· 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   Threaded   Pages: 1 greenglass professor emeritus Reged: 01/22/06 Posts: 540 Loc: Ontario, Canada Foucault tester modification (new idea?)       #3370529 - 10/04/09 12:01 PM Edit   Reply   Quote Quick Reply   Instead of a spring or rubber band to pull the carriage against the bolt I tried a magnet between the two. The carriage stop of course needs to be magnetic as well as the bolt. (I used the shiny round ones from an LED brooch). And there's no change in tension like a spring. Ronald -------------------- 10" f/5 dob unf. 7x50 Tasco binos Post Extras:       Luigi Post Laureate Reged: 07/03/07 Posts: 4933 Loc: MA Re: Foucault tester modification (new idea?) [Re: greenglass]       #3372116 - 10/05/09 07:48 AM Edit   Reply   Quote Quick Reply   Could work well, but one advantage the spring has is it can also have the effect of taking out the backlash in the screw's threads. -------------------- 17.5" f/5 Dob. IM-715 MCT. 120ED. Lunt 60mm Ha. Zeiss, Leica, Fujinon, Nikon, Pentax, Bushnell bins Post Extras:       neo professor emeritus Reged: 02/12/08 Posts: 610 Loc: Iasi, Romania Re: Foucault tester modification (new idea?) [Re: Luigi]       #3372128 - 10/05/09 08:10 AM Edit   Reply   Quote Quick Reply   Yep, I'm with Luigi here. I was thinking too to use magnets on my tester instead of springs but that could lead to some errors. I believe with good springs the results are more consistent at each measurement. On the other hand if you have very strong Neodymium magnets it would be nice to experiment. They will probably hold the carridge and the screw in good contact without backlash. -------------------- Russian 15x50 binos Home made 8" f/5 Newton on eq mount Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor www.astronomy.ro Post Extras:       greenglass professor emeritus Reged: 01/22/06 Posts: 540 Loc: Ontario, Canada Re: Foucault tester modification (new idea?) [Re: neo]       #3372530 - 10/05/09 12:49 PM Edit   Reply   Quote Quick Reply   Good point, ya that's right, the bolt is not pushed back with a magnet. And if the magnet shifts the carriage could move. Glue the magnet to the carriage and put a spring on the bolt works, I measured 3/1000" backlash without the spring on the outside bolt part. Edited by greenglass (10/05/09 01:43 PM) Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 10 registered and 5 anonymous users are browsing this forum. Moderator:  Don W, Mike I. Jones  Print Thread Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Thread views: 173 Jump to *International Year of Astronomy 2009* -----   Global Coordination   Cornerstone Projects   Special Projects   Special Task Groups   Global Activities   National and Regional Activities   IYA 2009 in Africa   IYA 2009 in the USA*Announcements and News* -----   Cloudy Nights Announcements   Discussion of CN Articles, Reviews, and Reports   Beginners Forum   Celestial Events   Light Pollution*Equipment Discussions* -----   ATM, Optics and DIY Forum   Binoculars   Binoviewers   Cats & Casses   Classic Telescopes   Equipment   Eyepieces   Mounts   Observatories   Reflectors   Refractors    Celestron SkyScout and Meade mySky   Video and Electronically Assisted Astronomy*Astrophotography and Sketching* -----   Beginning and Intermediate Imaging   Film Astrophotography   DSLR & Digital Camera Astro Imaging & Processing   CCD Imaging & Processing   Solar System Imaging & Processing   Sketching   Astro Imaging/Sketching Contest *Observing* -----   NEO   General Observing   Planetary and Solar System Observing   Lunar Observing   Deep Sky Observing   Double Star Observing   Solar   Variable Star Observing and Radio Astronomy*Telescope Specific Forums* -----   Celestron NexStar    NexStar GPS / CPC Telescopes   Questar Forum   Meade ACF/RCX / LX / GPS    Meade ETX*Other* -----   Science of Astronomy & Space Exploration   AstroWebsites   Space Rocks*Speciality Forums* -----   AstroArt   Astronomy Software & Computers   Stellar Media   Astro Outreach, Clubs and Star Parties*CN Feedback and Vendor Announcements* -----   Vendor and Group Announcements CN Forums Home

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