You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> ATM, Optics and DIY Forum Previous   Index   Next   Threaded   Pages: 1 Olivier Biot Amused Reged: 04/25/05 Posts: 13616 Loc: 51°N (Belgium) 80mm TAL to 44mm Synta dovetail adapter?       #2373314 - 05/05/08 06:38 PM Attachment (14 downloads) Edit   Reply   Quote Quick Reply   I want to set up my TAL-200K on my Orion Sirius EQ-G (Skywatcher HEQ5) mount. Problem is that TAL and Synta use a different type of dovetail (see also attached image for details and dimensions of the cross sections): The dovetail on the TAL-200K is 80mm wide, 11mm tall and 200mm long. The slants are at 60°. The Synta dovetail that came along my mount is 44mm wide, 15mm tall and 210mm long. The slants are at 75°. Both dovetails are pre-drilled and feature pre-tapped holes with a thread that looks imperial to me (not metric). Is there a custom dovetail adapter I can use for the TAL-200K and my mount, or do I need to find a means for connecting both dovetails? Cheers, Olivier -------------------- Tal-200K (#199) with JMI NGF-Mini2M focuser on GEM3 • Astro-Tech AT80ED on Orion Sirius EQ-G with EQDIR & home made wireless EQDIRECT • Celestron Regal LX 8x42 & 10x42 • Helios 15x70 ATM 14" f/5 (designing mirror cell and filter wheel/focuser) • ATM 10" f/6 Portable Truss (#1200 grit) • ATM 10" f/25 Dall-Kirkham (primary: polishing, secondary: #120 grit) AstroForecast Post Extras:       Olivier Biot Amused Reged: 04/25/05 Posts: 13616 Loc: 51°N (Belgium) Re: 80mm TAL to 44mm Synta dovetail adapter? [Re: Olivier Biot]       #2402726 - 05/17/08 09:31 PM Attachment (12 downloads) Edit   Reply   Quote Quick Reply   Since I had some spare (cloudy) time I decided to draw the TAL dovetail bar in a 3D modeling tool. All holes are threaded. From left to right: metric M8, centering pin (8.5mm diameter, tapered at 45°), metric M6, 1/4" photographic thread, one hole with imperial thread similar to metric M8, metric M6, centering pin, metric M8. In other words: the 2 holes at the center of the TAL dovetail are NOT metric. -------------------- Tal-200K (#199) with JMI NGF-Mini2M focuser on GEM3 • Astro-Tech AT80ED on Orion Sirius EQ-G with EQDIR & home made wireless EQDIRECT • Celestron Regal LX 8x42 & 10x42 • Helios 15x70 ATM 14" f/5 (designing mirror cell and filter wheel/focuser) • ATM 10" f/6 Portable Truss (#1200 grit) • ATM 10" f/25 Dall-Kirkham (primary: polishing, secondary: #120 grit) AstroForecast Edited by Olivier Biot (05/18/08 03:05 PM) Post Extras:       Olivier Biot Amused Reged: 04/25/05 Posts: 13616 Loc: 51°N (Belgium) Re: 80mm TAL to 44mm Synta dovetail adapter? [Re: Olivier Biot]       #2402744 - 05/17/08 09:39 PM Attachment (10 downloads) Edit   Reply   Quote Quick Reply   Viewed from the bottom: -------------------- Tal-200K (#199) with JMI NGF-Mini2M focuser on GEM3 • Astro-Tech AT80ED on Orion Sirius EQ-G with EQDIR & home made wireless EQDIRECT • Celestron Regal LX 8x42 & 10x42 • Helios 15x70 ATM 14" f/5 (designing mirror cell and filter wheel/focuser) • ATM 10" f/6 Portable Truss (#1200 grit) • ATM 10" f/25 Dall-Kirkham (primary: polishing, secondary: #120 grit) AstroForecast Post Extras:       Olivier Biot Amused Reged: 04/25/05 Posts: 13616 Loc: 51°N (Belgium) Re: 80mm TAL to 44mm Synta dovetail adapter? [Re: Olivier Biot]       #2402748 - 05/17/08 09:43 PM Attachment (7 downloads) Edit   Reply   Quote Quick Reply   And viewed from the front (I did not draw the 2 tapped M4 holes that hold the screws securing the end plate): -------------------- Tal-200K (#199) with JMI NGF-Mini2M focuser on GEM3 • Astro-Tech AT80ED on Orion Sirius EQ-G with EQDIR & home made wireless EQDIRECT • Celestron Regal LX 8x42 & 10x42 • Helios 15x70 ATM 14" f/5 (designing mirror cell and filter wheel/focuser) • ATM 10" f/6 Portable Truss (#1200 grit) • ATM 