loose screws on Dob ?

[Dazraz]

Ok ill try and explain this in english im new so please bare with me. Ok i got a skywatcher skyliner 200 8" Dobsonian telescope. Ok now before you mount the tube on to the mount you have 2 circular plates with screw holes for the handles to screw in to either side of the tube - My problem is that those circular plates are coming loose and the only way to tighten them is to slip my arm down the tube to get to the other side of the screw that hold the plate on. Will i damage the cross feature in the centre of my tube if i move it or is there another way to tighten those screws ?

If this is not understand what im saying please say and ill draw a picture of what im talking about

Regards Daren

[Dazraz]

here is what im talking about

[John]

I can understand the issue perfectly from your description and the picture. As long as you don't knock the cross feature (it's called the spider) which supports the small diagonal mirror, or brush against the diagonal mirror you should be OK - if your arm is long enough,

It might be easier though to come at the problem from the other end of the scope. There are 6 small screws that hold the mirror cell into the bottom of the tube - if you stand the tube upright on it's nose so to speak, mark the position and orientation of the mirror cell (it needs to go back on exactly as it was) then remove the 6 screws you should be able to gently lift the mirror cell with the mirror in it off the back of the scope - put it down somewhere safe. You will then have easier access to the nuts that you need to grip as you tighten the screws holding your azimuth bearings in place. Once done, you reverse the process to replace the mirror cell / mirror (aligning it with your marks). You may need to adjust the collimation a bit after doing this.

John

[Chris Stacey]

I had the same problem once, as I've got the same scope - but I have skinny arms so it wasn't a problem lol.....I didn't have to remove the cross vains, but if you have to you won't do any damage - just make sure you collimate it again after.

That said, someone else might have a better idea!!!

[Chris Stacey]

Scrap that - jahmanson has a better response.

[John]

Scrap that - jahmanson has a better response.

Either will work if you have long enough arms and are careful

John

[tinvek]

if you decide to do it past the spider then for god's sake make sure the end with the mirror is higher than the end you're doing your vets arm up a cow impression at. the last thing you want to do is drop anything on the main mirror

[Rusty Strings]

I'd go for Jahmanson's suggestion and I would add two small pieces of sticky tape to tube and mirror so that you can put back in the same position without any guesswork.

John

[acey]

I agree with above.

Recording the correct orientation of the mirror is helpful because if the tube isn't perfectly circular (it won't be) and if the securing screws aren't perfectly spaced (they won't be) you may find there's only one way of putting back the mirror cell so that all the screws will go in. I had this with my 8-inch and had to do a lot of hauling and pushing to get it back in.

But you should still recollimate the scope.

Don't expect the cell to just lift out - it may be a tight fit and you'll need to wiggle it out.

I personally wouldn't recommend standing the dob upright while doing this job - I always lie mine down, supported so that it's a little bit off the floor. Then the mirror never has far to fall in case of disaster, and the tube can't topple over.

[Dazraz]

Ok cheated a bit what i did and im not sayiny this is the correct way so please dont copy what i have done unless anyone proffesional from this web forum says its ok , but what i did was strap a lightweighted spanner to a long thin wooden rod turned the tube on its side and pushed the wooden rod with attached spanner down the tube attached the spanner to the offending nut and screwed it tight - job done happy man - but thanks again to the forum for all suggestions but i suppose i am one of those people who is steering away from collamination but i know i have to face my demons soon !!!!

[acey]

Good stuff - always go for the simplest solution that works!

[TheThing]

I used to shy away from collimation too, until I found this video tutorial. Short, simple and easy to do!

[Beulah]

I did this last week, as I noticed the two circular plates coming loose - I simply removed the primary mirror and held the nuts on the inside of the tube.

This could be due to the way I carry the scope - using the two adjusting handles instead of the handle at the front of the dob. It might be a good idea to screw a couple of carry handles to the dob mount to ease the pressure.

I told myself firmly NOT to look at the primary mirror, AT ANY COST, DO NOT LOOK AT THE PRIMARY MIRROR as I shouldn't have to clean it, and temptation is strong......but when you say to someone "don't look down..."

Needless to say I am going to give my mirror a clean soon....

[Dazraz]

I did this last week, as I noticed the two circular plates coming loose - I simply removed the primary mirror and held the nuts on the inside of the tube.

This could be due to the way I carry the scope - using the two adjusting handles instead of the handle at the front of the dob. It might be a good idea to screw a couple of carry handles to the dob mount to ease the pressure.

I told myself firmly NOT to look at the primary mirror, AT ANY COST, DO NOT LOOK AT THE PRIMARY MIRROR as I shouldn't have to clean it, and temptation is strong......but when you say to someone "don't look down..."

Needless to say I am going to give my mirror a clean soon....

How are you going to clean it ?

[Astro_Baby]

They aren't that hard to do but its pretty pointless I think as they never stay truly pristine for long - one night in dew and your back to square one. If you saw the state of Patrick Moores mirror on his refelector you'd see that a mirror can be totally grimed up and still give good views

Seriously - best way to clean them is a nice soak luke warm water with PURE soap flakes. Gently agitate and if there is any stubborn gunk then VERY gently use your nice softened fingers that have been soaked in the warm water and suds to very, VERY gently wipe it away. Dont use soaps that contain additives like Silicon.

Once done rinse throughly and then stand on its edge on something nice and soft and squirt distilled water (not de-ionised over the mirror). Leave to dry in warm air.

Needless to say dont put the mirror into something like a stainless steel sink - use a plastic washing up bowl thats completely free of any muck. Dont do it with kids or pets around and TAKE YOUR TIME and exercise maximum care.

If I am working around optics I always put on some sterile cotton gloves - you can get them from Boots for about a quid.

[acey]

VERY gently use your nice softened fingers that have been soaked in the warm water and suds to very, VERY gently wipe it away.

I prefer to keep fingers, gloved or otherwise, well clear of the mirror surface. Surgical cotton wool is the only thing I'd want touching it. I used bog-standard cotton wool the first time I cleaned my mirror and left a nice big scratch on it, thanks to a tiny bit of grit in the cotton wool.