Mark V 16" f/4.5
Albert Highe
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Notable design elements
1)
Asymmetrical design. Moving the top strut from the center (as in the Mark III)
to near the corner allows the mirror box to be smaller (like the Mark IVs). The
width of the mirror box is 19". The Ebony Star tube has an OD of
17-1/2". The rocker box is 21" x 21". Moving the top strut to the
side also results in a stiffer ring than the Mark III even though its average
width is smaller. Moving the top, center strut to the side also places the
finder closer to the observer. I found this position a lot more convenient on my
13".
2) Clamps (and corresponding struts) are three different diameters so the struts
nest like my 17-1/2."
3) Clamp shapes follow the profiles of the upper and lower rings. This allows
the use clamp knobs instead of wing nuts. The larger clamp knobs
are more accessible and easier to turn.
4) Much larger opening in the bottom of the mirror box. Improves convective
cooling and lightens the box noticeably.
5) The ends of the support triangles are glued directly to the mirror. A pair of
springs are recessed into milled blind holes alongside each collimating bolt.
This holds the springs in position and allows the mirror to be closer to the
bottom of the OTA.
 
Figures 1 and 2 Mark V 16" f/4.5 scope. |
Mirror "box"
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Figure Details of mirror box construction. Underside of mirror box top ring with clamps.
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Figure Underside of mirror box top ring showing clamp detail.
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Figure Details of mirror box construction. Underside of mirror box top ring with clamps.
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Figure Underside of mirror box top ring showing clamp detail.
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Figure Details of mirror box construction. Top of mirror box bottom ring with clamps.
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Figure Underside of mirror box bottom.
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Figure Dry fit of the mirror box parts.
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Mirror cell
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Figure Top view of mirror cell. |
Figure Bottom view of mirror cell. The central triangular support is cast aluminum. |
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Figure Detail of collimation springs. Each is contained with a blind hole. |
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Process of attaching cell to mirror.
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Upper ring
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Figure Simple upper ring. |
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Rocker box and ground board
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Packed for transport
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| Nesting struts. Three OTA struts and two wheelbarrow handle struts all nest within each other for transport. A plastic cap slips over each end. | Three OTA struts - 1-3/4", 1-7/8" and 2" OD. |
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| Cutting wheel barrow brackets and focuser shelf from C-channel. |
Lightweight ramps
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| Bottom and top view of lightweight ramps. | Mid span, bottom and top view. |
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| Upper end of ramps, bottom and top view. | Lower end of ramps, bottom and top view. |
All images and text copyright © 2005-2006 by Albert Highe, unless otherwise noted.
Last updated March 2, 2006.