Guest peepshow Posted May 13, 2014 Share Posted May 13, 2014 (edited) Many years ago I ground and polished an 8 inch mirror made with Pyrex glass. It was quite successful. At the time I then made plans to make a 24 inch mirror, but to save weight, cost and hard work I planned to cast it in fibre glass resin and to polish that. I never got around to trying this out but have always wondered if it would have worked OK, even if the figuring was not up to glass standard. A spinning dish of mercury has also been tried as a fixed mirror pointing at the zenith but Health and Safety or the EU would ban that idea these days. http://en.wikipedia.org/wiki/Liquid_mirror_telescope Biggest is in Canada and is 6 metres in dia rotating at 8.5 RPM. No grinding or polishing required. Water would be too turbulent for a spinning mirror. Edited May 13, 2014 by peepshow Link to comment Share on other sites More sharing options...
andyboy1970 Posted May 14, 2014 Share Posted May 14, 2014 Never heard of using fibreglass but a few years ago people were using Black vitrious ceramic mirrors. Link to comment Share on other sites More sharing options...
fwm891 Posted May 15, 2014 Share Posted May 15, 2014 Your fibreglass mirror would not be stable enough for optical work but would be great for radio... Link to comment Share on other sites More sharing options...
stash Posted May 15, 2014 Share Posted May 15, 2014 Google Satellite Dishes in an DIY Array for radio Telescope makes interesting reading (USA trio) Link to comment Share on other sites More sharing options...
Guest Tweedledum Posted May 15, 2014 Share Posted May 15, 2014 I don't know if it should be dismissed out of hand!, if you were to use two layers, one base layer interwound with carbon as a structural element and the top layer with a vinyl ester which has excellent thermal properties... All I've used it for is patching up boats . Link to comment Share on other sites More sharing options...
Tweedledee Posted May 15, 2014 Share Posted May 15, 2014 I don't know if it should be dismissed out of hand!, if you were to use two layers, one base layer interwound with carbon as a structural element and the top layer with a vinyl ester which has excellent thermal properties... All I've used it for is patching up boats . A 1/10 wave parabolic boat hull perhaps? :D Link to comment Share on other sites More sharing options...
Guest Tweedledum Posted May 15, 2014 Share Posted May 15, 2014 I've seen one of the best long distance blue water yachts come off the delivery lorry where the two halves of the hull did not meet under the keel!!!... However have made with John Adams a parabolic antenna where the base was epoxy resin with aluminium mesh embeded as the reflector, from memory it came out of the arrl antenna handbook. Link to comment Share on other sites More sharing options...
Guest peepshow Posted May 16, 2014 Share Posted May 16, 2014 A 1/10 wave parabolic boat hull perhaps? :D Bet you could sea well with that. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now