SUMMARY REPORT ON RESEARCH ORDER NO. 30

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03645A000200030001-2
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 43
• Document Creation Date: December 22, 2016
• Document Release Date: May 25, 2011
• Sequence Number: 1
• Publication Date: January 31, 1957
• Content Type: REPORT

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March 19, 1957
Enclosed is the Summary Report on Research Order No. 30,
which describes the activity under this Research Order from March 8,
1956, through January 31, 1957.
As a result of this activity and in accord with recent dis-
cussions, we sent you a proposal, dated January 22, 1957, covering the
further evaluation of 3/16-inch-diameter diamond drills and the prepa-
ration of another Type 2 Prototype Drilling Kit. This effort is cur-
rently being implemented under Work Order No. XI, Task Order No. A.
Another proposal, concerned with the preparation of 10 Type 2 Proto-
type Drilling Kits, specifications, drawings, and an operator's manual,
is being written and will be transmitted to you in the near future.
We would appreciate any comments that you or your associates
might care to make with regard to the effort under Research Order No. 30.
Sincerely,
ABW:dp
Enclosure
In Triplicate
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SUMMARY REPORT
ON
RESEARCH ORDER NO. 30
January 31, 1957
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TABLE OF CONTENTS
Page
INTRODUCTION . . . . . . . . . 1
DETAILED SUMMARY . . . . . . . . . . . . . . . . . . . . . . . 2
ENGINEERING ACTIVITY . . . . . . . . . . . . . . . . . . . . . 5
The Evaluation of 5/16-Inch-Diameter Diamond Drills . . . 6
Procurement of Drills . . . . . . . . . . . . . . . 6
Test Equipment . . . . . . . . . . . . . . . . . . . 6
Test Procedure . . . . . . . . . . . . . . . . . . . 13
Test Results . . . . . . . . . . . . . . . . . . . . 14
Drilling Rates in Other Materials . . . . . . . . . 17
Development of a Lightweight Drilling Unit . . . . . . . 18
Selection of the Electric Motor . . . . . . . . . . 18
Tests With the Electric Motor . . . . . . . . . . . 19
Design of the Lightweight Drilling Unit . . . . . . 20
Lightweight Drilling Head . . . . . . . . . . . 22
Power-Supply Unit . . . . . . . . . . . . . . . 22
The Dust and Water Collector . . . . . . . . . . . . . . 25
Lightweight Drilling Kit . . . . . . . . . . . . . . . . 30
Cursory Evaluation of 3/16-Inch-Diameter Diamond Drills . 33
FUTURE WORK . . . . . . . . . . . . . . . . . . . . . . . . . 35
APPENDIX I ... . . . . . . . . . . . . . . . . . . . . . . . . 36
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LIST OF FIGURES
Page
Figure
1.
Figure
2,
Figure
3.
Figure
4.
Figure
5.
Figure
6.
Figure
7.
Figure
8.
Figure
9.
5/16-Inch-Diameter Diamond Drills Tested . . . .
Drilling Test Equipment . . . . . . . . . . . .
Schematic Drawing of Equipment for Measuring the
Power Input to the Test Drills . . . . . . . . .
Equipment for Measuring the Power Input to the
Test Drills . . . . . . . . . . . . . . . . . .
Drilling Rates and Axial Loads With 1/10-
Horsepower Input . . . . . . . . . . . . . . . .
Drilling Rates and Axial Loads With 1/5-
Horsepower Input . . . . . . . . . . . . . . . .
Experimental Hand-Held Drilling Unit . . . . . .
The Lightweight Drilling Unit . . . . . . . . .
Circuit Diagram of the Full-Wave Bridge
Rectifying Unit . . . . . . . . . . . . . . . .
. . .
7
. . .
9
. . .
11
. . .
12
. . .
15
. . .
16
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21
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23
. . .
24
. . .
26
. . .
27
. . .
28
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29
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31
. . .
32
Figure 10. Water-Collector Design No. 1,, Disassembled . . .
Figure 11. Water-Collector Design No. 2. Disassembled . . .
Figure 12. Front View of Water-Collector Design No. 3 . . .
Figure 13. Rear View of Water-Collector Design No. 3 . . .
Figure 14. Dust and Water Collector Incorporating a
Grease Chamber . . . . . . . . . . . . . . . . .
