I am about to begin yet another Dobsonian build project and to that end am looking for a new owner for my beautiful Excalibur 18
Excalibur was built by me a few years ago using very nice components and a design that made for a very stable structure while keeping the overall weight and dimensions reasonably manageable.
Excalibur structure features a welded aluminium lower assembly fitted with a welded steel cell frame, stainless steel 18 point mirror support and stainless steel components. The mirror is suspended on a pair of stainless steel 90degree slings that are attached to linear bearings running on stainless steel shafts located in each corner of the mirror box. The mirror box design is of a shallow type to allow rapid thermal equilibrium to be achieved, a Noctua near silent fan further helps in this. The truss clamps are by MoonLite.
The Primary mirror is a superb Suchting Precision Optics 18 F3.54 mirror which has been coated by Dr Wayne Sainty using the Enhanced SiO2/TiO2 coating process.
The upper assembly consists of marine ply rings with aluminium tubes connecting them and carbon fibre focuser board and an ultra lightweight ProComposites carbon/Kevlar baffle sheet to keep out extraneous light. The spider is a heavy duty Astrosystems 4 vane type with matching Astrosystems secondary holder.
Upper truss clamps are by Aurora Precision.
The Secondary mirror is a 4.5 Ostahowski mirror ( better than 1/10th wave )
The LTA and UTA are connected using eight ExelComposites 100% carbon tubes fitted with aluminium crushproof end sleeves epoxied to prevent galvanic corrosion.
The Focuser is the Starlight Instruments 2 Feathertouch which is attached to the SIPS Paracorr coma corrector and set to the ideal optic to optic distance.
The SIPS allows the use of any eyepiece while providing best coma correction without needing to know the focal plane position of the eyepiece.
This is a push to scope with object locating helped along with the excellent AstroDevices Nexus DSC attached to US Digital 10K encoders.
Nearly forgot ****The pictured Telrad has been replaced with a Baader SkySurferV red dot finder which is mounted on a Takahashi FQR1 quick release base ****
The scope features detachable wheels and handles to make moving it easy.
For times when you are not using it there is a custom made Telegizmos 365 cover that protects it from the elements.
Building this was not a cheap undertaking so I am hoping for a buyer who appreciates Excalibur .
