Re: [ATM] Tube length computation

[Adam Krause <krausea34@yahoo.com>]

Francis,

I would recommend a program called Newt by Dale Keller.  It can be found at this address:

http://www.dalekeller.net/ATM/newtonians/newtsoft/newtsoft.htm

It answers the questions you are asking about.

Regards,

Adam Krause


----- Original Message ----
From: Francis J. O'Reilly <foreilly@verizon.net>
To: atm@atmlist.net
Cc: PParkerrs@cs.com
Sent: Monday, April 21, 2008 7:13:13 PM
Subject: [ATM] Tube length computation

I'd like the list's collective input on the proper dimensions and hole position for an aluminum tube that I am about to buy for my 12.5 inch newtonian reflector project.

I am having the tube specially made by Logan Steel in Meridan CT. The cost is expensive, $567.00 plus CT tax for those who may have a need in the future.

The relevant (and some irrelevant) dimensions are as follows:

Mirror 12.5 inches
Full thickness, about two inches at the edge.
Mirror height when mounted in mount 4.0 inches
focal length 85.875 inches
Tube inside diameter 15.00 inches
Tube outside diameter 15.25 inches (Yes, I am considering 1/8 inch aluminum stock, Any comments on this issue?)
Focuser height from tube 3.25 inches
Focuser travel 1.875 inches

I come out with a hole at 80.125 inches. Tube length about 86 inches. I am considering going to 90 inches.

I'd like your input.

Thank you.

Francis J. O'Reilly
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