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My 16" f7.2 Newt project code named "Grace"

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#1 Sean Cunneen

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Posted 02 January 2013 - 11:18 AM

I am awaiting delivery of a 16" f7.2 mirror I've seen listed on and off for the past year on Amart.

I've decided to dedicate this project to My Grandma Grace who passed away this past Thanksgiving. She and my Grandpa always encouraged my love of the night sky which started at their farm in Indiana. When we would visit, I would sleep on the floor in a sleeping bag. They would turn up the heat before bed and I would just swelter. I took to opening the sliding screen door a crack to let some cool air in and I always told them it was to look at the stars! When I first became interested in telescopes, my first experience was the their farm with a 90mm refractor. My first view? Jupiter. The big guy just blew me away and she was amazed as well. After that my scopes grew and I would always set one up on my visits.

Needless to say, This scope is going to be huge. For my last big project each component had to pass the lift test. For this project, each piece has to pass the doorway test!

Parts and pieces are still arriving, so this will evolve slowly and there are some features that will have to develop as we go.

The quick summary is that I am putting together an open truss Newt on an equatorial platform using as many "found" objects as I can. So far I have the arms from a mission style recliner, some tripod legs and a moonlight focuser.

I picked up a load of wood last night and I'll start showing pictures soon... Stay tuned!

Sean

#2 Darren Drake

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Posted 02 January 2013 - 11:53 AM

This will be fun. Looking forward to it.

#3 MessiToM

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Posted 02 January 2013 - 12:09 PM

I am as well

#4 bremms

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Posted 02 January 2013 - 01:00 PM

Yes.. one BIG telescope. Will make my 12.5 F8 project look tiny. Looking forward to seeing this one.

#5 magic612

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Posted 02 January 2013 - 02:49 PM

Do you have the hydraulic lift to reach the eyepiece yet? ;)

#6 Jeff Morgan

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Posted 02 January 2013 - 03:24 PM

Congratulations Sean, and best of luck on the project. My 16" f/7 can see first light any night now, depending upon whether or not I want to wait for a bracket for my ServoCAT control box. My feeling is that such a scope deserves better than duct tape for it's maiden voyage.

The fact that northern Arizona temperatures are getting into mid-teens has nothing to do with my delays ;)

I thought about an equatorial platform for mine. I have first-hand experience with the Osypowski platform and nothing but good things to say about them. But given the scale of my project ServoCAT seemed like a better choice. And GOTO will be very handy with 2800 mm focal length. Driving the whole thing wirelessly with SkySafari and an iPad was icing on the cake.

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#7 MKV

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Posted 02 January 2013 - 04:14 PM

Jeff, simply beautiful! The split truss is the way to go for resistance to misalignment. It should be an awesome all-purpose telescope. Do you have a 3 or a 4 wave spider. A 3-vane is better diffraction-wise. How big is your central obstruction?

Mladen

#8 Sean Cunneen

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Posted 02 January 2013 - 06:08 PM

Do you have the hydraulic lift to reach the eyepiece yet? ;)


I spent my Morning at Menards asking each sales associate if any of the ladders were ASCOM compliant, none of them could tell me.

#9 Sean Cunneen

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Posted 02 January 2013 - 06:12 PM

Congratulations Sean, and best of luck on the project. My 16" f/7 can see first light any night now, depending upon whether or not I want to wait for a bracket for my ServoCAT control box. My feeling is that such a scope deserves better than duct tape for it's maiden voyage.

The fact that northern Arizona temperatures are getting into mid-teens has nothing to do with my delays ;)

I thought about an equatorial platform for mine. I have first-hand experience with the Osypowski platform and nothing but good things to say about them. But given the scale of my project ServoCAT seemed like a better choice. And GOTO will be very handy with 2800 mm focal length. Driving the whole thing wirelessly with SkySafari and an iPad was icing on the cake.


Other bands, their scopes only go up to 7. Ours go up to 7.2, for when you want to get just a little longer. Seriously, Jeff, that scope is beautiful. That truss looks so light and effortless. Here in the Midwest, we have to dress ours up a little more for the crazy winters.

I have always wanted to build a platform and this scope being as cumbersome as it is, I felt this was the project for it. If my jigs work out, I make make a couple for my other scopes.

#10 Jeff Morgan

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Posted 02 January 2013 - 07:45 PM

Jeff, simply beautiful! The split truss is the way to go for resistance to misalignment. It should be an awesome all-purpose telescope. Do you have a 3 or a 4 wave spider. A 3-vane is better diffraction-wise. How big is your central obstruction?

Mladen


Thanks. That picture was taken during tube trimming, still a few finishing touches to go.

I played around with wire spiders for a month, then broke down and got a 4 vane. The diagonal mirror is 2.6", for about 16% obstruction. If Mel Bartels diagonal calculator is correct, it should fully illuminate a 31 Nagler. Going with the next smallest size (2.14") was starting to get a little chancy. You see, there was another consideration - I used a Moonlight focuser and filter slide, and I wanted to have enough room to mount the slide completely outside the aperture defined by the tube rings so as not to create additional diffraction.

#11 Jeff Morgan

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Posted 02 January 2013 - 07:52 PM

Sean, will this be a permanent installation? If not what do you have to transport it?

