A 10"/F5 Newtonian

**Malibu** · 15th February 2010, 10:14 AM

G'day everyone, it's been a while since my last post, but I've been popping in and out as time permits.
My last project (yet to be completed) is this 10" Newtonian Telescope. The majority of material is hardwood (Some of it scrap and so I don't know exactly what type of hardwood)

The technical details :

Primary mirror : 10"/F5 Optical Glass/Aluminium with SiO2 overcoat
Secondary : 2"
Tube Diameter : 12"
Mirror Cell : 9 point floating
Focuser : 2" Crayford
Mount : Dobsonian (yet to be completed)
Outside finish : Satin Poly spray
Inside Finish : Matt black spray

A few pictures and short description...
(Sorry, pictures are few and far between because I'm a slacker when it comes to taking WIP photo's)

A) Glued and rough basic tube in it's form frame. Around 50 strips with the edges angled to keep the round shape. Made in 2 halves, then glued together.
B) The router setup on a manual sled with straight edge guides to true the outside of the tube.
C) A microwave turntable motor fixed to a center axle and self centering bearings to keep the tube rotating while I push the router along.
D) The first of many rings to hold the tube together, support various other parts and for general aesthetics. The rings are made for short cuts of scrap, glued in interlocking layers and trimmed round on the table router. Each ring has 36 to 54 segments in total depending on the function.
E) Gluing the Spider ring. I'm only using the tube to hold everything in place and aligned while the glue sets.

**Malibu** · 15th February 2010, 10:26 AM

Part 2...

Inside routing was the biggest mind warp of the entire project!

F) The entire setup for routing... A trim router mounted on aluminium rails with a variable speed motor/gearbox to pull the router along. A set of bearings for the tube to rotate on. Another motor to rotate the tube. A camera connected to a laptop to watch the route process. An air tube to clear the wood chips from the rails and a dead weight to stop any 'whip' on the pull setup. Phew!
G) A closer view of the router setup.
H) The motor to turn the tube using a rubber friction drive.
I) Motor/gearbox contraption to pull the router with some copper wire as the tow rope.
J) Inside view of the router being pulled.
K) Routing in progress using a 1/4" downcut spiral bit.

The last photo is a closer view of the camera setup.

**Malibu** · 15th February 2010, 10:32 AM

Part 3...

L) The basic spider assembly (To hold the secondary mirror). Made from laminated hardwood and vertical drape material.
M) The spider again. Aluminium and nylon all thread adjustment screws.
N) The spider mounted in the tube
O) Another view of the spider mounting with some rings attached to the tube
P) And again...

**Malibu** · 15th February 2010, 10:37 AM

Part 4...

Q) The focuser hole cut using a hole saw.
R) Focuser mounted with the spider showing the mounting rings.
S) The primary mirror in place on the mirror cell. The cell is made from laminated 6mm fibreglass and aluminium adjustment screws. Here I'm just checking the focal point before I glue it all together.

**Malibu** · 15th February 2010, 10:44 AM

Part 5...

The (Almost) final results -

T) An overall view. I still have to finish the Dobsoniam mount, once I figure out the best way to do it!
U) Looking down the tube to the primary mirror. The end cap (Behind the mirror) has been removed
V) One of the first photo's. A quick picture using my Pentax digital camera lined up as best I could in the eyepiece. No filters, no post-production on the image. It's 'as-is'

Hope you enjoy my project, I know I did, and it's only taken me 20 years to get this far!!

**Malibu** · 15th February 2010, 11:15 AM

One more for the road...
An AVI to show the inside routing... A more graphic description than the photo's if it's preferable..

Each run of the router took about 2 hours at around 10-12mm/minute feed rate.

The router noise gets a bit much after a while, so earmuffs were a must!! (as was an endless supply of coffee)

**Woodwould** · 15th February 2010, 11:20 AM

It's not rocket surgery, but damned close!

What a fascinating bit of work, and meticulously excecuted. Now you can take a look at Uranus any time you choose!

**petersemple** · 15th February 2010, 11:27 AM

That is quite extraordinary - and I mean that in a good way.

**chowcini** · 15th February 2010, 11:58 AM

Wow!!!!! A lot of work in that and some very clever jigs

**orraloon** · 15th February 2010, 12:01 PM

A really interesting project.
Now that you are all jigged up you will be able to do a production run
Regards
John

**RedShirtGuy** · 15th February 2010, 12:35 PM

Hot damn!!! That's a hell of a lot better than the cardboard tube they usually tell you to use for Dobsonian kits. Very well done.

**Dengue** · 15th February 2010, 02:12 PM

That is just brilliant - really amazing.

Congratulations on your persistence in getting it done. Loved the internal routing effort. Mind boggling for someone like me who has never seen this sort of workmanship before.

A real eye opener

**snowyskiesau** · 15th February 2010, 05:08 PM

Excellent stuff!
How heavy is the tube with that construction method?

[If you haven't already done so, you should consider posting this over at iceinspace.com.au. ]

**ivanavitch** · 15th February 2010, 07:05 PM

Brilliant. Just brilliant.

**timelord** · 15th February 2010, 10:04 PM

Lovely scope--I,m an amateur astronomer myself so appreciate the work.
I,m also sure that the forum members at Ice In Space would also like a look.
Certainly looks better than my 10" Steel tubed Newt.

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A 10"/F5 Newtonian

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