Figure 15. The Type 2 Prototype Drilling Kit . . . . . . .
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LIST OF TABLES
Page
Table 1. Manufacturing Companies and Types of Test Drills . . .
8
Table 2. Drilling Rates at 1/10 Horsepower for 5/16"-
Diameter Drills . . . . . . . . . . . . . . . . . . .
17
Table 3. Drilling Rates With 3/16-Inch-Diameter Diamond
Drills When Using the Type 2 Prototype Drilling Unit .
34
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SUMMARY REPORT
on
RESEARCH ORDER NO. 30
January 31, 1957
INTRODUCTION
This report describes the work performed under Research Order
No. 30 from March 8, 1956, through January 31, 1957.
The prime objective of the research program, as originally pro-
posed,, was to evaluate 5/16.inch-diameter diamond drills. The second ob-
jective was to prepare 10 experimental drilling kits for field testing by
the Sponsor; each would include: (1) a 50-cycle, 110 - 220-volt motor,
(2) a flexible shaft, (3) a drilling head, (4) collectors for dust and
water, (5) sets of diamond, and possibly carbide, drills for drilling
holes up to 30 inches in depth, (6) an axial loading device, (7) water
and air supply systems, and (8) a cheap carrying case. The third objec-
tive was to prepare drawings and specifications of the experimental drill-
ing kit and the drills, and an operator's manual covering the use of the
drilling kit.
As a result of discussions with the Sponsor, the original ob-
jectives were modified, by Supplement No. 1 dated September 28, 1956.
The second and third objectives of the proposed program were replaced
with two others. One of the new objectives was to conduct an investiga-
tion directed toward developing a prototype drilling unit equipped with
a lightweight, relatively quiet, electric motor integral with the drill-
ing head, to replace the separate electric motor and flexible-shaft drive
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of the prototype drilling unit developed under Research Order No. 21;
this included the design and development of suitable collecting devices
for dust and water. The other proposed objective was to conduct a study
of drilling with 1/8-inch-diameter diamond drills in granite, plaster,
concrete, brick, marble, and other mutually agreed upon materials.
This report presents a detailed description of the evaluation
of 5/16-inch-diameter diamond drills; the design, development, and evalu-
ation of a lightweight drilling unit; the design, development, and testing
of a suitable device for collecting dust and water; and the cursory evalu-
ation of 3/16-inch-diameter diamond drills. Diamond drills of 3/16-inch
rather than 1/8-inch diameter were evaluated because the smaller drills
could not be obtained commercially in practical configurations.
DETAILED SUMMARY
In order to evaluate 5/16-inch-diameter diamond drills, drill
manufacturing companies were contacted and representative drills were pur-
chased; suitable test equipment was designed and constructed; and the drills
were tested under predetermined conditions. Twenty-eight drill manufacturers
were contacted and 10 types of drills were received from 9 companies. It was
hoped that the test equipment that had been developed under Research Order
No. 21 would be satisfactory for the evaluation of the 5/16-inch-diameter
drills. However, even after some modification of the original equipment, it
was necessary to design and construct a special assembly to hold the material
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being drilled. With this assembly it was possible to measure the torque
that was imparted to the material from the drills by means of an arm in-
corporating a strain gage.
Tests were made to determine the drilling rate of the test drills
in marble at 1/10 and 1/5 horsepower for speeds of 1,000, 2,000, 3,000, and
4,000 rpm. Because of difficulties from plugging, overheating, or inade-
quate cooling and/or flushing, the drilling tests with five of the 10 drills
could not be completed. In tests with the five remaining drills, the fast-
est drilling rates were obtained with two core drills, and the third highest
drilling rate was obtained with a non-coring drill. It is recommended that
all three of these drills be field tested by the Sponsor, so as to ascertain
which are the best drills from the standpoint of the Sponsor's applications.
The non-coring drill should be the easiest to use, but the core drills
should provide a higher drilling rate.
The drilling rates for these three 5/16-inch-diameter diamond
drills were determined in plaster, brick, blue stone, marble, concrete, and
granite with a 1/10-horsepower input. The rates obtained varied from 1/2
inch per minute in granite and 2 inches per minute in concrete, to 50 inches
per minute in plaster.
