Bob's Rock Shop: The Christmas Bell

The Christmas Bell

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.

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

Index of Gem Designs

Perfect Transfer Index

Table of Contents

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

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.