1935-08-10 — Page 2

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GOLD AND GOLD ALLOYS

Tools For Drilling And Working

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teeth of saws for hand" feeding. but it is important to avoid rake.. a negative giving them The saw teeth must be given. proper clearance on the sides to avold sticking or retardation in the gut, which generates exces- sive heat.

Coarse teeth are de-

sirable, with rounded guliets and clean edges to facilitate chip re- moval.

TUNGSTEN CARBIDE

One of the problems confront- ing the worker in gold is that of drilling the metal. This par- ticularly in evidence in sampling Ane gold bars The ordinary high speed steel-fluted twist drill is not always as efficient as could be desired, owing to the sticky or tenacious character of the gold, which tends to clog the Autes of the drill with fine drill-

The ings.

actual trouble ex- perienced in this respect is that

Either to

the tungsten carbide as soon as the tool begins

tipped or the electrically-welded metal. the drill- penetrate the

super-high-speed composite tools ings pass up, the flutes to the

can be successfully used in ma- edge of the hole, where they do

chining gold and its alloys. It is not, as they should. fracture and

hard and difficult to lay down a kind of slip away, but form

fast

the speeds and te has

rules for which "growth,"

feeds to be used in working. On chiselled away with a cold chisel,

the whole. fine to medium feeds and in the process tends to weld

combined with high speeds, are into a solid mass

best, The feed may range trom as much as in, to as Uttle as three thousandths, according to whether the cut is a roughing or a finishing one.

As soon as the drill rather. deeper

to

.

its than

the

goes Own Autes become

the the

diameter. clogged with drillings, penetration difficult, increasingly becomes and the more power is applied In an endeavour to drive drill deeper. the greater stress on the tool, until it event- ually breaks. Usually, "hole at least in. in diameter is requix-, ed in these bars.

..

The trouble is not primarily the fracture of the drill, but the drill point risk of leaving the

embedded in the gold. "as its ex- traction is always a most tedious and dincult matter. The solu- tion is a special design of twist drill, made from either carbon or to high-speed steel, according the speed with which the work to be drilled. This drill has a quick spiral and an included point angle of 140 degrees. A. speed of 100-200 ft. a

minute

Actual speeds and feeds vary according to the character of the metal or alloy being cut, the type of work, the form and kind of

the

used coolant tod,

and di ma- the design and type chinë driving the tool. A good general quie is that as the feed decreases" the speed should rise. und the greater the curf on the chip the less should be the speed. I it is desired first to remove a large amount of metal in a giver. time this is best done by raising the speed rather than by In- creasing the teed Special should be devoted to preventing all chatter, which ruins the tool" cutting edges.

rare

and gola In working gold alloys, a coarse feed is always able to cause the metal to ex-

may be used, or even more, acpand as a result of heat, and this. cording to the conditions.

the

all,

For the specific purpose outlined, a diameter of i.in. drill of the measuring 21 in. long on flutes, and 4 in. long over would probably meet all require- ments up to a depth of hole of 2 in. No water or all for cooling purposes would be required with these drills.

TOOLS FOR GOLD Cutting tools for gold need a greater side and top rake tha those for cutting hard metals such as steel, and the edges must be kept at maximum sharpness. This can be attained by using a The very fine abrasive wheel. tools should have a front clearance of approximately 7 to 8 degrees. and a toprake from 40 to 50 degrees, though slightly smaller some- these may angles than

desirable. The total times, be angle of the tool-cutting edge' will range from 40 to 55 degrees. "It is important that the cut- ting-tuol edges should be com- pletely regalar and sharp, with no notches, fash, or grinding wheel marks, Lathe tools should have a side rake of 10-20 de- grees & clearance of 8 degrees, and top rake of 30-50 degrees. the entire angle of the tool-cut- ting edge being from 35 to 55 de- Trees If it is fou d that the chips of certain gold alloys do not break up readily enough, quicker curling and thus quicker breaking can be produced by re- ducing both top and side rake angles. Too great reduction may impair the finish of the job, however, and regard should be had to this.

Parting tools need a top rake of 12-20 degrees, with a front clearance angle not, more than 4 degrees. When circular form- ing operations have to be per-

to take formed, it is best roughing cut as a preliminary, and complete the operation with a very light finishing cut with p former tool.

2

Milling cutters for gold should be, for preference, of the type with coarse tooth spiral, and should have a good, deal of top rake on the cutting edges. Nick- ed teeth in milling cutters are often useful in breaking up the chips.

demands care. Sawing gold The fronts of the saw teeth call for adequate top rake and a cer- tain.... amount of side rake in. many instances, according to the form of tooth employed. The hook angle should be 10-25 de- grees. Care should be taken to avoid undue pressure on the saw. No book should be given to the

If not watched, "may cause the " work to finish wrongly to size. Before taking the final Anishing cuts, therefore the piece or part should be viven a chance to cool down. It can then be measured and finished to accurate dimen- slons.

