neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Hi everyone!
Here's my little big summer project which is still an on going process to redo a small refractor I have. The scope is based on a 70mm f/6 Rodenstock Rotelar lens found on ebay at West Coast Camera if I remmember corectly.
Very good lens, pretty much an Apo, some time ago I did a ronchi test on it and came out very nice.
As for the fabrication itself I tried to keep things simple and I used usual materials found on my local hardware store.
So for the tube I used a 110mm PVC pipe reinforced with plywood rings treated with epoxy to seal them from moisture and for stiffness.
The lens had initially an aluminum ring which I used now to make the push&pull collimation system.
The focuser it's all custom made Crayford style fitted inside the OTA because the focusing distance is short, in fact quite critical so no room for a classic one.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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The collimation ring seats on a thick plywood ring.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
Edited by neo (09/09/09 06:20 PM)
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Collimation screws...
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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The focuser was pretty tricky cause without special tools was quiet difficult tu allign the four bearings to get an even contact with the focuser's tube. So VIVA epoxy 
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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...
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Focuser...still some details to finish, like the screw that press the brass rod over the focuser's tube and the lock screw.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8334
Loc: Bremerton Washington
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Well Neo....that is pretty nifty. I like your application of epoxy.....It's tough stuff.
How does the little guy take magnification?
Rob
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www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Thanks buddy!
Fun stuff epoxy.
The magnification goes amazingly well for a photo lens ( assuming that is a photo lens..I'm not very sure) about twice its diameter if it's very well collimated..so about 140X. But I expect that its true strength stands on astroimaging cause it has a super flat field. To bad i don't have one of those fancy SBIGs to take some pics.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
Edited by neo (09/09/09 07:19 PM)
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magic612
professor emeritus
Reged: 09/30/08
Posts: 561
Loc: Somewhere south of Chicago, IL
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neo - that looks great! And I'm with you on the epoxy thing; that's great stuff.
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- Celestron C8+, Orion 90mm f/10, Orion ST-80, 5" f/8 Dob, 127mm f/9.4 refractor, 114mm f/8 on DS GoTo, 60mm Sears 6333-A, 127mm f4.4 refractor lens (current project), 12" f/5 mirror (future project)
- Orion Vista 10x50s (5 deg), Sears #6207 7x35 (7 deg), Jason #138 Statesman 7x35 (11.5 deg)
Yes, I'm addicted to telescopes and binoculars. I am getting help. Every time I look at the heavens, it helps.
http://www.eyesonthesky.com
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Thanx magic 
I've just learned something new today...a fellow ATM guy from our local astronomy forum suggested mixing aluminum filings (or other powders...I guess) with epoxy. The new composite material could be poured in molds to get different parts. A very exiting ideea anyway.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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Owen
professor emeritus
Reged: 06/21/07
Posts: 514
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I know guys who have been doing this with diamond powder. The resulting part is 'very' durable....
Owen
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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A small update:
I've put up some detailes on the focuser like the locking screw and the tension screw. The focusing axle being on ball bearings I added a small teflon piece from a CD-rom to act as a break. Also I prepared the thumbscrews made out from aluminum potentiometer knobs which will be screwed on the brass axel.
I plan to add a planetary reduction knob..sort of  ... well...in fact a ball bearing atached to the thumbscrew from the right side which will be tightened against a rubber washer causing some friction, so when I turn the ball bearing's outer ring (with another knob on top) a few times the focusing axle turns ones. Ah...I guess you got the idea
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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The focusing knobs
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Today I've assembled the focuser, mounted the thumbscrews after I threded the both ends of the brass axle.
Also I experimented some more with my improvised planetary gear which....shamefully I realized that the principle is a bit wrong. After some research I've learned that I could build such a gizmo with 3 small ball bearings so I'll see how it turns out...I hope I still have some tiny bearings.
Anyway ..pictures...so here's the focuser..
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
Edited by neo (09/16/09 04:51 PM)
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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....
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Just a quick assemble of the scope.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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..
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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David Castillo
scholastic sledgehammer
Reged: 09/09/06
Posts: 882
Loc: Carmel Valley, Ca
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That is SWEET, eo. I like your idea of rigging a vernier reduction knob- puts it up there on another level 
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Dave
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Thanx Dave !
I've found (finally) a Chinese site where was explained with tons of pictures the design of those vernier reduction knobs from GSO, I guess. So now everything is clear; still I need to try to build it with the materials in hand.
http://bbs.astron.ac.cn/thread-54988-1-3.html
Here's some paint job I've done today, in fact only the primer, tomorrow I have to buy a paint can to finish.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Today I've received from my local work shop the focusers tube after some adjustments on lathe and now it's all nice and shiny ( good old table leg ). I've drilled three holes at 120 degrees and threaded them to be sure it holds my 2" Meade UHTC diagonal which is surprisingly heavy.
Because the tube is quiet thinn and I can't grind it flat for more grip with the focusing axle, I cut a narrow piece of fine sand paper (320#) and glued it with a double sided duct tape on the fousers tube. This way the axle will hold tight the focusing tube even with a heavy load.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Here's a quick assembly with half of the scope to check the things out, and it seems I have to pay attention on some detailes like flection of some pieces. Man...nothing is easy  !
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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grendel
sage
Reged: 04/12/09
Posts: 250
Loc: Canterbury, Kent, UK
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I made a reduction drive using the planetary gearbox from a cheap electric screwdriver. 1:7 reduction from one stage of the gearbox.
