ATM Need help with lengthening the tube on my Dob

["Bill Kocken" <wmkocken@hotmail.com>]

Help,
  I made a newbie mistake.  I bought an Orion XT8 tube from a guy, and 
ordered an 8" f6 mirror and other parts. Anyway, after putting it all 
together, I find that the focus point is about 2" above my focuser, even 
when it's racked all the way out out. I have several options, but only one 
good one (#3, I think)
1.) Move the spider and focuser further out to the end, but I don't want to 
cut new holes, and I really don't have 3" of room anyway.
2.) Add height to the focuser, but 3" is way too much.
3.) Move the main mirror back.  In order to do this, I need to lengthen the 
tube.
Does anyone have a good idea on how to best move my main mirror back about 
3".  The tube I'm using is balck sheet metal.

Thanks,
I really enjoy reading helpful hints and discussions in this forum.
Bill Kocken

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