While gold alloys can some- "times be machined dry if properly designed tools have been used. It is always better to use a cutting compound. eg. a soluble cutting oll, or a mixture of lard di and kerosene oil.

CHINA'S RIVER

TRAFFIC

Novel Vessel Used

1ne fah Chung Hua Dockyard, Shanghai, under the supervision of Mr. Chang Chung-wha, a gra- duate mechanical engineer, re- Presenting the Bureau of Industry of Szechwan Province, is building an unusual type of stream-lined vessel for fast passenger work on the Upper Yangższe,«

The boat, which has been build- ing for the past six months, is 27 ft. long, has a beam of 8 ft. and a draft of but 8 in. The craft will be propelled by an Austro- Daimler airplane engine, set high dver the stern of the craft and turning a specially designed air- plane-type propeller. The engine is 120 horse-power, and it is esti- mated that she will drive the ship At a maximum speed of 42 land miles per hour.

The boat will be used exclusive- ly for carrying passengers. When completed some time this monta she will enter the Chungking- Chengtu passenger service on the Yangtsze and Min, Rivers. If the craft proves a success, additional " boats of the same gencral design, but larger, will be built. One of the best features of the boat is her extremely shallow draft that will be especially adaptable for running the rapids of the Min and for operating during the low- water winter months.

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HONG KONG DAILY PRESS, SATURDAY, AUGUST 10, 1935.

ENGINEERING

RAILWAYS IN JAPAN

New Developments

The proposed tunnel under the Shimonoseki to con- Straits of neco Kyushu with the hanshu railway system will, according to the preliminary plans, leave the Kobe-Shimonoseki main line at Hatabu, 2 miles east of Shomo- nosekt, as its junction with the San-in line, and join the Kyushu system at Kokura, the junction of the Kagoshima, and the Nippo main lines, 7 miles west of Moll

AND

BUILDING

EXCAVATION WORKS

Operation Of Modern Plant

Great works of excavation, un- a constructional like those of character, have never been sub- ject to any imitations of size, other than time and coat. There is ample evidence, dating back to prehistoric ages, that the pracu- cability of undertakings involving. the removal of large volumes of earth or gravel, or even rock, was never in doubt if time and a sufficiency of labour were avail-

It will be electrifield, and will pro-able, and funds for the labourers' bably be bgun in 1936.

main line

Extension of the third and icurth tracks on the Osaka-Kobe main line section, into Kobe, from Nada station in the Kobe suburbs. is now in progress. The Nada- Kcbe section is at presenu double track" only, forming a bottle neck in which are Sannomiya, an im- portant station, and Motomachi, a busy halt, both in the Kobe business centre. Both stations have only one up and the down platform line, at Sannomiya there is an island platform, and at Moto- machi separate up and down plät- forms. Even Kobe station has only four platform lines to serve ut the main line traffic of the Tokyo-Shimoniseki main fine as well as the dense interurban and suburban traffic on the Kobe." Osaka section. The iratas are steam operated, and the suburban trains electric; the trains follow each other at inter- vals of from 4 to 8 minutes dur- ing the day. For the greater part of the three miles from Nada to Kobe the new double track line is carried on a separate vladüet. which, like the existing one, is constructed of reinforced concrete plers and spans, but with steel girders over street crossings. New platforms are being built at San-

and nomiya, Motonachi

Kobe and the station buildings at San- nomiya and Kobe are being ex- tended. The works are expected to, be completed by the end of the present year at a cost estimat- ed at v.3.100.000 of which about one-half is spent on the three station extensions.

WORLD POWER

CONFERENCE

The report of the World Power Conference for 1934 states that.. circumstances have arisen to pre- ven the holding of the third plenary. conference in the United States next year: it is possible. however, that the meeting may take place in 1937, if not in the United States, in another country.

Details are given of the way in which effect is being given to the seventh object of the Conference -the establishment of a perman- en: world bureau for the collec- tion of data, the preparation of inventories of the world's resour- res and the exchange of industrial and scientific information. The first active step was the circula- tion of tables for completion by the National Committees, and it

maintenance. The development of mechanical appilcances "for in quantity Handling materiai operated first to reduce the time factor, so bringing down the cost of labour-in which item, "main- tenance may be a heavier charge than wages on a large contract. remote from the amenities of civilisation.

