12" truss dob

[GrahamL]

Started about 3 weeks back and have allowed a year to get it done
The ply is a laminate of 2x 12 mm (plantation pine ) I believe.

planning to use moonlite connecters if I can track down some tube to suit the inserts .. have a 2.6 " secondary ..unsure of a primary mirror cell yet or were I'll get the mirror from.. just time .. and money ;)

10 " dob for scale ..patiently waiting for dark and scorpius to rise :)

take care and thanks for looking

[JethroB76]

Interesting, what are you using in the way of plans?
Excluding the mirror, do you have a rough budget that you think is required for the project?

Keep us updated on your progress:thumbsup:

[iceman]

I wish I had the time and skills to build something like that, I look forward to seeing your progress!

[GrahamL]

thanks guys :)



I purcahased a S/H copy of kriege and berrys book several months back , unfortunately it got lost in the mail somewheres,so this so far is mostly just copied from pics from round the net

Budget ? .. I reckon maybe $700 plus primary ? .. can't see it much cheaper
than that maybe a little if some more used parts show up .

take care :)

[JethroB76]

Thought you'd be referring to Kriege.

Interested in your progress, I hope to build something in the 15-18" range in a couple of years.

[glenc]

Looks good Graham. :thumbsup:

[CoombellKid]

Excellent Graham!!!

I'll be following your footstep soon I hope.

regards,CS

[GrahamL]

started the mirror box this weekend .

[monoxide]

birds having a good feed ready to centre spot your mirror :lol:

[GrahamL]

Couple of rainy days kept me home so a little more got done :)
mirror box is nearly finished , reminds me of an old thunderbox :D

started a mirror cell today I think I'll try some 6mm aluminum +12mm ply
as a start and see how it goes ..

[rmcpb]

Looking great, how did you fix the bolts onto the spacers on the OTA?

[GrahamL]

hi rob

there a small piece of dowl sanded down in each end of the tube
two small stainless screws hold it in place .. the 1/4 x 50 coach bolts
are centred through .. 50 mm is a little long btw 45 would of been better as the secondary has to mount directly below them,, though I think it will still squeeze in there.

cheers graham:)

[CoombellKid]

Coming along nicely there Graham. I would thought you might of used
treaded rod in those tubes,well that what I've been planning on using.
Still at the end of the day you cage will be lighter for it.

regards,CS

[CoombellKid]

What sort of Plywood are you using? Marine Ply?

regards,CS

[Satchmo]

Just for future reference the flower shaped threaded furniture tube closures normally used for mounting the spacing tubes on the top end as shown in Kreige's Truss Dobsonian book, are available from Maumac's in Sydney.

[GrahamL]

hi rob

bit cool out your way last night ?.. yeah I thought of some thread bar
to go right through but the extra weight seemed to much for
the little thing your trying to do .. the sanded broom handle bits weigh almost nothing but are a PITA to fiddle with ..the things mark mentions I was aware of but had no idea of what there called or who to source them off .. and theres not many people in a small town to chase after them.

the ply is just a laminate of 2x12 mm ac pine I think .. 24 mm is a fair
thickness but its still light and is very strong .I was always going to paint it black so the nicely finished marine plys would of been a bit of a waste and ..double the price .

FYI rob theres a new specialist aluminium dealler not long opened in ballina
he has everything in stock and a very nice band saw that will cut any angle thickness you might want ,and is fairly cheap those 4 cage spacers were less than $1 each .

thanks for passing on the info mark .. is the company a furniture manufacturer ?.. I so wanted to hold of some of those knowing how simple they make things .

take care graham

[CoombellKid]

Dam right it was Brrrrr... had the fire going at 4:30am this morning.

Thanks for the info on the new specialist aluminium dealler in Ballina. Do
you know where one can source marine ply over your way? I dont mind
paying extra. I might need someone to cut it for me too.

I'm still a while away from starting my scope, just compiling ideas and
sources for material.

regards,CS

[stringscope]

Looking good Graham.

Have you decided on mirror cell design yet?
Number of mirror supporting points?
Mirror edge support?

