of water once built. It has horribly efficient coating, needs to be baked at high temp to soften the coating, and no one around here can do it. The few manufacturers I have tried to communicate with just ignore messages.
Rumour has it that some western EU countries use aluminium. Is this true? If so, who knows how to contact the manufacturers? I would like to get some reflectors before the powder coat goes on...or used
Also, used will do if they have the coating that comes off with ordinary paint stripper.
thanks,
William Moore
retired electronics guy

 

[archive10]

Gibertini makes the OP125L(P) and OP150S, they come in both steel and aluminium versions.
You may find the used from time-to-time, but they are still manufactured in Italy, so perhaps a direct inquiry for a dish without coating might give good results?
(Assuming shipping is not too great a problem).

Gibertini SRL :: Satellite Antennas and Accessories

 

[William Moore]

Based on the high prices for poorly designed and built solar cookers on eBay, the shipping will probably be worth it...
thanks, I will research Gibertini. Are they used in Italy only? I will be in Amsterdam next week.

 

[Channel Hopper]

Best go right to the manufacturer so yes, Italy

What is your ideal size though, if the reflector is efficient can you work on a reduced size ?

Solar cooking does rely on a particular food product though , parabolic dishes provide a point focus , but for something like a hot dog or a pot stew, it requires diffusion into at least one other plane so you may be looking at toroid shapes, or stirring via a motor to do the deed.

 

[William Moore]

High efficiency lets you build smaller, otherwise portability is out the window. So yes, I am trying to be efficient. Parabola cookers can cook food, or melt cookware. It is important to place cookware above or below the melting effect of the tight focus. Stray reflections are an issue to the cook's eye, one of the big reasons to control where the light goes after first bounce. Ideal size depends on how many eaters there are. The Gibertini SE series in 75/85/100 are about right, and have a fold down LNB arm as well.

If you want to try this, bolt the LNB arm do an upright 25mm x 50mm steel tubing that is anchored or weighted to the ground so it provides stability enough that the stew pot doesn't throw things off centre and fall out. I use a wire cage utensil holder big enough to hold a 125mm stainless steel canister painted black for a cook pot... The reflector will be on its back looking somewhat upward, and the pivot point allows for angular positioning of the dish relative to the post. Your cook pot will hang from the post where ever it needs to be to place the lower part of the pot in the focal point. I have a nice design for a less powerful cooker made from a 22 inch high bay ceiling light, with snap on glass cover.

 

[archive10]

Solar cooking does rely on a particular food product though , parabolic dishes provide a point focus , but for something like a hot dog or a pot stew, it requires diffusion into at least one other plane so you may be looking at toroid shapes, or stirring via a motor to do the deed.

Or mount the cooking vessel somewhat closer to the dish prior to the reflected waves reaching the focal point - or preferably a bit beyond the focal point to avoid obstrcuting the path of the incoming light - where you should have a nice circular area of heat.

Edit: Ah, I see OP already pointed this out

 

[William Moore]

Right....the hard part is getting a clean, un-scattered light pattern about the same size as the bottom of the pot....and polished AL is a lot better than foil tape. The SS canisters I use for the pots are tall relative to diameter and aiming at the lower half does a decent job without burning holes in the metal.

 

[Channel Hopper]

If you want to try this, bolt the LNB arm do an upright 25mm x 50mm steel tubing that is anchored or weighted to the ground so it provides stability enough that the stew pot doesn't throw things off centre and fall out. I use a wire cage utensil holder big enough to hold a 125mm stainless steel canister painted black for a cook pot... The reflector will be on its back looking somewhat upward, and the pivot point allows for angular positioning of the dish relative to the post. Your cook pot will hang from the post where ever it needs to be to place the lower part of the pot in the focal point.

Triax is out of the running then.

 

[archive10]

High efficiency lets you build smaller, otherwise portability is out the window. So yes, I am trying to be efficient. Parabola cookers can cook food, or melt cookware. It is important to place cookware above or below the melting effect of the tight focus. Stray reflections are an issue to the cook's eye, one of the big reasons to control where the light goes after first bounce. Ideal size depends on how many eaters there are. The Gibertini SE series in 75/85/100 are about right, and have a fold down LNB arm as well.

If you want to try this, bolt the LNB arm do an upright 25mm x 50mm steel tubing that is anchored or weighted to the ground so it provides stability enough that the stew pot doesn't throw things off centre and fall out. I use a wire cage utensil holder big enough to hold a 125mm stainless steel canister painted black for a cook pot... The reflector will be on its back looking somewhat upward, and the pivot point allows for angular positioning of the dish relative to the post. Your cook pot will hang from the post where ever it needs to be to place the lower part of the pot in the focal point. I have a nice design for a less powerful cooker made from a 22 inch high bay ceiling light, with snap on glass cover.