The primary problem connected with the design of a lightweight
drilling unit was the selection of an electric motor which would fit into
a hand drill, provide sufficient power, and be relatively quiet. Electric-
motor manufacturing companies were contacted to determine the feasibility
of redesigning high-speed motors presently used in hand tools, in order to
obtain quieter operation. It was the opinion of these companies that the
noise of these units could not be materially reduced. A discussion of the
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problem was held with Robbins and Myers, Springfield, Ohio, and a 1/8-
horsepower, 2,500-rpm, shunt-wound d-c motor was selected as a unit that
would provide the best combination of power, low weight, and little noise.
Tests with this motor in our laboratory were satisfactory and a
lightweight drilling unit incorporating this motor was designed. This
unit consisted of a drilling head and a power supply. The drilling head
included the electric motors a lightweight housing, and a water swivel
for supplying water to the diamond drills. The power supply included the
necessary electrical cords and a rectifying unit to supply the motor with
direct current. The appearance of the lightweight drilling unit is very
similar to that of commercial 1/3-horsepower hand drills.
Several devices were designed and tested before a suitable unit
was found for collecting both dust and water. The satisfactory unit used
two rubber seals in contact with the drill shank to restrict the flushing
medium. A chamber between these seals contained grease, which lubricated
the drill shank. As the grease was used up, the grease chamber was reduced
in size by turning a threaded plug. The collector was designed to be held
against the wall by a plastic anchor such as the one developed under Research
Order No. 21.
A drilling kit was assembled from the units developed under Re.
search Order No. 30 and those which had been developed under Research Order
No. 21. The components of this kit, called the Type 2 Prototype Drilling
Kit, consist of a carrying bag, 20 feet of electrical connecting wire, a
rectifier, a drilling unit, a water-filled tank, a C02 cylinder, a dust and
water collector, the necessary tubing, and three 5/16-inch-diameter diamond
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drills. The entire kit weighs 15 pounds and has the appearance of an
overnight bag.
Subsequent to the development of the lightweight drilling kit,
3/16-inch-diameter diamond drills were purchased from one of the drill
manufacturing companies. The drills were fitted with 1/8-inch-diameter
shanks and drilling tests were made in brick, bluestone, concrete, marble,
and granite. At first it appeared that three 3/16-inch-diameter drills
would be necessary in order to drill a hole 30 inches deep; during drill-
ing, each drill would have a maximum unsupported shaft length of 10 inches.
However, it was possible to drill with an unsupported shaft length of 15
inches if the operator was careful during the first 3 or 4 inches of drill-
ing. Cursory tests with the 3/16-inch-diameter diamond drills were so suc-
cessful that we believe that the 5/16-inch-diameter diamond drills could be
replaced by the smaller drills for many of the Sponsor's applications.
ENGINEERING ACTIVITY
The engineering activity required to accomplish the objectives
of this project was divided into four phases. The first phase consisted
of the purchase of 5/16-inch-diameter diamond drills, the construction of
test equipment, and the evaluation of the purchased drills. The second
phase comprised the selection of a suitable motor for the lightweight drill-
ing unit, and the design and fabrication of a unit incorporating the motor.
The third phase was concerned with the design, development, and evaluation
of the dust and water collector, and the fourth phase, with a cursory eval-
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uation of the 3/16-inch-diameter diamond drills.
The Evaluation of 5/16-Inch-Diameter Diamond Drills
Procurement of Drills
In general, there are two types of 5/16-inch-diameter diamond
drills: the type which produces a core, and the non-coring type. Either
of these types can be made with surface-set diamonds or with a matrix im-
pregnated with diamond chips. Because each drill manufacturing company
has developed its own type of drill, it was not considered practical to
eliminate any particular drill on the basis of visual examination. There-
fore, two drills of each type were purchased from each company for evalu-
ation. Of the 28 drill manufacturers that were contacted (see Appendix I),
nine supplied drills; the rest of the companies were unable to furnish
drills, for various reasons. Figure 1 shows the drills which were received
and Table 1 lists the manufacturing companies and the types of drills.
Test &iuirment
The equipment shown in Figure 2 had been developed under Research
Order No. 21 for use in evaluating various sizes and types of drills. The
material to be drilled was contained in the barrel at the left, the drill
was loaded and driven from the table which was mounted on the two parallel
shafts, and the values of the different variables were indicated on the in-
struments mounted on the panel. The load on the drill was applied through
the drill table by an air cylinder, part of which can be seen below the
parallel shafts. The drill was driven by a variable-speed transmission
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Drill No.
