· Get a Cloudy Nights T-Shirt · Submit a Review / Article    Click here if you are having trouble logging into the forums Cloudy Nights - Official Forums of the 2009 International Year of Astronomy Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User   You are not logged in. [Login] Forum Archives · Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> ATM, Optics and DIY Forum Previous   Index   Next   Flat   Mark Harry Post Laureate Reged: 09/05/05 Posts: 3120 Loc: Northeast Re: RTV, Glass, and Holder Material       07/03/09 07:18 AM Edit   Reply   Quote   Quick Reply:   With secondaries up to 2.6", I pretty much have followed Bryan Greer's suggested method, with a few beads about 1/8-1/10th inch thick; RTV on either aluminum, or spun plywood plugs. Used his included spacers. For primaries, either particle board (repair/test) or plywood/aluminum backer plates with new Dob construction, RTV @ 1/4" thick, a minimum of 6 blobs at the 70-80% radius, and maybe 3 blobs inside of that, about quarter/half-dollar size. I used 1/4" nuts for spacers, a minimum of 24 hours before removing. Up to 14" size, absolutely no issues at all. Any backers of ply or PB/MDF I made a good effort of assuring stability by checking flatness, and sealing adequately. Unless I did the analysis Preston did, I would -NOT- go as thin as he did. I have never gone that thin personally, but had to fix some who had. Thinner is better as far as collimation is concerned, but it can be a headache with distortion of the optics. Silicone in the thicknesses I outline seem to be adequate to prevent distortion from ocurring. Mark -------------------- So many projects, so little time! Post Extras       Entire thread Subject Posted by Posted on RTV, Glass, and Holder Material Steven Aggas 07/02/09 04:20 PM Re: RTV, Glass, and Holder Material mark cowan   07/02/09 08:33 PM Re: RTV, Glass, and Holder Material Biff   07/09/09 03:03 PM Re: RTV, Glass, and Holder Material Mark Harry   07/03/09 07:18 AM Re: RTV, Glass, and Holder Material PrestonE   07/03/09 03:36 PM Re: RTV, Glass, and Holder Material mark cowan   07/04/09 02:42 AM Re: RTV, Glass, and Holder Material PrestonE   07/04/09 04:12 PM Re: RTV, Glass, and Holder Material Steven Aggas   07/06/09 03:18 PM Re: RTV, Glass, and Holder Material PrestonE   07/06/09 08:55 PM Re: RTV, Glass, and Holder Material Steven Aggas   07/07/09 12:25 PM Re: RTV, Glass, and Holder Material PrestonE   07/07/09 04:11 PM Re: RTV, Glass, and Holder Material Steven Aggas   07/07/09 05:34 PM Re: RTV, Glass, and Holder Material mark cowan   07/07/09 09:10 PM Re: RTV, Glass, and Holder Material Steven Aggas   07/08/09 12:39 PM Re: RTV, Glass, and Holder Material PrestonE   07/10/09 02:43 PM Re: RTV, Glass, and Holder Material Steven Aggas   07/10/09 03:33 PM Re: RTV, Glass, and Holder Material PrestonE   07/11/09 11:12 PM Re: RTV, Glass, and Holder Material Steven Aggas   07/13/09 12:14 PM Re: RTV, Glass, and Holder Material PrestonE   07/15/09 05:50 PM Re: RTV, Glass, and Holder Material Steven Aggas   07/16/09 11:28 AM Re: RTV, Glass, and Holder Material PrestonE   07/17/09 10:37 AM Re: RTV, Glass, and Holder Material Steven Aggas   07/13/09 12:16 PM Re: RTV, Glass, and Holder Material Steven Aggas   07/13/09 05:06 PM Re: RTV, Glass, and Holder Material mark cowan   07/08/09 03:42 PM Re: RTV, Glass, and Holder Material Steven Aggas   07/09/09 12:28 PM Re: RTV, Glass, and Holder Material Charl   07/06/09 06:43 PM Re: RTV, Glass, and Holder Material PrestonE   07/02/09 06:13 PM Extra information 10 registered and 4 anonymous users are browsing this forum. 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