Something fell out in the Primary Mirror

[redsquash]

PANIC
I started to take took out the primary Mirror to mark it.
Two rubber washers or grommets fell out and I suspect
there is a third one somewhere.
What the hell are they doing there and where do I put them back?
I realise now I started removing the mirror in the wrong order


the primary Mirror appears to be held by 3 rubberised mounts
that are sandwich together,
I will continue disassembling but the rubber washers / grommets are a complete mystery
Vixen R130 Newton f/5 650mm.

The manual is useless about how to perform collimation.

[Starkler]

It would appear that you took the mirror cell apart, rather than just undoing the 3 clips holding the mirror into its cell.

The rubber washers you refer to go between the mirror holding cell and the fixed part which attaches to the main scope tube. The collimation screw goes through them and they perform the same function as the springs found in larger scopes.

[redsquash]

Thanks geoff for the quick reply



Geoff just to be absolutely clear
After taking off the rear cover plate there are 3 large screws. These are the collimation screws you refer to I believe. Is that right?

Also in practical visual viewing terms if I accidentally locate dead centre off, by 0.1mm or 0.2mm , then is that gong to translate into a perceivable difference by the human eye when observing the night sky?

BTW, installed Astro Navis in the Vixen 130rf last night.

[Starkler]

The 3 large screws are the collimation screws. The 3 small grub screws located next to them are the lock screws.

Collimate by backing off the grub screws and adjust the large screws which have the effect of pulling the mirror toward you and compressing the rubber rings. The grub screws bear against the mirror cell and push it away from you. So when its close to being collimated, nip the grub screws so they seat down fairly loosely and check again.
Its a bit of a balancing act.




Not sure what you're referring to here. By the way, leaving the cover plate off will allow your mirror to cool more easily.

[redsquash]

I have the holes but not the grub screws.:eyepop:
This is a new scope.


Am I screwed?

CAN i COLLIMATE WITHOUT THESE?


My other question was,
what happens if the primary mirror isn't centred properly.
Ie if it is 0.1mm or 0.2mm or 0.3mm or 0.4 mm off
Is this error acceptable.
or put another way
What margin or error is there available when marking the primary?

[Starkler]

Take another look. These are grub screws with a hex socket in them which are buried into the hole drilled and tapped in the cast aluminium. Similar deal to the 3 secondary mirror adjusting screws.



Do the best you can. I doubt anyone can guarantee better than 0.5mm accuracy and even 1mm out isn't the end of the world.

[redsquash]

here are some shots . How deep are they buried . What size allen key?
sorry have to go to ballet!

[redsquash]

geoff I sent you a pm