Welcome to my computer everyone. I've been lurking for some time and now we have wireless BB I can annoy the outside world.
My question is this: Are there any premium dob makers whose scopes are NOT made from twigs and mucus?
Having owned a wooden boat, I have no intention of maintaining the 'decking' of a big telescope.
Surely it's easier, cheaper and ultimately better to use metal or CF for the tube assemblies? Why wood? I can see that some might appreciate the aesthetic value, but is there actually an engineering reason for using it?
Ta!
'Twigs & mucus' is used to reduce the cost of making in expensive scopes. Unfortunately, both scope buyers & manufactures can see dobs as the poor cousin of telescopes. This can also mean that alot of people end up striping the optics out of their shop bought scope & making thier own scope, or making significant modifications to the scope. Both instantly kill their warranty.
If you are after a seriously good dob, with a few bucks in your pocket, have a look at SDM scopes. They are an Aussie crew who have really, really impressed everyone. I had a look through Norm's 14.5" SDM. Oh-Boy! Sweet as! http://www.sdmtelescopes.com.au/SDM026.html
In so far as wood is concerned, plywood is lightweight & strong, can be made moisture resistant, easy to work with, and the grain can look beautiful with a lick of varnish. All aluminium is also used, particularlly in making ultra-light scopes, similar to SDM013. It is just that tooling up for it is expensive, & an all aluminium frame is more expensive, just from the raw material.
Both ends of this scope are all aluminium. I'm sure we all would like a scope like this, few of us could make one, let lone afford one. Damn beautiful, aint it!
Also note, that regardless of the materials used in a dob, you will be 'maintaining the deck', the deck being collimation. No one gets away from that. But that becomes second nature eventually, & only takes a moment or two on setting up.
The only grease & oil change that is then required is occassionally cleaning the bearing surfaces. Again, no one escapes that one.
If you are really keen on the engineering aspect of dobs, borrow or get a copy of 'The dobsonian telescope' by Kriege & Berry. Even if you don't make your own, the info in it will help you make informed decisions on any future dob you may buy.
Thanks mental. Alas the astro-fairy has yet to leave 10 grand under my pillow, so any of those is out. Also while the view from a 16 inch plus newtonian is hard to beat, the combination of long sessions and really big scopes tends to do nasty things to my back.
I was just curious to know if there was something in between the off-the-shelf dobs and the super-expensive custom "funiture" scopes.
I had assumed that hand finished wood would be more expensive than machine extruded CF or Al. Also I just can't shake the feeling that wood might de-laminate or get eaten by termites, but clearly other people have no such issues.
My ideal grab 'n go dob is the 12.5 Porta-Ball, but current exchange rates and zero info on the new owners sort of gives me pause.
Erik,
I have heard, tho' have no first-hand experience, that quite few OOUK scopes have serious QC issues. Though they are usually well reviewed, they don't appear to be much better than the competition and are more expensive. If they were just up the road, I might take a punt, but being half way round the world sort of nixes the idea.
I do like their all-metal bases though - but at 300 GBP, they're a tad expensive.
Exchange rate issues again as not only would I be paying approx. 2.3 times the local price, I'd have to pay transport, and import duty and GST would be based on the converted GBP to AU$ price. Ouch!
. Also I just can't shake the feeling that wood might de-laminate or get eaten by termites, but clearly other people have no such issues.
I have never ever heard of termites eating a telescope - you should be using and shifting it about too much for them to find it, anyway! And the glue in the laminates would put them off, I would think. I know someone who wasn't serious about their astronomy left a basic 6" dob on the veranda and bees set up a hive in it, but that's probably the worst, and only happened because he had basically abandoned it. Also the bigger scopes tend to get made with marine ply, which is better quality than the thinner cheaper ply at the local hardware (as you probably know, having a marine background). Good scope maintenance means drying the dew off after an observing session so there is no reason why moisture intrusion leading to delamination should be a problem. The biggest problem I see is just nicks and dents in the finish, cosmetic problems, not structural.
You tend to see so much wood used in big scopes as the north Americans have a love affair with and disdain metal in telescope contruction, and they are the most active telescope makers in the english-speaking world (Europe does have some active atm-ers and big dob beauties, but the language barrier means they don't often come to our english-speaking attention). There is a couple of reasons for this. One is they are lucky enough to have a large range of different woods on hand at cheap prices. Another is they do it just because they can. But more importantly there are some that believe the expansion/contraction properties (I've forgotten the correct term, forgive me) of metal are too large to make a useful scope. And when you have a huge diurnal temperature range, like up in Canada, they might have a point. Here in Australia the diurnal ranges aren't so large, so using metal isn't such a problem.
If you want to make an all metal telescope, go for it. Plenty of people here in Australia have and the scopes work just fine. There is no reason why you have to copy-cat anyone, anyway. If you know the principles of a telescope build there are many ways to solve the problems - or as the common saying goes, "There is more than one way to skin a cat."
I KNOW! I know Intellectually, that there is no really good reason for eschewing a wooden scope. It just seems so...so...primative, and heavy and expensive and fire-prone and just plain weird in the 21st century.
I grew-up in British Columbia, wood is in my genes, but it's just down-right wrong, to make precision optics out of fir trees!
OMG. A telescope for hobbits!!! Or racoons.
Next thing you know, we'll be using "difference engines" powered by "aetherial essence" communicating through "wireless telegraphy"!!
It's the 21st century - No more wood!
Thanks Eric, they're not to my taste, but I appreciate the craftsmanship which has gone into them. Works of art!
I particularly like the smaller of the two in the seconds image of the second link.
I believe that if it wasn't for the popularity of the timber Dobsonian and many of the innovative designs and features of using timber in telescope construction, this wonderful hobby would not have been as easily accessible to the wider public, and sparking an interest in someone out there who would otherwise may have hesitated in taking up the hobby due to cost. Timber is easy to buy and work with for the amateur astronomer. I highly doubt any well made timber telescope is going to fall apart for many years.
Peter I do like the design of the base and the bearings on the Portaball!
mate to IIS.
