INSTALLATION:
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- Install Scilab 2025
- Regarding the Scilab version: 2025 works throughout.  2023 works
  fine except perhaps the Print function; The maximum plot axis size
  is smaller in 2025 than in 2023, so there is a risk that the 
  printed output is wrong.  Best to use 2025.
- Unzip the archive and place the scripts in a directory.
  This is where results will be stored.

USAGE:
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- Double-click on vnsDob.sce
- Wait for Scilab to start up.
- Press F5 in the editor window that has vnsDob.sce open to start the GUI
- Use the right-click to rotate the 3D image to examine the results.
  With a touchpad, use right-click and the regular pointer.
- If you want exact alignment with the X, Y or Z axis, use the
  Edit->Axes->Viewpoint tab
- Tune the parameters until you are satisfied with the design
- Use Apply/Save to apply changes and save the model in vns.dat
- When starting, vns.dat will get loaded if present.  It will always
  have your latest saved configuration.
- Print saves the model and segments in CSV format, and plots the data
  for use with Letter or A4 sized paper.  Print it full size for
  the design in mm to match mm on paper exactly.  This can be
  done using Word, for instance.  You may have to disable aspect
  ratio and remove margins, depending on your program and printer.
  A test page is printed with a 100x100 mm square.
- The origin in the plot is chosen at the top of the butt of the
  bottom board of the platform.  This is different from the design
  document where the origin is at the cone apex; it was done to have
  a physical reference for building as opposed to a virtual origin.

GEE VS VNS:
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- For higher latitudes, a pivot can be used.  This is easier to
  make than a South Gee design.
- The VNS sectors are assumed to be infinitely thin.  Do not make
  the VNS sectors of thick wooden panels as it will cause slippage
  regardless of the design.
- The Gee design will have no slippage regardless of how thick the
  sectors are.  However, the mechanical motor control is harder.
  Gee sectors work best for lower latitudes.
- The Gee sectors have a backing of an empty frame of which the
  top is aligned with the bearing contacts along the RA axis.
  This makes it easy to implement the backing with bearings and
  separator.
- When using VNS sectors North and South you need to implement
  a way to keep the platform from slipping / shifting in the
  N/S direction.  The only exact proper way is to add a pivot 
  but that defeats the purpose.  Any alternative type of constraint 
  will cause a small error.
- The console prints an error estimate due to the usage of a VNS
  North sector (and Gee or a pivot, South) when driving the sectors
  with a constant motor speed.  The errors appear small enough
  to ignore.  They will be zero when driving the sector at an
  appropriate speed, but it does not seem worth the trouble.

HINTS AND TIPS:
---------------
- Unlike other design programs, the cone apex is not necessarily
  aligned with the horizontal plane through the bottom bearings.
  This extra degree of freedom makes it possible to raise the
  cone axis and to accommodate the Dob center of mass more easily.
  It can also make it easier to use a South pivot.
- By setting the top sector margin to zero the top of the sector
  becomes aligned with the top of the bottom board.  This reduces
  the height of the platform if that is desired.
- By setting the bottom margin to zero, the bottom of the sectors
  will be aligned to zero in the extreme positions.  This too will 
  help reduce the height of the platform. The bottom board will need
  to have a cutout that may contain a stop.
- When striving for a platform with a minimal height, there is
  often no space for placing the motor on the inside, and an
  inconvenient extension has to be added for the motor.
- When using a small low-powered motor make sure that the center 
  of mass of both the top board and the Dob is as close as possible
  to the cone axis.  Adding or removing accessories near the
  focuser (camera, binoviewers, heavy eyepieces, Barlow) has a
  significant effect on the center of mass.
- The Dob is represented by a circular board, 3 feet and a hole in 
  the middle.  When using the displayed T / crossbow design, it is
  clear where to put the Dob without having to drill holes for
  the feet.  For closed tops, holes will need to be made.  The
  6 most likely places are displayed in the GUI.
- The Sim resolution can be used to increase the resolution and
  slow the simulation down, along with the Sim delay.  If the
  Sim resolution is set to 1, the console will display the errors
  of the sectors touching the bearing lines.  This validation is
  done using the graphics representation, which is more or less
  independent of the design.
- The GUI is primitive but adequate and effective.  There are
  no plans for updating it.

VALIDATION:
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- A script vnsCal.sce is included to measure the cone axis angle
  and North Gee disc radius of the finished product.  Check the
  script and the document to see how to set up the test and how
  to run the script.