TABLE to MANUFACTURING COMPANIES
AND TYPES CF TEST DRILLS
Wheel Trueing Tool Company
Surface-set non-coring drill
Anton Snit and Company
Impregnated core drill
Fish-Schurman
Impregnated core drill
Triangle Equipment Company
Impregnated core drill
Koebel Diamond Tool Company
Surface-set and impregnated
core drill
J. K. it & Sons
Surface-set core drill
Diamond Wheel and Instru-
Impregnated core drill
ment Company
Hoffman Brothers Drilling
Surface-set core drill
Company
Hoffman Brothers Drilling
Impregnated core drill
Company
F. F. Gilmore and Company
Surface-set non-coring drill
Ta
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N30728
Figure 2, trilling Test Equipment
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mounted on the table and the depth of drilling was measured on the steel
tape mounted below the drill table.
In order to make this equipment more sensitive, the original
parallel shafts were replaced with special hardened-steel shafting and
other related parts were re-machined to provide better alignment. A
gear box was used with the transmission to provide a speed range of 0 to
5,400 rpm and an aluminum platform was substituted for the steel plat-
form.
During subsequent conferences with the Sponsor concerning the
proposed use of the test equipment, it was decided that the drills should
be evaluated on the basis of power inputs of 1/10 and 1/5 horsepower.
Unfortunately, the test equipment modified as indicated above could not
measure within t5 per cent of these power inputs, and it was decided that
additional equipment would have to be designed and built to provide the
necessary accuracy of measurement.
Several different means were studied for evaluating the 5/16-
inch-diameter diamond drills. These included different types of strain-
gage applications, a cradle dynamometer, a torque meter using a changing
air gap in a magnetic field, and an electronic speed-control unit. These
methods required either expensive equipment or equipment with a long de-
livery date. Finally, a simple method was evolved that permitted the
measurement of the reaction torque. Thus, most of the equipment shown
in Figure 2 could be used, but the barrel was replaced by the test-materi-
al-holding assembly shown in Figures 3 and 4. During drilling, the torque
that was imparted to the material from the drill was resisted by an arm
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Double ball bearing
pillow block
FIGURE 3. SCHEMATIC DRAWING OF EQUIPMENT FOR MEASURING THE POWER INPUT TO THE TEST DRILLS
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I _ - --T -
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incorporating a strain gage. To simplify the apparatus and maintain a
constant moment of inertia, only one hole was drilled in each piece of
test material. Pieces of marble 3/4 inch square by 3 inches long were
used as the test material, and the torque on the marble was calculated
from the strain data obtained on a Sanborn recording instrument.
Test Procedure
During a discussion with the Sponsor, it was decided that
drilling rates should be measured at 1/10 and 1/5 horsepower for drill
speeds of 1,000, 2,000, 3,000, and 4,000 rpm. From these tests the
best speed for each drill could be chosen for each horsepower level,
and the drilling rates of the different drills could be compared. Thus,
the drills yielding the best drilling rate at 1/10 and 1/5 horsepower
could be selected.
At the beginning of each day of testing, a warm-up period of
approximately one hour was required to stabilize the recording equipment.
After warming up was completed, the test equipment was calibrated by bal-
ancing the strain-gage amplifier used with the Sanborn recording equip-
ment and free loading the strain gages with various amounts of weight.
When the equipment was calibrated, a marble test block was inserted and
drilled, with the drill rotated at one of the predetermined test speeds.
In order to determine the axial load required so as to use
1/10 and 1/5 horsepower at each test speed, it was necessary to make
preliminary tests during which the axial load was varied and the result-
ing torque was observed. When the proper axial load for each torque was
determined, three tests were made for each horsepower rating at each test
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speed. The average of the results from the three tests was then calcu-
lated.
Test Results
The tests showed that the diamond-impregnated core drills were
less efficient and less rugged than the diamond-surface-set core drills.
During drilling, the impregnated core drills cut out cores of approximately
the same diameter as the ID of the drills. Because these cores reduced the
flow of water to the drill tips, the drill tips became hot and the drilling
rates decreased.
The surface-set core drills, due to the irregular spacing and
high peaks of the diamonds, produced cores which were smaller in diameter
than the ID of the drills. No trouble with reduced water flow was encoun-
tered while drilling with this type of core drill.