An option you might want to look at is a rolling platform ladder (McMaster-Carr). They are incredibly comfortable and stable. And surprisingly easy to move around too. I could post a few pics, but I don't want to hijack your thread (pm me if you want me to email them). I bought one for my scope, and Jon Issacs has been using one with his 25" scope, which I believe has just a bit more focal length than you or I have.

The only downsides of this approach is transporting it. Easy if you have a trailer. Perhaps easy if you have a pick-up truck or a van. Impossible with a car or SUV.

If you are looking more of a standard ladder, the Little Giant ladders look like a good option. If you have a roof rack on your car that would be workable.

#12 Darren Drake

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Posted 02 January 2013 - 11:15 PM

Sean is quite an experienced atmer. Tonight he brought his homemade 12 inch dob to my back yard. It is quite unique looking. The trusses are made of shower pipes. The 16 will be a fun project to follow.

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#13 Sean Cunneen

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Posted 02 January 2013 - 11:50 PM

Jeff, the scope will dissemble into 3 main pieces and everything should just fit into the back of our caravan. Kids will ride on the roof.

#14 magic612

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Posted 03 January 2013 - 10:18 AM

Which is rather unfair too, given that Sean's kids are sweethearts, and his scopes - well, let's just say they don't hold a conversation very well.

#15 StarryHost

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Posted 03 January 2013 - 10:38 AM

Can't wait to see this come about. When it's done, we can play "Patriot" vs. "Scud" with our two rocket scopes. ;-)

Jack

#16 k9yr

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Posted 03 January 2013 - 09:05 PM

Jeff and Sean, killer scopes! Much braver than my little 16" F4.5. :bow:

#17 Sean Cunneen

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Posted 03 January 2013 - 09:52 PM

So I thought I'd start with some of my ideas behind my design aspects. I've been fortunate enough to have built a lot of scopes and I've also spent a fair amount of time traveling with, setting up and viewing through scopes that I have built.

So to massacre one of my favorite speeches ever, There are knowns I know and knowns I don't know. There unknowns I know and unknowns I don't know, you know?

So I know that I like to have a very quick setup. I don't like fiddling with lots of pieces. When my scope breaks down, it has to break down into 3 or four manageable parts.

I know from where I usually observe that stray light is a constant problem. The 12" dob Darren took a picture of was built to be as open as can be. It was since rebuilt to shield the mirror from as much ambient light as possible.

I like for my scopes to be as stiff and "tight" as I can manage. No wobbles.

stuff either has to move or it has to never ever move with nothing in between.

I don't mind heavy scopes (once they are set up)
Fans are important.
Baffles are important.
Having the mirror protected is important.

As I learned from my 12", crazy looking scopes are great but take a walk around a star party and check out which scopes are getting used and they all tend to look the same.

Here is a photo of "Big Tom" in his original form:

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#18 Sean Cunneen

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Posted 03 January 2013 - 09:58 PM

I've decided to make my platform in the style of Warren Peters. You can find his article here:
Warren Peters Platform

There are three or four different designs, all have some strengths and weaknesses. The Warren Peters design is a little harder to make as there are two arcs of different radius you have to cut out but the plusses for a large heavy scope is that the actual platform can be a square or slight rectangle and the weight is supported on all four corners. A Poncet platform is a little simpler as the back arc is replaced by a single angled pivot but for a scope this size and weight, the extra stability should more than pay for the extra work.

#19 Napersky

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Posted 04 January 2013 - 12:39 AM

Very cool Sean I admire your craftsmanship especially the equatorial mount you made for your 6" refractors.

I can't wait to look through your 6" Jaeger's although I won't be building mine any too soon. I am totally occupied with my Interferometer project and have the 6" AP for my observing.

Mark

#20 bremms

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Posted 04 January 2013 - 08:18 AM

Yes, TOOOO many projects. I suffer the same. I did get a Jaegers 6" F10 from SS and need to make a cell and all the fixins. My 4" F15 Jaegers is almost done.
On a side note, What do a lot of you use for artificial stars?
I was going to make pinholes like the old days, but it's hard to control the size. We do have a laser at work I could make some holes with. I cold shoot some spots at some copper foil.

#21 Napersky

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Posted 04 January 2013 - 08:36 AM

Sean,

With that F Ratio your scope should be excellent for Planetary and blow away anything else around including short focal length Dobs of larger apertures!

Mark

#22 Napersky

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Posted 04 January 2013 - 08:37 AM

Hey we got to call the Internet Police and the Thread Police!

#23 Mike I. Jones

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Posted 04 January 2013 - 08:58 AM

and don't click on a spam link, EVER!

#24 Napersky

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Posted 04 January 2013 - 09:23 AM

Very scary!

#25 Jeff Morgan

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Posted 04 January 2013 - 10:41 AM

So I know that I like to have a very quick setup. I don't like fiddling with lots of pieces. When my scope breaks down, it has to break down into 3 or four manageable parts.


An admirable goal, but I would not make it the top of the list.

Realistically, the limiting factor on getting the evenings observing started is the primary mirror. Even with fans, there is not a lot to be done for the first hour anyway. While it's nice to be set up in five minutes and then have time to sip a coffee as twilight progresses, ultimately you're always waiting on the mirror.

A different story at the end of the night of course, but still not enough to make it the #1 design criteria.






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