Transfer of dimensions: a simple problem

Transfer of dimensions is often necessary in manufacturing processes.
Unfortunately, most of the professionals and technicians that I've met
haven't heard about it, even when they are involved in design and
manufacturing work.

I have often applied the simple problem posted here, in order to test for the
most basic understanding of design and manufacturing processes.

However, when I have presented this problem to persons who should be
experts in solving manufacturing problems, such as university professors
(and some of them have been teaching drafting, design and manufacturing for
many years), I have found that they have no knowledge of this matter.

My intent is to promote better understanding of manufacturing problems.
Please click on the figure below, in order to read or print the problem.

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Suppose that the task at hand is to manufacture a lot of several thousand parts as pictured below in figure 1. In that figure, only the dimensions of interest for this exposition are indicated. Those dimensions have been carefully determined by a designer, based on his best knowledge, applying state of the art science and technology. Those dimensions happen to be all 10 mm, with a tolerance of ±0.1 mm. This means that the part is expected to function properly if those dimensions are kept between 9.9 and 10.1 mm.

Fig. 1. A design showing the functional dimensions of a part.

 

Now assume that, for the purpose of manufacturing those parts, the manufacturing people in the factory floor request that the print, as used in the process, be modified so that all the dimensions are taken from the left end of the part, as shown in figure 2. The challenge is to calculate x, y and z.

 

Fig. 2. Design is modified, to show all the dimensions measured from the left end of the part.

 

 

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Multiple solutions are possible for the problem, but there are few truly correct

solutions, and I've found that most engineers totally miss the point of this problem.

 

The cost of mechanical manufacturing is increased very much, by lack of

knowledge about functional dimensioning and transfer of dimensions.

 

My next post in this blog will present the solution of this problem.

 

The best book to learn about functional dimensions and transfer of dimensions

is in the French language, "Guide du dessinateur industriel", by A. Chevalier.

There is a translation to the Spanish Castilian language, "Dibujo Industrial",

published by Limusa.