The Design & Use of
Instruments and Accurate Mechanism

by TN Whitehead
reprinted by Lindsay Publications

For most of us just cutting threads on a quarter-inch rod with a 1/4-20 die is precision machine shop work. Compared to the topics discussed in this book, our threads would be considered butchery. (I can identify with that.) This book is a detailed discussion of the all the things that can go wrong and must be considered when building very precise mechanisms for measuring gear or scientific apparatus.

For instance, that die you and I use will cut off-center drunken threads that are good enough for our experiments. But it just won't do if you want to build a micrometer. And the systematic errors that enter into a micrometer design are one the very first topics discussed.

This isn't for the guy who needs Gingery-style "put bolt A in hole B" instructions. This is for the person who wants to understand the finer points of precision machines. Errors are discussed in a cross-slide movement that are fairly obvious to you and me. Then the discussion goes into the effects of uneven friction and the problems that creep in from the drive train that will drive that cross-slide.

Some of the examples of mechanism discussed are the Hilger photomeasuring micrometer, the Wimperis accelerometer, systematic errors in an assay balance, bias in the short period errors of a goniometer, relation between disturbing and restoring agencies in a nut and screw, the Barnes compensated altimeter, centering errors in angle measuring equipment, design and accuracy of a range finder, and much more.

Chapters in the first part - Theory of Errors - include: systematic errors, probability as applied to errors, short period errors, and erratic errors. Part II - Design - covers precision kinematic design, precision semi-kinematic design, stiffness and isolation of elements, accuracy, and the planning of an instrument.

And whenever you start talking about precision you have to use math to perfect the design. You'll find math scattered throughout this book to help you understand the problems that must be solved, but it's no more complicated than high school trig.

Very unusual book for the purist, or those of us who dream of becoming a precision machinist. From 1934. Reprinted a couple of decades ago by Dover, but even their reprint is hard to find these days. You'll need this when you go to build that essential stereoscopic rangefinder so you can accurately lob pianos and dead cows at your neighbor's house with your high-tech trebuchet!

A quality book. Consider it carefully. 5-1/2 x 8-1/2 softcover 283 pages

No. 22857 ... $16.95