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12" f/5 Newtonian on Horseshoe Mount

Built by Norbert Lichte of Schlier, Germany

Norbert reports: "I would have a telescope like the JMI NGT 12.5 but for a fraction of the cost. Base is the optical tube of a Meade 12" LightBridge Dobson. The tube is modified for a moderate horseshoe mount: Declination wheels are shifted 100 mm (4 inches). The self made rotatable top of the tube consists of sheet of 1 mm aluminum instead of steel (lighter weight), attached with 3 spring loaded toggle type fasteners. It was necessary to add a balance weight."

Technical Specifications:
Type: Newtonian
Aperture: 12 inch, f/5
Focal length: 1524 mm
Weight of optical tube: 20 kg
Balance weight: 6,5 kg
Weight of Mount: 20 kg
Wood thickness: 24 mm
Horseshoe diameter: 752 mm (ca. 30 inches, made by router and cycle)
Driving roll diameter: 69,4 mm
Angle polar axis (latitude): 48°, adjustable
EQ-3 stepping gear motor: n = 5,432/h
ONDRIVE worm gear reducer: i = 12:1
Built: 2009

This telescope won a first place award at International Telescopemeeting Vogelsberg 2009 (ITV 2009) Germany,

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A lot of telescope for little money. The rotatable top of the modified tube allows comfotable viewing of any part of the sky.
The Telescope
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Prize winner at International Telescopemeeting Vogelsberg 2009 (ITV 2009) Germany Photo: Jasper Stein
Prize winning Scope at ITV 2009
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Mechanical model, scale 1:10, for studying
Mechanical model, scale 1:10
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The horseshoe mount disassembled in 2 parts without tools
Horseshoe Disassembled
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Two Wooden rollers form the north bearing of the polar axis, horseshoe diameter 30 inches
Wooden Rollers support 30" Ring
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Support bearing with roller and console
Support Bearing Close-up
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Tube with balance weight, south bearing of the polar axis and precise adjustment in azimuth and polar declination
Tube with Balance Weight
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Felt bearing for the declination wheels and the motion link with gear wheel and tension spring; declination is not motorized.
Felt bearing for Declination Axis
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U-shaped distance holders prevents shifting of the tube on the declination axis.
Declination Axis Side Spacers
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Friction gear for tracking with stepping gear motor and controller of an EQ-3 mount, worm gear reducer 12:1 (ondrives) and driving roll with clamping clutch for tracking On/Off. Slipage prevented by water-resistant sand-paper (grain size 600) on driving roller.
Drive Roller with Clutch
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Declination gear with a ratio of 1:4; the large gear wheel is a turned by a toothed belt. The declination setting circle (diameter 5 inch) is calibrated on a star and to find any object by its declination, pointing accuracy is within 7.5 arc-minutes (precise polar alignment obligatory). Without gearing the Dec.-disk diameter whould have to be 20 inches.
Declination Setting Circle
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LED Illuminated Polar Finder
LED Illuminated Polar Finder

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