16" f4 Orion Optics UK Dobsonian Project

[Astrokev]

What I fancy is one of those cloaks that go over you head at the EP. I did see a commercial one some time ago but I guess they are easy enough to make. What I like is not only do you get to keep both eyes open and so reducing eye strain you also reduce any stray light distracting the eye doing all the work. I'm assuming these also help stop stray light entering the focuser ????? Not to mention it would also save me looking a total plonka with me eye patch.

So you wouldn't look a plonka standing in your garden with a cloak over your head then?!

[spaceboy]

It wouldn't matter as no one would know it was me. Got a cloak over me head remember

[Moonshane]

just drilled the holes for the focuser base plate and fitted it temporarily to check the fit. seems OK and also fitted the finder shoe for the same reason. just waiting for my cell to come back from welding and will hopefully be able to paint it this weekend.

then during next week I can hopefully flock the OTA, add the focuser, the finders, the secondary, the cell and primary and a mid range eyepiece, apply the laminate to the alt bearings, drill and temp fit the alt bearings and then gauge the balance point.

then next weekend I can have a go at sorting out the base.

maybe even first light! but realistically, the weekend after, just on time for my mid July deadline (approx.).

[Moonshane]

further small steps made

yesterday I painted the cell triangles and bars with primer and they are now ready to be hammerited when I get the cell back after some further welding. I can then build it up.

the 'dob knob' was improved slightly smoothing it down and then cutting the threaded rod to size. I cut the nyloc nut in half to reduce the profile into the tube.

I temporarily fitted the telrad base with masking tape and this will be a little further round the tube than I'd like, possibly. I may change the position in the future when I see how it works in reality.

also filled, sanded (again), drilled and fitted the alt bearings to check for fit etc. quite pleased with them. only 2mm difference between the front and back widths which can be sorted in due course with shims if required.

if I can get the balance position anywhere near as show I'll be very happy as this will mean a low, stiff and less weighty rocker box.

just need to fit the formica bearing faces with contact adhesive, after a final sand with both bearings bolted together to ensure they are identical.

pics as always.

[scogyrd]

I must say your build is starting to look very nice now. I can't wait to see it when it's finished.

[John]

It's looking good Shane. You can tell the scale of the thing by the relative sizes of the Telrad base and finder shoe !.

Ever thought of doing this sort of thing for a living ? - we will need some more UK manufacturers if the Chinese supply ever falters

[russ]

Looking really good Shane.....that's one big scope!

[Glen]

Thought you was making a scope..

Not a glockenspiel..

Thanks for the update and pics Shane

EDIT: have you seen this site > Setting Circles

[Moonshane]

I must say your build is starting to look very nice now. I can't wait to see it when it's finished.

cheers matey

me neither!! first light will be quality (i ntheory!).

It's looking good Shane. You can tell the scale of the thing by the relative sizes of the Telrad base and finder shoe !.

Ever thought of doing this sort of thing for a living ? - we will need some more UK manufacturers if the Chinese supply ever falters

ha ha yes John, it's massive. I will be making a trolley of some kind or wheel barrow handles at minimum. I could consider making some for money I suppose. I have a new job which is term time only and 4 days per week!

Looking really good Shane.....that's one big scope!

ha ha sure is mate.

Thought you was making a scope..

Not a glockenspiel..

[ATTACH]62388[/ATTACH]

Thanks for the update and pics Shane

EDIT: have you seen this site > Setting Circles

well, if it's good enough for Sir P!

thanks for the site details - in the memory banks!

[Astrokev]

Looking great Shane. Don't worry about your deadline though. Better to do a quality job and miss mid-July than to rush to meet your DL.

Changed my view now. Your build no longer looks like a horse and cart, but would make a great cannon!

Look forward to seeing it on your base.

[Moonshane]

cheers Kevin

yes, I agree and although it's frustrating as I want to get looking through it, I really want to do pretty much everything now rather than have to re-do things in the future as I rushed them now.

that said, I am pretty sure I'll make the deadline, especially as a mate has offered a loan of a spray gun - yet another thing I have ever done before!

the base will follow shortly as I need to gauge the balance point - I really want it as low as possible as low = inflexible.

[Moonshane]

just did a little bit on this today as I am working this afternoon. bolted together the two bearings and sanded so that all surfaces match. also established the exact position of the bearing surface so that I can mark the position and fix the laminate next. I bought some 'ebony star 60' from Wilsonart which has a textured surface but is not as 'bobbly' as the usual material. I am sure this will work fine with a scope of this size and a coat of turtle wax will of course help too.

also later I will be gluing some 'penny washers' in place so that the weight bears on the washer as well as the wooden surface which should reduce wear - although there should be little if any movement in the fixing anyway I suppose. so by the end of today I should have completed alt bearings with the exception of painting which will be done all in one when the base is made, masking off the laminate of course!

[Astrokev]

Sounds good Shane.

I've read lots of mentions of Ebony Star. What is this exactly? Is it just a fancy name for kitchen worktop type laminate?

Look forward to the next set of pics.

[Moonshane]

Hi Kevin

yes, ebony star is a pattern of worktop laminate which is more bobbly than others and deemed by the experts to give the best surface for buttery smoothness. it's sold by Telescope Service but costs quite a bit. I got all of the laminate I need for my scope for £20 and same would have cost maybe £60 from TS so I'll take a chance for now.

if it does not work as hoped, I'll eventually replace with 'the proper' stuff although I am sure it will.

