The Kunama Reflector

[Kunama]

With inspiration from conversations with John Bambury (ausastronomer) and Pete Read (SDM Telescopes) I have decided to undertake another little DIY project ...............

Over the coming months (hopefully not years...) I will be keeping a log of my attempt to make a telescope on a Dobsonian mount. (Yes Col & Lewis .... a DOB)

I want to thank Pete Read of SDM Telescopes who has given me a great deal of advice and encouragement and has also agreed to supply some of his custom components.
Pete has also offered to answer my questions along the way (an offer he may later regret )
Thanks also to Les Sharpe and to Julian O'D for his recommendations on scopes.
Here is the plan for the 'Kunama Reflector'

Specifications:

Aperture: 18" (457mm)
Focal Ratio: F5.58
Focal Length:100.5" (2552mm)

Primary Mirror: Galaxy Optics 18" F5.58 by John Hudek (Thanks Les S.)
Secondary Mirror: Galaxy Optics 3.11" or 3.50"
Focuser: Feathertouch FTF2015BCR LW
Altitude bearings: SDM Cast Aluminium 23" ø
Mirror cell: 'Kunama Industries' 18pt with SDM Laser cut S/S Triangles

At the moment I am gathering the materials and components, and to that end, have now bought:
Galaxy Optics 18" F5.58 Primary, 2 secondaries, Novak Secondary holders
SDM Altitude bearings and assorted bits
Austral Hoop Pine plywood 2440x1220 @16mm
Aluminium tubing 32mm x 1.6mm wall 3 @ 6.5metres

Paints and varnishes and 2Pac Epoxy painting services are supplied by Fluid Painting Solutions of Canberra free of charge !!! Thanks Gabriel (my son-in-law)

[ZeroID (Brent)]

TPIWWP...

And you better keep them coming ...

[LewisM]

You need the De Grasse Tyson seal of approval

http://gifrific.com/wp-content/uploa...g-His-Head.gif

Too bad - better luck next time.

[FlashDrive (Poppy)]

Awesome Matt .....

A ' BIG ' Hand for ' Kunama Industries '

Col......

[glend (Glen)]

Wow! That's a few steps up to the focuser. Are you going to deflect the image back down with a diagonal, go electronic, or buy a ladder from Bunnings? Please take lots of photos.

And here I was about to sell my "16, might get inspired to keep it.

[Kunama]

Originally Posted by glend

Wow! That's a few steps up to the focuser. Are you going to deflect the image back down with a diagonal, go electronic, or buy a ladder from Bunnings? ...... .

A bit bigger than I initially planned so I will be enlisting the aid of:
Little Jumbo Safety Ladder 410B to get up to the eyepiece.

[FlashDrive (Poppy)]

Originally Posted by Kunama

enlisting the aid of:
Little Jumbo Safety Ladder 410B to get up to the eyepiece.

Just watch you don't get ' altitude sickness '

Flash.....

[Larryp (Laurie)]

Sounds interesting, Matt. I look forward to your updates on construction.

[MattT]

Is this going to be the 'Great Kunama Reflector' ????? Is see a steampunk inspired bolts and rivets everywhere type of thing….

Only one thing better than a refractor is a BIG reflector….can't believe I just wrote that…. 18" is a good size.

Will be following as this is the sort of thing I have in mind later on…after the 2" PB and 8" r35 f9.

Matt

[glend (Glen)]

Originally Posted by MattT

........ sort of thing I have in mind later on…after the 2" PB and 8" r35 f9.

Matt

Matt is that the 8" iStar objective? When does that start?

[Kunama]

Dear Diary: It is the 11th of June and the parts are slowly accumulating and the bank balance is a little smaller

Thanks guys for the comments, and Yes MattT, there will be some resemblance to my prior DIY projects when this is finished, though not quite 'Steampunk' !!!
At the moment the plan is just to make something that will come to focus but also to make it presentable in the daytime. As we all know, all scopes look good in the dark, it's only in daylight that you see the differences.

At the moment I am playing a waiting game:

Hopefully a parcel from SDM will arrive soon, in the meantime:

A custom Starlight Instruments Feathertouch FTF2015BCR LW lightweight 2" focuser is now being assembled for me in the USofA.

Picked up my Austral 16mm Hoop Pine Marine Plywood today. Turner's Building Supplies even let me go through the pack to pick out my sheet.

