FINAL REPORT - REDESIGN OF CLAM

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03639A001300110002-7
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 7
• Document Creation Date: December 22, 2016
• Document Release Date: September 20, 2011
• Sequence Number: 2
• Publication Date: June 14, 1957
• Content Type: REPORT

Sanitized Copy Approved for Release 2011/09/20: CIA-RDP78-03639A001300110002-7
L;:NIIAL
June 1L, 1957
F -I
F I N A L R E P O R T
REDESIGN OF CLAM
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,UCUT- CONFIDENTIAL
FINAL REPORT
REDESIGN OF CLAM
Since the present Clam was designed to be used with the Mark II Time
Pencil, which never became available, it became necessary to develop a
unit which could accommodate the Mark I Time Pencil.
In the process of redesigning the Clam, it seemed advisable to inves-
tigate other features which would improve the over-all functionability of
the Clam. These improvements primarily consisted of improved plastics of
higher tensile and impact strengths and flexible mounting brackets for the
magnets in order to absorb shock better as well as increase the magnets'
holding power on irregular surfaces.
Design studies were made on the "closure" to determine the feasibility
of including the delay pencils adjacent to the body. This was accomplished,
however, by incorporating a cavity in the body of the unit to permit the
pencil to be snapped in place rather than in the cover as originally planned.
The igniting flame from the pencil to the detonator could then be guided
through tubes provided or molded-in during the manufacture of the unit.
In addition to the above investigations, studies were made to simplify
the manufacture and assembly of the Clam.
The initial phases of the work involved design changes which would
facilitate volume production. Two separate approaches were considered
practical, and temporary molds were fabricated to produce prototypes for
evaluation. Polyvinyl chloride resins were selected to make up the first
prototypes for the purpose of obtaining dimensions and establishing the
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feasibility of the proposed design. Polyethylene containers were also
procured for evaluation in high and low temperature tests. The informa-
tion gained from these tests aided in the final structural design of the
Clam.
The first design featured a copper tube which was imbedded in the
plastic case. This tube provided a channel for the igniting flame pro-
duced by the delay pencil. The flame was then transmitted through the
tube to the detonator.
Consultations with various molders indicated that the channel used
for the igniting flame could be molded directly into the plastic during
manufacture, thus eliminating the need for the copper tube.
The proposed igniting channels, from the delay pencils to the detona-
tor, were formed between two pieces of polyethylene sheet stock providing
a half channel in each of the two halves. The two pre-formed halves were
then cemented together, thus providing a channel similar to the channel
formed by the copper tube. Several prototypes weremade, and test firings
proved very satisfactory. This feature is provided in the final design.
The next step in the redesign of the Clam consisted of an investiga-
tion of the maximum allowable wall thickness for the detonator well in
order to insure proper and reliable initiation of the explosive. This was
accomplished by fabricating several units having various thickness of poly-
ethylene sheets between the detonator and the explosive. In order to estab-
lish maximum reliability limits, a number of polyethylene sheets, stretch-
formed from stock of 1/32", 1/16", 3/32" and 1/8" thicknesses were cemented
into polyvinylchloride prototypes for evaluation. Twelve units were
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fabricated and test fired without failure on either of the 3/320 or 1/8"
wall thicknesses. It was concluded from these results that further inves-
tigations were unnecessary since a sufficient margin of safety was obtained.
Further investigations resulted in a new mounting bracket design for
the magnets which would give greater rigidity to the partition separating
the payload and magnet cavities, and thereby eliminatedbinding of the mag-
nets when the payload compartment is filled with explosive. Several pro-
totypes were tested utilizing these modifications with success.
The second phase of the work involved an objective analysis of the
Clam with respect to moldability and performance. Consultations with quali-
fied injection molders resulted in a few changes to the design as it now
stood. One of the changes involved a detonator adaptor, so that if the
detonator size was ever changed, it would affect only the adaptor mold
rather than the box mold. Another change involved the payload compartment
closure. This change improved the moldability characteristics of the unit
with no sacrifice to its functional use.