Cheers,

Ian

[GrahamL]

rob hurfords had some great looking sheets of marine ply a while back
$90 I think 2400x1200 x12mm .. lismore would probably have the same
you sure wouldn't need 24 MM of them .
Most large kitchen makers would cut all your straight cuts for a few dollars
on one of those benches you just press a keypad to set the blade at the width you want ..takes no time .

lots of circles and half circles in a scope I've found.. borrow my router if you want cutting circles isn't that hard .. do you have a flat slab or some sort of work area?

thanks Ian.. planning to copy this basic one
http://www.ultralightscopes.com/Products.htm
I drew out some weird looking hexagonal shape around this (no idea why:rolleyes: )
at first 6 points at 61%.. no edge support fitted as mentioned above
to sit on a drop down tailgate .. but I'm not sure yet and still
looking around ... any suggestions ?

take care
graham

[stringscope]

Graham,

You might want to research the mirror cell issue a little further. There is a program for optimising mirror support locations called PLOP. The link below may be of interest if you haven't already seen it.

http://www.atmsite.org/contrib/Holm/Plop_optimized_cells/index.html

In summary about 50% radius is about right for your 6 pt cell support locations.

The Albert Highe mirror cells rely on RTVing the mirror to the supports. Appears to be quite successful. Mag1 Portaball scopes used the same system.

Peter Bobroff recently posted images of a 27 pt all RTV'd mirror cell on IIS. Appears to work quite well. You might want to discuss further with Peter.

Bruce Sayre also uses RTV to attach mirrors to cells.

http://www.foothill.net/~sayre/

As I see it the advantages are simplicity and no edge supports for retaining clips. Possible disadvantages are:

1. Astigmatism introduced through incorrect glueing technique
2. Mirror has to be cleaned while attached to the cell.

Cheers,

[Satchmo]

Yes, they sell furniture hardware to furniture manufacturers. They will sell to anyone though. Be sure to say that your order is `for prototyping purposes' and you won't have to buy bags of 100 . Last time I visited I bought a large mixed selection of star knobs with threads and threaded tube closures for $1 each .

[GrahamL]

good to know thanks mark:thumbsup:

Ian am I reading wrong ? ..r2 was were I got the 59 /60 % from .
(61% was just a circle I had already drawn )
and about 50 % for the support beams being r1.. ?
thanks for the links i did see bobs post and looking at again realised the whole
cell was mounted on silicone.. we used some of this adhesive in a fairly heavy
work situation once ..and I remember thinking no way thats going to hold on
for long .. I believe some years on its still firmly attached :)

[CoombellKid]

Personally I would avoid using silicone to set the mirror in, if that whats
your talking about. You want to be able to remove the mirror for cleaning
at some point. You need to get yourself off to a major astrofest and look
at how the ATMer's do the job.

If your not talking about the above then I'll just shut up lol

regards,CS

[stringscope]

Graham,

My apologies, must have been too late at night :doh: . Yes 50% for beam pivot points and 58% (pretty close to 60%) for support points.

Re RTV, properly applied, I don't believe there is a strength or adhesion issue (providing you use the correct RTV) for mounting telescope mirrors. As I understand it however, there is real potential for astigmatism to be induced into the mirror due to incorrect application and/or shrinkage. I have only used RTV for a couple of secondary mirrors and an 8" conical mirror so I just don't have the personal experience of RTVing a standard primary mirror onto a multi point cell.

Cheers,

Ian

[AstroJunk]

At last!

An ATMer building a scope the right colour!

How shallow am I ;) ?

[CoombellKid]

Well I took my first steps towards building my telescope. I ordered a copy
of Dobsonian Telescope: A Practical Maunual by Kriege & Berry.

regards,CS

[Omaroo]

Just done the same a little while ago. It's a great book, but the only thing I have a problem with is that it assumes that the smallest scope you're going to build has a 14" mirror. I plan to build the 12" bino using Mark's mirrors and I find that at least the formulae described in the book can easily be adapted to any situation.

