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  #1  
Old 03-04-2015, 05:29 PM
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ags_ (Phil)
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508mm Imaging Newt

This is my 1st ATM and I have dived in at the deep end. First a little about my reasons for starting this project. I began this new hobby only a couple of years ago after selling my boat and retiring from target rifle shooting plus at 65 it was time to slow down from my job as an electrician. I had an interest in astronomy so bought a 5" Meade and enjoyed using it for a year before aperture fever grabbed me. I had the opportunity to by a 14" Meade for a reduced price and built a ROR to house it and was very content viewing & taking images with my converted Canon 600D. Then one day I had a phone call from a chap who was planning to visit my area and had heard I had a polar mounted 14" and wondered if he could use it with his camera to take images of planets. NP I replied not knowing what I was letting myself in for. Bird arrived a few weeks later and spent some time collimating and adjusting my badly setup scope. I spent 2 weeks watching with amazement as he created many wonderful images of Mars and got hooked on planetary imaging. Several visits during the next 18 months during which he brought his 16" Newt culminated in Bird buying a block not far from me and starting to build a new observatory. With lots of help from Bird I have had some success with my 14" & although it is good all round scope not ideal for planets so the new build begins.
Gary Mitchell has built the 3 part 600mm tube. Normand Fullum is making the 508mm F3.95 Tech Mirror which is in the polishing phase. The Titan mount has been purchased. Moonlite 2.5" focuser and Atik 9 pos filter wheel will align the ZWO174mm camera. I'll upload photos and update as parts arrive, the observatory is extended and tuning begins getting ready for Mars in 2016.
These images from Normand this morning and he has confirmed the weight as 17.7kg which is just below my anticipated 18kg, figuring tomorrow.

Cheers, Phil.
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Last edited by ags_; 04-04-2015 at 08:10 AM. Reason: add images
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  #2  
Old 03-04-2015, 05:37 PM
glend (Glen)
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Wow that is a big tube. Re the three sections, how do you give it the necessary stiffness to carry a 508mm mirror (which is going to be a heavy). Tube rings, dovetail, etc all the components are going to have to be custom made or do you have that sorted already?
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  #3  
Old 03-04-2015, 06:29 PM
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ags_ (Phil)
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Quote:
Originally Posted by glend View Post
Wow that is a big tube. Re the three sections, how do you give it the necessary stiffness to carry a 508mm mirror (which is going to be a heavy). Tube rings, dovetail, etc all the components are going to have to be custom made or do you have that sorted already?
Tube rings, Mirror cell, radius blocks, end cap, all made by Gary.
Mirror is a Tech type front and rear 5/8th " supported by piers and a 100mm hole in the base and an estimated weight of below 20kg I'll have exact weight in a couple of days.
My estimated total including focuser, filter wheel, camera, guide scope, 2 x dovetails, cables, spider with 112mm Antares secondary under 40KG.

cheers, Phil.
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Old 03-04-2015, 07:02 PM
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Nice. I'm doing something very similar but with an 18" f3.3 mirror and an alloy truss scope. I have the mirror done but not coated yet and the scope is just about done. The main use for mine will be planetary imaging and some visual work.
Mines looking so far to be just under 30kg.
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  #5  
Old 03-04-2015, 08:08 PM
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Quote:
Originally Posted by Rac View Post
Nice. I'm doing something very similar but with an 18" f3.3 mirror and an alloy truss scope. I have the mirror done but not coated yet and the scope is just about done. The main use for mine will be planetary imaging and some visual work.
Mines looking so far to be just under 30kg.
Sounds nice, any more details, photos?
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  #6  
Old 03-04-2015, 08:13 PM
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DavidTrap (David)
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That tube is a work of art itself.

Look forward to the end results.

DT
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Old 04-04-2015, 12:11 PM
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Here's a shot of mine. The secondary is just a make do setup for now. I'm going to make a spider that holds the camera(asi120) at prime focus so no secondary will be needed.

It ended up being 24.5KG and the CGE mount seems to be able to take it ok.

The mirror is still uncoated as I've made it myself.

Click image for larger version

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  #8  
Old 04-04-2015, 12:50 PM
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Quote:
Originally Posted by Rac View Post
Here's a shot of mine. The secondary is just a make do setup for now. I'm going to make a spider that holds the camera(asi120) at prime focus so no secondary will be needed.

It ended up being 24.5KG and the CGE mount seems to be able to take it ok.

