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The Christmas Bell
by Walt Heitland
GemCad Ray Traces for RI = 1.76
Random Model Cosine Model ISO Model
GemCad Ray Traces for RI = 2.15
Random Model Cosine Model ISO Model
The Christmas Bell
Designed by Walt Heitland - November 2001 wrheitland@shaw.ca
Merry Christmas!
Angles for R.I. = 1.76 and up 27 facets + 9 facets on girdle = 36
1-fold, mirror-image symmetry 80 index
L/W = 1.407 T/W = 0.631 T/L = 0.448 P/W = 0.491 C/W = 0.156 H/W = (P+C)/W+0.02 = 0.668 P/H = 0.736 C/H = 0.234
Vol./W^3 = 0.252 Brightness at 0° tilt for RI = 1.76 COS = 59.2 ISO = 74.6
Brightness at 0° tilt for RI = 2.15 COS = 55.6 ISO = 74.8
Pavilion
g1 90.00 13-67 Preformed
g2 90.00 35-45 Preformed
g3 90.00 38-42 Preformed
g4 90.00 06-74 Preformed
g5 90.00 80 Preformed
1 50.68 38-42 Match g3, establish lower girdle line
2 50.20 35-45 Meet g2.g3.1
3 49.08 13-67 Meet g1.g2.2
4 45.00 06-74 Meet g4.g1.3
5 45.02 80 Meet g5.g4.4
6 44.83 39-41 Meet 3.4.4.3, 3.2.1, 1.g3.g3.1
Crown
a 48.11 38-42 Match g3, establish upper girdle line
b 44.84 35-45 Meet g2.g3.a
c 31.38 13-67 Meet g1.g2.b
d 37.14 06-74 Meet g4.g1.c
e 41.89 80 Meet g5.g4.d
f 24.26 13-67 Meet d.e.d, a.b.c
g 20.00 13-67 Meet f.d.e
h 29.00 13-67 Step cut - make c,h,f equal width
t 0.00 Table Make width of g = c,h,f

Christmas Bell Preform
1 25.00 10-30-50-70 Make TCP
2 30.43 13-67 Meet TCP
3 37.42 35-45 Meet TCP
4 45.48 38-42 Meet TCP
5 25.04 06-74 Meet TCP
6 23.96 80 Meet TCP
g1 90.00 13-67 Match 2, set size
g2 90.00 35-45 Meet g1.2.3
g3 90.00 38-42 Meet g2.3.4
g4 90.00 06-74 Meet g1.2.5
g5 90.00 80 Meet g4.5.6
Note that the rough is offset on the dop rather than centered like you would for cutting a round. The "1" facets establishing the TCP will be cut away by subsequent facets. Be sure not to cut into the TCP - put a small dab of permanent ink on the exact point to make a more visible target.

The Christmas Bell Design File and Christmas Bell Preform Design File are available for GemCad users.

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