Nearly got my fingers burnt!

[Ratcatcher]

I have always thought of my self as a careful chap. Around my telescopes? ...even more than careful.....fastidiously safe even!

Imagine my horror at being caught out by crass stupidity while fastening bits and bobs to my scope!

Lets have some detail. In my quest for as full automation of my observing experience as possible the final  fence was focusing my scope from my front room while wiggling my toes in front of the double log burner while  enjoying a scotch and seeing the results of my frozen telescopes efforts on my TV screen.

In this day and age this is not a too hard a goal. Most of us have a lap top, and a tablet to borrow or knocking about to commandeer  even, enough freebie software out there? lets go!, lets cobble something together that's reliable and works! All pretty tame stuff.

Until that last fence....fixing the focus motor to the scope...easy!, ...I have a Celestron 5" Scmitt/Cass....Celestron's electric focus motor does not fit....look elsewhere.....got it! Skywatcher focus motor coupled to Hitec astro DC focus control! What can possibly go wrong!

In the past, when I was fit enough to chuck about my then Meade 10" Scmitt/Cass fitting things like a dew heater control and the like was no harder than fashioning a aluminium bracket, mounting the dew heater control on that, then taking out one of the many un-used hex bolts around the front or back end of the scope and fixing the bracket under it and screwing it back. Job done.

When it came to mounting the focus motor and the DC focus motor control unit on my 5" Celestron ,I did not think!....just used the same method!  It was only when I stood back to admire my handy work that I saw  what I thought to be a large amount of dust on the corrector plate!

O.K, no problem, a very careful use of a make up brush should clear it up.

It did'nt! what was worse was the small amount of tree sap/pollen/whatever smeared on the front of the plate!

It was then that I realized that what I could see was on the INSIDE of the corrector plate.... and it was SMALL GRAINS OF FILED ALUMINIUM!!!

Eventually my heart rate came down far enough for reality to sink in.....it was a  'take out and clean ' the corrector plate job!

Not done that before!

After a trawl of 'The University of Youtube' I felt able to tackle the job with confidence, the result being a clean corrector plate, no serious changes to the collimation via an artificial star, and a day time focus as well, just leaving a real star collimation to be done! 

Thanks Dr Clay!!

So, don't be like me! if you fit things to your scope think it through first!

 

 

 

 

 

 

[AstroTim]

Glad you managed to get it cleaned back up, but where did the filed aluminium come from and how did it actually get inside the tube? If you didn’t need to drill any new holes then I assume it got in through the finder screw hole somehow. Were there filings in the bracket hole that got pushed inside when putting the screw back in?

[Sunshine]

There seems to be an open cluster stuck to that corrector plate!

[MarsG76]

Sheeesh... Well done!!!!

I remember when I had to clean the corrector plate.. all I was thinking about it.. "Don't drop it!!!".. but the operation was successful.

 

[Ratcatcher]

Yes! a cluster indeed!....in fact a series of mistakes is also a cluster .... I think you can imagine what I mean!

Well, how the particles got inside the scope is a mystery to a degree, meaning that to fit the larger gear wheel onto the focus shaft I first drilled out the hole in the gear wheel and filed an interference fit. I thought I was very careful to blow out any metal dust from this wheel each time before offering it up to the shaft.

Maybe not! So the repeated offering up maybe a not perfectly debris clear gear wheel is a possibility.

As for the finder idea, when I first got the scope I did not bother to mount the red dot finder preferring to fit my starsense camera that I had previously used on the larger Meade. (I loved that Meade so much that one year I bought it a CGEM for it's birthday!)

This also needed a little fettling due to the smaller diameter of the tube on the Astrofi 5",  and no particle ingress was noted.

Also not dropping the corrector plate while cleaning took a lot of effort!

 

[AstroTim]

By finder screw, I was meaning the screw that you used to mount the bracket. I was assuming that you used one of the mounting points and screws that are typically used hold a finder bracket, or mounting plate in place.