Chriske

Indeed Robert,

All is done in Inventor. It's an old one. I got it from my employer about 10 years ago. Still use it every single day. It was in fact part of my job.
Although it's an old one it does what it's suppose to do and more...
The most rewarding item is 'Assemblies'. It gives you the ability to see in and outside to inspect  the project. It also detects collisions if needed. There's also a strain-detector.
There's in fact to much to mention...love it.
There's only one minor point. It does run only in Win.(I'm Linux user) So I run Inventor in a VirtualBox.  Using it in a VB I don't see any difference, it's in fact as fast as in a 'normal' Win.

8 minutes ago, Gina said:

Mmm.... Tricky.

I know, but I love this kind of stuff..., I love the challenge.
It's a rewarding instrument. It beats a long refractor of the same size easily.

The secondary holder needs a angled cut to allow free passage of incoming rays from the sky to the primary mirror. It's a very close fit.
The very last thing after collimation is to free that incoming lightpath from the secondary holder. To do this one of the adjustment screws of the primary mirror must be installed in the meridional plane. When done the angle of the primary mirror is automatically correct(ed).

Cutting the oblong hole in the secondary tube. That hole is in fact a cone shaped cut in a cylinder.  Even in Inventor not an easy task. For every other Kutter that oblong hole is different.
But once I have that drawing, I can print that part of the tube to use that printed part as guide to draw that hole on the StSt tube itself. To be sure I need to enlarge that hole a bit, taking care the light-path coming from the primary is not partly blocked.

Hi,

Lots of things have changed these last days while drawing.
First of all I've added three fans to cool the scope very quickly.  Powerpacks in the scope. It's a near open scope, so it's handy to dry optics with these fans if necessary.
Added also is a laserpointer. These scopes are very difficult to aim without an aid. (I never use finderscopes) - ( I use my lasers very cautiously, never point at people, planes, etc. And when I lit them it's only for a few seconds. It's tool, not a toy..!)
It's not a classic focuser. I didn't want to mount  a large focusing-device on top of that most upper tube. So I designed a Crayford-like focuser. I call it : 'Inversed Crayford'. (Maybe it's been done before, don't know) The focuser is nothing more than a tube containing 6 ball-bearings and a focusing rod. In fact just the same as a regular Crayford. Point is, while focusing I move the focuser itself +eyepiece up and down. This way it has a more 'elegant' look.
That eyepiece sits angled in it's focuser, it's part of that Kutter design. Eyepiece is tilted 3.86° away from the observer.
To insert the eyepieces I'll be using on-axis adapter. Purpose is to mount eyepieces in the exact centre of the optical train. So there's no thumbscrew required at all. These adapters are 'springloaded' in both ways, in- and outward. Also own design.

That's it for now, still some more drawing to do...

It's not very difficult to make this type of telescope.
There are a few different types of Kutters.
Actually the one I'm making right now is not really a Kutter telescope,  it is called a Neo-Brachy telescope.
Kutter read about it and improved the concept. The most important change he made was adding a correcting lens between secondary mirror and eyepiece(somewhere in the middle).
The Brachy version I'm making is a anastigmatic one. Advantage of this type is : There's only one mirror-set to make. Meaning the concave mirror is the primary(of course) and the tool is used to make the secondary. Both mirrors have the same curvature and on top of it both these mirrors can stay spherical.
A Kutter's primary mirror on the other hand  is a parabola(50%), so in fact elliptical. The secondary can stay spherical. The corrector is a plano-convex lens. Convex side is very shallow, and that lens is also wedge shaped.
There are other possible configurations but the one I'm building right now is the closest to the Kutter version. I do like it very much.

Unfortunately these 'planet-killers' can't be taken outside very often. They need steady skies. If the atmosphere is quiet and steady they will give you breathtaking superb images. Nothing can compare with it..! Because of it's long focus contrast is very high.

In the past I've already made a couple of these scopes mostly 150mm. Disadvantage is it's size. A Brachy is always on the long side.
I also made this one almost 2 years ago. I also was busy making a bino version of that one, but it's on hold now.
It will look like this :

17 minutes ago, Peter Drew said:

Also following with interest. I've had some experience with a 6" Yolo version. These TCT's (Tilted Component Telescopes) do have excellent false colour free, high contrast images. Like folded refractors they can be a challenge to collimate initially.   ?

Good optics too that yolo. In the early days I've written to Mr Leonard. Was no mail in those days.
Same as the other long scopes..

This one is not 12" but a 6"

Optics well done en tuned these Kutters are superb telescopes.
In our local observatory there use to be a 10" version. Focal length 5 meter.  Moon at primary focus fitted just on the negatives of my 6x6 camera.
It was a 'real' Kutter. To correct residual coma and astig there was a correcting lens installed tilted about 20°. Focal plane is tilted about 7°.
As you can see in the drawing, Focal plane of my 120mm kutter is tilted almost 4°, also to correct residual errors. But not all is corrected(there's no correcting lens in mine) But all ray's stay well within the Airydisk, no problem there.

Another one one my wish-list is a Gregorian. Two concave mirrors, one is a parabola and the secondary is an ellipse.

