Almost a disaster.

Finally the sky cleared tonight and lovely transparancy prevailed. I was doing a set up for a supernove search when I noticed my 10" Newt was VERY obviously out of collimation. I thought this was odd since it was only recently collimated and it was now so far out it looked like someone had been messing with it. The scope at this moment was pointing at the zenith.

Anyway I then looked in the drawtube and could see nothing. I looked into the top of the scope and was utterly horrified to see the secondary was dangling by the thinnest thread of silicone you can imagine. I immediately tried to grab it and realised due to where it was pointing I couldn;t actually get my arm in to grab it.

I then very slowly slewed the scope to the horizontal, praying that the thread of silicone would hold it long enough so that I could retreive it. Thankfully it did.

I have no doubt that if the secondary had fallen the 30 odd inches onto the primary it was bye bye to my 1/10th wave f/4 primary.

On inspection I see what happened, (I think) The epoxy glue didn't adhere very well to the dew heater pad and I guess the heat from the pad must have broken down what little bond there was between the mirror and the pad.

Now I have to think of a safe way of bonding the secondary to the heater pad. The heater pad is a kind of rubbery plastic material. Anyone got any ideas??

I consider myself one VERY lucky astronomer tonight!

That IS a lucky escape Dave. As a mend, would you consider an epoxy resin? I am amazed the silicoe gave way like that. Epoxy withstands higher temperatures. You can also egt automotive resin for use with e.g. the car radiator, but that stuff takes hours to set.

You're one lucky man...

Seanie.

Close one! Don't use silicone sealant to re-glue it. The stuff you want is called "All Fix Chrystal" made by Soudal. It is a flexable bonding goo like silicone but can withstand temperatures between -40C and +90C and is suitable for moist surfaces. It does not contain any solvents and is the all-round number one flexable adhesive for outdoor use... and I just happen to have a spare tube! If you can't wait, then you can pick it up in Chadwicks or Woodies. It's in the same sort of tube as bathroom sealant comes in.

Phil.

Thanks for the feedback guys.

Phil that stuff sounds like the boy for me. Have you used this on glass before, does it bind well to glass?

Phil that stuff sounds like the boy for me. Have you used this on glass before, does it bind well to glass?

Yes, it specifically states that it will bond well with brick, concrete, steel, aluminium, zinc, most plastics, polystyrene, polyurethane, timber, laminate, chipboard, plaster, cork, marble, natural stone, granite rockwool!, ceramics, porcelain, glass, glazed surfaces... and skin!

Phil.

Hi Dave
I think your solution is TEC 7,it's a mastic adhesive that is suitable for mirrors ,plastics & foam materials,it has an adhesion thermal rate of minus 30 to plus 195 C see following website.It's available from most electrical wholesale suppliers & good hardware stores ,retails c.10 Euro www.novatech.be/index.php?st=products&am...amp;key=&taal=en
This stuff DOES what it says on the tin!!!
As a precaution ,tie a piece of strong nylon thread to the body of the diagonal and super glue the other end to the side of the mirror.

Eugene