[CoombellKid]

The book looks awesome from looking at the contents list...

http://www.obsessiontelescopes.com/publications/book_contents.html

I should have my copy tomorrow when I head into town and pick up the
post. Looking forward to having a good read. I'm looking to build a 16"
so it wil be good to get some ideas on how to approach a few things. I'm
also looking at truss-erising my 8" for my boys to use. Hell I might even
have a go at mirror making. I figure if I want my 18-25"er I'll probably
have to make it myself to save on costs.... he wishes.

I also want to get at some stage, How To Make A Telescope by Jean
Texereau. I hear it's a must get if your into mirror making.

I also ordered Uranometria 2000.0 vol3: Deep Sky Guide completing my
set of 3. I'm looking for to getting that too :thumbsup:

regards,CS

PS: How's the scope coming along Graham have you done any more work on it?

[CoombellKid]

Sorry I missed this post.

$90.00 doesn't sound too unreasonable, probably need thicker than 12mm
so that will up the cost.

I'm going to build a decent work bench. I was in at Bunnings Lismore on the
weekend checking out prices for some tools. They had a portable work
bench in there you stick an electric hand saw into so you can do straight
cuts. I'll get my brother-inlaw who has a wood lathe to do up some fancy
knobs. It'll be a few months before I can really start. But I guess using this
time to read up and research will be a good thing. I might even truss-erise
my 8" first, make it more portable lol

regards,CS

[GrahamL]

hi rob :)

been doing a little bit on the weekends ,I ordered some moonlite truss
conecters a while back a protostar spider and some teflon
just waiting on them atm.

been putting together a mirror cell lately and its been a pain at times
I cut some aluminim for a cell and left it with a engineering shop to weld it up for me .. The only thing I really stressed at the time is that it had to be flat
Got it back last week to find a half inch twist along one edge .
I get on well with the owner of the buisness and he didn't charge me for doing it .. so I feel obliged not to take it back and whine .. the guy who stuffed it up has a history of cutting corners with jobs IME..In this case he just needed one more clamp and all would of been well .. such is life ..
I managed to put a little heat on it at work and smack it fairly straight.

pics later tonight if I can find some rechargeables for my camera:)

[CoombellKid]

I've made a note next to my cell plans, must pay for wielding to ensure good
job and/or refund lol. I'm going to make a jig to put the tailgate together
and a mate of mine will wield it with me observing lol. Actually I'm surprised
the mirror cell looks alot easier to put together than I had previousy thought.

regards,CS

[CoombellKid]

Ian,

Will PLOP run on an IBM clone running XP Pro?

Graham,

I would of thought you would of gone for at least a 9 point cell

regards,CS

[GrahamL]

Been doing a little more this week :)

might mount the moonlite connecters tommorow , I'm not sure how they'l go (long term ) screwed to the top of my mirror box ,in that the ply while being thick is fairly soft , if they don't work out that way I'll bolt them to a piece of flat plate in the corners and secure that firmly .
Az movement seems good I'll get the old man to turn me up another couple bushes like pictured to finish off ..Alt is just sitting on some felt squares for the moment.. surpriseingly it moves quite smoothly .. if it does so when finished I might leave them there .

thanks for looking

[CoombellKid]

Wow! by the look of that last pic, where you getting the 12" f/1 mirror
from? :P

Looking excellent there Graham, I've finally about finish my work shed
and bench.

Might need a few tips on the use of a router, never used one before.

regards,CS

[Orion]

Looks like it's coming together really well Graham.

I am also using the Moonlight connectors which will be bolted to the mirror box instead of being screwed. If you decide to bolt them and you have trouble finding long enough screws to go all the way through use a 4mm threaded rod cut to size. That's what I did.

