Definition i.-A raising press is generally understood to refer to a machine that has been specially designed to be used for raising into some hollow shape a previously cut blank.

Definition 2.-A drawing or extending press is a machine that is used for making deeper, or extending in length, any article that has been previously raised or cupped out of the flat metal, and the length of stroke in an extending press is usually much greater than that in an ordinary raising press.

Definition 3.-A cutting-out and raising press is a machine that cuts out its own blank, and simultaneously raises it into some hollow shape, at one operation and at one stroke of the press. This machine is also known as a cutting and cupping press.

In workshops where a limited number of machines are available for use, one press of an ordinary standard pattern is frequently used for an extensive variety of work. This often necessitates the use of special fixtures, which have to be provided to receive the different sets of tools that are required to perform the varied operations. But although a strong and well-designed press may at times be used as a general purpose machine, it is not always profitable to employ one press upon too many varieties of work, since the extra cost of providing fixtures, and the risk of breakages, that sometimes occur when executing heavy work, will frequently out-balance the apparent advantages. There is generally some special feature contained in the design of a press to make it particularly suitable for carrying out some special work or operation; in other words, the designer of any machine has invariably had in view some particular operation to be performed by the machine. With the assistance of a series of illustrations, it will be interesting to note some of these special features as they occur in the design of the machine being dealt with, as in this way the actual part of the machine may be seen. The author has known instances where an ordinary cutting-out or blanking press has been made, sold, and used for cutting, cupping, drawing, raising, and stamping, pimply because the stroke of the press happened to be of sufficient length for the work. From this it would seem to be difficult for one to be able to judge for which operation the machine is most suitable. The first thing required is naturally a sample of the work to be made in the machine; having this sample, and knowing the operation or number of processes required to produce the sample, the next step will be to select a machine giving suitable motions and of sufficient strength for the work. This selection can generally be made successfully by the mechanic who has charge of the section where the operation is carried out. But in important cases, doubtless the better course to adopt would be to seek the advice of the actual press maker, who with his special experience may be better able to recommend a machine suitable to the requirements.

The following brief points are generally considered to be of importance in selecting any screw or power press:-

No. I.-Sufficient weight of metal used in construction of the frame casting to give strength and rigidity, and make it impossible to spring from its normal shape when dealing with the work for which it is intended, and ensure freedom from breakdowns.

No. 2.-The part of the press and its strips which guide the slide or ram in its motion, should be carefully and accurately planed, being finished absolutely at right angles to the base, or table of the press, which receives the bolster or bottom die. This point is of particular importance in the case of a drawing or extending press of long stroke.

No. 3 -The slide or ram to be as long:as possible, its bearing surfaces and those of its guide strips to be of sufficient area, and of suitable shape, to provide a steady motion to the tools, thereby preventing the cutting edges of cutting or forming tools being damaged after the slide or ram has once been properly adjusted.

No. 4.-The press bed, the ram, and the adjacent parts to be as heavy as possible consistent with the size of the press, to enable the principle of the anvil to be successfully carried out. Plenty of metal to resist the sudden blows to which the press may be subjected, and to reduce vibration to a low limit.

No. 5.-The details or smaller working parts, to be of sufficient proportions to give the necessary strength, and the wearing surfaces should have ample bearing surface, suitable metal being used for their construction, and hardened where necessary, durability of working parts receiving proper attention.

No. 6.-There should be ample room on the bed or table of the press to receive the various bolsters and dies, the ram or any other working parts which have to take variable positions to have sufficient length of adjustment. This point is of particular importance in the case of the ram, unless all bolsters, dies, and punches are designed to one standard length, which is not often the case.

No. 7.-The methods of manipulating the press, starting and stopping the operating levers and adjustments should be designed to give the greatest amount of ease and convenience in working.

In seeking out the foregoing points endeavour should be made to select the machine which, in its general design, is of shapely outline. This is often overlooked as being of no direct benefit; even should this be so, the indirect advantages are worth obtaining, especially as no addition is necessary to the cost. These indirect advantages being, the makers are far more likely to take pains and carefully finish the working parts of a shapely machine than of an ugly one. The operators also have more encouragement to keep the machine in good working order by cleanliness, and usually take greater interest in machines that show the improvements than they do if the machine is clumsily designed and of indifferent finish.

The fly-press, fig. 156, is a design suitable for a variety of work. The slide is of the dovetail section, as was seen at fig. 12. This provides a large wearing surface to the slide and steadiness for guiding the tools, thereby ensuring to them a long life. In fly-presses the slide guide is sometimes cast separately, being fixed to the press body casting by a bolt; this is, however, though common, not good practice. In the case of fig. 156, the guide being cast solid to the press body makes a much stronger job. The connection between the slide and screw is provided with a screw adjustment that serves to take out all play due to wear, the details of which connection are seen at figs. 19 and 22. The extent of the slide's descent is regulated by adjusting screws and stop plate. The stay-bolt seen on the front of the press be readily inserted or removed, its object being to make the press nearly as strong as if double-sided, in case the press should be required to do exceptionally heavy work. It is often necessary to execute work under this type of press that is too large in area to be placed under a double-sided press, and it is when this class of work has to be dealt with that the stay-bolt would be removed.