Help needed mounting secondary on Newt

multiweb (Marc) · #1 22-04-2011, 06:32 PM

Hi guys, I'm putting my newt back together after getting the mirrors recoated. I need to "glue" the secondary on the alu cylinder that screws into the spider. What's best to do? Glue the glass straight on the face? Originally I think it had some kind of double sided rubbery compound(?) , maybe 1to 2mm thick. I was thinking of using some double sided stuff from bunnings? Good enough? No-no? Will it hold in colder temp? ... secondary fals on primary... ouch! Thanks for any pointers.

gbeal · #2 22-04-2011, 06:41 PM

Marc,
I use a simple silicone stuff, "Bostick" from memory, just make sure it is a sealant as well as an adhesive, the emphasis on adhesive (many are just sealants).
Spread a bead around the circumference, a bit in from the edge, and maybe a small dollop in the middle. When I use this to attach the primary to a cell, I normally use 3 matchsticks as spacers, so it doesn't all get squeezed out. Let it cure for a day or so, and be happy. I don't store mine with the primary facing up anyway, more on an angle or horizontal.
Gary

multiweb (Marc) · #3 22-04-2011, 06:54 PM

Quote:

Originally Posted by gbeal

Marc,
I use a simple silicone stuff, "Bostick" from memory, just make sure it is a sealant as well as an adhesive, the emphasis on adhesive (many are just sealants).
Spread a bead around the circumference, a bit in from the edge, and maybe a small dollop in the middle. When I use this to attach the primary to a cell, I normally use 3 matchsticks as spacers, so it doesn't all get squeezed out. Let it cure for a day or so, and be happy. I don't store mine with the primary facing up anyway, more on an angle or horizontal.
Gary

Thanks Gary. I'll get some from bunnings.

gbeal · #4 24-04-2011, 05:53 PM

In my case I have an ATM mate, who brings his scope around often and we observe. He is a kitchen bench-top maker by day and uses the aforementioned silicone. I end up with the old tubes, the ones that are all but done, but still have three blobs of gooo in them. Most of my newt projects are with this stuff, the remnants if you like.
Gary