Chriske

33 minutes ago, Mandy D said:

@Chriske I fell about on the floor laughing as I read your story about this ingenious telescope. I can just imagine the look on the man's face when you asked to have your gin bottle bottom aluminized! I have to say that I love the concept and I think the finished product has a certain beauty. Maybe, you have started a trend. So, how does it perform optically?

26 minutes ago, Mandy D said:

@Chriske I fell about on the floor laughing as I read your story about this ingenious telescope. I can just imagine the look on the man's face when you asked to have your gin bottle bottom aluminized! I have to say that I love the concept and I think the finished product has a certain beauty. Maybe, you have started a trend. So, how does it perform optically?

Well, as a matter of fact when my friend, who loves Bokma gin, saw my little scope for the first time he started grinning and a few days later he gave me another set of (empty)Bokma bottles.
He said, I know you like to build bino's, so make me one please... Needles to say ...I'm tempted...very...😄

Well, this is how I rebuild this little scope. Much nicer then the old one. It has more elegance with these printed parts imo...

I added a few items :
-It has a Helix focuser running 6 ball bearings.
-The dispenser is an improvement imo...😉
-The 'primary mirror' has a very smooth collimation system.
-The only thing to do is adding a light shield opposite the eyepiece.
-and yes, I need to glue a new 'Bokma' label at one side of the 'telescope'.

-Problem is... I don't like Bokma at all. But I suppose I could fill it up with something else, like Martini...?

After silvering I had a quick peek through it (after 30+ years) and I must say I was very pleased with the quality of this little 'scope'

This little scope has a square mirror and also a square secondary, so now the million dollar question :
Will I see square diffraction patterns...???...🔷

😄

Two mirrors silvered today. We used the 'Spray silvering technique'.
Works fan-tas-tic..!

This is my buddy Fred blowing off the last water drops.
It takes about one hour to finish a 400mm mirror.

30 minutes ago, Mandy D said:

@Chriske Thank you for the further explanation. Are the plane mirror and screen both tilted at a slight angle to the spherical mirror? I guess focal length is rarely, if ever, critical as long as it can be measured and known where necessary.

I look forward to seeing more about this project as it progresses.

Only the flat is tilted toward the sun and projects the solar light toward the spherical. The spherical and screen are parallel

32 minutes ago, Elp said:

Is there a solar filter somewhere or is it screen projection?

screen projection, no filter

The size of the sun is about 470mm.
Marc who made the primary mirror aimed at 40 to 45m focal length. Measuring was done with a 120mm diameter spherometer. The goal was grinding to 0.022mm on the dial gauge, but I suppose during MOT he ended up with a longer FL. But that's ok the sun will be a little bigger, we don't mind.

For both mirrors there's no tube involved at all. The screen has a nearly 1m tube hanging about 2.5m high. That tube is blackened at the inside and has a oblong hole at the bottom to allow the observers to see the sun from standing position on the pavement.
I'll post some more pictures very soon.

The setup is very simple. This drawing is NOT to scale, in this drawing both mirrors should be farther away from each other. The flat and the screen are very near (at left). The spherical at right is also standing at 2.5m high.

This test setup was only to find its FL.
The mirror stands on a very old Vixen mount.
The tapes will be replaced with strong hooks of course.

Busy making a solar'scope'. Optics nearly done, only silvering of the two optical parts needs to be applied.
There are three parts involved, one 400mm diameter flat, tracking the sun, one stationary spherical mirror (400mm f/137.5) and a 500mm square white screen.
All parts are mounted just high enough so the spectators(during open door at our observatory) cannot walk through the light beams.
Both mirrors will be silvered to achieve maximum reflection.

Tracking the sun will be done using an old Vixen mount.

Almost finished...

These will be hung aside our 1:10 scale Orion capsule. One more to go.
I know not the correct suits but it has to do for now. They will be replaced in the near future.

Working, working, working....

Busy redrawing using a 3mm pitch...

Need to adjust my callipers...

...or my eyesight...😃

🥸

looking a second time and more closely to this print my printer did the job very well.
Using a smaller layer height it would even be better. Say 0.1 instead of 1.5 as I used now.

Anyway I'm not going to. As I told before I'll use the same layer but a larger pitch instead.

Measured value of this pitch I think it's about 0.8mm... correct...?

The idea making a Helix this way is very nifty indeed but imo a pitch this small is not practical at all while focusing.
Lets assume working with a 1mm pitch. Turning the barrel say 1/8 of a revolution, you'll end up with a axial shift of only 0.125mm. Using a camera with a pitch this small would be perfect I agree.

Using this focuser for visual observing, or even with little bit a coarser pitch, again, it is not practical, it is to slow.
In the past I made rotating Helix focusers with a 3mm pitch and it worked very well.

I'll try and redraw the two threaded parts with a coarser thread.

Can't print this thread, to small for my printers, pity...  Even with a 0.3 nozzle. I'll try one more time lowering Extrusion Multiplier.

Finally found some free time to start testing this Helix.
Sorry about the delay. I was very busy these last months.
Before starting I have a question ; you added a  13mm long thread into the lower part of the casing. It is not needed at all imo, correct..?

Could it be zamak..?

ZAMAK (or Zamac, formerly trademarked as MAZAK^[1]) is a family of alloys with a base metal of zinc and alloying elements of aluminium, magnesium, and copper.

Zamak alloys are part of the zinc aluminium alloy family; they are distinguished from the other ZA alloys because of their constant 4% aluminium composition.^[2]

The name zamak is an acronym of the German names for the metals of which the alloys are composed: Zink (zinc), Aluminium, Magnesium and Kupfer (copper).^[2] The New Jersey Zinc Company developed zamak alloys in 1929.

The most common zamak alloy is zamak 3. Besides that, zamak 2, zamak 5 and zamak 7 are also commercially used.^[2] These alloys are most commonly die cast.^[2] Zamak alloys (particularly #3 and #5) are frequently used in the spin casting industry.

A large problem with early zinc die casting materials was zinc pest, owing to impurities in the alloys.^[3] Zamak avoided this by the use of 99.99% pure zinc metal, produced by New Jersey Zinc's use of a refluxer as part of the refining process.

About NASA's new space suits

Yesterday during pre-opendoor there were two astronauts walking amongst visitors in Urania(our observatory)

Koen wore a replica of SaturnV space-suit and the second person(me) in a brand new suit that will be used for the Artemis crew.
The suit was made by my wife(Nicole) btw.

And this is the actual crew for SLS NASA's second mission.
To be clear, the SLS 'astronaut' in the pictures above is not one of them...🤣

Meanwhile a second SaturnV is in the making, also scale 1:33
The little one is 320mm high.

In the picture(right) is also the very tip of Orion's escape rocket at scale 1:10

Meanwhile printed at scale 1:10...

Printed @ scale  1:10 this Service Module is about 500mm in diameter.