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Minor surgery on my 180 Mak

Posted: Wed Sep 23, 2020 11:27 am
by gabrieli
I’m not sure that this is board section is the right place for this but, if not, could one of the mods reassign it?

This concerns my recently acquired (this past summer) Celestron 180 Mak. In all, I really love this scope. It has a very manageable weight and has shown very good optical quality judging from some lunar images taken with it. It works very well with the Celestron focus motor but shows a bit of image shift during focussing.

There were 2 annoying aspects using the 180 Mak that I finally got around to correcting recently:

1. The way the dovetail is attached

2. Its lack of a carrying handle (there is nothing to hold the scope securely)

The dovetail on my larger c9.25 is secured at both ends with bolts that attach to the front and back cell of the tube, a very sturdy arrangement. I attached a handle on some available accessory holes on the mirror cell so that, when I carry it, one hand holds the handle and the other hand is placed under the front of the scope.

On my 180 Mak, the dovetail is attached directly to the body tube at both ends, secured by what look like very thin bolts with retaining nuts on the inside of the tube. The metal in the body tube is thinner than I expected. Although the dovetail is fairly wide, I didn’t feel good about having the scope always oriented hanging on its side when it looks south. I decided to mount the scope in rings (217mm diameter) which I ordered from Parallax.

I had done some reading about detaching the dovetail from this scope online (actually for an Orion 180Mak and a Televue 180 Mak which are the same instrument as my Celestron 180). This procedure involved removing the front cell to access the retaining nuts holding the dovetail bolts.

I learned that the front cell holding the corrector and secondary is held in place by 4 bolts at the front of the instrument and that removal was a very simple matter. It was.

The obvious cautions are to mark the orientation of the cell relative to the tube for reassembly without collimation problems and to take care that the scope is secured so that when you remove the heavy front cell it doesn’t rock backwards due to imbalance.

The entire operation took about 1/2 hour (mostly involving unscrewing and replacing the bolts).
The collimation was confirmed by star testing afterwards and was still fine.
I read that collimation on this scope (if necessary) is done by using 3 pair of push-pull bolts on the main mirror cell. It sounds like collimation is adjusted by tilting the main mirror!

Once I make a handle in the next few days, it will be attached to mounting holes on the top of the rear ring. Then I’ll go back to hoping for some good weather.


Re: Minor surgery on my 180 Mak

Posted: Thu Sep 24, 2020 7:31 am
by Montana
I had to replace the dovetail mount on my C11, it was ridiculously small. I bought 2 and added a carry handle to the top. It is much better, why a carry handle isn't supplied as standard is beyond me! mine is all a bit dubious though as none of the bolts in the kit fitted the scope properly so I make sure to have a second hand elsewhere on the scope at all times when using the carry handle. It seems they completely changed the design of the C11 for my version so no kits for any of the C11 extras fitted properly any more. Do they do this just annoy the customer and all the other companies which supply extras?