[GrahamL]

Thanks for the kind words guys :)

funny you mention that rob it crossed my mind when I sat it there

thanks ed ..yeah finding a stainless bolt long enough and narrow enough
has been a hassle.. you found that to eh ?
Additionally I can't bolt straight through as the side panels of the mirror box are under the mounting points .. I'll try the screws ,I've ordered
a hc-2 focuser http://www.kineoptics.com/HC-2.html so my upper
cage will finish up very light .

take care and thanks for looking

[GrahamL]

my protostar spider showed up friday so mounted it up today

I mounted up the mirror cell today ..I so over complicated this by forever changeing my mind as it was built .. its sits well and is nice and rigid
i can get the smallest bit of flex through that 6 mm cross member when i push at it ,,I dosn't move where the collimation bolts sit so i don't know if it is really an issue ..think i'll attach anothe piece to stiffen it up .. theres
not enough bolts in this thing anyway:P

take care

[Satchmo]

Graham , You'd best make those 6 pads compliant because that is not a flotation cell , so hard flotation points will warp your mirror, as the frame sags. Even putting 6 pads of Velcro ( just the furry side) over your six hard pads, will save your bacon :) Theres a lot of work in your cell : it would have been just as easy to mount your 6 points on the tips of 3 bars for a true flotation cell.

[GrahamL]

Thanks for stopping by mark..yes I'm going to go with velcro
I should of mentioned I shuffled in some differant pieces of flat bar
and can secure to 12 or more points at the 60 % zone now.

I came across another who used velcro a little while back
and unless I'm reading wrong did something fairly similar to what you use
and the only complaint they had was it wouldn't let go !

yep it sure would of been easier to build a flotation cell and was going to
at the start ..Im going to blame the internet :shrug: for to much info
being available .

take care :)

[CoombellKid]

I'm a little confused about how you columinate with your cell. I can
see where the three main supports are but how are you adjusting them?

I was thinking of flogging the support feet you get on the bottom of
some white goods to level them, they come with a ready made handle.

Here's a pic of my shed. I spent yesterday putting in a bench along the back.
I need to get a sheet of laserlite for the back window, and probably build a
bi-fold door for the front tool keep my tools secure. Although you dont get to
many unwanted visitors done this way. Now I have a place to build things I
can start to look at my plans for our 8". Also a parallelogram mount for my
20x80's to go on the tripod for the EQ5.

regards,CS

[GrahamL]

Nice shed rob :thumbsup:.. collimation is through the long (to be trimmed) bolts
its seems to work well.. whats the slab on your bench ?

[CoombellKid]

3 sticks of 12"x2"x8' bloodwood from memory I think, sitting on 4x3"
ironbark legs. You wouldn't want to try lifting it.

regards,CS

[GrahamL]

bit of rain about this week so a little more got done
these moonlite connecters are great .

[glenc]

Looks great, is it finished?

[CoombellKid]

She is coming along there Graham, must feel good to see it taking shape.
You got a focuser yet?

You should grab that 12.5" Zambuto someone is selling in the buy and sell
forum. It's only $1900.00 : ) nice mirror though.

regards,CS

[GrahamL]

thanks stopping by. :)

no its still a fair way off glen , lots of little things to do mainly
I could have it rough finished in a couple of days if i really had to
but arn't in any hurry.

I have one of these http://www.kineoptics.com/HC-2.html
no bells and whistles on it but its smooth and light.
I'd still like to have a go at makeing a mirror for it rob
but realise that would be a few years before I'd even think about it.
so cheap will do for now..,$1900 s/h seems a lot when you price
it against new from any of the well known suppliers..:shrug:

take care

[GrahamL]

where did you get that venneer from btw rob ?

[CoombellKid]

Carl Zambuto is considered by many one of the best mirror makers on
the planet, although I've never looked through one. He is quite well
known in the states. But like you, if I'm going to spend that sort of
money on a mirror I rather spend more and get something 16" or bigger.

I'm still in two minds about a 16" GSO and they're still not available here.
Might be looking at ordering something from Mark next year.

regards,CS

[Stevo69]

Hi Graham,

You sound pleased with the Moonlite connectors! It looks like you have used the double ball-joint connectors at BOTH ends. Am I right? How do they perform?

hoo roo, Steve

[GrahamL]

they seem fine steve ,, I havn't secured the inserts though as they are a tight fit and i was thinking they'd be hard to remove when i cut them to length.. they are just pushed slightly into the tubes so are differant lengths ,but they still align well and the whole structure is very rigideven before the clamps are tightened .Until I remake the focuser board i'm not going any further regarding securieng the inserts.. this weeks been good for observing so I'm looking through a scope rather than at one ..:D:)

yes double ball and sockets top and bottom

cheers graham

[CoombellKid]

Graham you shouldn't be to far from finishing. Have you acquired a mirror yet?

regards,CS

[GrahamL]

not yet rob , not in any hurry to finish it really ,by the time i get home from work its to late to do anything through the week, and the wifes
suggested I'm a bit obsessive about spending every waking moment on the weekends on this project :D.. so I have to "appear" to be doing other stuff as well on the sat/sun 's .. theres not a lot left to do really but
i have to finish one small job before i can start another.