A

As invention has proceeded. alternative kinds of machine have been developed for most excavat- ing requ rements, and the further refinement of comparative costing has come to depend more and more upon analysis of the func- tioning of one-type or another in the particular circumstances. The number of operatives and labour- ers has now been reduced to point at which it almost ceases to affec: the choice of equipment. On the other hand, when a contrac- cor plans to employ mechanical excavators which will remove at one swing of the bucket as much material as three men could shift" "In a day with shovel and barrow, The service of the machines de- mands a degree of organisation quite comparable with the com- missariat arrangements of less mechanised days, and its effic- lency may decide the success or otherwise of the undertaking.

are

crane

NOT VARIABLE Marine excavation can hardly be compared with land operations, as marine conditions are not so variable. For underwater work of any extent, the chalce lies be- dred- tween ladder and suction gers, but for small excavations in shallow water, land-type: applian¬ -ces are also used, either from the bank or from a pontoon. For dry. excavation, and for suih work as deepening drains and canals, the power shovel, o "crane navvy," and the "dragline excavator the machines most widely used. The power scraper, the slackline

the grab cableway, and have advantages in some situa- ttons, and excavators of the buc- ket-ladder type are occasionally The applied to land purposes. "hydraulic glant", of American mining practice has little "scope in the British Isles, where

suficient quantity and natural head of water is seldom available. The power shovel dates from the beginning of American rail- way development, and for that reason was first designed to move on railway track of standard gauge, being steadied by screw jacks when cutting. Until recent- ly, all railway-type shovels were steam driven, but petrol, heavy- oll and electric drives are gradual

#

is hoped to publish the first rely displacing steam in most forms

gular statistical year book at the end of the current year. Another means of fulfilling the seventh "Object" has been the publication of "World Survey under the au- spices of the Conference.

The Conference does not under- take the work of standardisation. but as representing "users," con- ceives it its duty to bring before the appropriate organisations maiters in respect of which it considers standardisation to be desirable, and steps have been taken to this end,

Other matters touched upon in the report are coal specifications; the prevention of radio interfer- ence; the transport and transit of... electric power; and hydraulic re- search. Mention is also made of the work of the International Commission on Large Dams and of the Chemical Engineering Con- gress to be held in London "next" year.

The boat presents a long, sweep- Ing. stream-lined appearance to "the extreme. Ample seating foom is provided for up to 15 passen- gers, all of whom will have an

The Difference. unobstructed view in all direc

Her hat was on one side, her tions. The cabin section of the clothes rumpled, her shoes in craft where passengers will be shreds. "Were you knocked down sealed is entirely glassed in. by a motorist?" Asked a sym Space is also provided forward for pathetic friend. 'hand luggage and express pack- *ages.:

"No, I was picked up!" she snapped.

of power excavator. As the jib and bucket of a rallway shovel must be placed at one end of the truck, the working are is limited to about 180 deg.. and the re- moval of spoil from a fast-cutting shovel may be difficult to organ- ise. Broad-tyred road wheels give some extra mobility, but the ca- terpillar track now tends to super- sede practically all wheeled mountings. The majority of mo- dern shovels are of the full-cir- cle type, on a caterpillar mount- ing. Such a machine can dig or dump with equal ease at any point of its 360-deg, swing, and can travel over any fairly even Gurface, cutting its own road if

necessary.

has

· DRAGLINE EXCAVATOR The dragline excavator evolved from the horse-drawn acraper, and is a product of the present century. The empty buc -ket is dropped at the full radius of the jib, or may be thrown beyond that radius as the jib swings, and is pulled towards the machine by a separate drag rope, Alling Itself as it comes. When full, the buc- ket is lifted by the hoisting rope or by topping the jib and swung as necessary for dumping. The centrifugal force of the swing can

be used again to throw the bue- ket outwards, so that dumping can take place considerably beyond "the "Jb

radius. The dragline should not be confused (as is sometimes the case) with the po- wer scraper or the "slackline" al- ready mentioned, of which the buckets travel respectively with and on a cable suspended be- tween two masts, or a mast and.. a movable anchorage. These ap- pliances are very efficient in work- ing a gravel deposit or stripping overburden, but limited mobility affects their utility to the general contractor. "Engineering."

CHINA'S COMMUNICA-

TIONS

Dr. Chu Chia-Hua, the Chinese Minister of Communications sta- tes that the construction of tele- phone trunk lines to afford direct communication between any two principal cities in Klangsu, Che- Kang, Anhwel. Klangse, Hupeh, Hunan, Honan, Shantung and Ho- pei is expected to be completed before the end of the year. With a view to facilitating communica- tions with the North-Western pro- vinces, the original scheme would be extended to cover Slan, Tai- yuan, and Lanchow. In addition, branch telephone lines would be installed in Anhwel and Honan, and trunk lines were being con- structed between Wanhsten and Chungking. The Ministry contemplating the establishment this year of direc: radio communi- cation with India, Australia and Canada. Further, in considera- tion of the large number of in- ternational telegrams from or to Tientsin, Tsingtao and Hankow. medium

automatic powered transmitting and receiving - sta- tions would be set up in these places to communicate directly with Japan, the Philippines, and French Indo-China. Twelve more radio-telephone stations would be installed in remote parts of China, and this would complete the first stage in the development of na- tiona! telephone network.

was

BRIGHTENING DOWNING

1

STREET

¡Special Air Mall Service)

London, July 22, Mr. Baldwin has decided to con- tinue the flower window-boxes, at 10 and 11, Downing-street, and to make them more or less a perman- ent feature.

