· Get a Cloudy Nights T-Shirt · Submit a Review / Article Click here if you are having trouble logging into the forums 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] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> Mounts Previous   Index   Next   Threaded   Pages: 1 MHamburg professor emeritus Reged: 06/21/06 Loc: Brooklyn, NY/Berkshires, MA CGEM RA Axis Backlash       #5516312 - 11/12/12 04:40 PM Edit   Reply   Quote Quick Reply   Hello All, While I am waiting for an answer from Ed Thomas, I thought this forum's brain trust could also help. I recently finished a hypertune of my CGEM (which went reasonably well and taught me a lot about the mount) and believe I have increased the backlash! The RA axis wiggles (whether fully loaded or not) about 3/32". When slewing under power the motors sound fine and are responsive. Since I did the hypertune to improve the mount's imaging capabilities, I welcome all suggestions that would reduce this slop. I would love to avoid having to disassemble the mount again. Thanks in advance for the help. Michael Post Extras:       MHamburg professor emeritus Reged: 06/21/06 Loc: Brooklyn, NY/Berkshires, MA Re: CGEM RA Axis Backlash [Re: MHamburg]       #5516358 - 11/12/12 05:24 PM Edit   Reply   Quote Quick Reply   Just got explicit instructions from Ed Thomas how to adjust this backlash. He has been the most supportive and deserves our patronage whenever possible. Michael Post Extras:       orlyandico Carpal Tunnel Reged: 08/10/09 Loc: Singapore Re: CGEM RA Axis Backlash [Re: MHamburg]       #5517358 - 11/13/12 07:11 AM Edit   Reply   Quote Quick Reply   don't take out all the backlash, you would stall the motor. i notice that the closer the worm is set to the ring gear, the noisier the RA motor will be. you cannot eliminate all the backlash so don't even try; backlash in RA is not a big deal, just make sure to be slightly east heavy. Post Extras:       MHamburg professor emeritus Reged: 06/21/06 Loc: Brooklyn, NY/Berkshires, MA Re: CGEM RA Axis Backlash [Re: orlyandico]       #5517553 - 11/13/12 09:31 AM Edit   Reply   Quote Quick Reply   Thanks for the advice, Orlando. I'll let you know how it all works out. Michael Post Extras:       orlyandico Carpal Tunnel Reged: 08/10/09 Loc: Singapore Re: CGEM RA Axis Backlash [Re: MHamburg]       #5517565 - 11/13/12 09:40 AM Edit   Reply   Quote Quick Reply   in spite of the large-ish backlash and huge periodic error (40") on my CGEM, i can still guide effectively.. https://dl.dropbox.com/u/63497702/20121022-cgem-m57.PNG notice the RMS error for the RA which is 0.18 - with my finder-guider and Meade DSI, that's about 1.4" to 1.8" - not fantastic, but that's what you get for the money. Another of Ed's words of wisdom - don't kill yourself trying for perfection, you won't get it. Not with the CGEM anyway. Personally getting 2" accurate guiding is a bit annoying but it is what it is. It all depends on the magnitude of your CGEM's 8/3 (the famous 2.6667X harmonic). If it's large - like mine - then guiding is always a challenge. If it's small, then lucky you. My CGEM has an Aeroquest worm, but since the 8/3 is so large (larger than the fundamental) it still screws things up. Post Extras:       MHamburg professor emeritus Reged: 06/21/06 Loc: Brooklyn, NY/Berkshires, MA Re: CGEM RA Axis Backlash [Re: orlyandico]       #5518310 - 11/13/12 04:59 PM Edit   Reply   Quote Quick Reply   I would be very happy with a graph like that. Michael Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 37 registered and 31 anonymous users are browsing this forum. 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