Fully Polished Mirror, and the Support

After 4 months of work, my telescope primary mirror is finished.  I started this project on the 18th of August and finished on December 31st, with a few hours to spare before the new year.  I thought that would be a goal, because I’m going to submit my work (a report basically) to win the National Young Astronomer Award, from the Astronomical League.

The winners (first, second, and third prize)  get an all expense paid trip to the ALCON (Astronomical League Convention) and of course the prize.  First place wins a five inch refractor telescope- a pretty good prize, see the details of this scope here.

Anyway, the telescope mirror is finished and that’s a huge part of the telescope.  For the reflective optical coating I chose Destiny.  My mirror will run a mere 30 dollars- after checking other companys, they averaged about 50 dollars for a mirror of this size.  I also bought a secondary mirror and spider for a small sum.  1/10th wave optics, 1 inch size, 15 bucks is pretty hard to beat.

Upon finishing my mirror, I counted up all the time working on my mirror, from start to finish.  Total time of the glass in motion was over 25 hours!  It may seem like not that long, but it feels longer because of the precision I had to maintain during the process.  Total polishing time clocked in at 6.7 hours- a little longer than expected.  But it’s rouge, one of the slowest polishing compounds you can buy.  And it was worth it considering that it is said to give a finer polish than Cerium Oxide, which is also three times the polish.  Oxide polishes faster, but the increased price was not worth it to me.

Finished Mirror

For me, one of the most important parts of the telescope making project is putting your initials and the date you finished it on the back of the mirror.  It was just as exciting as I thought it would be.  It may seem insignificant, but I liked doing it.

IMG_3203

Also completed was the mirror support, or cell.  It consists of two circular pieces of wood, one the size of the mirror and one the size of the telescope tube.  The mirror sits on the upper piece, and is secured with “L” shaped clamps.  In between the pieces are 3 long screws, and attached are 3 springs.  Next comes the wooden piece for the tube.  Under that, the the ends of the screws are exposed, and wing-nuts are then threaded on.  By twisting on of the wing-nuts, it compresses the spring and moves the mirror on top slightly downward on that side of the mount.

IMG_3210 IMG_3209

mirror in the support

Pretty good huh? I bought an aluminum tube at the hardware store for 7 dollars.  It is five inches round, so the bottom piece of the support matches that.  Obviously, the “L” clips will need to be painted black and other stuff to eliminate reflections.  There’s not that much left to do on the scope really.  I had the bottom base for the Dobsonian mount finished- with a CD as the bearing material, which works really good by the way.

I'm building a mount similar to this.

I’m building a mount similar to this.

Well to wrap things up, I finished a big important part of my telescope and I’m glad I took my time with it.  Pretty soon I’ll be gazing upon galaxies and nebulae.  I think the biggest help will be the aperture.  If you’ve heard great things from Orion’s Skyscanner, my scope has the same aperture.  It also has a much longer focal length (f-12) and should, if collimated correctly, provide sharper images.

2 thoughts on “Fully Polished Mirror, and the Support

  1. HI JUSTIN;
    I’VE GOT TO TAKE MY HAT OFF TO YOU FOR DOING SUCH A SPLENDED JOB ON YOUR MIRROR. IF MR. CARLE WERE ALIVE HE WOULD BE IMPRESSED. THE PICTURE OF YOUR MIRROR CELL LOOKS LIKE THE ONE I MADE FOR MY 6-INCH. IT LOOKS VERY PROFESSIONAL AND SHOULD DO THE JOB. YOUR IDEA ABOUT USING STRING TO CALULATE THE FOCAL LENGTH SETTINGS FOR THE MIRROR AND DIAGONAL IS INGENIOUS.
    HOPE YOU DO WELL IN THE COMPETITION COMING UP I’LL BE ROOTING FOR YOU. I KNOW YOU WILL ENJOY TAKING YOUR TELESCOPE TO SCHOOL AND GIVING YOUR TALK ON ASTRONOMY
    I’M SURE THE STUDENT’S WILL BE FASINATED

    LOVE;
    GRANDPA NEIL
    CLEAR SKYS……

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s