The leadscrew B is brought close in under this saddle guide, thus reducing to a minimum the unavoidable "wringing" action between these two elements, and ensuring a clean, steady saddle movement. Thus the cut itself holds the saddle to a long narrow guide at the front of the bed. The rear way C is seperated from the saddle by clearance D, and the saddle is firmly held to the top face of this way by the stiff gib strip shown. The vertical downward component of this thrust is taken on the top surface of the front way, A the horizontal forward component of the cutting thrust is met squarely by the back face of this way. Referring to Fig.2, it will be seen that the design gives a 90 degree vee saddle guide at the front of the bed, the centre line of which coincides approximately with the average line of cutting thrust. The Drummond form of lathe bed combines the accuracy of the long narrow guides of the "American" type with the long wearing qualities consequent on the large wearing surfaces of the "English" type. Although the top surface of the bed is flat, it is not the ordinary so-called "flat English bed". The bed is a complete box section casting, stiffened internally, and is of the same general design as our new toolroom and manufacturing lathe beds. This Drummond cantilever design is unique in that it enables the lathe to be bolted down on any floor, no matter how uneven, without distorting or affecting its accuracy in any way it is the only form by which a small table lathe can be made or guaranteed to remain accurate wherever placed. THE BED AND SADDLEThe bed has a longitudinal form that is completely self-contained and stiff in itself, and therefore needs no outside support whatever. Design has continued to progress, and details to be improved, and now the modern lathe, complete with the many special features described in this list, can confidently be claimed without hesitation to be in every way the finest and most complete 3.5-in. The lathe was made heavier throughout, the round belt was replaced by a flat one, ball bearings were fitted to flywheel and pitman - a special cone lock fitting to headstock - etc., etc. Here our work on precision screw production and measurement to fine limits had its effect in influencing both design and manufacturing methods. The lathe was again modified in 1921 the points in design previously found to be most desirable as giving great ease of handling, large scope for varied work, and accuracy in operation being retained, and other features incorporated in the light of further experience gained during and after the war. This model enjoyed even greater popularity than its predecessor.
The details of the design were gradually improved in the light of experience with lathes of this type and in accordance with current practice, and in 1912 a revised design, incorporating the results of continuous experiment towards efficiency, was marketed.
and was the first lathe of its size designed on really efficient lines. lathe may be of interest, and will show how uniformly successful this design has been since its first appearance. Foreword.A few words on the origin and development of the Drummond 3.5-in.