Drummond M type Handbook

Page 6

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THE TAILSTOCK

The tailstock is a stiff box casting, with steel barrel and square thread screw, and for turning long tapers it has a set-over adjustment, which may be set by means of a zero graduation.

It is guided in similar manner to the saddle (see Fig.5). A single action of the lever at its back rigidly locks the tailstock to both the front and rear ways by means of adjustable eccentrics. This is done without putting any distorting or squeezing strains upon the bed, and gives a very large weight taking and wear resisting area. Note that the alignment of the tailstock is obtained by locking to the same vertical face of the ways as the headstock, and that this face also guides the saddle.

Fig.5

The tailstock design

THE SPECIAL TOOLHOLDER WITH HEIGHT ADJUSTMENT

(Norman's Patent).

The toolholder on the new Drummond has been evolved as the result of continuous experiments and many years of experience in the design of various types, and we think we can now confidently claim to have produced what has hitherto been lacking - a perfect toolholder for small lathes.

A comparison with older types. In considering the advantages of the new holder over other types the following points should be noted.

Firstly, there is the question of the manner in which the tool is clamped to the topslide, and on this depends to a great extent the rigidity and accuracy of the latter, as well as the freedom from chatter, etc., of the tool. The single clamp bolt with tool block and double setscrews, as provided in the previous DRUMMOND 3.5-in. lathe, gives an excellent holder, providing care is taken in securing the block on the topslide before the tool itself is screwed in position. The four bolt and double clamp plate method is exceedingly cumbersome, and in both these methods the stresses due to clamping the tool are imposed on the topslide itself, with a tendancy to impair the accuracy of the latter. In the case of the tool post holder, this means a weakening of the topslide caused by the necessary base slot.

Secondly, there must be some means of adjusting the height of the tool; this is usually done by packing or by the provision of a holder of the tool post type. Paking the tool is not an ideal method, and in the case of the tool post holder with its arc-shaped packing wedge - although this gives a fairly simple tool setting in one respect - it alters the cutting angles of the tool with each adjustment for height.

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