Bell Casting
Bell casting 5" tall and 6" wide with ringer.
Flask- 10"x 10" inside dimensions.
Cope and drag mate up with a pin and hole. A nail without a head makes a good pin. See "flask making page" for more info.
Flask height- 7" cope (top), 1.5" drag (bottom). The casting will be in the cope, the cope should be at least 1" taller than the casting.
Dust with parting to keep pattern from sticking.
Completely cover the pattern with sand using the fine riddle (sieve).
Fill the rest of the flask with a coarse riddle. If you do not have a coarse riddle, make sure lumps have been broken up and fluffed.
Use the paddle rammer to tuck the edges.
Use the peen side of the rammer to tuck around base of bell first, then evenly ram the rest.
Ram east to west and then north to south. Ram soft around the bell and then get progressively harder with each step.
Fill cope about 2-3" over the top, ram hard with peen side of rammer, east to west and then in a north to south pattern.
Use butt side of rammer last.
Strike off mold leaving a few handfuls of sand to cushion the bottom board.
Place bottom board on and FLIP mold.
After flipping....
Remove 1.5" drag section and pattern board.
Cut down to the parting line on the ringer using your spoon.
Smooth around ringer with your spoon.
Make a slight dent in the sand with 3/4" hole maker, this marks the "sprue" (where you pour metal into the mold).
Replace drag section of flask, apply parting dust to separate the cope from the drag.
Fill inside of the bell with sand from coarse riddle. Ram lightly with the handle side of rammer or dowel.
Fill drag section about 2" taller than drag with sand. Ram edges with a paddle rammer, then using the peen side of your rammer make an east to west pattern. Again with the peen side go north to south, finish with the butt side of the rammer.
Strike off mold with a straight edge (1X1X12" stick). Leave small amount of sand on top to cushion the mold, about 2 handfuls.
Place another bottom board on the top and FLIP! Clamps make this easier.
After flipping the 7"cope section is on top and the shorter drag section is on the bottom.
Smooth cope with trowel.
Remove cope and set on its side. Note the sprue location on the cope and drag.
Cope before cutting sprue and pop-up.
Form sprue with a 3/4"pipe sharpened on the end.
Form pop-up with a sharpened 1/4" dowel, about 2" from casting over the runner. Place your hand on the opposite side of the cope while cutting to reduce damage. The sand is drying during molding, DO NOT DILLY-DALLY! There is about 15-20 minutes of molding time before it starts to dry too much to work with. Sand starts to not stick.
Clean and round edges of holes to prevent erosion of outside corners. Make another 1/4 hole on top of the bell from this side of mold. Personalizing your bell can be done at this stage by lightly pressing shapes into the sand or carving. Remember, the mold must not have any loose sand. Gently blow loose sand out and pack tight with your finger. Do not rub with your finger, push in and come straight out.
Cut and smooth a small cup at the sprue hole. Clean up other holes by pressing with finger and reinserting 1/4" dowel.
Cut and smooth a small gate from the bell to the runner. 1/4" deep, 2" wide and 2" long.
Drag section.
Cut runner bar from the sprue mark past the bell, stay at least 1" away from the edge of the mold and 1" from the bell. Make runner at least 3/4" thick and 3/4" wide, any less will allow the metal to cool prematurely.
Smooth runner with spoon, erosion will eat away at any rough spots.
Cut a gate from the runner to the bell about 1/4" deep and 2" wide. Cut a gate from the runner to the ringer about as deep and wide as your finger. Smooth both gates!
Rap bell lightly with a wood object to loosen from sand.
Use a small torch to remove any excess moisture from the mold or allow to sit overnight. Molds can sit for weeks before they are poured!
Replace the cope and move to pouring area
Mold after pouring. Due to the large size of the cope, no clamps are needed with this mold. When pouring a bronze bell all the steps are the same.
Mold after shake-out.
The first time we poured this mold, it did not come out so well. Everyone must follow the rules, even me. The pattern used was not quite 1/8" thick (3/16" or more is best), I thought a stiff rap on the pattern before removing would thicken the casting. It thickened the top section OK, but not the vertical sides.
To thicken our bell we will carve the inside, this will leave the outside of our bell mold untouched.
Start by dividing the bell into 4 sections by lightly dragging your spoon.
Carve about 1/8" to 1/4" deep.
After carving our mold is left very rough.
Smooth all rough areas with a spoon, quickly, the sand in your mold drying fast!
After smoothing. It does not need to be pretty, as it is the inside of the bell.
Pouring is the easy part!
Ding-Dong Dude!
The idea is that the bells serve as a sort
of diploma. Only a graduating
senior makes them. They cast only two identical bells, one for the school
which stays with us and one for them after which the "mold" is destroyed.
So.. just enough stuff to make two at a time. There is a rather emotional
and elaborate ceremony that goes with it. The entire concept of fire and
metal is morphed into a metaphor of their lives up to this point. The use
of Bronze is also significant in that it is ancient as well as nearly and
perfectly indestructible. Part of the ceremony talks about how these two
bells will last nearly forever. That thousands of years from now time and
nature will erase every trace that they ever were, all except these two
bells. An idea that a relative 100 generations distant may find one and in
holding it, in nearly the same condition as it was the day it was made,
wonder who and why it was made and in doing so; keeps the spirit of the
maker immortal. A bit dramatic I know but special none the less.
By Bill Knopf ......7-14-05