The prescribed test program could not be completed with Drills
Nos. 2, 3, 7, 9, and 10 for different reasons. For example, in some in-
stances, the core drills plugged readily, and, as a result, either the
drill tips overheated and "burned" or the drilling rate decreased very
rapidly; in other cases, the drills with water holes located on the shank
behind the tip were not cooled and/or flushed adequately by the water and,
consequently, the above-indicated difficulties were encountered. The
drilling rates and axial loads for the remaining drills at 1/10 and 1/5
horsepower are shown in Figures 5 and 6, respectively. Although Drills
Nos. 6 and 8 gave the highest drilling rates, it is recommended that
Drill No. 1 be considered also for use by the Sponsor because it produces
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-- ( -15-
Drill No.1 B
a,
0
a_
i
is - diameter drills
To-- horsepower input
Drill No. 16,
Drill No.8 A
Drill No. 5
B
Drill No. 4 B
Drill No.I B
1,000
2,000
3,000
4,000
0-24228
FIGURE 5. DRILLING RATES AND AXIAL LOADS WITH io HORSEPOWER INPUT
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0
4-
0 6
c
Drill No. 18
511
s -diameter drills
-L-horsepower input
a
Drill No.5 B
Drill No. 8 A
Drill No. 6
Drill No
4 8
.
Drill No.6
Drill No- 8 A
Drill No.I B
Drill No.5B
Drill No.4 8
1,000
2,000
RPM
3,000
4,000
0-24229
FIGURE 6. DRILLING RATES AND AXIAL LOADS WITH s-HORSEPOWER INPUT
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no core. Thus, during an operation, Drill No. 1 would not have to be re-
moved from the material in order to extract the core; it may well be that,
in the drilling of deep holes, the over-all drilling rate with Drill No. 1
may approach those obtained with Drills Nos. 6 and 8.
Drilling Rates in Other Materials
Following the evaluation work, tests were then made to determine
the drilling rates of the three recommended drills in plaster, brick, blue
sandstone, marble, aggregate concrete, and granite when using 1/10 horse-
power. These values are given in Table 2. The tests were made by using
the experimental hand-held drilling unit which is described in the next
section of the report. An ammeter was connected in the circuit with the
drill, and the drilling rates were measured while the operator maintained
the drill load necessary to give an ampere reading corresponding to 1/10
horsepower.
TABLE 2. DRILLING RATES AT 1/10 HORSE-
POWER FOR 5/16"-DIAMETER DRILLS
Drilling Rate, inches per minute
Drill No. Plaster Brick Blue Stone Marble Concrete Granite
1
27.50
8.50
3.50
1.50
2.25
0.50
6
52.25
24.25
4.50
6.75
2.25
0.25
8
31.00
14.50
5.00
3.25
2.25
0.50
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Development of a Lightweight Drilling Unit
The hand-drilling unit developed under Research Order No. 21
was tested by the Sponsor and was found to be satisfactory in many re-
spects. However, the unit, which weighed 30 pounds, was too heavy to
be carried easily. It consisted of a 1/4-horsepower, 1,725-rpm electric
motor which was connected to the drilling head by a flexible shaft.
Because the 5-foot length of flexible shafting weighed 9 pounds,
it appeared that any significantly lighter unit would necessarily have the
motor located in the drilling head in order to eliminate the weight of the
shafting. Thus, the primary problem in developing a drilling unit which
would weigh 12 pounds or less involved the selection of a lightweight motor
which would develop sufficient power without being excessively noisy.
Selection of the Electric Motor
It was realized that most types of electric hand drills which
develop approximately 1/4 horsepower are quite noisy. It was hoped, how-
ever, that the noise could be greatly reduced by maintaining closer toler-
ances or exploiting other factors which might not be of paramount impor-
tance in commercial hand drills. Manufacturers of fractional-horsepower
motors and electric hand drills were contacted in order to determine whether
the noise originating in electric hand drills could be reduced appreciably.
Most commercial units use a high-speed series-type motor with a reduction
gear box. The combination of high speed (10,000 to 20,000 rpm)., the gear
box, the commutator brushes, and the cooling fan causes most of the noise.
In the opinions of the manufacturers, it was not feasible to bring about
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an appreciable reduction in the noise level of such units.
