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Need help with first telescope project

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#1 Sol Selegna

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Posted 12 August 2020 - 03:58 PM

Hi everyone, I'm a first time ATM'er with access to only basic hand tools (drill, saw, driver, workbench). I'd like to make a nice all-around telescope for lunar, planetary and DSO's, I'm looking to build something that's modular and lightweight. I originally thought to go f8, but someone told me that f6 is easier to work with.

 

I happened to come across a 4.5" f4 travelscope on Gary Seronik's website (https://garyseronik....st-travelscope/). I also subsequently found a detailed youtube video of how to go about building a 4 inch newtonian reflector, and it's very similar in design to Gary's travelscope. Here is the youtube link: https://www.youtube....jyScs4EM&t=32s.

 

I am interested in rescaling the design of Gary's 4.5" f4 travelscope to either fit a 6" or 8" f6 mirror. Gary used aluminum, but on the website he mentioned that either cardboard or PVC pipe would probably work fine, too. So I'm thinking to buy a Sonotube and fiberglass it for reinforcement. However, since this will be my first build, I was wondering if a 6" or 8" f6 newtonian like I have in mind would require bending or stooping into an uncomfortable position in order to get good views?

 

I'm also planning to buy the mirror instead of make it. Agena Astro has a GSO 6" f/6 parabolic primary and 50mm secondary ($190 for the set). They also have an 8" f/6 and 50mm secondary set for $230. In your opinion, are there any pros/cons in using an 8" mirror over a 6" for my project (in terms of the seeing, etc.)? And also, do Agena Astro's prices sound reasonable to you?

 

And finally, since I have only basic tools, I was thinking to make the strut out of wood instead of aluminum. And, if I can figure out how to do so, I'd like to use latched pieces to make the strut modular. Please let me know any thoughts or opinions that you feel might be helpful?

 

Thanks for your assistance, I appreciate it!



#2 Pinbout

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Posted 12 August 2020 - 04:17 PM

 

and it's very similar in design to Gary's travelscope. Here is the youtube link: https://www.youtube....jyScs4EM&t=32s.

Don’t build that for your 1sr scope

 

4.5”f8 

 

6”f8 

 

are both fine and very easily mounted on a tripod 

 

you can purchase the mirrors and build the scope 

 

afterward you can learn about testing the optics and if you want fix them yourself

beats the manual labor grinding, and gets you to the fun part, playing pitch, cerox and figuring the mirror.

 

what atm’er doesn’t love the smell of pitch in the morning, deep breath in ... yum grin.gif


Edited by Pinbout, 12 August 2020 - 04:19 PM.


#3 Sol Selegna

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Posted 12 August 2020 - 04:42 PM

Hi Pinbout, thanks for your message! 

 

So, an 6" f8 would be an all-around good 1st time project for lunar, planetary and DSO's? The price tag on Agena Astro for the 6" f8 primary and secondary set is $145, which is more affordable. smile.gif

 

Any thoughts about using fiberglassed sonotube to make the two modular pieces?  



#4 hamishbarker

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Posted 12 August 2020 - 04:45 PM

I built my 8"f6 with gso primary and secondary mirrors. A little cheaper than retail as telescopes are a bit overpriced here in new zealand but mirrors can be posted internationally at low cost. 

 

If you have a bit of patience, some good deals occasionally come up in the classifieds if you are prepared to be a bit flexible with the size and f ratio.



#5 hamishbarker

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Posted 12 August 2020 - 04:50 PM

I used galvanised 0.55mm (20 thousands of an inch if you are stuck in the imperial unit age) steel duct. a 1200mm length of it from a local heating/aircon duct supplier should be very cheap. No need for messy fiberglass, just paint the inside black, leave the outside bare. If you want to you could router some plywood end rings to stiffen it, but mine is ok without (although the edges are a little sharp. Maybe plastic edging could be nice addition, possibly find it at a hardware store?