Mirror Cell Frame materials bought from Metal Mart in Fyshwick,
Due to the focal ratio of the scope combined with the 1.6" thick Galaxy mirror, the mirror cell will be made heavy duty. No wimpy hollow steel here, 25mm x 25mm solid mild steel bar with 32mm x 10mm side plates. I will no doubt have fun drilling and tapping holes into this !!!

Aluminium tubing should arrive tomorrow:
3 lengths @ 6.5m of 32mm x 1.6mm wall courtesy of Aluminium Warehouse, Fyshwick.

To kill some time while waiting to get started I thought I would use up some spare timber and make a storage box for the mirror to keep it safe till First Light:
(Sorry Les, the old original one will be retired to the long yard !!!)
Tasmanian Oak & Marine ply Box (555mm x 555mm x 90mm) with 3 coats of Estapol, tomorrow the foam lining, latches and handles go on:

[FlashDrive (Poppy)]

I might put my order in now ..... ... while he's motivated ...!!

Yep ... that's a nice box there Matt.

Flash.....

[Kunama]

Originally Posted by FlashDrive

I might put my order in now ..... ... while he's motivated ...!!

Yep ... that's a nice box there Matt.

Flash.....

Postie brought me lots of goodies today Col, cast aluminium side bearings, laser cut mirror support triangles and lots of shiny bits. I'll be building the mirror cell over the weekend and starting the Upper Assembly next week. Found a friend of a friend who has a computerised saw table that can take a 2400 x 1200 sheet in one go and cut it up to the required sizes ........ probably for a couple of slabs of beer !!!!

Side bearings are going to the powder coaters on Monday.

[Kunama]

Saturday 13 June
Spent an enjoyable couple of hours on the project today.
a. Cut and grind the mirror cell frame steel to size
b. Set out the hole pattern for Collimation bolts (PCD = 235mm)
c. Drill Collimation bolts (5/16") and Tap 3/8" UNC threads
d. Set out and drill holes for Mirror Sling mounting bolts (10mm)
e. Set out Cell mounting bolts and drill to 8mm

Time taken 2hrs 45 minutes

Consumables used:
1.6mtrs 25mm x 25mm Square Solid Mild Steel Bar
1.0mtrs 32mm x 10mm Mild Steel Flat Bar
1 x 125mm cutting disc
2 x Carlton Draught Stubbies and
some WD40.

[FlashDrive (Poppy)]

What colour will she be ... Kunama Cream

Col...

[rrussell1962]

Sheesh Matt, at the rate you are going it will be finished before the book gets there!

[Kunama]

Sunday 14 June:

Colour yet to be decided Col
I think your book will have plenty of time to get read before this job is done Richard.

Very little progress (wife insisted on some gardening instead )

I did manage to get the stainless steel mirror support triangles drilled.
Funny how you forget how much of a pain S/S can be .......

For those contemplating drilling stainless steel remember:
a. Just like most of us, drill bits lose their temper at 120º C / 250ºF
b. have a bowl of water nearby (better with ice in it) splash some water on the steel where your hole is to go
c. cut the drill speed to half but press down firmly, when you see steam your bit is about 20 degrees from being stuffed, COOL the BIT in the water
d. drill a pilot hole first, then go larger COOL the BIT

Note the DIY plate vice, easy to make, fast to use and cheap ! (The screws are set so the plate slips in and then rotate it clockwise till it engages under the screw heads)
Beats having it spin like a fan blade.

Anyway I only broke 1 bit today:

[FlashDrive (Poppy)]

... slow down mate... your making me sweat ...

Nice going ..... more to come I guess...

BTW ...you should have been a ' Manual Arts ' Teacher ... teaching Metal Work and Wood Work.

Col......

[LewisM]

Colour.... cream and Tak green

I hope you at LEAST put a Tak 7x50 illuminated finder on it...

[Kunama]

Thanks to Richard (rrussell1962) I now have the Kriege book on Dobs, my new Bible !!!
First thing I did after opening the parcel was to flick to the section on Mirror Cell design to see how my ad-lib cell compared.
I was relieved to see that I am only 0.5 mm outside the Kriege recommendation.
This book will make things a lot easier (previously I was going off photographs on my screen and my trusty vernier calliper)

I am going to mount the Tak FC76DC on the Mirror box Lewis.

Spent my lunch money at Specialty Fasteners, Fyshwick, today (in fact spent next week's beer money as well) This build is starting to remind me of my boatbuilding days, you skip meals so you can spend the money on shiny stainless steel bits.

Tomorrow I will be arc-ing up the welder once I build a jig to keep the bits in their places when the heat hits.