[CoombellKid]

Sorry missed this one....



Casino Joinery, i'd try a joinery shop over you way. they seem to be the
place to get it from. You can pay $20-$100 per sheet depending on the
type of wood. They had some very nice birds eye maple in there for $100
per sheet. Might look at that next time.

regards,CS

[stringscope]

Looking very nice Graham :thumbsup:

Cheers,

[GrahamL]

Mounted up the focuser board and focuser this weekend
It was way off centre and I couldn't believe I measured the centre that far out .. my wife in the backyard hearing me curseing made a passing coment
"are you sure that board thing is the right way up" ?...:whistle:

I have to think a little more on what length to cut my poles , this focuser has a little less travel than the gso on my 10".. and my pretoria eyepiece
needs a lot of out focus than my other 3 .
centreing the secondary under the draw tube was tight .. probably due to it
being 2.6 ".

thanks for looking

[CoombellKid]

I hope you got the fouser sorted ok. I've had to do a little modifying
on mine, through errors in my plan :doh::lol: oh well we live and try and
we learn.

Still your scope is coming along nicely, I bet your looking forward to
trying it out.

regards,CS

[GrahamL]

getting a little closer :)

balance seems ok ,(3 pavers as a mirror substitute)
looking at some of weights of the well known comercial truss
dobs mine is almost the same ... the stiction on the felt pads seems pretty good so far..so I may leave them there.the secondary seems fairly well
centred in the assembly .. though i did leave a few mm adjustment in the
mirror cell frame just in case .

my old man has machined up some bushes for the centre bolt and some sort of sleave with a marble mounted within ? . that he wants me to look at
to see if it will work as well as teflon .
The side bearings will be covered by 2 mm polished brass which I'll pick up later this month.

thanks fer looking:)

[Orion]

Well done Graham....another great looking scope!

[CoombellKid]

Great stuff! Graham,

When do you get the mirror?

started building the mirror box on mine, have finished the secondary cage.

regards,CS

[Orion]

Graham concerning the bearings you mentioned on Robs thread can you post a pic of them so I can get a better perspective?

[GrahamL]

I havn't seen them yet:P...what they are afaik is a brass sleave
machined to allow a glass ball to sit within .. the base board is drilled
and they are inserted in it .. the balls sit a few mm above the base board
and the formica on the bottom of the rocker box rides on them .


yeah I really need to have a pic of them don't I:)

[Orion]

I'll wait for the pic.

[GrahamL]

A little more to do yet... stuck the velcro on the cell today
Its very sturdy stuff bunnings now sell it .. they claim it will hold 2kg in shear
per 50x50 square.. the edge supports have a 6mm rubber pad on them are to large and I cant squeeze the primary in .. so its back to 3mm like i was going to do originally:whistle:

[GrahamL]

oops wrong pic above.. I found this old camping matt in the garage its really sturdy stuff and will be good for a light baffle i think.. it is a little thick though and comes within 12mm of the light path ... Is that likely to be a problem at all ?

[GrahamL]

wire the fan up , mount and align the primary.. theres not a great deal left to do I think... this is getting pretty close enough to finished .

[GrahamL]

A couple more .. preasure photography here .. the wife is standing over a green ants nest and neither of them are happy about it:D

[CoombellKid]

Looks awesome Graham :thumbsup::thumbsup::thumbsup: looks as solid as an Ox!!! Have
you sorted out the finderscope yet?

