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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,

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
Prize winner at International Telescopemeeting Vogelsberg 2009 (ITV 2009) Germany Photo: Jasper Stein
Prize winning Scope at ITV 2009
Mechanical model, scale 1:10, for studying
Mechanical model, scale 1:10
The horseshoe mount disassembled in 2 parts without tools
Horseshoe Disassembled
Two Wooden rollers form the north bearing of the polar axis, horseshoe diameter 30 inches
Wooden Rollers support 30" Ring
Support bearing with roller and console
Support Bearing Close-up
Tube with balance weight, south bearing of the polar axis and precise adjustment in azimuth and polar declination
Tube with Balance Weight
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
U-shaped distance holders prevents shifting of the tube on the declination axis.
Declination Axis Side Spacers
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
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
LED Illuminated Polar Finder
LED Illuminated Polar Finder

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