10" f/25 Dall-Kirkham (primary: polishing, secondary: #120 grit) AstroForecast Post Extras:       Olivier Biot Amused Reged: 04/25/05 Posts: 13616 Loc: 51°N (Belgium) Re: 80mm TAL to 44mm Synta dovetail adapter? [Re: Olivier Biot]       #2403325 - 05/18/08 08:41 AM Attachment (7 downloads) Edit   Reply   Quote Quick Reply   And here's a front view of the Vixen dovetail bar that came with my Orion Sirius EQ-G. It is 8.25" (210mm) long, 1.75" (44.2mm) wide and 15mm high: -------------------- Tal-200K (#199) with JMI NGF-Mini2M focuser on GEM3 • Astro-Tech AT80ED on Orion Sirius EQ-G with EQDIR & home made wireless EQDIRECT • Celestron Regal LX 8x42 & 10x42 • Helios 15x70 ATM 14" f/5 (designing mirror cell and filter wheel/focuser) • ATM 10" f/6 Portable Truss (#1200 grit) • ATM 10" f/25 Dall-Kirkham (primary: polishing, secondary: #120 grit) AstroForecast Post Extras:       Olivier Biot Amused Reged: 04/25/05 Posts: 13616 Loc: 51°N (Belgium) Re: 80mm TAL to 44mm Synta dovetail adapter? [Re: Olivier Biot]       #2403366 - 05/18/08 09:24 AM Attachment (4 downloads) Edit   Reply   Quote Quick Reply   A 3D rendering of the Orion dovetail bar: -------------------- Tal-200K (#199) with JMI NGF-Mini2M focuser on GEM3 • Astro-Tech AT80ED on Orion Sirius EQ-G with EQDIR & home made wireless EQDIRECT • Celestron Regal LX 8x42 & 10x42 • Helios 15x70 ATM 14" f/5 (designing mirror cell and filter wheel/focuser) • ATM 10" f/6 Portable Truss (#1200 grit) • ATM 10" f/25 Dall-Kirkham (primary: polishing, secondary: #120 grit) AstroForecast Post Extras:       Olivier Biot Amused Reged: 04/25/05 Posts: 13616 Loc: 51°N (Belgium) Re: 80mm TAL to 44mm Synta dovetail adapter? [Re: Olivier Biot]       #2403380 - 05/18/08 09:31 AM Attachment (3 downloads) Edit   Reply   Quote Quick Reply   Here's a top view with dimensions. The threaded holes are threaded with imperial 1/4" (4 holes at the extremities of the dovetail) or photographic thread (2 holes close to the middle of the dovetail). There are 2 apparently metric through holes, untapped, of 6.5mm diameter (between the 1/4" threaded holes): -------------------- Tal-200K (#199) with JMI NGF-Mini2M focuser on GEM3 • Astro-Tech AT80ED on Orion Sirius EQ-G with EQDIR & home made wireless EQDIRECT • Celestron Regal LX 8x42 & 10x42 • Helios 15x70 ATM 14" f/5 (designing mirror cell and filter wheel/focuser) • ATM 10" f/6 Portable Truss (#1200 grit) • ATM 10" f/25 Dall-Kirkham (primary: polishing, secondary: #120 grit) AstroForecast Edited by Olivier Biot (05/18/08 11:48 AM) Post Extras:       Olivier Biot Amused Reged: 04/25/05 Posts: 13616 Loc: 51°N (Belgium) Re: 80mm TAL to 44mm Synta dovetail adapter? [Re: Olivier Biot]       #2403909 - 05/18/08 02:58 PM Attachment (7 downloads) Edit   Reply   Quote Quick Reply   Here's the solution I am currently considering. The attached drawing renders the TAL dovetail with transparency. I will reuse two threaded M6 holes on the steel TAL dovetail, and will add 2 extra M6 threaded holes at 31.25mm (this is 1/5th of the distance between the centers of both holes I will reuse). On the Vixen dovetail (that came with my Orion Sirius EQ-G mount) I will have to drill 4 holes for M6 bolts as well as one hole for accepting the 2nd alignment pin of the TAL dovetail: -------------------- Tal-200K (#199) with JMI NGF-Mini2M focuser on GEM3 • Astro-Tech AT80ED on Orion Sirius EQ-G with EQDIR & home made wireless EQDIRECT • Celestron Regal LX 8x42 & 10x42 • Helios 15x70 ATM 14" f/5 (designing mirror cell and filter wheel/focuser) • ATM 10" f/6 Portable Truss (#1200 grit) • ATM 10" f/25 Dall-Kirkham (primary: polishing, secondary: #120 grit) AstroForecast Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 11 registered and 7 anonymous users are browsing this forum. 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