Bola Spider by Bob Keller

This design borrows heavily in concept from Greg Glenn's Window Spydey design. When I saw Greg's novel spider gemstone design I concluded that a spider stone bola for myself was a webmaster must-have, and this variation of Greg's design evolved as I did some preliminary checking out and playing around with it in GemCad. The spider on this version is a little less work to cut as it employs 2-fold, mirror image symmetry for the legs and fewer facets to make the body. I'm going to cut my Bola Spider from clear quartz and mount it in a silver bola "shadow box" constructed to shadow the pavilion. I'll polish only the spider leg, body and pincer facets on the stone's pavilion, leaving all the other pavilion facets (a,c,d,e) frosted.

The pavilion facets are all cut well under the critical angle for quartz. The idea being to create a black spider standing out in high contrast as the viewer looks through the large table and windowed pavilion facets creating the spider silhouette on the frosted facets forming the background. The girdle and crown side facets will all be polished. If you cut one of these for yourself you can get as nit picky as you want on the crown side step facets that make the spider's web, but don't sweat the small stuff if your steps don't come out exactly equal width or don't meet up perfectly. If you've ever looked at a spider's web closely, you'll see it isn't perfect either, but it gets the job of catching flies done just fine...

I'm thinking in the 50 mm range for this one, and the only part about cutting this design I'm not looking forward to is polishing that humongous table. However, the results should be interesting and will hopefully yield a bola that will be the envy of every fellow webmaster and CGI programmer in the Tucson Computer Society... ;)

Bola Spider

Bola Spider by Bob Keller March 2001
Angles for R.I. = 1.54176 facets + 16 facets on girdle = 192
1-fold, mirror-image symmetry96 index
L/W = 1.000 T/W = 0.756 T/L = 0.756 P/W = 0.242 C/W = 0.089H/W = (P+C)/W+0.02 = 0.351 P/H = 0.690 C/H = 0.253
Vol./W^3 = 0.140 

Pavilion
a33.00°03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93Cut to centerpoint
b90.00°03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93Match a, establish level girdle and size
c29.40°06-12-18-24-30-36-42-48-54-60-66-72-78-84-90Cut to centerpoint, leave desired border outside spider for web (crown steps) - Do not cut a 'c' facet at index 96!
d25.94°03*-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93*Meet ac - cut to centerpoint
e22.61°96*-06*-12-18-24-30-36-42-48-54-60-66-72-78-84-90*Meet c.d - cut to centerpoint
f31.27°08-40-56-88Meet a.c - make 4 innermost leg tips
g28.00°11-37-59-85Meet a.c.f - make 4 innermost leg outer mid sections
h24.59°14-34-62-82Meet c.d.g - make 4 innermost leg inner mid sections
i22.14°15-33-63-81Meet d.e.h - make 4 innermost leg body sections
j31.23°14-34-62-82Meet a.c - make 4 outermost leg tips
k28.00°17-31-65-79Meet a.c.j - make 4 outermost leg outer mid sections
l24.68°20-28-68-76Meet c.d.k - make 4 outermost leg inner mid sections
m22.16°21-27-69-75Meet d.e.l - make 4 outermost leg body sections
n13.00°48Meet m.e.m - make head
o21.00°44-52Meet d.e - make pincers
p24.68°02-94Meet e.i - make abdomen
Note: Facets marked * are subsequently cut away by the p facets forming the spider's abdomen.
Crown
q48.00°03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93Step cut - match girdle facets, level girdle
r42.00°03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93Step cut - match q facets
s36.00°03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93Step cut - match r facets
t30.00°03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93Step cut - match s facets
u24.00°03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93Step cut - match t facets
v0.00°Table 

Download PDF format printer friendly cutting instructions: [ Download Icon Bola Spider Printer Icon ]

Download the GemCad format design file: [ Download Icon bola_spider.gem ]

If you cut a Bola Spider of your own be sure and let me know what you cut and how you made out.

Shown at left is a Bola Spider cut by faceter Bob Collins. Bob cut this 18mm stone from pale blue synthetic quartz.

Bob reported "In order to provide maximum contrast to the spider silhouette I cut a thin circular piece of black onyx and had that mounted in the bottom of the pendant basket mount. The 'Spider' was then mounted above it in the usual manner. There was plenty of room to do this because the stone is cut very shallow by design. This worked out great as the spider silhouette stands out boldly as solid black when viewed through the table."


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