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Mirror diameter: 12inch (311mm) Focal length: 66inch (1672mm) Mirror thickness: 1 inch (25mm) Material: Borofloat Diameter secondary: 2inch (51mm) Entire weight : app.10kg |
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The focuser board is connected to the ring by means of an angle profile which also reinforces the joint of the ring tube.
The focuser is a helical one, the parts are homemade.
The spider is made from 0.3mm thick brass sheet.
The center is made from aluminium rectangle pipe 34x19,5mm.
The upper part of the seccondary mirror support has got a groove which fits exactly to the rectangle pipe. This ensures quick remounting after transport in "travelmode".
The first observations showed a sensitivity for stray light caused by the open construction of the secondary cage. Motivated by a posting of Jim Miller on the ATM- List I searched for an Iris- Baffle.
The one I found has an OD of 70mm, an ID of 50mm, the minimum opening is 3mm. The weight is 50g and the baffle has an height of 7mm:
The opening can be adjusted by means of the small lever.
Three different openings of the Irisbaffle.
For bending tubes I use hardwood templates and a bench vice. The radii of the templates should be appr. 10% smaller than the target value.
One should not try to bend the entire radius at once, it works much better to take a lot of small steps.
The 6-point mirror cell was calculated with plop. The design is similar to that of the 16incher. The sling is made from steel tape.
The mirror cell is connected to the mirror box by Brass screws, the mirror adjustment is done by turning the knurled nut.
Adjustment of the primary mirror is done from below.
The mirror box is made from 9mm "Multiplex" plywood. The Wheels have 330mm radius and are made from 15x15x1 aluminium square pipe.
The truss tubes are made from 16x1 aluminium square pipe.
The base board of the rocker box is made from 19mm "Multiplex" plywood. It has got a hole in the middle, the side boards are made from laminated 1,5mm plywood, reinforced by pine strips.
The base frame is made from aluminium square pipe 10x10x1mm and can be disconnected from the rocker easily.
On top, 1,5mm thick plywood is bonded to the base board, so the rocker can be used as cover.
For protection of the mirror during transport a made a lower and an upper shell:
The mirror box is set on the lower shell, the edges are beveled so the shell is well centered.
The cover has got spacers which fit to the chamfer of the mirror when the srews are fastened:
The cover is fastened by the screws, and the mirror is kept safe for transport.
The scope in "travelmode". The cover on top of the mirror is connected by three bolts to a bottom cover and protects the mirror during transport.
This package measures 17x17x4,7 inch and travels together with the altitude bearings inside a hard shell suitcase.
Link to the commercial homepage of: Traveldob
More pictures and comments on the scope can be found in threads on "Astrotreff.de" (in german language), here are the links:
Thread 1;
Thread 2;
Thread 3
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