Assembling a Dob 8" - instructions?

[Kolya]

Hi all, just wanted to say hello from Brizzie.

I've been slowly, painstakingly trying to come to grips with binocular astronomy over the last year with the help of this very site (which is fantastic) and Stellarium.

Given that between Lemmon, PANSTARRS and (hopefully) ISON, this year is going to be a great one for comets (even if the northern hemisphere will get the best of them), I have decided it's time to head toward buying an 8" Dob. as it seems to be the instrument of choice for beginners. I haven't seen one in real life yet but will definitely do this before buying.

I am planning to attend a viewing night at our local astronomy club where hopefully someone will have one set up but am a little nervous at the reception I might get being female, non-scientifically minded and comparatively ignorant when it comes to astronomy (but eager to learn!!).

The other thing I'm concerned about is putting together the Dobsonian when I buy it. I've read that it doesn't come with instructions. Is it pretty straight forward in a common sense type way or is there a site that might have instructions?

When the time comes, I will probably buy a Dob online from Andrews because so many people at this forum have posted about how great their service is.

[raymo]

Hi Kolya, welcome to astronomy.
If you buy a Dob I would suggest spending a little more and
get yourself a collapsible one which makes it much easier to carry,
and easier to find room for it in your car. If you get the opportunity
before you buy, try to check out a 10", for not many more dollars they
offer great viewing. A Skywatcher 10" tube assembly weighs about
14kg; I don't know if that weight would be o.k. for you. A 10" will
keep you satisfied for longer than an 8".[most of us succumb to
what is known as aperture fever sooner or later].
I can't vouch for other brands, but Skywatcher Dobs come with
full assembly instructions, and take 30 to 60 mins to assemble[depending
on how good you are with a screwdriver]. It's only the base that you
have to assemble, the tube assy. is complete.
I wouldn't worry in the least about how you will be received
at your local club. If it is seen that you are really interested in
learning, there will be no shortage of people only too happy to help
you. Don't get me wrong, an 8" is fine if you don't want to spend the
extra money, or you think that 14kg is a bit heavy.
hope this helps
raymo

[Allan_L]

Hi Kolya,
:welcome:
I have no doubt you will be welcomed warmly at any astro group upon displaying any interest in astonomy in general and other peoples scopes in particular.
Congratulations on your decision to buy a DOB, and on the way you have gone about it to date.
In relation to your choices, I agree completely with everything Raymo has said above.
And if you do a search on dobsonian manuals you should be able to download one in advance to see how easy assembly is. (I know you can with skywatcher manuals at least)

Feel free to ask any questions you have.
Clear skies
Allan

[barx1963]

Hi Kolya and welcome to IIS! :welcome:Astronomy is a bit male dominated but don't let that put you off.
The 8" dob is a great starter scope. As you mentioned some, namely the GSO solid tube, do not come with assembly instructions. Mine came with out of date ones that didn't relate to the particular scope I purchased. If you buy from Bintel, they rebrand the GSO dobs as Bintel ones but I am not sure if they include assembly instructions. I found that it wasn't hard to put together as I had seen a few assembled so I knew were I was heading.
I can recommend going to an observing night or star party before buying anything as if you can see some scopes in action and get an idea as to what views they provide, ou will be more informed when making a choice. You will find that usually observers are more than happy to hae others look through their scopes.
With size, eg 8" vs 10", it is really a mix of factors, price, aperture and portability being the main ones. Once dobs getup to 10" and bigger they are large instruments.

Malcolm

[Cumbrian]

:welcome: Kolya.

I purchased a 10" dob from Andrews only two months ago. You're correct that there are no instructions but, as already said, there is only the chipboard base to assemble and it's pretty straight forward - it must be if I managed to assemble it! Just take your time in putting it together 9you should have plenty of that with all the cloud currently knocking about Brisbane).

I must admit the 10" is a bit of a beast size-wise. I keep mine in my living room and carry it upstairs to use it. This involves carrying the base, then the scope itself, before re-assembling. It only takes five minutes though. It's not too heavy, more awkward than anything else, but much heavier and it would be a pain.

I haven't transported my scope anywhere yet. I'm a little apprehensive about doing so but once this weather clears up I'm going to head to Maidenwell and hopefully get away from this light pollution. I'm also thinking of building a case to put the scope in, in the car so it doesn't roll about etc.

