Chriske

19 minutes ago, Mognet said:

module adjustment_thread(height, threadTolerance = 0) {
    threadDepth = screwThreadDepth - threadTolerance;
    innerRadius = rScrewThread - screwThreadDepth - threadTolerance;
    
    function ra(x, z) = [x * sin(360 * z), x * cos(360 * z)];
    input = [
        for (lp = [0:0.05:1]) ra(innerRadius + (threadDepth * lp), lp / 4),
        for (lp = [0:0.05:1]) ra(innerRadius + threadDepth, 0.25 + lp / 4),
        for (lp = [0:0.05:1]) ra(innerRadius + (threadDepth * (1 - lp)), 0.5 + lp / 4),
        for (lp = [0:0.05:1]) ra(innerRadius + 0, 0.75 + lp / 4)
    ];
	
    translate([0, -adjustmentBlockPlateLength, offsetToTop - bodyThickness / 2]) rotate([0, 180, 0])
        linear_extrude(height = height, twist = -(height/(screwThreadDepth*4)*360)) 
                polygon(points = input);
}

 

Not my cup of tea....😳😳😳😳

ok, now I'v got it..!  I thought the upper grey and black part were also printed...silly me...😁
Suggestion, change the threaded rod with something more stable, as Peter also explained. I'd print a wedge to fill in that gap + a little possible polar tuning. Or is there really need for that long threaded rod..?

That rod btw: nice print, very nice print indeed...!

Hey,

Nice 3D-print project. Could you explain a bit more how this tracker works.
I can't figure out how you track stars with this device(it's probably me, I know, sorry...😳)

One row done, seven more to go...
Need to buy 470 nuts and bolts M3...😯

And while we're busy drawing and printing SaturnV parts, I have some spare time at hand so I started building JWST, same scale as HST I made a few years back(1:7). In this project there are (almost) no printed parts.
JWST will be 3m long and  2m wide. The primary mirror will be almost 1m diameter.  Lucky me these hexagonal mirror are for sale, they have a 'golden' reflection layer and on top of it they do have the correct size for this model.

The only printed parts for this project are the primary mirror holders. These holders have different angles to simulate the curve of that 1m mirror.

For testing I use regular mirrors to avoid scratches. When all is done I'll glue the 'golden' one in place.

These (72) panels will be screwed against the elevator shaft. Only the front panel will have doors of course.
At the left there are data lines.

.

8 minutes ago, tomato said:

Those cleats from the crawler track give some idea of the scale, awesome. 
Just out of interest, how many spools will this consume, and I wonder, how many 3D printers?😊

How many printers..?  Five, Peter has one, Michel also and for the moment I have 3.
How many spools do we need, well don't know yet, but this project will consume lots of filament.

Cool.!!!!??????????????
Ok there are a few others going even higher but this SaturnV ....one word : IMPRESSIVE .!!!
What about this one....

1 hour ago, Ouroboros said:

How are you going make the liquid hydrogen and oxygen?  

We'll see about that in a few weeks, but you forgot to mention petrol. The Crawler runs on petrol...😉 That crawler consumes LOTS of it..!
In case of liquid hydrogen and oxygen shortage here, I'll call my good friend Elon..😁

Busy building one last SaturnV.
This one will be 4.2 meter high. That includes the Launchplatform and the Crawler.

In this assembly these two last two parts are shown as a brown and a blue block. Busy drawing...
SaturnV already partially printed.
 

Peter is busy drawing the lower(conical) part of the LUT.

Michel is busy drawing the connection parts at the end of the swing-arms

I already started printing the caterpillar-shoes for the Crawler and also the central elevator walls.
We'll need 464(!) of these shoes...
461 to go...

After a quick search found a few pictures from long ago...

Here you can see there's no mirrorsupport at the perimeter of that 10". The mirror is held in place by the central bolt that is glued at the back of the mirror.
Just below the mirror you'll see the neoprene ring (the pusher part of the flex unit).

If it is a f/4 mirror you should not flex it.
A while ago I posted a thread called 'Printsonian', well that was a flexed 10" f6 primary mirror.

5 hours ago, Honeybadger152 said:

I don't suppose you have any before and after images Chriske? Demonstrating the improvement in optical accuracy?

I have been searching the net far a wide just for some sort of practical demonstration but can't find much at all.