 

 

 

Hi Pinbout, thanks for your message! 

 

So, an 6" f8 would be an all-around good 1st time project for lunar, planetary and DSO's? The price tag on Agena Astro for the 6" f8 primary and secondary set is $145, which is more affordable. smile.gif

 

Any thoughts about using fiberglassed sonotube to make the two modular pieces?  



#6 Pinbout

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Posted 12 August 2020 - 05:15 PM

i spliced my sonotube together for my 6inf8... cut extra pieces of cardboard tube and white glued the "big *** ears" on opposite sides of the tube...

 

6inf9 tube.jpg

 

 

 


Edited by Pinbout, 12 August 2020 - 05:17 PM.


#7 Pinbout

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Posted 12 August 2020 - 05:17 PM

my sanding bench

 

bondo'd and sanded all seams

 

sanding bend.jpg



#8 Pinbout

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Posted 12 August 2020 - 05:21 PM

finding how long to make the tube.

 

6inf8 longer tube.jpg



#9 Sol Selegna

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Posted 12 August 2020 - 05:24 PM

I used galvanised 0.55mm (20 thousands of an inch if you are stuck in the imperial unit age) steel duct. a 1200mm length of it from a local heating/aircon duct supplier should be very cheap. No need for messy fiberglass, just paint the inside black, leave the outside bare. If you want to you could router some plywood end rings to stiffen it, but mine is ok without (although the edges are a little sharp. Maybe plastic edging could be nice addition, possibly find it at a hardware store?

Unfortunately, I only have basic hand tools, no lath, etc. That's why I thought it would be easy to work with sonotube and fiberglass (although messy). 

 

I built my 8"f6 with gso primary and secondary mirrors. A little cheaper than retail as telescopes are a bit overpriced here in new zealand but mirrors can be posted internationally at low cost. 

 

If you have a bit of patience, some good deals occasionally come up in the classifieds if you are prepared to be a bit flexible with the size and f ratio.

Thanks for your messages, Hamish! Are you satisfied with your GSO mirrors so far?

I'm planning to start the build within the next couple of weeks or so, so I may go ahead and move forward with the Agena Astro purchase if nothing else comes up.



#10 Sol Selegna

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Posted 12 August 2020 - 05:28 PM

my sanding bench

 

bondo'd and sanded all seams

 

attachicon.gifsanding bend.jpg

Thanks for the pictures, this is great! I read somewhere that the inside of the tubes are waxed. If so, did you remove the waxy paper before blacking out the interior? 



#11 Pinbout

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Posted 12 August 2020 - 05:55 PM

Thanks for the pictures, this is great! I read somewhere that the inside of the tubes are waxed. If so, did you remove the waxy paper before blacking out the interior? 

not from homedepot.



#12 Sol Selegna

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Posted 12 August 2020 - 08:17 PM

not from homedepot.

Okay, that's good to know! I'll try and buy it from home depot. Have you ever fiberglassed a tube before?



#13 Pinbout

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Posted 12 August 2020 - 08:39 PM

I prefer to veneer them... but yes I've played with plenty of fiberglass in my day...

 

https://www.youtube....8rBwA&index=101



#14 Pinbout

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Posted 12 August 2020 - 09:23 PM

But filling in the spiral seam with bondo and painting it seals it anyway

 

AB44E241-702E-4D1A-9697-526AAD213831.jpeg


Edited by Pinbout, 12 August 2020 - 09:24 PM.

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#15 Sol Selegna

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Posted 12 August 2020 - 11:19 PM

I prefer to veneer them... but yes I've played with plenty of fiberglass in my day...

 

https://www.youtube....8rBwA&index=101

Pinbout, I checked out your youtube site. Wow, nice scopes! bow.gif

 

Is it possible to build any of these with only simple tools:

 

6inf5 travel telescope
8in Telescope for a Bike
10in UL travel dob
Travel Dobsonian Telescope
16in Single Pole Telescope

 

I don't have a lath, router, or anything like that. Only basic hand tools (drill, driver, saw, workbench). I'd be interested in building any of those designs, if it's possible to do so! 



