Cracked secondary mount?

Hey, all...
I have an older C11 (purchased used here on AM). I recently noticed a crack in the plastic outer cover than holds the collimation screws for the secondary. So I have a few questions...

Did I cause this crack by over tightening Bob's Knobs?

Is the pivot that the secondary is centered on bearing on this plastic, and is it trying to come through?

Is this plastic structural, or cosmetic?

The plastic is bulging outward at the location of the crack. I feel compelled to try to fix it. Is it glued to the corrector?

If I remove the corrector, and remove Bob's Knobs, the secondary will come off, right? Would I then be able to get access to the cracked part?

When using the knobs to collimate, one of the knobs seems to bottom out, making final collimation difficult. It seems I have lost some range of motion, thus the concern and the desire to FIX!

Any help (Uncle Rod...anyone??) would be appreciated!

Steve

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Steve Mathis said:

Hey, all...
I have an older C11 (purchased used here on AM). I recently noticed a crack in the plastic outer cover than holds the collimation screws for the secondary. So I have a few questions...

Did I cause this crack by over tightening Bob's Knobs?

Is the pivot that the secondary is centered on bearing on this plastic, and is it trying to come through?

Is this plastic structural, or cosmetic?

The plastic is bulging outward at the location of the crack. I feel compelled to try to fix it. Is it glued to the corrector?

If I remove the corrector, and remove Bob's Knobs, the secondary will come off, right? Would I then be able to get access to the cracked part?

When using the knobs to collimate, one of the knobs seems to bottom out, making final collimation difficult. It seems I have lost some range of motion, thus the concern and the desire to FIX!

Any help (Uncle Rod...anyone??) would be appreciated!

Steve

http://www.astromart.com/forums/viewpost.asp?forum_post_id=644419&poll_id=&news_id=&page=

One reason I do not go to tight when collimating. Yes the secondary pivot is bearing on this central portion, is NOT (only) cosmetic, IS structural.

Yes, if you remove the corrector and Bob's knobs you will be able to replace the secondary holder as a seperate part.

Steve Mathis said:

Hey, all...
I have an older C11 (purchased used here on AM). I recently noticed a crack in the plastic outer cover than holds the collimation screws for the secondary. So I have a few questions...


Steve

Hard to say why this happened. Unless your name is The Incredible Hulk ("HULK _SMASH_ LITTLE TELESCOPE!"), I very much doubt you caused this by overtightening the Bob's Knobs. Plastic can become brittle, but I don't believe I've ever seen that happen with a secondary mount. Solution? Probably easiest thing to do is call Celeston. Otherwise, I suppose you could try to find a surplus one.

This is a structural assembly. The secondary mirror is mounted to a backing plate, and the collimation screws extend through the secondary assembly and into this backing plate.

I assume the scope can be collimated and this is not causing any immediate problem?

I got a final E-mail reply from Celestron today. Their solution was for me to send the entire OTA to them for replacement of the secondary assembly. No getting the part from them and replacing it myself! I already fixed the problem by bolting a 1" steel disk to the outside of the plastic, with some JB weld under it. No more flexing of the crack during collimation... 8). The repair is visible, but not too ugly. This scope had some hard use before I got it, and had lots of extra holes drilled in it, and scuffs in the finish. The repair just adds to its character.