Chriske

3 hours ago, Jonk said:

Try PLA, it’ll be strong and drillable.

Drillable yes, but do support it from the inside very well. If you don't, the drill will split the part when entering the inside perimeter..! That's because larger drills will force itself inward with the 'speed' of the drill's flutes. Smaller diameter drills will work.

On 23/10/2020 at 21:30, Jonk said:

I always tell people at work, if you can draw it, we can print it (within size restrictions)!

CORRECT...!!!😆

I'm installing Raspian-Buster on Rpi4's.
These Rpi's does each one thing and one thing only.
One Rpi serves as a music streaming-device in my workshop. A second one I use exclusively to brows the net. A third one I use to transfer images from one location to another in a network at our local Observatory. I make Focograms using one Rpi, then transfer it to another Rpi to beam it onto big screen for the spectators to see and discuss.
Another serves as remote server to activate the cooling of our bell-jar(mirror coating). Very handy when we want to coat a mirror and the cooling is already set to -10°C when we arrive at the observatory.
In the past I needed (small) PC's to all do these jobs. Now I only need a few Rpi's to do just the same for far less £££$$$...😃

32 minutes ago, stash_old said:

wouldn't try swapping with power on.

No not at all..!!!!😳😳😳

What I absolutely should add to this thread : a better solution in a case like this, it would be far better to use a 'small' SSD as main drive, and a HD as storing-device.
Although it is much slower a HD is far better to save and read/write very often. If you buy a good HD it will last a lifetime.
A SSD has a limited ready and write capability. Therefore it would be better to use it as boot-device. Booting OS and software from a SSD is way faster.
But for most users it is rather difficult to completely rearrange your computer this way. Don't even know if MS would allow you to reinstall your OS on another drive. (I'm Linux user myself).

That said, for most users re-installing all again from '0' : your PC will be even faster.

I know this is a astronomy forum, but as more and more items in astronomy are PC/laptop related and so more data needs to be saved/stored, I thought this post would benefit to you(us) all.
Thinking about RAW images, to name one.
not..?

Hi,

I know not the correct spot to post this item but in a way it is, because it helps storing even more data on your laptop, even when you're getting 'out of space' on your HD. Most of you, me included, uses USB-HD these days. But these things are rather slow.
I recently bought a CD-to-HD tray. Purpose is to replace the CD with a HD. Works flawlessly.
Remove that one screw on the back of your laptop(that one screw hold the CD-reader in place. And the good news is : most of the time that one little screw is marked with a 'CD-logo') pull the CD-reader out of that laptop and replace it with a HD or SSD. Booting again that new HD-SSD is automatically detected by BIOS and OS.
Not all CD-trays have identical shapes of course. But the good news is(again)  for every other laptop there's a specific tray.
Depending on the OS you're using, there's no limit of the HD-SSD size you can put in.

Yep, I thought might ask... No I didn't use my CD-reader anymore at all, for years now. It only sits there gathering dust, doing absolutely nothing.
And I think there are lots of people thinking now : yep indeed, when was the last time I did use my CD/DVD...😉

This is mine :
For a laptop 10+ years old.

The best action I ever did with my laptop :  erase Wintendo and install Linux, a few years ago now.  Never got to W8 or W10, and I was not planning to...😡
W7 was the best MS ever produced imo, XP second place. Both could be tuned, almost to the core of the system.

It's a few years now I use Linux Mint18.3 Xfce. It has the 'feel' of a W-XP machine.
It does everything I want I want it to do and more. And what's more everything I ever need is on board for free. If I need some other software that's not on board Linux-package I go and ask on the Linux-Mint forum. Literal minutes later you get a reply. These guys are super..!

And btw I had a great local helpdesk : Gina

To do my raytrace 'stuff' I always use 'Spotplotter'. A very small but powerful thing.
I could use 'Oslo' or other PRO-software, but it is over the top for just two surfaces, and you end up with the same result.

