My apologies in advance ....

[Ian Robinson]

I've just about finished my 10" f4.66 OTA rebuild/upgrade .

See my thread at CloudyNights http://www.cloudynights.com/ubbthrea...rt=1&PHPSESSID= for details.

As off this avo (boy what a cracker of a day for winter .... was over 30 degC on my garage and that breeze was pretty warm , as was the sun coming in through my recycled front sliding door (on the side of my garage ....) I've completed the following tasks :

----- cutting and squaring up the ends of my offcut of 316mm OD plastic water pipe
----- installed my custom made low profile 2" crayford focusor
----- spaced out precise position of my new AstroSystems spider and drilled the bolt holes for the fins (my Astrobeam laser collimator was great to getting the centre for the "new" 2.6" Nova secondary)
----- modified the side clamps on the new Orion Optical mirror cell to fit my old Nova 10" mirror
----- spaced the tube bolt holes for the mirror cell for 2 modes of Astrograph
Mode 1 - near fully ranked in focus with my Lumicon 2" EsyGuider + Lumicon Coma Corrector / Field Flattener + 40D + Orion Starshoot Autoguider
Mode 2 - near fully racked in focus with my MFCC + 40D
(visual I should be able to do with most my eyepieces and if need be I'll get a 1" long 2" OD extension tube so I can use all my eyepieces and my Paracorr Visual
You got it .... I really don't like coma !!!
----- flocked the entire inside of the tube with ProtoStar Self Adhesive Flocking Material << is super sticky stuff >>

Next job on the agenda
clean that dirty mirror , I'm hoping some dilute warmish dishwashing detergent using some left over surgical cotton pads (from my shin injury and surgeries a few months ago) , followed by rinsing with tap water followed by final rinses with demin water using some left over syringes.
Got some dust and stains on the coating that I hope will come off with this treatment , failing that , it's off to Kotara to buy some AR grade anhydrous isopropyl alcohol to really sock it to the stains , if that doesn't lift them, it's off for a recoat (I like the idea of high reflectivity dielectric coating with high transmission TiO2 and SiO2 overcoast , will be like having mirror nearly an inch bigger !!).
If I can't find someone who does that here , then the mirror will be off to the USA or UK for recoating.

Anyone do dielectric high reflectivity coatings here in Oz ?

Then if all goes to plan , the mirror and secondary will be installed and I'll have a go at collimating the OTA.
(I'll probably use a trick I picked up a while ago of collimating with a coma corrector in place).
The good old Laserbeam will come into it's own here.

First light for the enhanced OTA and first use of that New Atlux that's been decorating the lougeroom for over 12 months will be on Monday or Tuesday night . ..

.. so you can expect the clouds and rain to come back and stick around for a few weeks or months .... so here are my preemptive appologies to everyone in Victoria, NSW and Queensland .... the rain and pea soup like clouds will be all my fault..... sorry .

Then I'll get serious about my ROR shed.

[kinetic (Steve)]

Would love to see some Pics Ian,

sounds like a great project!

Steve

[Ian Robinson]

For anyone interested in how I designed the OTA for the various modes pf Astrograph and for visual use - see attachment .

I've also attached my design for my customised side clamps

[Ian Robinson]

Update :

Stains on mirror cleaned up OK with dilute dish detergent soaked 5x5cm cotton surgical absorbant pads and multiple rinses (warm dilute detergent) using a left over syringe (the community nurses used these to wash my surgical wounds out with sterile saline each day before repacking and bandaging my big open surgical wound and repacking the drain after I had been sent home to complete my healing).

The tap water rinses using another left over syringe ensured no detergent residue was left on the surface.

When the water was beading nicely I knew all the detergent residue had been rinsed off.

Then immediately following the tap water rinse , I did not allow the mirror to dry , I rinsed thoroughly with demin water, again from left over syringe.

Wife has been told not to go near the sink until the mirror has been removed , currently standing with the back edge on the dishtowel on the draining area of the sink , leaning with the mirror back against the window sill.

Running the A/C to warm the air and get it circulating in order to get the mirror totally dry so my wife can do her things in time to see her shows tonight. Glared at me when I told her to wait 30 - 60 minutes for the mirror to dry .... she didn't like that idea at all ....

A few very small scratches at the edge of mirror - from handling the mirror and from the old mirror cell also about the edge , have to look close to see these so I am not terribly worried about them as I don't think they have any noticeable effect on the images I will see or record.

I did notice when I looked over the mirror with a hand magnifying glass that there lots of very small pin holes in the aluminium coating .... I don't think they have a noticeable effect but .... there are lot of them.
Can't see these pin holes at all without a magnifying glass.

Mirror will be ready to go into the cell tomorrow .

Will take those pictures tomorrow before I install the mirrors .... that's a promise folks .

Additional notes : while my wife was watching Dancing with the Stars I checked the state of my tube's flocking (been 24 hr) and was very cool tonight - so I figured it was worth checking on a JIC basis .

Noticed some bubbles trapped (some about 2" long x 1" wide) under the flocking material and noted that some of the flocking material looked a bit loose (not coming away from the tube or drooping .

The tube is currently on two builder's workhorses - and orientated horizontally , it wont be ordinarily be stored between uses in this orientation until I build my ROR shed (that will be parked position) but will be stored standing up with mirror facing to the zenith with a bit end cap over the top of the tube.

So I have gotten busy this evening pressing it as hard ar I can by hand to the tune when I can reach the flocking to ensure good contact , and using some pressure applied the 1" wide straight edge on on my 1m straightedge/spirit level and giving the areas of flocking I can't reach with my arms as good a press down as I can , after I used the stanley knife make small cuts in the flocking material where there are obvious bubbles (spotted these bu shining my miners' lamp down the tube and as close to he surface as possible (the bubbles and rinkles (there are some small rinkles too) are highlited by their shadows. The cuts made it possible to press the flocking onto the tube surface and allowed the trapped air to escape doing the rub / press down process.

May be worthwhile letting the flocked tube settle and checking once a day over a few days (rotating the tube a bit between checks and giving flock that is starting to look the least bit loose or droopy another good pressdown) before I complete the OTA assembly but installing my optics and collimating.

In a few days I should be more confident of good contact and adhesion of the flocking material with the tube , and the tube will have had a chance to thermally cycle a few times from very cold / humid air conditions at night to warm and sunny in the day ..
.. if there's any problems with adhesion it should become apparent , -- if there is I can take steps and glue flock that wont adhere with a stronger paint on or spray on adhesive before I install my optics.

Will keep you guys posted on how things develop over the next few days or so.

Improve the technique of pressing down in long tubes :

Next tube I flock I'll be smarter and I'll get hold of nice bit of straight 50mm diam steel pipe or 10kg length of steel round bar (maybe 20mm diam ??) about 1m long whose ends I'll caffer and I'll use this to press the self adhesive flocking down in rolling manner rather than rubbing while pressing it down with a straightedge - it'll be easier and less wear and tear on the flocking). Wish I'd thought of this before I started flocking.