141 replies to this topic

[catboat]

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!).

[plyscope]

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.

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

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[plyscope]

Two coats of primer after some filling and sanding.

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[DanWray]

Andy,

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

Dan

[plyscope]

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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[s800]

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

[plyscope]

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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[plyscope]

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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[eric_zeiner]

Nice work as always Andy!

[plyscope]

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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[plyscope]

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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[plyscope]

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

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[plyscope]

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

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[plyscope]

Eventually I managed to get the red dot on centre.

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[plyscope]

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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[plyscope]

The side on view.

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[plyscope]

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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[plyscope]

From the rear.

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[Don Allen]

Beautiful.

[plyscope]

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

[drshr]

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.

[plyscope]

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

[drshr]

You are a brilliant man Andy

[mercedes_sl1970]

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

Andrew

[drshr]

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