ROAD AND WORKSHOP by HANDYMAN
Page 43
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The Garage Lathe-1
I N the large vehicle workshop dealing with overhaul and heavy repair, one can expect to find a lathe tucked away in a corner, giving a good service at the hands of an experienced turner, In many smaller garages. however, a lathe often can be found apparently little used, yet in the hands of a useful machinist it could be saving many pounds and vehicle-days out of service.
From time to time the question is asked: What is wrong with the lathe? --and the answer is, just as often: Nothing at all, except the need for an
operator who understands lathe tools and their application.
Few of those engaged in medium-size haulage operations can afford to have a profess.onal turner on the payroll, but
only a part-time one. So there is no reason at all why a keen and interested motor fitter should not learn some of the tricks of the trade applicable to a normal centre-lathe, thus increasing his value to the firm and also his own stature in the process.
The big problem for the beginner faced with his first turning job is the lathe tool itself, and in connection with lathe tools for standard tasks, there are key features common to all.
The most important feature of all lathe tools is, of course, the cutting edge, but equally important is the shape and support provided by the metal adjacent to the cutting edge. Fig, 1 shows the meaning and purpose of the terms "rake angle, cutting angle and clearance angle ". These angles will vary with the nature of the material to be turned, and for satisfac tory results on vehicle metals up to six changes of cutting and clearance angle arc required. For garage application, thc accompanying table should apply.
PracLical experience has shown the value of holding a limited number of tools, maintained at the above angles. thus eliminating the need for a constant change of shape, and requiring no more than a gauge check to select the right tool for a given material.