[FraserClarke]

Hi Kevin

yes, ebony star is a pattern of worktop laminate which is more bobbly than others and deemed by the experts to give the best surface for buttery smoothness.

Apparently David Kriege (I think?) spent years going round DIY stores in the US pulling a block of teflon over ever bit of laminate he could find -- "ebony star" was the best in class.

It's out of production now I believe, which explains the high prices... There may even be a better alternative out there now -- but who fancies spending their weekends touring round B&Qs with a block of teflon?

[Astrokev]

Hi Kevin

yes, ebony star is a pattern of worktop laminate which is more bobbly than others and deemed by the experts to give the best surface for buttery smoothness. it's sold by Telescope Service but costs quite a bit. I got all of the laminate I need for my scope for £20 and same would have cost maybe £60 from TS so I'll take a chance for now.

if it does not work as hoped, I'll eventually replace with 'the proper' stuff although I am sure it will.

I'm sure you're right. When I made a Dob years ago, I bought an old off-cut of laminate from the local DIY shop. Worked an absolute treat. The other thing to bear in mind is that with the length of your OTA, there'll be a lot of leverage when you move the tube in alt and az, which I reckon will make for a much smoother bearing action.

[Moonshane]

yeah true enough Kevin, especially re the leverage.

looking forward to my cell coming soon.

might give the sanded areas (where I took off the black square) a bit of a spray paint tomorrow and then flock the tube in prep for the big build up.

[Glen]

If your at a pinch, an old milk carton does alright for washers, easy to replace too

[Moonshane]

cheers Glen

I have enough teflon etc and parts to finish the project, it's just main expenditure I cannot do for the time being. thankfully all my main expenditure has been made already!

[Moonshane]

made some good progress today with two of the more fiddly jobs. painting the area I recently took the black square from and flocking the tube.

first job was to remove the temporarily fitted finder shoes, focuser plate, rings and trunnion blocks.

this done I gave the tube a proper clean with a wet cloth and then lighter fluid to remove some residual glue from velcro patches which had been used to hold on the tube caps. with the outside nice and clean and drying off ready for paint, I then took to the inside. I used isopropyl alcohol to clean off any greasy residues and the brushed out to clear any 'fuzz' left from the paper towels.

I then masked off the holes in the tube where I was painting and masked the OOUK stickers (might actually replace these to be honest).

ok, with some trepidation, I took my £3 (delivered) can of gloss white spray paint (care of Ebay) and started spraying. I covered it in three light coats and it seemed to go pretty well to be honest. once dry, after half an hour or so of polishing with T cut, a quick polish with wax and it was looking and feeling pretty much the same as the rest of the tube. OK I may have to get a proper buffer to get the same finish. there's the odd cosmetic scratch and bump etc on the tube but it's looking a lot better and in the dark.........

pretty happy with the results, I then decided to tackle the flocking. you can see that the tube was pretty reflective inside beforehand. unfortunately the 4 foot x 2 foot sheets did not quite got all the way round the tube and I had to do a little patchwork quilting at the end to ensure the three sheets covered the whole interior, but it worked well and makes a big difference.

it's not easy flocking a scope with a 63" long tube, but at least at this diameter, you can get head and shoulders in to reach. it was a lot easier than the 6" f11 of the same length!!

now I can do a final trim of all the holes and after leaving overnight to ensure none of the overlaps detach themselves (in which case I will add a little PVA) I can then start putting things on permanently and building the thing up.

next will be the build up and the cell painting when this comes back from the welder's.

Cheers

Shane

[johninderby]

Looking good Shane

BTW posted off the bits to you this aft.

John

[Moonshane]

cheers John

I am so glad that I got rid of the black square. It would have annoyed me no end. It's amazing how easy it was to use the spray can. Never done this before but might even invest in a mini spray gun as it will come in useful for many jobs (painting the fence etc. too). I suspect it would actually be easier to spray the whole tube rather than try and sort out a patch. I now have no fear of doing this in the future if required.

Thanks so much for doing those bits for me - totally appreciate it matey. I'll report back with them fixed onto the OTA in due course.

[Moonshane]

did a bit more tonight, adding back the spider, focuser base, optical finder base, Telrad base, dob knob and top end trim. Also glued the 'Shane's knobs' for the secondary collimation.

I have to say the end trims on the OOUK scopes bigger than 14" are appalling. Extremely thin and brittle plastic a bit like the end caps but even thinner and more brittle. Unfortunately, I don't think their machinery can make the aluminium ones bigger than 15".

I may eventually make or try and get someone to make, some CNC or moulded (or even pressed thin gauge steel) versions that will be far better.

Pics to follow tomorrow.

Cheers

Shane

[johninderby]

I use the Astrozap breathable dust covers on my OO dob. Keeps the dust out but lets the moisture escape so you can put the covers on as soon as you bring the scope in.

http://astrozap.com/scripts/prodView.asp?idproduct=248

The Astrozap ones aren't cheap, but if you can get some of the right breathable material and convince someone with a sowing machine to make some up for you it shouldn't be too expensive.

John

[Moonshane]

cheers John, yes, after seeing yours I was going to ask my neighbour to make me some for the caps - she's a whizz with a machine and she'll do anything for a wine bribe. well, not anything obviously!!