A few screenshots.

                       0.5° field - The circle in the centre is the Airydisk                                                                                                         0.12543°(your value)

On 05/10/2020 at 14:14, Astrobits said:

I think you will have to have a longer "back working distance" than that in your Cass calculation as it has to accommodate the radius of the tube plus the working distance outside the tube for focuser and camera.

Nigel

Indeed it as bit short.
But there is an easy fix.
I did a simulation and ended up with exactly the same optical(raytrace) result.
 

Lower the ROC  of the SecMir. to 595mm
Correct the CC of that mirror to -2.14
You'll end up with a distance of about 330mm instead of 250mm back focal length.
But : The telescope has a different end value now, it has grown now to f/25.5, so   F=6395mm.
This is just an example, you can play with these two figures as needed.

😳

Did not read the whole thread, sorry.
Could older camera's be used for debayering ..?

Overhaul all SaturnV rockets in our observatory.
A bit more detail in the upper parts of the rockets.

One last picture.
A fourth astronaut is added to HST today
Mission specialist Koen is busy installing HST's corrective optics...
C.O.S.T.A.R...😁

Added two second stages...

That wasp-trap was ok, but not efficient enough.
Made a modification and now it works just perfectly.
I'll show the drawing because it is not nice to see at, with all these wasps in it...😬

This is V2, nono not the one Werner has built a 'while' ago...
That little thing goes inside the jar to keep the wasps from escaping.

Hey guys...

Buy a printer 200x200mm bed, learn how to work with a 1.5mm nozzle and I'll send you the STL files. Printing time about 48 hours(SpiralVase modus)
I redrew this model myself, made 5 of these rockets. Don't remember how much I spend on filament. (see higher up) If I'm correct I've spent just under 100€ for one rocket. But most of it was spent on wood and paint for the consoles.
You also need a few threaded rods, nuts, washers, black paint, that's about it.
My SaturnV rockets are at scale 1:55, that's the largest you can get on a 200x200mm bed.

The last SaturnV I'll be printing will be at scale 1:33. With LUT, crawler and all it will be 4.1m high.

Just found this....😳😳😳😳
Is anybody buying this..????

I could make a living out of building these things I suppose...😁

With these two ends the falcon9 project.
Up to the next one...!

Busy painting these.

One is Falcon9 with Fairing and the other is with Crew-Dragon and trunk.
To be hung on the ceiling above the other two Falcon9 rockets.

Standard PLA is perfect to use in the sun, only use white PLA..!

A few smaller prints to be hung at the ceiling of our planetarium,

second stage, Crew Dragon, etc...

This is a picture of the two engines Falcon9 uses.
The smaller engines(9) for the first stage 'D' type thruster, and the bigger engine(vacuum engine) is used for the second stage.

While printing these I had an idea...🤭

I modified the big one, like this...

Added an empty pot of mayonnaise...

Still waiting for the decals to arrive, so I can finish this one.

Grab a headphone and while Falcon Heavy is busy launching and also returning set it as hard as your brain allows you.

It's not completely finished yet.
I'm waiting for the decals to arrive. We're also drawing the LUT this very moment.
And now I'm busy assembling the second Falcon9. That second one is no more then the landed first stage covered in soot and landing feet wide open.
Those two Falcon9's will be standing side by side.
The printed parts did not take to long. The main body is a PVC tube. The largest Falcon9 part is Fairing. But that didn't take to long as it is printed in SpiralVase modus.
The longest parts to print (and also in time) were the landing feet. It was a challenge to warm them up an pushing them against a dummie tube. The feet need to have the correct size and shape, there's no room for error. They must connect side by side in the brackets and still be able to rotate the feet up and down.
It took an estimate 22 hours to print all parts.
It's a completely different story compared to the SaturnV rockets I made in the past. All parts of SV were printed. SV took about 48 hours each to print, again in Spiral vase modus and using a 1.5mm nozzle.