This section is from the book "Lathe Design, Construction And Operation, With Practical Examples Of The Lathe Work", by Oscar E. Perrigo. Also available from Amazon: Lathe Design: Construction And Operation.
In sharp contrast to these conditions is the bed shown in Fig. 48. In this case the front cabinet is of a length on the bed equal to the length of the head-stock, hence the front bearing of the head spindle has a support of solid iron down to the foundation, or floor upon which the cabinet supports rest. The tail-stock is similarly supported by a cabinet occupying the distance equal to its length upon the bed. An argument in favor of this method of supporting the bed is not necessary as the conditions are self-evident.
Fig. 48. - Form and Proportions of Cabinet Supports.
But there is still another reason why the cabinet support is the more rigid, and that is the fact that with the long distance on the bed to which the cabinet is firmly and solidly bolted comes additional stiffness and rigidity, not only in a vertical direction for sustaining weights, but also to withstand the torsional strains to which every lathe bed is subjected, and which are multiplied rapidly as we load the lathe with heavier work, take heavier cuts, and use high-speed tool steel, by which much greater speed may be used.
The next matter to be considered is the form of the cabinet, although this is a secondary consideration, the first being that we have the cabinet and that it reaches out under the bed to the practical length as shown in Fig. 48.
For small lathes, say from 12 to 20-inch swing, the cabinet is frequently made nearly square While this is wrong in theory, as has just been explained, it is an improvement upon the old-style leg. The form shown in Fig. 48 is substantially that used by Lodge & Shipley in their smaller lathe. Its peculiar feature is the strength, vertical end walls, without projections at the base, while the regular projection is made in the front and the rear. This form is less expensive in its pattern work and somewhat easier to mold, but its appearance is not as good as the one shown in Fig. 50
Fig. 49. - The Lodge & Shipley Cabinet for Small Lathes.
Fig. 50. - Ideal Form of Small Lathe Cabinet.
which has equal projections on all four sides and at the top and bottom, thus giving it a more symmetrical appearance. It may have only three sides enclosed, the side walls turning the corner for only an inch or so, and this side be placed underneath the lathe bed, as is now done by some of the builders. But as this cut-away portion would come directly under that point of the head-stock where the most support is needed, it is of doubtful utility to cut it away, or to reduce the support of solid iron at this point.
Fig. 51. - Cabinet and Cupboard.
Lathes for light work, of 12 to 18-inch swing, may be supported by square cabinets, but if for heavy duty and continuous hard work the cabinets should be considerably longer than they are wide and support the bed as shown in Fig. 47.
In Fig. 51 is shown a form for head and tail cabinets, or "Cabinet and Cupboard," for medium-sized lathes, say from 20 to 28-inch swing. These answer the conditions as represented in Fig. 48, and are not excessively expensive. They also furnish one closed cabinet and an open cupboard, both of which are available for storing tools, gears, and similar articles. The arched opening at A affords a convenient space for introducing a lever or bar for the purpose of moving the lathe. This arch should be placed in the cabinets of all but the smallest ones, and even in them a small arch suitable for the use of a crowbar will be found convenient.
Fig. 52. - The Lodge & Shipley Form of Cabinet for Large Lathes.
In either of the styles of cabinets shown the shelves may be cast in, but the usual method is to cast strips upon which the ends of wooden shelves may rest, thus making not only the pattern work but the foundry work more simple and economical.
Fig. 53. - The Hendey-Norton Form of Cabinet for Large Lathes.
In Fig. 52 is shown the form of cabinet used by Lodge & Shipley for large lathes and which gives an excellent support to the bed and its superstructure.
In Fig. 53 is shown a similar cabinet used by the Hendey-Norton Company, differing from the last one in having the inner end cut away. This cabinet does not, of course, admit of the introduction of shelves. In the larger lathe, say from 30 to 40-inch swing, inclusive, doors are not usually provided, as the height does not admit of it. Above 40-inch swing the bed usually rests directly upon the foundation.
The cabinets here shown are given simply as examples, but they give a good idea of the forms used by most of the modern lathe builders at the present time, and the reasons for their continued and enlarged use. It is altogether probable that the future will witness an increase rather than a decrease in the use of the cabinet for supporting machines of all kinds where it is possible to introduce them, on account of their great rigidity in proportion to the weight of cast iron used, as well as the fact that they furnish a safe and convenient receptacle for tools.