Regreasing SCT focuser

[Tony_ (Tony)]

I have had recent problems losing focus on my c9.25" SCT.
Also recently, I discovered that the lubricant from the focuser/baffle had leaked out and dripped on to my secondary mirror.
The loss of lubricant has probably caused too much slack in the focusing system causing the mirror to flop after focusing. I have cleaned the secondary but now I have to regrease the focuser. Does anyone know the best lubricant to use?

Regards,
Tony.

[casstony]

The mirror needs to be removed from the scope and existing grease cleaned from the baffle before applying new grease.
Dow Corning High Vacuum grease is one that is recommended though I haven't done this job myself. The high vacuum grease would probably never seperate or outgas like the original grease.

[Tony_ (Tony)]

Thanks Tony - I'll give this a try.

[casstony]

Be sure to read a guide and remember to mark the corrector so it goes back in the same orientation before doing the job.

[The_bluester (Paul)]

I concurr with that. I had read that the corrector should have index marks but found none on mine. I had to recently clean the inside of the corrector as there was a haze on it, presumably from the grease.

I am yet to get a chance to re test it and check the collimation after cleaning it though.

If you remove the corrector, it will probably be sticky and then pop free, it will be lighter than you expect. With a fastar compatible one you can remove the secondary and the secondary baffle gives a handy place to hold it.

[Tony_ (Tony)]

I have removed the corrector a few times already.
The first time I didn't realise there were little spacers holding it in place - I am sure I did not put these back in the right place.
The rotational position is correct (according to the markings) but it probably isn't positioned correctly with the spacers - not sure what difference it made.

The last time I removed it - it was really hard to get out. I had to squeeze alcohol into the gap to release it.