I had both boys this weekend, so I couldn't do too much. Fixed the
secondary ring that got busted during a storm on Friday. I've got
it pretty much together with the wall sitting in it, need to get more
veneer for the focuser board. And this afternoon I started on the
rocker box, while I think about SC connectors.

regards,CS

[GrahamL]

No not yet rob ..its happy enough on the 10 " ftm;)
yes its solid alright ..it wasn't moveing much in all the wind yesterday
21 kgs of mirror box holds it down farly well

[astro_south]

Looks great Graham ... just need to paint the rocker and mirror box white to have a truely stunning looking scope ;) :D :D :D

I might have to wander down to another Northern Rivers observing session soon and check it out :thumbsup:

[GrahamL]

:lol:..It would probably be easier If I bought along a can of flat black paint
Andrew and you can finish the change:thumbsup:

The scope balances well .. which was something i was concerned about as i did change a few things .

I mounted the primary and did "rough" alignment .. unfortunately nothing will come to focus atm:shrug:..there was a bit of rain about so I was only in the back yard and the trees I was looking at were pretty close .. If I remember right with my 10" I had to aim a lot further away ( double or more) to get to focus ?

[Orion]

Graham your scope looks great .....even it's black!:P

[CoombellKid]

Jeepa's Crickey!!! if this is the weather we're going get with you building
your 12" we better batten down some when I start my 16" lol

Have you seen another star yet lol, is Ballina still attached to Australia?

regards,CS

[GrahamL]

nope just archenar and a few others through heavy cloud .. but it will come to focus though.. I sat outside like an idiot for two hours the other night trying to find a hole in the grey .. then it started to rain:lol: .

[CoombellKid]

Still cloudy here

regards,CS

[GrahamL]

velcroed in the mirror cell today , and it was a bit of a worry at a glance as i could lift the
mirror a little in the cell with some upward preasure, not free it but definately move it up .
lateral play was non existant though...there are 12 mounting points on an anulas
at the 60% zone.. Its probably worth mentioning this mirror is around 1:8 or so
if I have that right? .. a thicker piece of glass might need a differant approach ??
You were right mark my fears were not an issue when I tested it out
checking collimation through differant altitudes showed no movement of the optical axis
in any of the positions .. I have left it in almost horizontal for a couple of hours with no differance noted.I guess that movement in the cell isnt a bad thing regarding distortion then if the velcro has such a passive grip on the mirror.Despite me turning it upside down (pictured) and giving it a shake it won't budge , I actually broke a piece of ply trying to split the two yesterday it just dosn't want to let go .

I just have to wire up the fan and come up with a counterweight so i can mount an f 50
It balances well as is but I didn't plan for the finder when I started out .
Where should I mount the countewrweight...under the mirror box?

[CoombellKid]

I have been thinking of this problem myself, as I think I will need to counter
my bottom end. My thoughts were, is to figure out how much counter was
needed and then have an engineers shop make up something I could bolt
to the inside corners of the mirror box. I was thinking perhap of something
like a square of 1" to fit the inside of the mirror box and fill it with something.
But I'm still yet to find out if I need this and then what weight is needed.

But then again if I went and stuck a 10" in there that would help too lol

Looking forward to some clear skies

regards,CS

[CoombellKid]

Graham,

Just looking at your collimating bolts, are they spring loaded? Have you
thought about finding some threaded inserts to fit the thread and making
some wooden knobs. That way you wont need a shifter or whatever to
collimate. Or are they turnable by hand?

regards,CS

[GrahamL]

clear skys?? what is this clear skys you speak of ??.. glen sure picked a good month to go north :lol:.

regarding a counterweight I did allow for the possibility of one under my mirror box . I was thinking a piece of class 6 to 12 pvc(1 " or less) with some lead sinkers
down inside with a couple of open clamps to allow the piece of pvc to be slipped in an out as required.

yes rob they are spring tensioned when I get it all sorted I'll have something a little more friendly in there... I found a nice little hobbiests site that you can buy something in regard
for a couple of dollars in whatever thread you need .

the little I've seen of your scope .. dosn't look to bad for balanceing out .. like we ..spoke of the focuser is a pretty heavy addition up top on our small scopes.. you have a
fairly light upper cage though .. you might be able to get away with a slight adjustment around your alt bearings to make this work 'imo