Good luck and I may bump into you at one of the seeing nights if I ever get to one!

[Scorpius51]

Hi Kolya, :welcome: to the IIS forum.

I can say that my Bintel 10" Dob (and the other sizes, presumably) came with instructions - although some were a little vague. However, they are very easy to assemble - just take it slowly.

As has already been stated by the others, a 10" Dob is starting to get large and bulky. You can add locking casters to the base if you are using and storing on the same level.

I also have an 8", but it is mounted on an HEQ5 mount. The 8" Dob would be a very good scope to start with. It has about 40% less light-gathering power than the 10", but so much easier to move around and transport. It will still allow you to see most objects a 10" will see, but a little fainter. At a dark sky site you would not be disappointed!

Cheers
John

[raymo]

A 10" tube assy. collapsible or solid tube, sits nicely across the rear seat
of most cars, and can be held securely in place by the seat belts. The two
outer belts hold it straight, and the centre one stops it being thrown forward, so don't worry about taking it out and about. If your car has a small boot that won't take the base, lower the rear seats, put the base in the back, and lay the tube fore and aft wrapped in a blanket.
I have done this many, many times over the years, and no harm has
ever come to any of my equipment.
raymo

[CJ]

Hi Kolya.
My Andrews GSO dob arrived mid Jan without instructions. I was a bit surprised but the base is logical and easy to build.
The only bit I found that could be assembled incorrectly was the bolt that forms the base pivot. Working up, I've gone sleeve through the platter, big washer, ball race, small washer then plastic bolt/knob through to the base. I think that's right!

cheers

[Kolya]

Thanks everyone for the warm welcome and advice.

It seems some dobs come with instructions and some don't. Hopefully mine will! If not, you'll all be hearing about it!

I have read that there isn't really a lot of difference between an 8" and a 10" inch dob viewing wise so I'm not sure I want to shell out the extra for a very similar experience although the temptation to go straight to a 10" is definitely there. When I first started looking at dobs, I definitely wanted a 12" until I found out how large it was. The portability factor is important to me. If I can't move it around that easily, it's more likely to sit in the corner and gather dust. Having said that, the 14kg 10" is not too bad.

I think I need to get to a viewing night (or astronomy store given the weather we've had in Bris. of late) and take a look at a dob. first-hand to get an idea of size and weight (and find out how the jolly things work). I'm in the Redlands so I'm going to hit up the group at Birkdale/Wellington Point. If anyone's familiar with it, do let me know what it's like.

I'll definitely keep the casters suggestion in mind, too. I have a Mazda 3 hatchback so, folding the back seat down, I reckon I could get a 10" in, particularly if it's collapsible.

Thanks again for the warm welcome and no doubt I'll be back with more questions later down the track.

[barx1963]

Kolya
There is a definite difference in brightness between an 8" and a 10". I tend to recommend an 8" for newcomers as it will be easy to physically handle for nearly everyone, very tolerant of collimation errors, gives nice views of 100s of easy to find objects without spending too much. But a 10" will give you nicer views again and bring more objects within reach.

Malcolm

[Bill.davey]

Zhumell sell gso dobs in the us and have a good instruction video on their site re assembly. http://www.zhumell.com/telescopes/dobsonian/z10-dobsonian-telescope/

[AstralTraveller]

I have a 10" dobs that I assembled and a second-hand 16" dobs that someone else threw together. The difference is obvious. The big problem I see is that the timber is laminated particle-board. This stuff is pretty water-proof on the faces but open at the ends. Over time moisture will get onto the ends and degrade the board. Also, screwing into the end of particle board is not very strong.

If you want a long-term solution try this: Dilute some PVA wood glue 50:50 with water and paint all cut edges. Let dry and repeat. Then paint with straight PVA wood glue. This will soak in, harden and strengthen the end of the timber. Then paint with two coats of exterior house paint - colour doesn't matter as it won't be seen. This will help seal the end of the timber. Assemble as per instructions or instinct (whichever is appropriate ;)). Finally run a bead of waterproof silastic around all joins. This will also help seal the timber and add strength to the joins. I did the job over about a week working perhaps 30 minutes (or less) a day. Mostly you are just waiting for things to dry. If you don't have the materials lying around (I did) they aren't expensive. Alternatively, most handy-people will have them in their workshop. Throw yourself on someone's mercy. I'd do it but I'm too far away.