I do have images somewhere, need to search my HD's.
But it works just perfect. As a matter of fact using this technique you easily can pull the mirror to any CC you require, from ellipse to hyperbola, as long the mirror is not to thick.
That's the beauty of the system.

I know Nigel, but I do have a coater myself(lucky me..😃). Had never any problems coating flexed mirrors at all.

Never tried it myself(!) but maybe this is a easier way.
Going to try it one of these days.

Collimation of the primary mirror is a classic push-pull system.
Secondary mirror is a completely other system. There was not enough room for a push-pull so came up with something completely different. I've actually used the classical push-pull principal, but in completely different way.

This is the scope with it's top cover on.

Top cover removed and the scope tilted to see inside the collimation part.
All collimation holes, side by side.

Seen from the other side.
The red parts is mounted in the big telescope unit and rotates in only one direction. It is secured with one push-pull set of bolts
In the lower right drawing you see two parts. At the far right in the 'assembly2 drawing' you'll see somewhat smaller hole. That hole allows the blue part to rotate just a little bit. The rotation in the drawing is strongly exaggerated of course. The rotation of that  blue part is done with the two push-pull bolts at the far left. That central hole there has noting to do with that last collimation.
For that last collimation I only needed one set of push-pull now that I come to think of it.

The difference between the classical collimation system is that I tune in only 2 directions instead of three.
And again I could remove on set of holes in the blue part.

As a matter of fact, many years ago it used to be standard procedure during telescopemaking course at our local club.
There are many things to consider using flexed mirrors.
The procedure has to be performed ab-so-lu-te-ly perfect. There no room for error.
After a while we abandoned the procedure because some course members were to sloppy during the gluing procedure.
But there's a reason why you should not do this. When a flexed mirror need a new coating, all companies will refuse that mirror. Reason : they will not put your mirror with a neoprene disk glued on it's back in their coater.

Made a small telescope for our youngsters. At the moment it's only a 'paper version', Just started printing the parts.
It is a 75mm f/20, So basically to watch the Moon and maybe a few planets.
The pole is 25mm thick aluminium.
Main issue was to make this little thing as cheap as possible.
The mirror I made for this scope was a 250mm f/6 spherical. After final polishing I used a 75mm diamond coring bit to drill out  7 smaller mirrors.
I chose this f/value because it has a rather good spotdiagram. The central spot fits exactly in the airydisk(somewhat smaller in fact, not absolutely perfect), but good enough imo.

The focuser is of own design. There's no focusing knob. Focusing will be done by pushing the eyepiece barrel very slowly up or down. While moving up or down I need to rotate that barrel very slowly to have a smooth action. I did something similar in the past and it works very well.

To tune the scope the very first time you need to lay the scope on a flat surface. All three parts do have a plane at the side. Pushing the scope firmly to the flat surface you need to fasten these three parts(mirror holder, bearing part and the focusing unit) to the main pole. Next you need to collimate the optics.

This is the plane at the primary mirror holder.

Focusing unit and secondary mirror combined in one part.

To hold the eyepiece barrel in place there's a spring involved

Focusing unit,  friction between the unit and focusing barrel should hold the eyepiece in place.
Cost to print this focuser : 0.36€

Scope seen from the business end ...

Shortly I'll start posting about two projects..

Next project has just started...😉

let's try again...

On 18/09/2021 at 16:49, Stub Mandrel said:

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As JamesF already said, under a cover it gets rather hot. But in the open and backing sun white PLA will do the job.
I have lost of stuff printed in white PLA, and for many years now there's no degradation at all. And no, these parts are not in the shade at all. most of them are even all day long in the backing sun...!

Once more I'll post a few pictures of a test I performed years ago.
Tested PLA, ABS, nGen. Put it even during a heatwave all year long in the sun with a load of one kg.

Started in March (if I'm not mistaken)

These 6" rings are hollow. The perimeters are just 0.8(!)mm thick.

Started with 0.5kg

a few weeks later I filled the bottles so now 1kg.

midsummer

...and a few months later...

And the winner is white PLA. As you can see it is also a bit deformed. But after it was released from its load it (almost) got back to its original shape.
The others did not. Needles to say, what if I had used white ABS or nGen...? Who would have won.....??
Point is I wanted to test white PLA in the sun.