Regluing Secondary Mirror

The edge of the secondary holder was pretty tight against the mirror and I read that sometimes the holder can pinch the mirror and mess with the views.  So until I can afford a better secondary mirror I decided to pry the mirror off and sand the holder.

  I also read that sometimes the mirror is held on with three pieces of double sided tape and sometimes silicone.  I had no idea what was holding this mirror so I drilled a couple of holes in the back of the holder hoping to be able to push it out from behind but the mirror was pressed in pretty tight and I couldn't get it to budge.  So the next step was to pry it loose from the front.
  I used a couple little flat screwdriver tools from my fishing reels and proceeded to follow the edge of the mirror around the holder to loosen it up a bit.  It was in pretty tight so I went slow and easy so I wouldn't chip the mirror.  Then I put in both tools and slowly pried the mirror up until I could feel the glue popping loose.

Finally I felt the last of the glue pop loose and the mirror was free!  This process took me about 30 minutes as I was being really careful not to chip the glass or slip and scratch the face of the mirror.  Very nerve wracking half hour!  The folks at Apertura just put globs of silicone on the back and pressed it in tight.  There was more silicone on one side than the other.

I scraped the silicone off with a razor blade then used alcohol as a degreaser for the back. Then I started on the holder.  I sanded the inside edge and kept checking until the mirror fit without touching the sides.  Once I got it to my liking I used alcohol to clean the holder edge where the silicone would sit.  

While the mirror was out I blackened the edges better with a Sharpie.  Being careful not to get it on the face of the mirror.

In my reading I found that there is supposed to be a space between the holder and the mirror so that the mirror can expand and extract on top of the silicone as it cools and not touch the holder itself.  I saw that most used toothpicks as spacers.  Since there was no way to pull out the toothpicks after the mirror was glued in , I figured I could use a thin cord that was about the same thickness as a toothpick.  For the silicone I used black Aquarium sealant from Petco.

I marked 3 spots with the sharpie where I would put the silicone then threaded the cord through the holes I drilled when trying to push the mirror out.  I also threaded some cord through the center screw holder.  Then used small pieces of tape to keep them in place.

Three globs of silicone and the holder is ready for the mirror!

I cut up a business card and used them to center the mirror in the holder.

I let the mirror dry for a couple days then pulled out the cord.  It worked like a charm!  The mirror was stuck on pretty good and there was a space between the mirror and the holder.  I screwed on the little holder at the top edge of the mirror and it was ready to be installed.  In my excitement to install and collimate the newly redone secondary I forgot to take a picture!  

The final step is to wait for the clouds to clear so I can try it out!

Update:

The secondary is working great!  Pinpoint stars in the clusters and great definition in Saturn.  Next is to take it out to my dark spot on a moonless night!