A trip was made to the Robbins and Myers Company, Springfield,
Ohio, a major manufacturer of fractional-horsepower motors. After con-
siderable discussion, it was decided that a shunt-wound d-c motor driving
the drill directly would provide the most power for the least amount of
noise and weight. A shunt-wound d-c motor was then run in their labora-
tories at different speeds to obtain same indication of the different
noise levels. The noise at 2,500 rpm was low, but at 3,000 rpm the noise
level increased very appreciably, and at 4,000 rpm the noise was definitely
too loud. On the basis of these tests, it was decided that the electric
motor for the drilling unit should run at approximately 2,500 rpm. Robbins
and Myers manufactures a 2,500-rpm, shunt-wound, 1/8-horsepower, d-c motor
which weighs 6 pounds. It was believed that with this motor a suitable
drilling kit weighing 12 pounds could probably be prepared; consequently,
an order was placed for the motor.
Tests With the Electric Motor
There was considerable question concerning the temperature rise
and the associated problems that might be encountered with the 1/8-horse-
power motor during drilling. Because this motor furnished only half the
horsepower of the motor in the original drilling unit, and because the orig-
inal motor could be stalled, it was realized that the 1/8-horsepower motor
would be stalled frequently during drilling. The manufacturing caapany ex-
pressed doubts concerning the suitability of the motor for our application.
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Nevertheless, an experimental hand-drilling unit was designed
to permit the use of the 1/8-horsepower motor for actual drilling tests.
This unit is shown in Figure 7. During drilling tests with the experi-
mental hand-held unit, the temperature of the motor rose to 156 F in
20 minutes of constant drilling. A motor that is this hot cannot be
held in the hand; however, it was decided that the temperature rise was
not great enough to militate against the incorporation of the motor in
a satisfactory hand tool, since 20 minutes of constant drilling would
be encountered only occasionally in service. Furthermore, it was con-
sidered possible to reduce the temperature rise by means of a more effi-
cient fan or to mount the motor so that the heat generated would not
bother the operator.
The Sponsor drilled with this experimental unit in marble,
concrete, and granite, and the weight, power, and noise level of the
motor appeared to be satisfactory. Therefore, a lightweight drilling
unit incorporating this particular electric motor was designed.
Design of the Lightweight Drilling Unit
The lightweight drilling unit consisted of a drilling head
and a suitable power-supply unit. The drilling head included the elec-
tric motor, a lightweight housing, and a water swivel for flushing the
diamond drills. The power-supply unit comprised a rectifying unit to
supply the motor with direct current and the necessary electrical con-
necting cords.
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Lightweight Drilling Head. During discussions with Robbins and
Myers, they indicated that a Model 281 Skil electric drill was designed
for the motor frame which was used for this electric motor. Therefore,
the necessary parts were purchased and the motor with ball bearings was
mounted in the rear housing of the electric drill. This fortunate turn
of events facilitated the fabrication of a satisfactory motor and housing
unit with existing production parts.
In previous drilling units, water had been supplied to the
drills through swivels which used 0-rings. Because of the low horse-
power of the lightweight electric motor, it was necessary to use a lower
friction type of seal in the lightweight drilling unit. Therefore, a
water swivel incorporating two carbon-faced seals was designed, fabri-
cated, and adapted to the drill housing. Included in the water swivel
were a small metering valve and a bayonet fitting for the drill similar
to that used on previous units. The completed drilling head is shown in
Figure 8.
Power-Supply Unit. Because the motor used in the lightweight
drilling unit was a d-c unit, it was necessary to supply a suitable rec-
tifying unit. The current supplied to the motor when stalled was 3 am-
peres. A full-wave rectifying unit with a 5-ampere capacity was fabri-
cated with four silicon power rectifiers connected in a bridge circuit,
in a perforated aluminum and plastic housing. This unit was designed to
be used with 110-volt current, either 50 or 60 cycles. A diagram for the
circuit used is shown in Figure 9.
The power-supply unit included 10 feet of electrical cord from
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N36 /69A
Figure 8Q The Lightweight Drilling Unit
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No. No. 15 PZ Sarkes
Tarzian silicon
rectifiers
(4 required)
FIGURE 9. CIRCUIT DIAGRAM OF THE FULL-WAVE BRIDGE RECTIFYING UNIT
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the wall plug to the rectifier and 10 feet of cord from the rectifier to
the drilling head. A ground wire was supplied for the protection of the
operator.