[CoombellKid]

Your scope is an f/5? taking a word out of Kriege's book. You will need
5 pounds for every pound on the SC to counter weight.

re: Glen, he sure did, I think he's home tomorrow or the next day. I've
been collecting solar radiation maps for him. My place is swamp land
at present. Cant even use the drive way, have to drive across the
paddock to the big red house and use their drive lol.

regards,CS

[GrahamL]

well It works:)

seeing was average with a lot of high cloud around

At first i thought i had some alignment problems... as views didn't seem to clear.. but as the night air cleared a little and I went inside and cleaned the antibiotic cream out of my eyes (horrid flu) .. things wern't to bad at all
47 tuc.. not to differant at a glance but no there were many more stars visible around the core .. on to m41/42 wow it just glows in the larger scope .. back to the tarantula very nice the mottling isn't easily visible from my back yard but despite the poor seeing its looking great.. m1 average
cloud hanging around out to see still brighter than the 10 ".. had a look at
mars for the first time in years and back inside.

Overall i'm very happy .. I had to cheap out on the primary as my wife got hurt at work and loseing her job was/is a possibility so urring on the side of caution regarding spending was a priority.. the 12" gso mirror is good enough for my needs for the moment .

what I have to fix.. my small counterweight under the mirror box is pretty crap and wobbles around way to much .. my 27 pano and 28 pretoria come to focus but 7 and 13 naglers need just a little more infocus .. this was always going to be hard as the pretoria and the naglers are at opposite ends
of the travel of most draw tubes .. the hc 2 focuser still has a lower mounting position so hopefully I can squeeze them in without the focuser
drawtube entering the light path.. If not its a trim of the poles
isn't it ?:confuse3: .. I havn't drilled the moonlite conecters and probably won't as there a nice snug fit.


thanks to all who share there time and expertise around the numerous atm forums on the net its very much appreaciated.. and of course google images
search > truss dob<.

take care and thanks for looking :)

[glenc]

Congratulations Graham, look forward to seeing it.

[CoombellKid]

Excellent Graham,

Well done mate, must be good to have it all done (pretty much) hopefully
I'll be able to star test Buzz over the weekend. You keen on a get together
this month? we could head up to Alex's place but after bumping into him a
few days ago I dont think he will be there this new moon. I think Glen is
heading west, so my place will be available :thumbsup: which would probably be
easier for me as I'll have the boy's with me. Let me know if your keen.

Anyways I'm keen to have a look through your new beasty :D

regards,CS

[AstroJunk]

Turned out very nice - I particularly like the 'go darker' brass detailing which is both original and very smart:thumbsup:

[GrahamL]

thanks guys:) yeah I'd like to try for next weekend rob
health and weather permitting.

The brass has a longish past attached to it actually
back in 98 I think when we first got online my son and I were well hooked on astronomy.. A small 4' reflector was around $1000 .. but could you make your own ?.. I found the sidewalk astronomers website with all the instructions to build your own scope .. there was VERY few other sites around regarding astronomy at the time .. I had no idea what sonotube was or were to get it so came up with a square ply tube (black of course)which was going to be mounted on a pretty steel frame of 1 " flat steel .. ( its probably good things didn't work out as i think it might of resonated like a tunning fork):lol:
Anyway my father being a marine engineer and always doing little jobs at home always used a lot of brass .. it always goes with stained or painted timber I noticed so planned to drop a little around my scope when i built it.
Well the falling ausie dollar put an end to my plans ..( mirrors and such )
were just very pricey even in small appertures .. anyways I kept the little thought that brass would look nice on a scope tucked away all those years and when finances this time allowed me to have another go ..
well there it is .

[CoombellKid]

Sounds good to me mate :thumbsup:


regards,CS

[GrahamL]

first flight .. er i' mean light..:D;)
prety much finished now and in use . .works great

[astro_south]

looks great Graham - looking forward to seeing it operating in the flesh in the coming months :thumbsup:

[Starkler]

As someone who took the easy way out, I tip my hat to those with the skills and patience who build their own. Well done!

