Scope not holding collimation

[Essex nightsky]

I received my new scope yesterday (surprise, surprise it rained all day and night) its a skywatcher 114/500 on a dob base. I'm yet to try it out due to the rain, but when I place the front dust cover on the front, it is enough to knock it out of collimation. I have tightened the locking screws (hand tight) but am abit weary about using a screwdriver as I don't want to "pinch" the primary by applying too much force.... Thoughts/suggestions?

Thanks in advance

Grant

[RLWP]

Are the collimation screws on the vanes tight enough?

Richard

[Essex nightsky]

Thanks for the reply, the secondary is fine, its the primary that goes out

Grant

[rwilkey]

How do you know the collimation is out if you have not been able to view with it yet, are the parts loose?

[Essex nightsky]

No, the center spot on the primary moves from the center of the secondary.

Grant

[brantuk]

So the center spot isn't stuck down in the middle of the primary correctly? If that's the case then it won't change the collimation of the primary mirror. Neither will putting the front dust cover on. When you focus tightly on a star at night then slightly defocus in or outwards - you should see several perfectly concentric airy circles. If anything is oblong or mushy then it's out of collimation.

I think a little more specific explanation of the problem will help us to diagnose it for you.

[Essex nightsky]

Sorry that wasn't clear, the center spot is stuck down, but its reflection (in the secondary) moves. I'm going to do the star test tonight if sky is clear. What it comes down to is should the licking screws on the primary be tightened with your fingers or I it ok to use a screwdriver to tighten them even further without "pinching" the primary

[Essex nightsky]

*locking

[happy-kat]

I only use my fingers to finger tight.

Are you sure your secondary is not loose?

[RLWP]

Sorry that wasn't clear, the center spot is stuck down, but its reflection (in the secondary) moves.

Just going back, the dot cannot move, the secondary could though. And it's the secondary that is most likely to move when you put the dust cover on. So... Are the screws on the secondary and the vanes tight?

Richard

[Essex nightsky]

I feel like the dust cap may be slightly to snugly fitting (the scope was purchased second hand from astroboot) so when it is pushed on it caused a knock which may be just enough to bump out of collimation, going to try and order another cap from skywatcher

Grant

[happy-kat]

The dust cap on my Heritage 130p is a tight fit but it does not knock collimation out.

Try to gently see if the vanes on the secondary move.

[Moonshane]

do you check collimation after you finger tighten the locking screws?

if not they are more than likely the cause. I'd take them out completely.

[Essex nightsky]

Just re collimated it and tightened primary locking screws by hand then gave a quarter turn with screwdriver on each and when I put dust cover on and then remove and checked,everything was still aligned, so I guess I wasn't tightening locking screws enough

[brantuk]

Yes that sometimes happens if the springs are a bit slack and the locking screws aren't done up enough. Glad you have it sorted now though and hope I helped a little.

[Essex nightsky]

Yes... Everyone on here is very helpful im glad to be a part of this community... Thanks alot