November 25, 1915 AMERICAN MACHINIST—
What Flat Turret Lathe
Operators Should Know about Bar turners turning set up.
HARTNESS FLAT TURRET LATHE
ONE of the revolutionary features of the original Flat Turret Lathe
was the taking of fairly heavy chips down to finished size at one
Gut, maintaining the size through long periods of time, and at the same time producing a fine, ~moo1kfinssl.z
The latest design of the Flat Turret Lathe with bar equipment is as
good as its predecessor at this work, and even better; the
improvement comes from the use of the roller back rests for
assisting in the finish in place of the old-fashioned solid V yaws A
case n point is shown herewith.
How to maintain accuracy and
finish on bar work
Pig. 1 shows the first piece of a lot of small parts, the tool with which it is turned and the last piece. There were 150 pieces in the lot. A high, smooth finish is observable on the first sample, and the same polish, without tool adjustment or sharpening meanwhile, is observable on the last piece. In fact, it is impossible to tell by examinaticn which is the first and which is the last. This case is a typical and by no means an unusual one. It is chosen for illustration merely because it makes quite clear the elements of success in maintaining accurate finish.
In the first place—
as all machinists know, one of the various forms of cutting compound is superior to lard oil for turret lathe work in machine steel. It is superior from the standpoint of keeping the tool
cooler, thereby keeping the edge in better condition; and it seems to have as good an effect as lard oil in keeping the cut smooth and free from pitting or ragged edges.
In the second place
the smoothness of the finish is improved by the use of the roller back rests, which act as burnishing rolls following behind the cut. The old fashioned solid back rests which were used for so many years were all right until the high speed steel came; they did their share in burnishing the work; but with the rates of rotation possible with high speed steel it was impossible to keep these solid jaws from roughing on the work, thus spoiling its appearance instead of improving it. The rolls, on the other hand, have an ideal burnishing action which not only improves the appearance, but the quality of the outer surface as well.
Finally, there is the shape of the tool itself necessary for making a smooth cut with a high finish. The particular tool to use has been illustrated before on this page, but is shown again in Fig. 2. It should be merely noted in passing that success is obtained by grinding the end at just the proper angle
to take a skiving cut to finish out the feed
with; it must also be provided with a sufficient
round at the cutting point so that the tool will
generate considerable side pressure on the work,
forcing it against the roller back rests and giving
it the desired burnishing action. The form of tool
holder shown is desirable for work above 3/4'' or so
diameter. Below that the height of the tool point
above the base may be decreased to 3/8'' or so.
Jones & Lamson
Springfield, Vt., U. S. A. and 97.Queen Victoria Street, London, E.C.
Germany, Ho1land,~Switzer1and and Austria-Hungary: M. Koyeman, Charlottenstrasse, 112 Dusseldorf, Germany,
France, Spain and Belgium: F. Auberty & Co., 91 Rue de Maubeuge, Paris.