The Dust and Water Collector
Several collectors were designed and tested before a device was
constructed that satisfactorily collected both dust and water. The unit
shown in Figure 10 consisted of a metal chamber which was sealed against
the wall. The drill passed through the chamber and into the wall, and it
was expected that the flushing water would be confined within the chamber
as a result of the small clearance between the diameter of the chamber
and of the drill shank. This collector was based on a commercial collec-
tor design, but it was unsatisfactory because during drilling water seeped
out of the chamber along the shank of the drill.
The collectors shown in Figures 11, 12, and 13 were similar to
the first design except that rubber was used as a seal around the drill
shank. In the design shown in Figure 11, the rubber shank seal was separ-
ate from the rubber used to seal the collector against the wall. In the
design shown in Figures 12 and 13, the rubber shank seal was also used to
seal against the wall. Both of these designs worked satisfactorily with
water if the operator exercised some care to maintain a film of water be-
tween the drill shank and the rubber seal. However, if the water film
was not maintained, the rubber quickly overheated and eroded. These de-
signs were completely unsatisfactory for use with compressed air as the
flushing medium because of the absence of a lubricating film between the
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100810
Figure 100 Water-Collector Design No. I, Disassembled
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N30809
Figure 11. Water-Collector Design No. 2, Disassembled
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Figure 12. Front View of Water-Collector Design No. 3
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Figure 13. Rear View of Water Collector Design No, 3
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rubber seal and the drill shank.
The design shown in Figure 14 provided a grease chamber which
furnished a grease film to the drill shank, so that either water or com-
pressed air could be used as the flushing medium. Prior to drilling
using this device, the operator removes a threaded plug, fills the cham-
ber with grease, and partially reinserts the plug. With the plug in this
position, there is a rubber washer at each end of the grease chamber.
When this collector is used, the drill passes through the first rubber
washer, through the grease chamber, through the second rubber washer, and
then into the wall. As the hole is drilled, the volume of the grease cham-
ber can be reduced by turning the threaded plug; thus, the drill shank is
continuously lubricated with a film of grease. Tests with this device have
shown that it will collect both water and dust very satisfactorily. It is
believed that the use of grease will not inconvenience the operator because
only one filling of the grease chamber is necessary in connection with the
drilling of several 30-inch-deep holes.
Lightweight Drilling Kit
A drilling kit was assembled from the units developed under Re-
search Order No. 30 as described above and from those which had been devel-
oped under Research Order No. 21. The components of this kit, called the
Type 2 Prototype Drilling Kit, are shown in Figure 15. They consist of a
carrying bag, 20 feet of electrical connecting wire, a rectifier, a drill-
ing unit, a water-filled tank, a C02 cylinder, a collector, the necessary
tubing, and three 5/16-inch-diameter diamond drills. This kit weighs
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Figure 1., Dust and Water Collector Incor-
porating a Grease Chamber
~ I 1
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ON
1-
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15 pounds. Although this is more than the desired weight of 12 pounds,
it is believed that the kit will be satisfactory.
Cursory Evaluation of 3/16-Inch-Diameter Diamond Drills
One objective of this program was to conduct a cursory evalua-
tion of 1/8-inch-diameter diamond drills for drilling 30-inch-deep holes
in granite, plaster, concrete, brick, and marble. The nine manufacturing
companies that supplied 5/16-inch-diameter diamond drills for evaluation
were contacted concerning the manufacture of 1/8-inch-diameter diamond
drills for use in drilling to a depth of 30 inches. All of these companies
said that it was not practical to drill holes deeper than a few inches with
1/8-inch-diameter diamond drills. In fact, only one company, the Hoffman
Brothers Drilling Company, offered to supply even 3/16-inch-diameter dia-
mond drills. Because a 3/16-inch-diameter hole has only about 1/3 the
area of a 5/16-inch-diameter hole, it appeared that the 3/16-inch-diameter
diamond drill would probably drill faster than the larger drill and should
be evaluated.
Two 3/16-inch-diameter diamond drills were purchased and fitted
with 1/8-inch-diameter shanks. At first, it was believed that three drill
lengths and therefore three drills would be necessary in order to drill a
hole 30 inches deep; thus, each drill would have a maximum unsupported
shaft length of only 10 inches. However, it was actually feasible to use
an unsupported shaft length of 15 inches if the operator exercised some
care during the first 3 or Q inches of drilling. Thus, only two drill
lengths were needed to drill 30 inches.