Just curious - a lot of discussion on this forum relates to parabolic antennas tracking the sat arc.
How do you get the reflector of a sun-cooker to track the sun when you need to cook anything that takes more than a couple of minutes?
And how do you control the temperature of the cooking vessel? Do you only cook stuff that boils in water?

As an academic contemplation, I can see a "stove"-mount that tracks the sun (probably a computer controlled El-over-Az mount), with a pot hanging from some suitable arrangement allowing it to be moved up and down in the focus, giving control of more or less sunlight/cm2 to adjust heat irraditation.
And of course a short-time mechanism to compensate for clouds etc.

Now there's a challenge for the polar mount builders of this site...

 

[blademedia]

Now there's a challenge for the polar mount builders of this site...

easy project use solar panel sun tracker sensors
How to Make a Control System for a Sun Tracking Solar Panel

 

[Channel Hopper]

Just curious - a lot of discussion on this forum relates to parabolic antennas tracking the sat arc.
How do you get the reflector of a sun-cooker to track the sun when you need to cook anything that takes more than a couple of minutes?
And how do you control the temperature of the cooking vessel? Do you only cook stuff that boils in water?

As an academic contemplation, I can see a "stove"-mount that tracks the sun (probably a computer controlled El-over-Az mount), with a pot hanging from some suitable arrangement allowing it to be moved up and down in the focus, giving control of more or less sunlight/cm2 to adjust heat irraditation.
And of course a short-time mechanism to compensate for clouds etc.

Now there's a challenge for the polar mount builders of this site...

Frying an egg on Tatooine will ratch it up a notch.

 

[archive10]

Frying an egg on Tatooine will ratch it up a notch.

Which begs the question: How big a dish would you need to boil an egg in moonlight?
(Yes, I know, the infrared does not reflect as well as visible light blabla...)

 

[blademedia]

some interesting diy solar tracking systems here, use dish instead of panel
LED3X Solar Tracker Assembly

like this one

 

[blademedia]

A few ideas here if you have no luck with dish, I like the solar grill idea
Build Your Solar Cooker | Solar Cooker at Cantina West

 

[William Moore]

Gibertini makes the OP125L(P) and OP150S, they come in both steel and aluminium versions.
You may find the used from time-to-time, but they are still manufactured in Italy, so perhaps a direct inquiry for a dish without coating might give good results?
(Assuming shipping is not too great a problem).

Gibertini SRL :: Satellite Antennas and Accessories

They emailed me, they say no reps in USA, and apparently no interest in solar....

 

[Channel Hopper]

They emailed me, they say no reps in USA, and apparently no interest in solar....

You may be on a hiding onto nothing with this forum, the weather for the majority of mods and admin isn't exactly BBQ at the time of asking.

There are multiple threads in the techi section, which provide detail on the formulae/mathematical equations for parabolic design/fabrication. Are you able to set up a cottage industry yourself ?

 

[blademedia]

I'm going to use this old aluminium prime focus dish as a cooker when things warm up, it should polish up nice

 

[Vipersan]

Facinating ...but cerainly _not_ a project for Manchester ..
Now..if you could focus rain with a dish ???
A precipitation jet washer ??????

..'course ..there are worse places to be ..
What is the wettest place in the UK?

That pales in comparison to the 115cms of rain racked up by Cardiff - the wettest city in Britain. Glasgow (112cms) is second, Preston (103.4cms) third, and Huddersfield (102.8cms) fourth. Manchester comes in eighth - behind Plymouth and Blackpool, too.17 Oct 2014

 

[blademedia]

Facinating ...but cerainly _not_ a project for Manchester ..
Now..if you could focus rain with a dish ???
A precipitation jet washer ??????

..'course ..there are worse places to be ..
What is the wettest place in the UK?

That pales in comparison to the 115cms of rain racked up by Cardiff - the wettest city in Britain. Glasgow (112cms) is second, Preston (103.4cms) third, and Huddersfield (102.8cms) fourth. Manchester comes in eighth - behind Plymouth and Blackpool, too.17 Oct 2014

Yes up against it with uk weather, it will give me something to do i would only bin the dish otherwise, might manage a bacon and egg sandwich at some point

 

[William Moore]

Facinating ...but cerainly _not_ a project for Manchester ..
Now..if you could focus rain with a dish ???
A precipitation jet washer ??????

..'course ..there are worse places to be ..
What is the wettest place in the UK?

That pales in comparison to the 115cms of rain racked up by Cardiff - the wettest city in Britain. Glasgow (112cms) is second, Preston (103.4cms) third, and Huddersfield (102.8cms) fourth. Manchester comes in eighth - behind Plymouth and Blackpool, too.17 Oct 2014

Had a musician friend over here in USA for 2 years, when we lived in Arizona. He was on a church mission. Once the green mold flaked off, I was able to determine his true skin color....
He really wanted to stay, but apparently was not able to. Why is it so hard for honest english speaking people to emigrate here? If we let in more from the UK, we would be better off. Heck, I would even let in the Irish. We did it once, it seemed to work out..