So how do you stick....

[DanDare]

your secondary onto the holder? I read that silicone is fine but for obvious reasons I want to get it right, would something like ordinary decorators caulk be OK or something more specialised? Any suggestions would be welcome.

It has also been suggested that a couple of toothpicks should be placed between the mirror and holder to get the right spacing to avoid any stress being put onto the mirror, is this really necessary?

I have a home-made hack-saw blade secondary holder/spider and will need to shorten the blades by about an 5mm, I think that I'll need to snap the excess off which I'm feeling a bit nervous about. I've attached a piccy of it.

Thanks for looking

Roy

[barkis]

:DI have seen lots of secondary mirrors glued to a profiled stem, and I'm sure they are safe. Personally, I would put mine into a proper cell, but it's just because I've always done it that way.

They just don't look finished properly just stuck on there defying gravity. Silicon cement is pliable and causes no distortion, and it's very safe.

Regarding your hacksaw blades. Grip with pliers, or place in a vice at the point where you wish to remove the excess. A vice is best as the piece to be retained cand be held rock steady.A sharb tap with a hammer will break the blade at the place where it exits the vice. Alternatively, you can grind it easily with an electric grindstone. Weaken the blade with the stone half inch away from where you need the break, twist the weakened bit back and forth with pliers and it will easily break off. When all four have been reduced, use the grinder to tidy the ends up. Be careful not to hold the blade directly at the stone, but point it in a downward direction so that the stone rides over it. This will prevent the stone from kicking the blade back at you, and possibly hurting your hand, or even breaking the blade.

Apologies for the instructions, I'm sure you know how to use a grindstone.

Ron.

Ron.

[DanDare]

Thanks Ron, I know what you mean. It was worrying me slightly but I'll go with the silicon cement. The spider was made for me as a favour, I just sprayed it up and added the screws and springs.

Thanks for the suggestion.

Roy

[barkis]

Thanks Ron, I know what you mean. It was worrying me slightly but I'll go with the silicon cement. The spider was made for me as a favour, I just sprayed it up and added the screws and springs.

Thanks for the suggestion.

Roy

OK Roy, just ignore the long edit to the post, I was typing it as you replied.

[Doc]

From what I have read in the past silicon is the way to go.

Never heard of the cocktail sticks though

[George]

My home made dob I did many years ago had a siliconed secondary, worked a treat with no issues.

[brianb]

I read that silicone is fine

Used to use Copydex, fixed it fine but was easy to remove when required for recoating.

[DanDare]

Ron, I think I'll go with the vice and pliers (as I don't have a grindstone:))

Thanks for the replies Guys.