The mirror is still uncoated as I've made it myself.

Attachment 180132
that looks awesome, it will be very fast at prime though you will need plenty of mag for planets. Just need to paint those counterweights..lol
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Old 04-04-2015, 01:16 PM
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Haha yeah, the paint has been falling off them for a long time but i then used them for weights when I was making the mirror so they are a bit rusty now. The mount is an old spare I have, my main(good) imaging mount is a Tak NJP.

I need to get a 2.5X powermate, I've got a 5x powermate i use with my 10" f4 scope.

If your mirror figure turns out good you are going to have an awesome planetary scope.
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  #10  
Old 04-04-2015, 05:22 PM
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sopticals (Stephen)
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Smile

Quote:
Originally Posted by Rac View Post
Here's a shot of mine. The secondary is just a make do setup for now. I'm going to make a spider that holds the camera(asi120) at prime focus so no secondary will be needed.

It ended up being 24.5KG and the CGE mount seems to be able to take it ok.

The mirror is still uncoated as I've made it myself.

Attachment 180132
Nice.
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  #11  
Old 04-04-2015, 06:50 PM
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ags_ (Phil)
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Quote:
Originally Posted by DavidTrap View Post
That tube is a work of art itself.

Look forward to the end results.

DT
I hope to have the tube in a few days so I can try it on the Titan mount which I have stripped and serviced. Also the counterweight extension and 25kg weight.
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  #12  
Old 05-04-2015, 06:43 AM
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That mirror looks interesting!
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  #13  
Old 05-04-2015, 07:24 AM
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ags_ (Phil)
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Quote:
Originally Posted by Rac View Post
That mirror looks interesting!
I chose this type for it's advanced thermal cooling properties and light weight. Active cooling via an exhaust fan in the cap then passive via the hole in the centre should keep the mirror very close to ambient all night. That is why the tube is so large it is 100 mm larger than the mirror but very light using 1.1mm aluminium sheet. We will see.

http://www.normandfullumtelescope.co.../large-mirror/
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  #14  
Old 08-04-2015, 09:49 AM
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rustigsmed (Russell)
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this is going to be a beast!
what a great undertaking.
can't wait to see your results when its all up and running!

cheers

russ
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  #15  
Old 08-04-2015, 01:20 PM
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Phil,

that is looking like a great project - you will end up with a great scope in time for Mars next year so cannot wait to see your results!

Did you consider using a carbon fibre tube instead or would that have created a weight issue?

John K.
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  #16  
Old 08-04-2015, 01:56 PM
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ags_ (Phil)
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Quote:
Originally Posted by rustigsmed View Post
this is going to be a beast!
what a great undertaking.
can't wait to see your results when its all up and running!

cheers

russ
Sure is a beast Russ, glad I have Bird building so close as I will need his help to tune this monster.
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Old 08-04-2015, 02:05 PM
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Phil,

that is looking like a great project - you will end up with a great scope in time for Mars next year so cannot wait to see your results!

Did you consider using a carbon fibre tube instead or would that have created a weight issue?

John K.
Cheers, John. I considered carbon as well as truss construction and both would have been too heavy for the Titan. Plus aluminium has very good ambient properties. I am starting to design a cable pre-stress system to prevent tube sag with resultant and constant collimation changes.

cheers, Phil
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Old 08-04-2015, 09:22 PM
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Thanks Phil,

Makes sense.

One more question, how are you planning to mount your mirror, and are you going to be using some edge support brackets as well on the mirror cell?

Also - gather there is no need to peltier cool a mirror like this and fan cooling is more than sufficient?
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Old 09-04-2015, 03:01 PM
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Thanks Phil,

Makes sense.

One more question, how are you planning to mount your mirror, and are you going to be using some edge support brackets as well on the mirror cell?

Also - gather there is no need to peltier cool a mirror like this and fan cooling is more than sufficient?
Hi John,
I'll use 2 flexible steel wires which will be supported by old antenna parts as in this image, they are sikaflex'd to the bottom only.
Yes no need of a Peltier as the Observatory is air conditioned and the top cover fitted extractor fan will be run prior to the roof opening and natural convection through the mirror central hole will work continually during use.

Cheers, Phil
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  #20  
Old 09-04-2015, 03:17 PM
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Is that vivid around the edge. Did the edge end up turned?

It'll be interesting to see how well it holds collimation with that cell setup, is it sitting on bubble wrap?
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