[glenc]

Great job Graham.:thumbsup:

[CoombellKid]

Excellent Graham:thumbsup:, I also like the extra two drink holders for Glen and I.
Nice of you to think of us :whistle:

Hope you had the same nice skies last night.

regards,CS

[GrahamL]

thanks guys :) . I havn't been able to collimate for a week or two as I don't have an adapter to hold my cheshire.but the views are still great.the larger secondary seems to realy bump up the contrast/detail on dso's.or maybe its the extra apperture ?
I couldn't be happier atm .well I could .a little less tension on alt motion needs a tinker but all in all I could and will probably live with it :)

[GrahamL]

my final tinker with things was to trim 5 mm off the inner and outer of my
upper cage ..I went with 50 mm rings originaly which in hindsight was
overkill and a bit to much weight ..trimming off 10 mm on both dosn't sound a lot ..but the scope balances much better now and i can lose a couple of kgs in counterweight.

take care graham

[CoombellKid]

LOL, I'm the other way around. I've been thinking of drilling holes in my
counter weights in the bottom end. But then using it the other night I
remembered I cut about 15mm too much off the the truss poles. I have
to set my low powered ep out about 10mm off the focuser seat. I figure
remaking the truss poles will only cost $14 for the tube and I'll get the
joinery shop to cut them.

Hope to have a look through your scope soon :thumbsup:

regards,CS

[GrahamL]

try again .. type a reply ..can't submit or copy text to paste again .

hows next weekend looking for your place?... I think glens away

btw I have a drop saw to trim your poles If you need to.

[CoombellKid]

Try highlighting the text and doing a Ctrl + C when I trying to right
click and copy or cut, I only get paste from the popup menu in these
text boxes... weird.

I'll probably have the boy's next weekend maybe the weekend after
I'll let you know when it's closer. I was going to go with Glen out to
Leyburn but I cant confirm I can make it due to school holidays and
an ex that has no idea. But you are more than welcome to come out
next weekend I'll be here just dont know how involved I will be with
the lil one here.

I'm yet to re-order the ali for the truss poles. It's not a big issue as
I have a lil counter weight (medium size bolt, those holes in the SC
rings come in handy) I have a pole cutter, a hand one. But was
thinking the joinery shop might be able to set ali tube into a jig to
replicate the lengths more precisely.

regards,CS

[GrahamL]

Its all a no go for me now rob anyway .. driving down by the beach this arvo my gearbox /clutch had a meltdown ..LOL..car still goes great .. it just dosn't go anywhere :P.. couldn't of happened at a better place..rolled into a carpark and theres my son getting out of the surf.

[CoombellKid]

Sorry to hear that dewd, hope you can get mobile again soon. What sort
of car you got as I can get some second hand parts pretty cheap. My
auto-transmission is on the way out too.

what are you doing on the 12 April?

regards,CS

[CoombellKid]

Mark,

Thank mate :thumbsup: sorry to beat an old thread. But I ordered some of these
a couple of days ago from Maumac, they have a website and online product
guide. I rang them on Tuesday and spoke to a nice lady and really helpful.
To order was as simple as Email/Fax order with part number and your details
and you'll recieve a package 2 days later with an invoice and how to pay.
It may of arrived yestarday but I didn't go to town yestarday.

So all I'm saying is, this product is easy to get and the supplier Maumac
are as good as any Astro shop that I have ever had the pleasure to deal
with.

btw, the ones I got are for 1" OD tube and cost per item $2.30 excluding GST
$10.00 postage.

regards,CS

[Satchmo]

Great to hear :) They also sell different kinds of knobs with threaded inserts or threaded extension which are really good for ATM's too.

[Ian Robinson]

Not too shabby...:thumbsup:

[GrahamL]

Rob check this site out for knobs / bearings teflon etc they sure have some
nifty bits and pieces :)
http://www.minibearings.com.au/cgi-bin/store/product.pl?alpha=M&opencat=EX46#EX46

[CoombellKid]

Yeah, I'm kicking myself as I should/could have grabbed a couple of other
bits.

Graham, thanks for the link you posted... they also have distributers in
Lismore... Well I'll be, something that isn't half a country away lol

regards,CS