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Drilling rates with the 3/16-inch-diameter diamond drills were
established for brick, blue stone, concrete, marble, and granite, as
shown in Table 3. On the basis of cursory drilling in plaster with dia-
mond drills of this size, it is estimated that the drilling rate in this
material is probably as high as or higher than that in brick.
TABLE 3. DRILLING RATES WITH 3/16-INCH-DIAMETER
DIAMOND DRILLS WHEN USING THE TYPE 2
PROTOTYPE DRILLING UNIT
Material Drilling Rate, inches per minute
Brick 13
Blue stone 4-1/2
Concrete 3-1/4
Marble 2-3/4
Granite 1
The drilling was accomplished with the lightweight drilling
unit shown in Figure 15. Unfortunately, it is not certain that, during
these drilling tests, the rectifiers were supplying full power to the
drilling unit, and there were not sufficient funds available to permit
these tests to be repeated. Therefore, it is very possible that higher
drilling rates can be obtained with 3/16-inch-diameter diamond drills
and the lightweight drilling unit than are indicated in Table 3.
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FUTURE WORK
During discussions with the Sponsor, two proposals have been
requested. One is concerned with the further evaluation of 3/16-inch-
diameter diamond drills and the preparation of another Type 2 Prototype
Drilling Kit. The second proposal involves the fabrication of 10 Type 2
Prototype Drilling Kits and the preparation of specifications, drawings.,
and an operator's manual. These proposals will be forwarded in the near
future.
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APPENDIX I
Companies Contacted in Connection With Drill Procurement
1.
Acker Drill Company, Inc.
725 West Lackawanna Avenue
Scranton 3, Pennsylvania
12.
Gateway Products Corporation, Inc.
200 Main Street
La Crosse, Wisconsin
2.
Action Diamond Tool Company
4547 Grand Avenue
Chicago, Illinois
13.
General Industrial Diamond Company
611-21 Broadway
New York 12, New York
3.
Blanchard Diamond Tool Company
735-41 East 87th Place
Chicago 19, Illinois
14.
F. F. Gilmore and Company
725 Boylston Street
Boston 16, Massachusetts
4.
Chicago Pneumatic Tool Company
8 East 44th Street
New York, New York
15.
Glenbard Tool Manufacturers, Inc.
214-18 North Clinton Street
Chicago, Illinois
5.
Christensen Machine Company
1937 South 2W
Salt Lake City, Utah
16.
Charles F. Haake
47-49 Ann Street
New York 38, New York
6.
Cle-Cut Products, Incorporated
1921 Main Street
Santa Monica, California
17.
Hoffman Brothers Drilling Company
Punxsutawney, Pennsylvania
18.
Industrial Diamond Company
7.
Clipper Diamond Tool Company, Inc.
21 West 46th Street
New York 36, New York
2392 Wolcott
Ferndale, Michigan
19.
Koebel Diamond Tool Company
8.
Diamond Drill Carbon Company
244-246 Madison Avenue
New York, New York
9456 Grinnell Avenue
Detroit 13, Michigan
20.
E. J. Longyear Company
9.
Diamond Wheel and Instrument Co., Inc.
93 Elm Street
Yonkers 2,.New York
Foshay Tower
Minneapolis, Minnesota
21.
Malco Drilling Machines, Inc.
10.
Felker Manufacturing Company
Torrance, California
1100 20th Street, N.W.
Washington, D. C.
11.
Fish-Schurman Corp.
70 Portman Road
New Rochelle, New York
22.
Mott Machine and Manufacturing Co.
Huntington, West Virginia
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23. Refinery Supply Company
625 East Fourth
Tulsa, Oklahoma
24. J. K. Smit & Sons
9105 Macomb Street
Grosse Ile, Michigan
25. Anton Smit & Company
333-49 West 52nd Street
New York, New York
26. Starlite Industries, Inc.
58th at Market Street
Philadelphia 39, Pennsylvania
27. Triangle Equipment Company
47 River Road
Nutley, New Jersey
28. United Diamond Tool Corporation
51 Prospect Avenue
Lynbrook, L.I., New York
29. Wheel Trueing Tool Company
3200 W. Davison Avenue
Detroit 6, Michigan
CO
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