National Geographic 70mm Refractor (2017 model)

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GCoyote
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National Geographic 70mm Refractor (2017 model)

#1

Post by GCoyote » Thu Jan 23, 2020 6:22 pm

Picked this up as an (almost) complete kit for $20 last week.
20200123_103250 (800x600).jpg
I'm already reusing the mount, tripod, and other components in other projects but the OTA is missing the threaded plastic clamp that retains the eyepiece. :flame:
20200123_103313 (800x600).jpg
I tried to swap with the eyepiece holder from a 70mm Meade but the threads on this scope are a tiny bit undersized and the Meade part just falls off.

The carbon fibre tube seems really sturdy and I'd hate to just toss it. Online search is not getting me exactly what I need which isn't surprising as that's not something you'd normally remove I don't think. There is no actual manufacturer info on the data plate. That and the fact that a Meade part doesn't fit makes me hesitant to make a blind purchase.

Any ideas on a substitute part or a simple fabrication? I wondering If I can make it out of PVC.
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#2

Post by gregl » Fri Jan 24, 2020 4:56 am

I think PVC would work fine. Canvass your neighborhood for someone with a lathe. It would be about a ten minute job to make up an adaptor from a PVC pipe coupling. There are more folks out there with home lathes than you might imagine. Check the local model railroad club and the local hotrod club. The Chesapeake & Allegheny Live Steamers certainly has members with lathes: http://www.calslivesteam.org
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#3

Post by GCoyote » Fri Jan 24, 2020 5:46 am

Possible. There is a hobby store in town that has a model railroad club. I'll check them out.
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#4

Post by Lady Fraktor » Fri Jan 24, 2020 8:12 am

Check with Explore Scientific, they sell this telescope and may have some parts around. https://explorescientificusa.com/collec ... -telescope
You could also check Astro-Parts Mall, Telescope Warehouse or even Scopestuff.
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Mounts: Celestron AS-GT, Celestron CG-5 w/ Argo Navis & tracking motor, SLT w/ pier & tripod mods, Manfrotto 028b w/ SV M2C, Mantrotto 055Pro w/ 128RC, TAL MT1C, Vixen SXP w/ HAL-130 & half pier
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#5

Post by pakarinen » Sun Jan 26, 2020 1:07 pm

Heh. I just saw one of those 70mm at Hobby Lobby yesterday. Didn't check the price.
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#6

Post by GCoyote » Thu Jan 30, 2020 5:11 pm

pakarinen wrote:
Sun Jan 26, 2020 1:07 pm
Heh. I just saw one of those 70mm at Hobby Lobby yesterday. Didn't check the price.
The one I rescued was the 2017 model which came with a terribly over bright LED finder scope. The newer ones seem to have reverted to more conventional/useful finders. Having already dropped the OTA once, I can attest to the sturdiness of the carbon fiber construction! :oops:

I found a bit of PVC scrap that seems about the right size for the eyepiece holder so that's option 1.
I also picked up a an old Meade 60mm OTA for a whopping $6 that I might be able to extract the entire focuser from to repair the NatGeo so that's option 2.

What I neglected to mention is that this is ongoing project #4 and I just had a brainstorm for project number #2 so I need to run out and get more parts for that one!

Thanks for the help everyone and stay tuned. :popcorn:
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#7

Post by GCoyote » Thu Jan 30, 2020 7:55 pm

Update: Well the Meade focuser was a bit to small. The gear teeth and the focuser knob couldn't mesh when moved to the larger plastic focuser body. So much for option 2.

Back to the hardware aisle! :D

Edit: Oh and while I had it disassembled, I reversed the focuser tube so instead of the undersized threads, I now have a clean square plastic tube end to work with.
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#8

Post by gregl » Fri Jan 31, 2020 12:30 am

Too much fun!
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#9

Post by GCoyote » Mon Feb 03, 2020 3:54 am

Brain storm; instead of trying to manufacture a custom part, can't I get a cheap 1.25" extension tube and either glue or screw it in place to hold the eyepieces?

https://www.ebay.com/i/192591340777?chn ... 8sQAvD_BwE
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#10

Post by Lady Fraktor » Mon Feb 03, 2020 4:41 am

No reason not to try it out :)
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Proper Telescopes: Antares 105 f/15, Celestron 150 f/8, Stellarvue NHNGDX 80 f/6.9, TAL 100RS f/10, TS 102 f/11, UR 70 f/10, Vixen ED115s f/7.7
Mounts: Celestron AS-GT, Celestron CG-5 w/ Argo Navis & tracking motor, SLT w/ pier & tripod mods, Manfrotto 028b w/ SV M2C, Mantrotto 055Pro w/ 128RC, TAL MT1C, Vixen SXP w/ HAL-130 & half pier
Diagonal: 2" A-P Maxbright, 2" Baader Herschel Wedge (P), 2" Zeiss/ Baader Amici Prism (DX2), 2" Orion Amici Prism, 2" Stellarvue DX, 2" TeleVue EverBrite
Eyepieces: Antares to Zeiss
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#11

Post by gregl » Mon Feb 03, 2020 5:16 am

Well for eight bucks you can't go far wrong.
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#12

Post by GCoyote » Mon Feb 03, 2020 4:19 pm

Ordered!
Expected delivery on or about Mar 9.
(to be continued ... )

And while I wait, on to the next project!

:D
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