THE 8 INCH TELESCOPE THAT I BUILT FOR MY BROTHER AND KIDS!
The 8 inch Dobsonian Telescope, with a focal length of 4.79. Figured to 1/25th to 1/28th of a wavelength, to close to call. The main mirror took approximately 85 hours to complete, and with the due care and attention to detail, it emerged to within a hairs breath of a perfect parabolic curve. On second thought a HAIR is WAY to thick, it's more like within 1/6th millionth of an inch away from a perfect parabolic curve!! WOW! WHATTA MIRROR!
The skeletal frame work for the 8 inch telescope. The plywood rings of the spider and focuser cage are attached to the aluminum pipes, by inserting a bolt through the plywood and slipping a rubber gromit over the end of bolt, then attaching a nut to the end of the bolt the entire affair is inserted into the tube(s). The nut at the end of the bolt is held in place by the friction of the rubber gromits. (in this case rubber cord protector's that fit tightly inside a 1/2 inch aluminum tube, these cord protectors are available at most hardware stores, I cut them in half to accomidate the length of the bolt!) This inturn squishes the rubber causing it to expand within the pipe, making a very nice tight hold, the end result is a very rigid spider and focuser cage. The same is done with the struts from the base of the mirror box to the spider and focuser cage. The struts are bolted into place at the bottom of the mirror box.
I also attached drawer sliders, to the sides of the mirror box and to the back the mirror cell, to offered me an accurate way to adjust the main mirror to the proper depth and setting for optimal range of focus in the focuser.
The spider was made using aluminum stock, cutting two slits on either side of the aluminum, inserting the metal viens, and then bending them to the appropriate angles. I cut the viens to the proper length, for easy clearance of the four aluminum attachment struts. And then by drilling some holes through the four viens and the heads of four thumb screws, attaching the thumb screws to the spider viens, I had an easy way of attaching the viens to the struts as well as being able to properly adjust the spider as well.
The Mirror cell was made by Tony Bolivar, you can visit his website via a link provided on the main page of our website. He is a draftsman by trade. And does some very precise work! He did an awesome job on the mirror cell and I thank him greatly for it!
Thanks Tony!
Help in the construction of the telescope, are Victor Pollock, Gary Lavoie, Gary Hargreaves, Tony Bolivar, Rip Kirby (RCA Aircraft hobbist), Rob Ladouceur, Miles Waite, Ernie Schmid and Myself! I know I said I built it! But the rest of the guy's were a great help in the success of this project as well. All offering a free hand to help! Thanks Guys!
Gary Lavoie a Member of the Fraser Valley Astronomers, stands beside the telescope to give you an indication of it's size. Rob Ladouceur inspects the optic's of the telescope. The body of the telescope is covered with a shrink wrap, activated by heat, the same product used to cover the wings of remote controlled aircraft. Be sure it is the thickest and toughest product the hobby store sells. (Around 20 dollars a roll, 6' 6" in length, 36 inches wide) Although very appealing to look at, it may not be a practical idea for very large telescopes. You be the judge!
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