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5" F12 Istar Refractor project

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#101 catboat

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Posted 30 May 2011 - 04:08 PM

Sweet looking boat! (Nice scope too.) I enjoyed your stacked-edge beveling technique. I'll have to send you a pic of "Plan B" (Bolger Nymph) when I get her finished -- the write-up said one weekend's work (hah!).

#102 plyscope

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Posted 31 May 2011 - 09:23 PM

The red rowboat took me over 4 years for (70-100 hours expected build time)! I got side tracked with moving house and the birth of our two kids. Still got there in the end. :p

Starting on the tube rings with 19mm (3/4")ply.

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  • 4613931-Istar scope build 098.jpg


#103 plyscope

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Posted 31 May 2011 - 09:24 PM

Two coats of primer after some filling and sanding.

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  • 4613936-Istar scope build 099.jpg


#104 DanWray

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Posted 01 June 2011 - 01:06 PM

Andy,

There must be some suppliers of irrigation tubing in Australia like Hastings in the US.

Dan

#105 plyscope

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Posted 02 June 2011 - 07:52 PM

I've tried doing a search online but it seems most of the pipe in Australia is poly not aluminium. Aluminium tubing in large sizes can be ordered but it is expensive and not generally available in short lengths.

Here is the red paint, two coats brushed on. This is a marine type alkyd enamel, 'bordeaux red". I probably should have thinned it a little and done 3 or 4 coats but it will do for now.

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  • 4617416-Istar scope build 101.jpg


#106 s800

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Posted 02 June 2011 - 08:07 PM

If the photo looks like it does "in the flesh" - that's a great color.

#107 plyscope

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Posted 02 June 2011 - 09:33 PM

If anything it is a bit darker in the flesh. I guess the boat photo shows it more like the eye.

I am starting to cut out the parts for a Berry mount. I can use one of my existing piers in the short term, until eventually making a tripod.

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  • 4617576-Istar scope build 105.jpg


#108 plyscope

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Posted 03 June 2011 - 05:00 AM

This part is more or less the same as described in Richard Berry's book Build Your own Telescope. A simple and effective mount for a refractor. You can use trunnions made of wood or metal. I have made wooden discs before foranother scope but for this one I have some aluminium rings cut from an old oil filter housing.

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  • 4617921-Istar scope build 106.jpg


#109 eric_zeiner

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Posted 03 June 2011 - 05:08 AM

Nice work as always Andy! :bow:

#110 plyscope

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Posted 04 June 2011 - 07:12 AM

Thanks Eric

Back to the telescope and I have now fitted the lens, finder and focuser. To check the focuser alignment to the optical axis it is handy to have a collimation laser. You need a paper circle over the lens to show the centre of the lens. Then with the laser inserted into the focuser you can see how close the alignment is.

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  • 4619856-Istar scope build 108.jpg


#111 plyscope

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Posted 04 June 2011 - 07:14 AM

In the photo above you should be able to just see the faint red dot from the laser just above the centre point. The red dot should be on the centre. The focuser needs to be shimmed to bring it into line. This photo shows the laser inserted into the focuser straight through.

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  • 4619859-Istar scope build 112.jpg


#112 plyscope

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Posted 04 June 2011 - 07:19 AM

Here you see my home made brass tube adapter with the focuser removed.

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  • 4619861-Istar scope build 113.jpg


#113 plyscope

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Posted 04 June 2011 - 07:20 AM

To shim it I simply used layers of sellotape (scotchtape?) and trial and error.

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  • 4619863-Istar scope build 114.jpg


#114 plyscope

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Posted 04 June 2011 - 07:22 AM

Eventually I managed to get the red dot on centre. :cool:

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  • 4619865-Istar scope build 115.jpg


#115 plyscope

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Posted 04 June 2011 - 07:24 AM

At this point it is a good idea to rack the focuser in and out and also try rotating the laser in the focuser to ensure that the red dot stays centred or at least very close under all conditions.

Next is collimation of the lens. This is done in a similar way using a cheshire eyepiece instead of the laser. The lens must be covered. A light is allowed onto the diagonal face of the cheshire while looking through the peephole. The eye should see small concentric circles in the crosshair centre. The lens is adjusted with shims or push/pull bolts until the little circles are aligned concentrically.

I am itching to try out the scope now but must wait a little longer until the mounting arrangement is finished. In the meantime here are some more pictures. The finder scope is a standard straight through GSO 8x50.

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  • 4619867-Istar scope build 119.jpg


#116 plyscope

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Posted 04 June 2011 - 08:42 AM

The side on view.

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  • 4619976-Istar scope build 122.jpg


#117 plyscope

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Posted 04 June 2011 - 08:45 AM

Teddy likes it! This shows the dew shield, it is held on with 4 brass screws. You can see my painting skills are limited but at least it is glossy looks good from a distance.

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  • 4619982-Istar scope build 123.jpg


#118 plyscope

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Posted 04 June 2011 - 08:47 AM

From the rear.

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  • 4619986-Istar scope build 127.jpg


#119 Don Allen

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Posted 04 June 2011 - 11:52 AM

Beautiful.

#120 plyscope

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Posted 04 June 2011 - 04:51 PM

Thanks Don

Using bathroom scales the weight is around 6.8 kilos (15 lbs) as shown in the photos complete with finder, diagonal and 40mm eyepiece. Tube rings will probably add another kilo. I am happy with that.

Andy

#121 drshr

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Posted 04 June 2011 - 06:16 PM

I have come round to the red. Goes well with brass.

Did you make the brass tube adapter on a lathe? I might go this way on my one simply because it looks so good! I am using the same focuser as you so should work.

#122 plyscope

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Posted 05 June 2011 - 01:48 AM

Yes Steve

It is an easy job on a lathe. Just copy the profile from the original GSO adapter. I used 100mm brass stock.

Andy

#123 drshr

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Posted 05 June 2011 - 03:04 AM

You are a brilliant man Andy :bow:

#124 mercedes_sl1970

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Posted 05 June 2011 - 03:08 AM

6.8kgs for a scope that size is excellent. Can't wait to hear how it goes under the stars.

Andrew

#125 drshr

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Posted 05 June 2011 - 04:11 AM

The weight is excellent. My 6" F10 weighs twice that.


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