Post by Alan Yates
I've never had any problems drilling the nozzle or core of rockets.
Post by Don T
Drilling a core, even by hand, is "not good". I hope you are drilling just
until you touch powder. Lots of folks have tried drilling a core and the
result is, more often than not, a salute on a stick. What happens is one of
a couple of things, either there is more core exposure of powder than can be
ignited and the gas pass through the orifice or the grain itself cracks with
the same result.
As far as shipping to your friend goes, FEDEX or UPS is worth a try. They
ship things like that regularly. But they won't get there by Valentine Day.
I've always preferred to ram or press rocket motors on a spindle
rather than solid filling and drilling out a nozzle and or core. For
those beginning to make skyrockets here's an easy tool to make 1-oz.
(3/8" bore rockets). This info came from M.P. Vander Horck's
"PYRONEWS" from 1967 I believe, and was based upon info supplied by
Bill Withrow to Van. The principle is the same for large display
rockets as well. Buy a 3/8" hardwood dowel, a 16d iron nail(sinker
type) and a roll of 3" gummed kraft paper tape (water activated).
Fuel is hand sifted 5/ 1.5/ 1 Potassium Nitrate/ Airfloat
charcoal/Sulfur dust. Clay is plain old Bentonite. Cut off a 5"
length of the dowel for use as a case former and rub it with wax to
prevent glue sticking to it. Cut a 4" length, a 2" length and a 7/8"
length from the same dowel. Carefully and as accurately as possible
drill a 5/32" hole in dead center of one end of the 4" length of
dowel. Drill it abou 2-1/2" deep. Take the 7/8" length of dowel and
drill a 1/8" hole clear through the long way dead center as well.
Slide the 16 penny nail through the 7/8" bored "nipple" and epoxy glue
it with the nail head flush against one end of the nipple. when dry,
cut the nail w/ hacksaw so that 2" projects beyond the nipple. Smooth
the cut with a file or sharpening stone. Take a scrap piece of 2x4
lumber (say 3-1/2" x 3-1/2") as a spindle base and drill a 3/8" hole
5/8" deep in dead center. Epoxy the spindle nipple into this base and
dry. Tear off a 10" length of the gummed paper tape and roll a motor
case (3" long x 3/8" I.D.)on the 5" case former, moistening the glue
and keeping the ends nice and flush. Roll the cases (still on the
former) back and forth between your hand and the table, using heavy
pressure to tighten them. Slip a dried case over the spindle assembly
and add a bit less than 1/4 teaspoon of clay. Slip the hollow 4"
rammer (drift) in the tube and over the spindle and with a one pound
mallet give it 6 or 7 moderate blows, consolidating the clay nozzle.
Withdraw the drift and add 1/4 tsp. fuel. Ram again and repeat until
the fuel reaches the top of the nail (spindle). Switch to the 2"
solid drift and ram until you have 3/8" to 1/2" solid fuel above the
spindle. Ram in another increment of clay as a bulkhead and carefully
twis the finished motor off the spindle assembly. Tape on a light
1/8" stick about 15" long, fuse w/ black match or visco and it should
reach 250' depending on fuel ratio. For a starburst, drill a vent
through the clay bulkhead using a 3/32" drill bit twisted with your
fingers, or else eliminate the clay bulkead entirely. Roll a small
Head out of light paper and add stars and burst. Two tips: after each
increment of clay or fuel is rammed in place, give the spindle a half
turn by holding the motor case and turning the base with the other
hand. This helps keep the spindle centered and keeps it freed up for
later removal. Keep the spindle waxed (rub w/ candle after every 5
motors or so to prevent rust. Wood may be varnished w/ poyurethane.
Also, make another shorter spindle (5/8" projecting beyond nipple) to
use for gerbes and wheel pushers. The three inch gummed paper tape is
perfect for learning case rolling; make spollettes, 1/2" bore
helicopter casings etc. Above all, read, learn and BE SAFE!! The old
timers know what an exciting, challenging and rewarding hobby this is.
Please don't add to the myriad problems we already have by doing
something stupid. JR