Grendel
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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That's a great idea Grendel. I didn't imagine that electric screwdrivers are based on planetary gearboxes. I presume you used a small one.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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grendel
sage
Reged: 04/12/09
Posts: 250
Loc: Canterbury, Kent, UK
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yes one of the little cheap hand held ones, I even made a eq drive out of 5 gearbox sections put togrether (I managed to pick up about 4 of the screwdrivers really cheap once in the january sales- about £3 per screwdriver the normal reduction on these is 1:49 (2 planetary sections) and I had a spare section after I had finished, which made the focuser reduction gear
Edited by grendel (09/19/09 06:00 AM)
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grendel
sage
Reged: 04/12/09
Posts: 250
Loc: Canterbury, Kent, UK
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The motor housing and gear were just convenient, it could have been smaller.
Grendel
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grendel
sage
Reged: 04/12/09
Posts: 250
Loc: Canterbury, Kent, UK
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another view of the planetary gearbox.
the screwdriver was an even cheaper version of something like this:-
http://www.amazon.com/Black-Decker-9074CTN-3-6-volt-Screwdriver/dp/B0000302UJ
Edited by grendel (09/19/09 06:10 AM)
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Hey, nicely done! Fantastic...I'll look for a cheap (ideally second hand) screwdriver. It would be way easier to mode the focuser like you did than just get everything from scratch.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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grendel
sage
Reged: 04/12/09
Posts: 250
Loc: Canterbury, Kent, UK
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you realise that it can be used almost as is for an electric focuser too dont you.
Grendel
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Today I've installed the objective on my Uber-contraption to check how the focuser works....like a charm..by the way...after a few tweaks.
Of course I couldn't resist and I got the first light (un collimated) through my window with my digital camera and a Japanese Meade 26mm SP. I'm very happy with the results. I can't wait to finish all the details and to collimate it properly.
Here are a few pics with the scope half assembled and of course the first light.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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and another
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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first light... 
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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yet another...the buildings are about 600 maybe 700 meters away.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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..........
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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jcham21
sage
Reged: 12/02/07
Posts: 358
Loc: Tucson, Arizona
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Cool images. Looks like there's some positive (pincushion) distortion. Could be due to being out of collimation?
James
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James
Canon XTi
Canon EF 200mm f/2.8L II Camera Lens
Celestar 8
Main Astrophotography Gallery
Comet Lulin Gallery
How To Make a 6" F/15 Refractor
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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I guess collimation is one reason, but it's not the only thing. The objective has a flat field (being a photo objective, from what I know) but it's more likely that the eyepiece + my cameras objective would cause the distortion. Usually a "normal" astro lens has a negative pincushion because the field is curved and the eyepiece could compensate for it but in my case overcorrected it.
Hey...what do you know?...this is the post no. 500 of mine here on CN...I have to celebrate!!  
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
Edited by neo (09/20/09 02:27 PM)
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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After a little break today I've finished the paint job on my scope and flocked the interior with "velur" paper as we call it back here. Tomorrow after the paint is dry enough I'll attempt to finally put everything togather. I hope I'll not have any "surprises".
For moment I'll set a bit aside the electric focuser idea, I'll sleap on it for sure. I'll search for a cheap electric screwdriver like Grendel here greatly sugested but first I plan to build the cradle and then a good alt-az mount to use with an aluminum tripod I've got, donated by a fellow from our local astronomy forum. Just a bit of cosmetic job, a bigger base to sustain the fork and it's ready to see the sky
Here're a few pics during the flocking and the back end of the scope after painting.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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.
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Well folks...it seems...I'm out of luck with my project.
 
Yesterday I managed to assemble my scope, even do an autocollimation test which was spot on from the first try, when disaster strikes. Curses....the focsuer's mechanism irremediably broke down. I guess because of the load...it doesn't meter anymore.
After the black period of frustration passed away...kind of...I decided to start a new design made by the book with aluminum tubing, some good milling and lathe work. I'll keep only the dewcover from the old project.
I don't want to give up on this Rodenstock lens cause in the short time I was able to see what a great little scope could be. The image is very sharp, well corrected and above all it could be superb for reach field astrophotography.
So after I've wiped out the tears  here's my new design...
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
Edited by neo (09/27/09 02:10 PM)
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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...and the focusing axle..
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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I got farther with my new design by drawing the ball bearings brackets. The idea is to get two bearings aligned on the bracket to keep them in even contact with the focusing tube. These brackets I still could make them by hand from a 5mm thick aluminum sheet. The bearings are the same 3x6x2,5mm.
Here's the drawing...man I really started to enjoy this 3D modeling...it's quiet addicting, it's like an extension of my imagination
Well....I hope I didn't bore you all with this..pretty..I guess is the word  ...but I have such a great time sharing my bad or good experiences with you. I hope my project will be a happy ending one
Your suggetions and thoughts are the most wellcome, as always.
Alex
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
Edited by neo (09/29/09 10:12 AM)
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stevenf
member
Reged: 10/11/09
Posts: 31
Loc: Vancouver, BC
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This little scope looks like it's going to be amazing when it's finished. Thanks for sharing it. I can't wait to see the results.
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Meade ETX-60BB
Meade ETX-90EC UHTC
Skywatcher ST80
Orion ST120
Skywatcher 90mm Mak
Meade 9x63 binoculars
Celestron Explorascope
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neo
professor emeritus
Reged: 02/12/08
Posts: 623
Loc: Iasi, Romania
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Thanks Steven. It's been a while since I wrote on this post. Unfortunately I had some serious health problems over the last weeks which kept me aside from tooling around so my project was on halt a bit, but I promise I'll go ahead with it as soon as possible. Of course sharing everything with you guys .
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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