Gregorian 150/f25

Compared to a (very long)Newt of the same size F=2000mm

f/31, so planetary and Moon observations only.
Busy grinding the optics.
And at the same time designing the telescope itself.
This is V1. The light leaving the secondary tube passes through the primary tube at an angle of 11.30°
The yellow transparent cone is to guide me where I need to cut that oblong hole in the secondary tube.
The focuser is a new design that has never been done before. It goes up the small upper tube. I'm not planning using 2" eyepieces at all in this scope.

It will be difficult I think because of that big hole. These printers can handle straight bridges, but in your case a bit of that circle will sag.

You'll need a bit  of support if you print it this way.
Looks good..

Was away, looks so much better..!

1 minute ago, Gina said:

I see what you're saying - it's relying on good inter-layer bonding which PETG is famous for but... 

Indeed....but....

It has noting to do with weight Gina, not at all...!
I'm always very careful myself when designing such a clamp.
Point is : When the screw is fastened a bit to tense the upper part could break. Maybe not the first time, but in time it could break.

To be strong in the direction the screws are mounted you should print it in the opposite direction. Whatever you do, how hard you turn that knob, there's no way it will ever break. Maybe, just maybe it well bend, but it never will break.
I would not over-engineer it at all myself either, but I would print it in the other direction, logic, not..?
If it were a part of no importance I(maybe) would print it just the same. But in this case, well....

Not a good idea imo Gina, to make this clamp very strong you need to make it in three parts and bolt together.

On 04/02/2019 at 00:11, Gina said:

I might make a combined print for holding camera, focus motor and electronics.  That would want just four screws to attach it to the dovetail bar.

How so..?

Resin for these printers is rather expensive ?

1kg(750ml)  :  79€
1kg of PLA 19€

Yep, I'll stick to FDM too...

33 minutes ago, DaveS said:

Edit: I'm not looking to print massive stuff, but small precise parts. I've an Amici prism that I'd like to build into a spectroscope, and this looks like it could be precise enough for printing components.

Dave,

Why not just build a very small printer yourself..?
Like I said higher up in this thread, my pall Marc has built one. Max printable part 100x100x100.

I just finished building exactly the same as Marc, except this new one can print 100x200x130mm max.
I've built it for a friend,  Who's planning to use it exclusively for modelling train-parts.
He will be using it with 0.25 and 0.15mm nozzles only.
This very moment there's a 0.4mm nozzle installed. Walter(the new owner) never used a printer before, so he has to master the skill first. After a while he can change to smaller nozzles.
In this extruder I designed a fast swappable E3D hotend. So he only needs to remove the parts-cooling-duct(2screws) and the hotend itself(2screws) and that's it.

17 minutes ago, Gina said:

there's still the size of the reel of filament.

Come on Gina, a bit of fantasy and you could install a nano-printer inside a 2.2kg ColorFab reel. Lots of space there...
And to have some flexibility I would allow some parts to stick out of the reel...

11 hours ago, Alien 13 said:

Loving this thread but I wish someone could make a printer that could fit in a 4 inch cube, how hard could it be?

Alan

My pal Marc made a printer able to print 4 inch cube max.
I know, not answering the question, but at least my sentence contains '4 inch cube'...
It's a gorgeous little thing and does work very well.

Mine does 200mm bridging just.
150mm is no problem at all.

23 minutes ago, jbrazio said:

BTW, in our plastic world.. they work nice even in PLA, here is a good channel about the topic: 

 

They would work very nice indeed, on one condition only. The perimeters of your print must be ab-so-lu-te-ly perfect..!

We abandoned these along time ago because of : way to much friction compared to regular gears. They  do look nice and very impressive but in our 'plastic' world they have no value at all. In the real mechanical world gears with angled teeth are mainly used to reduce noise in a reduction unit, and also because they're stronger.
Most important issue in a project like this : hole should be as concentric as possible with the outer perimeter.

Whatever you will use to draw your parts, point I want to make is, draw it all yourself.
Downloading thingiverse files you will end up with parts that cannot be edited if you need to.
A lot of these thingiverse files will end up ok if it's a standalone thing. But printing complex parts or assemblies, 99% of the time it will not work. It would work, but only if you slice it exactly the same way as its owner ad needless to say using other filament and most of all another printer, it will not work.

For instance If I draw a focuser, some parts need to fit into eachother. If after printing I cannot assemble parts because of error somewhere, I re-open that file correct/redraw and reprint until ok. Sometimes I end up with three four, or five corrections until perfect.
It happens a friend asks me to add a feature to that focuser, well I re-open, edit and reprint as requested.
You'll never be able to do that with Thingiverse files.

There is some software MeshMixer(Autodesk) that lets you edit stl's but it is very limited what you can do with it.

Needles to say I never print Thingiverse files, never will. A large part of the fun is drawing your own projects, be it small or large.
The hard part is learning how that 3D-software works, but you ill benefit from it a lot once you master it. And again (in my case it is) it's part of the fun.

Well no Gina, but depending on the height of your renewed Giant, you'll need a crane to lift these things...
And not to forget, we're only getting older...aren’t we..?

And btw ordered some more PLA, couldn't resist myself.(at these prises..)...?
Bad news is : prices of that ColorFabb economic-filament is at it's regular price again. 42€ for one 2.2 kg reel.