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Re: [ATM] New with starters questions
Thank you Alan, a very informative and nice page, wonderfully made scope
too, compliments
Alan Scott wrote:
> Joel,
> One solution among many is the web site that I put together. It is
> at www.xmission.com/~alanne/DS3Main.html. This will answer many of
> your questions - as far as I answered them.
>
> I would recommend buying your first mirror, and I would buy a 12"
> (0.30 m) because the cost isn't much more, 12" scopes can still be
> made pretty small, and they are pretty portable. As far as costs, I
> don't know about Europe, but check out Gary Hand in the states from
> "hands on optics". Maybe he could give you a place to buy, or
> shipping costs.
>
> By the way, this is an international group. Centimeters and
> millimeters are fine.
>
> My side bearings are half circles. Makes the scope smaller and
> lighter when it is torn down.
>
> No detailed plans, but I did put into my web site the "hows" and
> "sizes" of everything. Go to the bottom, and click on links.
>
> Order IS important. I made the mirror cell, mirror cage, and
> secondary. Then, you add trusses (as determinded by the focal length
> of the primary and how far the focuser is out from the center of the
> scope). Next, figure out the center of gravity. NOW, you can voodoo
> out the size of the bearings and the rocker box.
>
> Take a look at Mel Bartel's web site. It is located at:
> http://www.bbastrodesigns.com/. Mel's old web site at www.efn.org is
> old. Don't use that one.
>
> Also, go into the atmlist archive and do some back-reading - there
> are a lot of good ideas on this group. http://www.atmlist.net/
>
> Two more pieces of advice -
> 1) Telescopes are a compromise between being as big as possible, a
> reasonable cost, and as portable and easy to set up as possible. A
> good size for a first scope is an 8" to 12". Don't go too big too fast.
>
> 2) Never having made a mirror - here goes some advice. If you do
> decide to grind a mirror yourself, find someone else local to you that
> has made one to help you learn the ropes the first time.
>
>
> Alan Scott
> www.xmission.com/~alanne/DS3Main.html
>
>
>> From: "frog3@freeler.nl" <frog3@freeler.nl>
>> To: ATM@atmlist.net
>> Subject: [ATM] New with starters questions
>> Date: Thu, 14 Apr 2005 23:33:31 +0200
>>
>> Hello all,
>> i'm Joel, from the Netherlands, i'm new to the group.
>>
>> i would like to ask a few things to help me on the way to building a
>> first 20, 25 or 30 cm truss dobson telescope. (8", 10" or 12")
>>
>> probably a 10" as this seems to be the best compromise for me at this
>> time, regarding cost and final size, i would like to make it about
>> F/5, so around 1250mm in the case of the 25cm.
>>
>> first general question:
>> is it alright if i talk in centimeters and milimeters here? as it is
>> easyer for me to think about than to think in the feet and inch
>> conversions.
>>
>> first atm question:
>> if i want a 25 cm dobson tlescope, should i make the mirrorbox about
>> 30 cm? or is this too small or too big? (roughly 2" more than the
>> size of the mirror)
>>
>> 2:
>> What is better costwise: making a mirror out of a blank and having it
>> aluminized and coated or buying the most inexpensive ready-made
>> usable 10" f/5 mirror?
>> and what will both of these options more or less exactly cost?
>> and where should i buy it? here in the netherlands? or in europe? or
>> doesn't it matter? what would be the best for the price including all
>> shipment(s) and where should i 'shop'? and do any of the people of
>> this list also sell atm supllies?
>>
>> 3:
>> I would like to make the , what i believe are called sidebearings, in
>> sort of a half circle, instead of a circle, is this a lot more
>> difficult to do than just a making a plain circle, or does it make no
>> difference?
>>
>> 4:
>> does anyone have any drawings or plans (or how should i be calling
>> this in particular? please help the novice) with exact sizes for
>> everything? just to function as an example for me to 'draw on',
>> because it's quite difficult to be doing this from scratch, or even a
>> boook, that is what i find at least, i have the Kriege book of "The
>> Dobsonian telescope".
>>
>> 5: (very important, so i'm not sure why it ended on place 5 ;)
>> what to make first? and when does the balancing of the telescope have
>> to be done? which part is it that neds to be re-adjusted for the
>> balancing, and therefore
>>
>> 6:
>> What am i forgetting?!..... :) ....very important to ask. :)
>>
>> Thank you all,
>> Joel
>>
>>
>>
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>
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