The Equipment and Organisation of a Motor Repair Shop or Running Shed.
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SEVENTH ARTICLE.
A screwing machine will be found a useful and necessary tool in most repair shops. We illustrate one made by Messrs. Charles Winn and Company, of St. Thomas' Works, Granville Street, Birmingham. This firm makes a speciality of machines of this class for all sizes of work, and the illustration shows their No. 6196. Bolts, straight and bent tubes, up to 2in, in diameter, can be threaded with ease, as the tool ia back-geared. The construction is heavy and sub stantial, and the machine is well fitted, and a first-class tool in every respect ; it has all the advantages of the older types, and it has in addition an improved open-top vice, which allows of bends or any irregularly-shaped tubes to be properly threaded without difficulty. The jaws of the vice will come up close to the screwing head, which allows very short pieces of tube to be threaded with ease. The dies fitted are of the chasing tool type, and these screw a fulL thread at one going over, and are easily sharpened when required. They can readily be removed from the machine and ground upon a stone like an ordinary chaser, without being softened first. The dies arc also adjustable, and any variation in the diameter of the tubes can be easily dealt with, and long screws or tight joints can be made with equal facility. Two sets of dies are provided, and tubes or bolts tin., 'tin., and 2in. in diameter can be screwed. Cne set of dies would be sufficient, but Messrs. Winn prefer to supply a second pair, without extra charge, as better work can be done and the life of the dies is prolonged by doing so. A releasing motion is provided, which renders it unnecessary to screw the head in a reverse direction after cutting a thread, and the nut for operating this mechanism can be seen on the back of the face plate. The tool is band driven by gearing-, which is of the detachable two-speed type, and the speeds have a ratio of about 3 to u. This arrangement will be found useful when cutting threads on small work, when a higher speed is desirable than on work of larger size. The machine is well finished, and the bed is provided with a rack motion for moving the vice backwards and forwards. Extra dies can be supplied for cutting left-hand threads, at a reasonable price. An improved slide rest cutting-off apparatus can also be obtained. This consists of a powerful self-centring chuck, with hardened steel jaws, and a strong bracket fixed to the frame of the attachment, which carries the sliding tool rest. By the use of this appliance, tubes can be cut or faced perfectly square and smooth—. not squeeezed and torn off, as is generally the case when a wheel cutter is used. The price of the complete screwing machine, with dies for cutting threads on pipes and bolts from iin. to zin., is ;.C.T5, and the price of the cutting-off :attachment mentioned is We give an illustration of a disc grinding tool made by Messrs, Roberts Brothers, of Dukinfield, Manchester. The disc grinding machine has come to the fore of late as a quick and economical means for doing most conditions of grinding, and the example described below embodies the result of much thought and experiment. The correct speed for the shaft of a disc grinding tool is from 1,00 to 1,800 revolutions per minute; it is therefore plain that every running part must be perfectly balanced, anl constructed of the best material. The best part of the disc for grinding purposes is as far from the centre as possible. It has been found that after considerable use the discs buckle to some extent, owing to the pressure's being constantly maintained in one place. To obviate this fault, the firm fits a patent antivibrating back plate, which consists of a second disc placed a short distance behind the working one, the space between the plates being filled by a circular sheet of thick fibre. This arrangement has been found not only to give a much increased cutting power to the disc, but to deaden noise to a larg-; extent. The spindles are turned, hardened, and ground dead true between centres; and to ensure perfect lubrication, a self-lubricating bearing has been designed. This consists, in addition to the usual gun-metal bearing, of a large oil well and two oiling rings which revolve eccentrically with the spindle, but are loose on it. The two rings form oil collectors, and raise the oil to a distributor at the top, and this is supplied with two holes, by which the oil flows back again on to the journal. Two gauge glasses are fitted to the front of the bearings to show the height of the oil, and drawing-off taps and filling plugs are also supplied. The work table is moved across the face of the grinding disc by a hand lever, which may be seen in the illustration, and is moved vertically by a worm and pillion wheel. A transverse movement of the table is effected by a micrometer feed, graduated to one thousandth part of an inch, and it can be canted to almost any angle for bevel work. The table has i-slots for bolting work down when required, or for attaching jigs. Some of the dimensions for the 2410. machine are :—Size of table, 131n. by Hifi.; diameter of spindle bearing, 21n.; of back plate, i2in. ; and of spindle pulley, 6in. ; revolutions per minute, 1,350; height of spindle centre from floor, 3ft. 3in.; floor area, s ft. by 2ft. Sin. ; and approximate weight, 22cwt. The price, complete, is ;673. The work which can be done on a machine of this class is very varied ; in fact, it can be used in almost every job which has to be done in a repair shop. We may mention a few of the operations which can be accomplished expeditiously and economically--circular grinding on shafts and spindles; the facings on bearing stops, brackets, strips, glands, keys, cotters, dies; and the breaking up of large surfaces after machining, such as valve faces, etc.
Charles Churchill and Company, Limited, of o-is, Leonard Street, Xinsbury, E.C., sells some very useful powerdriven hack saws, one of which we illustrate. The machine will take in work either circular or square, up to sin. to Gin. in section. This law has some special features, the most important of which is a pivoted vice, and this can be adjusted so that the saw will cut at any angle up to and including 45 degrees. The machine has, in addition to the ordinary gravity feed, an automatic feeding device. The former is designed to give the proper advance of the saw blade in all the sizes and classes of stock within its range, and the latter is intended for use with pipes and small material. When desired, the ratchet feed can be easily disengaged by pressing two handles together, and this throws out the feed nut and allows of the saw's being worked by gravity. An automatic stop is provided, which enables a pre-determined depth of cut to be arranged for, and a gauge for cutting duplicate pieces is provided. The machine is started by a clutch fitted on the driving shaft. All rods and shafts are of steel, and the tool is well fitted and substantially built. Saw blades 14in. long are used, and some of the dimensions are as follows :—Net weight, 18o1b.; height over all, 3ft.; floor space required, 18in. by oin.; size of driving pulley, 141n. by 21in.; revolutions per minute, so; and the price of machine, complete, is .67 ins.
We illustrate a foot-driven milling machine made by Mr. Henry Milnes, of Ingleby Works, Bradford. The machine is adapted for use in small shops where power is not available, or in a larger establishment where a second machine is kept for doing the smaller and finer work. The main frame is one casting, and a double-geared head stock, with machine-cut wheels, is employed. The steel main axle runs in adjustable hardened steel bushes, and it is fitted with a
tapered arbour for carrying the milling cutters. The nose is screwed for accommodating any chuck. The work table is isin, long, by sin. wide, and it is provided with a well to catch any waste oil. A longitudinal traverse of 32in, is provided for the table, whilst the maximum transverse movement is bin. The milling head has a hollow mandrel, and is fitted with a machine-cut worm wheel, and a division plate and spring stop. The tool is thoroughly well built,• and is designed to stand prolonged hard work. The price, complete, with parallel vice, is Z,43.
The Scotia Motor and Engineering Co., Ltd., of Springfield Road, Bridgeton, Glasgow, makes some excellent vices with several new features. All the vices are made to swivel, and can be turned in a complete circle by loosening a lever underneath. The jaws are operated by a square-threaded
screw, which works in a large nut fixed to the base plate. Should the nut become damaged in any way, a new one can be fitted in a few moments. The price complete for sin, jaws is Li Iss. A vice is also manufactured with a canting base.