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alter   Enter OLD ANGLE List and %Z
this       OLD REFERENCE ANGLE =          42
column   Reference Angle Increment =      1
           FACET         OLD                          NEW ANGLES
      0      ID        ANGLE       35.0        36.0     37.0    38.0   39.0   40.0   41.0   42.0   43.0
      Reserve A45:Z200 for extraction of data from GemCad ASC File.
G     emCad 4.51                             G
a     -90.00000 0.90933 0 n G1 80 64 48 32 16 G Cut to equal depth - establish size.
a     -44.41141 0.73480 88 n P1 72 56 40 24 8 G Cut to Common Center Point, sets girdle.
a     -67.52169 0.84024 0 n P2 80 64 48 32 16 G Meet G1-G1-P1 at girdle.
a     -46.55234 0.75578 6 90 n P3 86 74 70 58 54 42 38 26 22 10 G Meet at the same point.
a     -43.00000 0.75230 91 n P4 5 11 21 27 37 43 53 59 69 75 85 G Meet P2-P3-P3.
a     52.12925 0.73870 0 n C1 16 32 48 64 80 G Set 2%W girdle thickness.
a     42.00000 0.67438 94 2 n C2 14 18 30 34 46 50 62 66 78 82 G Meet G1-G1-C1 at the girdle.
a     33.36383 0.60462 87 9 7 25 23 41 39 57 55 73 71 89 n C3 G Meet at the same point.
a     31.27157 0.58520 8 n C4 24 40 56 72 88 G Meet C2-C2-C3-C3.
a     0.00000 0.36516 0 n T G G Meet at the same point.

                   0 T           G         G          Meet

                OLD ANGLE LIST
           PAVILION           CROWN
44.0   Facet ID  Angle   Facet ID Angle

        Derivation of the Tangent Ratio formula can be found in :
                                          Facet Design
                                        Volume 1; Ovals
                                        by Long & Steele
                                      pages D-13 & D-14

        The objective of the tangent ratio procedure is to change facet slopes
        while preserving plan view geometry.

        Their Formula is: TAN(Bnew) = TAN(Mnew)*[TAN(B)/TAN(M)]
        with different notation this becomes NA= Atan(TANRAT*Tan(OA))

        where TANRAT = Tan(NRA) / TAN(ORA)
          NRA = New Reference Angle = Mnew       They are entered in ROW 6.
          ORA = Old reference Angle = M          This is entered in D3 via Dialog Box.
          OA = Old Angle to be changed = B       These are entered in COLUMN C.
          NA = New Angle = Bnew                  These are the Table D7:M38

        For example the crown MAINS of a design might have an angle of 42.00 and
           you want them to be set to 30.00 degrees. ORA = 42.00 and NRA = 30.00
           Then if the STAR facets are at 24.88 degrees = OA, NA = 16.56 degrees.

        Note that TANRAT can also be applied to the pavilion depth and crown height
          to obtain new heights and depths scaled to each new angle.

        In general, the Old Reference Angle should be one of the existing facet angles.
           but some other angle could be used. That may make the results more
           difficult to understand.

        The objective of this spreadsheet is to create a table of new crown or
          pavilion angles for 10 new reference angles each time the macro is run.
          The user has the option to print the entire table or any portion of it using
          the standard EXCEL tools or all or any portion of the table may be exported
          to another Windows application using the clipboard.

        SAVE does not preserve your results.

        An increment of 0.5 degrees for the New Reference Angle usually provides
          enough detail for the pavilion and 1.0 degree is good enough for the crown.
          Alternate increments may be chosen from the Tangent Ratio dialog box.
          The list in the dialog box can be changed in the macros.

        The Old Angle List may be typed directly into the Angle Translation Table or
          into the OLD ANGLE LISTS located at cell R1. The angle data may be taken
          from a text file using a word processor's editing tools to create new file
          containing only the Facet ID and Angle data. Data from spread sheets
          are simply transferred using the Windows Clipboard.
        If the GemCad ASC file is used the program automatically extracts the data
           for you when the GET DATA button is clicked. To transfer the data click
           either the Paste Crown or Paste Pavilion button. The crown and pavilion
           must be processed separately.

        The program does NOT extract Crown Height or Pavilion Depth. Get them from
          the GemCad .GEM file and enter manually into the tables.

Step 1 To begin the Tangent Ratio process click the GET DATA button; an options
       dialog box appears.

Step 2 Select one of the data sources available. [Click a DOT]
          A. GemCad ASC File When selected you will be asked for a GemCad
                filename. Do not use a file extension, the .ASC is assumed. The
                file need not be in the same directory as this program.
              The Facet ID and Angle lists for the Crown and Pavilion are
                 extracted separately. Optional Editing should be done at this
                 point. Rename facets for instance. If the P/W and C/W values
                 are added, skip a line after the last angle. There should be some
                 ID entry for each angle, even if only a comma. There should be
                 no blank cell in the ID data except before the P/W or C/W entry.
             The resulting Facet ID and Angle list for the Crown or Pavilion can
                 now be pasted to the Angle Translation Table using the Paste
                 buttons. The screen shifts to the Angle Translation Table.
             Click the Tan Ratio button. A dialog box appears showing the last
                 used Old Reference Angle and New Angle increment. Change if
                 needed. Enter the starting value of the New Reference Angle to
                 be calculated. Click the OK button to fill in the table. Cancel if
              Now paste the other list if it is needed and press Tan Ratio and
                 proceed as above.

           B. SPREAD SHEET an EXCEL or other spreadsheet data may be copied
               to the clipboard and pasted into the crown or pavilion lists. This is
               not an automated and will often require some fiddling about to get
               it right.

           C. Text files or specially formatted word processor files may also be used
                but will definitely require a lot of editing. It will usually be easier to
                punch the design into GemCad and save it in the .ASC format.

            D   Manual entry directly into TANRATER should be done only when the
                  data is known to be correct.

Step 3 Optional; edit Facet ID and Angle entries if needed.

Step 4 Optional; skip one line to append the P/W and C/W values.

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