They were put there for the Ju- bilee as part of the Office of Works acheme for decorating Government Departments facing Whitehall,

The cost of the latter was borne by Government funds.. The boxes of Nos. 10 and 11, however, were paid for out of the private purses". cf Mr. MacDonald, then Prime Minister, and of Mr. Baldwin as the occupant of No. 11.

Both are tond of flowers. The Office of Works have abandoned the boxes at windows in White- hall those in Downing-streeti bave been maintained.

They certainly give the drab fa- cades a brighter appearance, and the flowers are frequently changed.

HONOURING A CRITIC

(Special Air Mail Service)

London, July 22. When the India Bul becomes law the week after next only one Bri- tish statesman will have his name included in ia text.

Curiously enough, this 's Lord Lloyd, who moved what anwunted 10 the rejection of "the. bili lu the House of Lords, and described 1 as giving India "d'sunion, dyareny. and disruption."

Originally Lord Lloyd was not mentioned in the bill. Late in the report stage debate in the Lords an amendment was moved by Lord. Zeiland to change the name of the Butkur Barrage to what he said was the more correct tile of

Loyd Barrage, and Canals.”

Lord Lloyd blushingly expressed. be thanks

RANDOM NOTES

WORK COMPLETED

ADDITIONAL ROLLING

Kunming (Yunnanfu)., Aug. 2..

Constructión

of increasing of the Buitung steel bridge in Lunging, western. Yunnan, has been completed after two

year's work. The bridge is 389 feet long and feet wide and has been bulit at a cost of over $80,000..

In recognition of his Diligent supervision of the engineering operations. the Yunnan Provin- cial Government has awarded Mr. Chiu Tien-pel. District Ma- gistrate of Laungling, two Major merits.-

Kuo Min.

- HIGHWAY COMPLETED

Work on the Wush-Shanghai Highway, which was started in April last year, was completed on July 15. The road, which is 140 kilometers long links up Shanghal with the industrial gentre of Wusth. It passes through 24 cities and towns, including Nan- slang. Klating, Taltsang, Chang- shu and Tungting. There are 140 bridges and. 53 culverts along the route.

ANOTHER TRAIN FERRY

In order to cope with the de-

Te mands of increasing trade tween Halakuan and Pukou, the Ministry of Railways ta reported to have decided to "purchase a other train ferry and two more service launches for the Tientsin- Pukow Rallway, which wit in-

ם'

In order to meet the demands

trafic

the Tientsin-Pukou Raliway, the Ad- ministration of the Railway has petitioned the Ministry of Rall ways for authorization to pur- chase additional rolling stock The during the present year. plans of the Railway Adminis- tration call for the purchase of 10 locomotives and 300 freight that It is understood wagons the petition has been approved by the Ministry. **

THE MALAYAN MECHANIC

It has long been a common be- lief that the Malay is too proud to work. Like a good many others, he is not fond of coolie or clerical work, but give him a plece of machinery to look after; and he will be as proud of his charge as any Scosch engineer, despite the dirt, heat, noise and other dis- comforts of the workshop. The Johore administration report, for 1034 states: "The largest dred- ging company found local Malays inore reliable and regular in at tendance than Chinese, and parti- cularly useful in handling mechal- cal appliances." This official com- pliment to the much maligned Malay is long overdue, and we hope to hear less in future of his so-called laziness.

volve an outlay of $300,000. the same time, the ministry also

AC

plancing to expend the No. 5 wharf at Nanking

AND

PORT

EMERA

CEMENT

EMERALCRETE

RAPID HARDENING

PORTLAND CEMENT

IN PAPER BAGS OF 94LBS NETT

PRODUCT OF

GREEN ISLAND CEMENT CO.LTD.

EXCHANGE BUILDING,

HONG KONG.

THE TAIKOO DOCKYARD & ENGINEERING

COMPANY OF HONGKONG, LIMITED.

BUILDERS OF ALL CLASSES OF SHIPS. BUILDERS OF RECIPROCATING STEAM ENGINES. BUILDERS OF MARINE AND LAND BOILERS. BUILDERS OF TURBINE MACHINERY

Under License From Messrs, Parsons. BUILDERS OF DIESEL ENGINES

"Under Special License

From Messrs. Sulzer Bros., Winterthur. Licensed To Manufacture Lanz Perlit Iron. Specially Suitable For Internal Combustion Engine Working Parts.

DOCK & SLIPWAYS.

13

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