Chriske

The 'tube' of this scope will be made out of 18mm plywood.
The odd shaped side-panels will be made with a Maslow.
These panels will be made very accurately.  I expect their shape will be well within a millimetre correct. So when the mirror cells are all mounted in the tube, the mirrors to be almost at the correct location, requiring only a minimum of collimation.

Thanks to you all for the support and the kind words..😉

Together with my son Steven busy grinding the optics for this telescope.

It's a bit strange that someone wants to design such a printer. It must have been a time consuming design/built. Do not misunderstand me, it is quit an achievement and I take my hat of for it. Well done..!
But as I said higher up, I'd rather spend more time in searching to make my prints better looking. That alone is very time consuming, especially with these big nozzles.
 

48 minutes ago, Gina said:

Does that mean you're going to build a bigger printer, Chris?

Yes, but not to big, I'm thinking mostly Z-higher.

18 minutes ago, Dr_Ju_ju said:

If you have the space, then you could consider a Hang Printer (https://hangprinter.org/) ……   

Seen it, but I don' believe in that project.
There are to many issues with it.
Most important thing for me is that the perimeters are absolutely perfect. I know many people will react something like :  Nice perimeters with a 2.5mm...? yeah right..!
To me a nice perimeter is one with no issues, ripple, moiré, ghosting, etc... And that is what most printers suffer from, one or more of these. I design my own printers and make them very stiff. Even my smallest printer I have difficulty lifting it up. I dare to say I do print perfect perimeters.
Well, the perimeters printed with my bigger nozzles, yes indeed I can clearly see the layers, but these layers are all consistent, very regular, in fact very nice. There are no issues with the perimeters I print at all. If there were, I throw that part away, change whatever there is to change in the slicer settings to correct and start all over...
Needles to say I wont be printing small and detailed parts with it...😁
Don't think a hang-printer is capable of delivering these regular perimeters.

Busy working on a big astro (printing) project. It'll be 3.2 meter high, (yep 10'+)
Should be finished Sept 2020.
So that gives me plenty of time to test these 'little' guys... (But first I have to build a printer that goes with it.

Left is a 1.5mm(I have already one in use and works absolutely perfect) nr5 is 2.5mm and far right as comparison is standard 0.4mm nozzle.)

11 hours ago, Peter Drew said:

Looks like visual use is, thankfully, much more tolerant of aberrations  than imaging.    😀 

Indeed.
At the very centre these DK's are very good..!

3 minutes ago, Peter Drew said:

Whilst acknowledging the superiority of the Stevik-Paul system, I'm surprised that the plots look so bad for the Newtonian and the Dall-Kirkham. I have a 12" F8.5 Newt and 12" F20 D-K and don't notice coma over a 0.5 degree field visually.   🤔

Take a picture with it an you'll see. A starfield will reveal that typical Newt error
Visually you should not see it as in the ray trace.
But there's a tool to get rid of that coma, coma-correctors.

This is the ray trace is of your Newt Peter.

Most probably there's corrector somewhere in that Dahl-Kirkham of yours.
Without that  corrector it would look like this :
I know it's a 10" f/18, but the longer these DK are made the worse it gets.

Comparing with other telescope types, when all is correct : FL, distances between mirrors and angles, nothing can beat a Stevick-Paul.
This ray traces reveals it all :
The small circle in the centre is the Airydisk.
FOV is always 0.5°

Original Stevick-Paul

Because of its length, almost 2.5meter, I have chosen to use the folded version.
Not perfect but close.

Compare it with a Newt, even at F/10 it has severe coma.

A Original Cassagrain

Dahl-Kirkham

9 minutes ago, Peter Drew said:

With spacings being critical I would expect that focal lengths of imaging surfaces to be equally precise.     🤔

Indeed.!
That is why for this kind of precise work I always use a 120mm diameter spherometer combined with dial gauge capable of measuring 1/1000 of a millimetre.
Still during polishing constant monitoring all FL is required.

2 hours ago, lukebl said:

Interesting but surely, with four mirrors to deal with, collimation would be an absolute nightmare?

Not only standard collimation will be a nightmare Luke.
First thing to do is arranging the mirror so they're at the correct distance, within a millimetre or less. That's is a very important issue.
So all mirrors should not only be adjustable with their three 'standard' bolts but on top of it also moveable away from each other(or nearer)

1 hour ago, Mick J said:

Go for it Chris,  what a good idea and great way to remember your friend Marc.

That's the idea Luke...

11 minutes ago, johninderby said:

Think the complexity puts them off.

Think so too.
Been pushing glass for over 35 years now, so I like a challenge...😁

Hey Julian,

There's no lens involved, so there's no chromatic aberration present.
There's only one flat + 2 concave and 1 convex mirror.
You couldn't possibly see that of course, my mistake, I should have mentioned more about the configuration, sorry again.

Hi,

Busy drawing/building a scope my dear friend Marc was 'in love' with but never found the time to actually built it. Marc died only two weeks ago.
It is a rather odd looking scope, but is optically the best ever designed.
Looking at the spot diagram, no other telescope will ever beat this telescope type.
Anyway, this is what it will look like when it is finished. This scope is 1.7m long.

The large arrows is the COG(according to Autodesk-Inventor)

Taking a way one side panel, it looks like this

On 05/12/2019 at 00:22, upahill said:

I can highly recommend the silicone socks too for keeping the heatblocks/nozzles fairly clean externally. Got mine included with the E3D kit, but available for a variety of hotends on eBay.

+1

Thanks to you all very much for all the kind remarks and messages.

Aside been very good friends we were a very close 'two men team'.
I did all the designing and drawing work, together we grinded our glass disks side by side, and Marc was the electronics man.

As a matter of fact, we spent many hours sitting in my workshop in front of our two 24" MoM's.

Hi,

My best friend Marc passed away a few days ago.
In his honour I will continue and finish this(his) Gregorian. He was very eager to start using this scope.
Marc joined me building telescopes in '82. He was 20 back then. We never stopped grinding and building. We made 'a few' scopes together..!
Hard to believe he's gone...

Chris

Why not print these two overhanging parts separately and bolt it together with the main body.
As you're doing it now there's lots of support needed. Wonder if you're be able to remove it easily.

How are you going to print this one, I mean what is the contact surface with the bed..?

I always use selfmade linear-bearings. It's nothing more then a little (printed) block in which 6 small ball bearings are mounted. Two of them(in each linear bearing) are adjustable to rule out all play on all axis. For the X , Y axis and the extruder-unit I need 36 ball bearings. My first printer still runs without any problem and need no maintenance. And there's no wearing-out at all.

4 hours ago, Chriske said:

Just installed Raspbian-buster on a RPi4 4Gb. (Tested it before with a RPi3-B.)
Works very fast.
Going to use it do drive three 3D-printers at the same time.

Oh and btw, there's a special firmware for these RPi-4 in case you do install a fan on it.
That fan does a good job and is a huge difference compared to that large cooling-fin..! That little fan does a far better job.

Just installed Raspbian-buster on a RPi4 4Gb. (Tested it before with a RPi3-B.)
Works very fast.
Going to use it do drive three 3D-printers at the same time.

I'd split that part in two and bolt it together with to small bolts, nice and clean parts.
Did a quick drawing