#16 dave brock

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Posted 13 August 2020 - 12:23 AM

Coating the tube with fibreglass glue is good enough to seal and strengthen. Did that with

my 10" Dob

If you get a waxed tube it peels off easy enough.



#17 Sol Selegna

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Posted 13 August 2020 - 02:14 AM

Coating the tube with fibreglass glue is good enough to seal and strengthen. Did that with

my 10" Dob

If you get a waxed tube it peels off easy enough.

Dave, thanks for that tip! smile.gif



#18 Pinbout

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Posted 13 August 2020 - 04:51 AM

Pinbout, I checked out your youtube site. Wow, nice scopes! bow.gif

 

Is it possible to build any of these with only simple tools:

 

6inf5 travel telescope
8in Telescope for a Bike
10in UL travel dob
Travel Dobsonian Telescope
16in Single Pole Telescope

 

I don't have a lath, router, or anything like that. Only basic hand tools (drill, driver, saw, workbench). I'd be interested in building any of those designs, if it's possible to do so! 

You need a router so you can put it on a trammel and cut clean, consistent arcs 



#19 m. allan noah

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Posted 13 August 2020 - 07:03 AM

You seem to be gravitating toward the travel and UL scopes. Those are the ones that require the most work, and hence benefit from the most tools. You should walk before you run, and build a simple 6"f8 dob. You can use plumbing parts for the alt bearings so you don't have to cut clean circles, etc. Something like a simplified version of the stellefane plans would be pretty easy.

 

allan



#20 Sol Selegna

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Posted 13 August 2020 - 09:24 AM

You need a router so you can put it on a trammel and cut clean, consistent arcs 

Okay, thanks for letting me know. 



#21 Sol Selegna

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Posted 13 August 2020 - 09:28 AM

You seem to be gravitating toward the travel and UL scopes. Those are the ones that require the most work, and hence benefit from the most tools. You should walk before you run, and build a simple 6"f8 dob. You can use plumbing parts for the alt bearings so you don't have to cut clean circles, etc. Something like a simplified version of the stellefane plans would be pretty easy.

 

allan

Hi allan, thanks for your message. Space is at a premium for me, so I was hoping to build something that could be broken down and put away when it's not being used.confused1.gif



#22 Pinbout

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Posted 13 August 2020 - 09:54 AM

Hi allan, thanks for your message. Space is at a premium for me, so I was hoping to build something that could be broken down and put away when it's not being used.confused1.gif

you need faster optics... like f5 or faster.

 

I could cut you parts... I have templates for 10" and 12" 

 

tablesaws are necessary to keep stuff straight.

 

but if space is a premium, a 6"f5 is a nice scope to have...f8 will be too long.


Edited by Pinbout, 13 August 2020 - 09:58 AM.


#23 Sol Selegna

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Posted 13 August 2020 - 11:19 AM

you need faster optics... like f5 or faster.

 

I could cut you parts... I have templates for 10" and 12" 

 

tablesaws are necessary to keep stuff straight.

 

but if space is a premium, a 6"f5 is a nice scope to have...f8 will be too long.

Pinbout, thanks for your generous offer to help me out! In terms of the seeing, would the f5 be "okay" as an all-around scope? For the time being, I don't anticipate buying or building another scope after making this one. Also, I've heard someone mention f5 coma, is it as gnarly as they say?...but of course, that said, beggars can't be choosers! bow.gif



#24 Pinbout

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Posted 13 August 2020 - 11:45 AM

 

ould the f5 be "okay" as an all-around scope?

its a great scope and a 6in f5 very tripod mountable, coma? its there but if you have good optics, doesn't bother me.


Edited by Pinbout, 13 August 2020 - 11:46 AM.



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