A prototype of the detonator adaptor was made and tested for leaks.
One end of the adaptor was inserted in a detonator and the other end in a
3/16" diameter hole (simulating the detonator hole in the box). The unit
was then submerged in 12 inches of water for 12 hours with no leakage of
water noted.
After all of the Clam parts were finalized, drawings and specifications
were submitted to the Engineering Department oo
for dimensional and molding verifications. One or two minor changes were
suggested and the drawings were changed accordingly.
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Several custom molders were contacted and their recommendations were
included on the semi-final drawings. The
was awarded the contract for the fabrication of molds and
1,000 complete Clam units.
awarded the contract for the fabrication of 4,000 Alnico III-B magnets
for insertion into the finished Clam.
A prototype of the coil spring, used in the Clam assembly, was made
and tested. The results proved satisfactory; however, it was felt that
the pre-load of the spring should be increased by 25 per cent. This was
accomplished by decreasing the coil diameter from 13/32" to 5/16" using
the same 0.054" diameter wire. This spring was tested and passed all the
required specifications.
The bracket which contains the spring when assembled was modified so
that the pin originally used in the spring and bracket assembly was elimi-
nated. This resulted in a much simpler assembly. Th~
was contracted to furnish this simplified bracket
assembly.
The first production samples were received and a thorough inspection
was made. This inspection revealed that several modifications to the mold
were necessary. These modifications were as follows:
1. The wall thickness of the box around the center cavity was
increased to insure a better seal between the box and cover.
2. The outside edges were modified to provide a 1/8" radius to
provide easier concealment and handling.
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3, The outside surfaces of the box were sandblasted to lessen its
reflective qualities.
4. A portion of the box edge was removed to permit easy removal
of the time pencil's safety pin.
The two outside 3/16" diameter holes were increased to facili-
tate assembly of the time pencils.
6. All flash marks were removed at sealing points.
7. The adaptor was modified to facilitate its assembly to the
box and the detonator.
8. The magnet coating mold was modified to improve mold safety
aspect and decrease the molding time required.
Samples incorporating the above modifications were submitted and in-
spected. The seal between the box and cover was found to be watertight, a
feature not expected initially.
The final phase of the program involved various assembly and packaging
methods. Various methods of sealing, i.e., cementing, hot gas welding, and
direct heat sealing, were investigated with the latter proving to be the
best from the standpoint of sealing, appearance and time consumed. The
direct sealing method was used to seal both the insert and the magnet
bracket in place. A regular 300 watt soldering iron, modified to include
a flat aluminum tip, in place of the regular tip, was used.
The following is the procedure recommended for the assembly of the
insert, brackets and magnets:
1. Assembly of the Insert
Wipe silicone grease across exposed insert end and areas of the
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box to be sealed (silicone prevents the gumming up of the soldering
iron tip). Wipe soldering iron tip across insert and end of box.
This provides a watertight seal between the box and cover.
2. Assembly of the Brackets
Assemble brackets in box at each end. Dip soldering iron into
silicone and melt down the 3/l60 diameter boa pins. (Soldering
iron should be dipped in silicone prior to melting each set of
pins.) The melting of the pins seals the brackets into the box.
3. Assembly of the Magnets
Assemble the magnets to the torsion spring in such a way that the
magnets are not positioned alike in respect to the north-south
pole faces, rather, they should be assembled as shown in Drawing I.
Snap the magnets into the already sealed-in bracket assembly. This
can be accomplished by pulling the two tongues of the bracket to-
gether with a pair of needle-nose pliers. This secures the spring
and magnet to the bracket.
Five units containing delay pencils, non-electric Corps of Engineers
blasting caps and Composition C-b explosive were test fired in order to
obtain information as to their reliability and functionability. All units
functioned properly; however, many more test firings are required to properly
evaluate each feature of the Redesigned Clan.
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