# Validation of a Manual Methodology for Measuring Roundness and Cylindicity Tolerances
## 2 Materials and Methods
### Experimental Procedure  
#### 2.2.1 Manual Measurement Methodology in the Lab Environment (MM)  
The application of manual measurement methods in the laboratory environment is essential to ensure that technicians understand the concepts of roundness tolerance and cylindricity according to the experience of the teaching staff. Practical activities, consisting of measuring with a standard roundness machine, did not allow the future technicians to acquire the metrology competencies completely, i.e., the fundamentals about the evaluation of roundness and cylindricity. After the experience, users focus properly on the management of the equipment software, selecting functions from the different menus to find solutions that are automatically given by the program. Thus, sometimes, the technical concepts are applied without a critical analysis, for example, it can be highlighted by the magnitude of the results obtained. Therefore, with MM, users are forced to acquire skills regarding the manipulation of metrology instruments, in order to control the different sections to be measured and to obtain the coordinates of the part profile, later used for the analytical calculation. Furthermore, these methods have industrial applications, especially in job-shop layouts, where it is not possible to have costly metrology equipment that is high in quality [25; 26]. The manual method for roundness and cylindricity tolerances evaluation established in this paper follows the recommendations of the ISO standards and can be easily carried out. The materials needed to take the measurement with its purpose are listed below:  
* Two V-blocks to hold the part to be measured. * A dial indicator to register the variations in the radius of the part at each measured point. The resolution used was 0.001 mm. * A support for the dial indicator is also required. It is recommended to use guided support, so that the dial indicator can be moved parallel to the cylinder axis, reducing positional errors. * A standard granite surface plate to locate the measurement assembly in order to control and reduce possible errors in measurement readings due to surface waviness. If this is not available, it is sufficient to use a smooth table, although measurement errors may be added. The assembly for the measurement procedure is shown in Figure 5. Although any part can be used for the evaluation of roundness and cylindricity tolerances, from an instructive perspective, a cylinder previously machined and then subjected to intentional deformations to produce large roundness and cylindricity defects should be selected. For that purpose, it is recommended that the extremes of the cylinder should not be deformed to ensure correct positioning on the V-blocks. The measuring process for roundness and cylindricity evaluation consists of the following steps:  
1. First, marks are made on the front face of the cylinder using an indelible pen. The marks must be located at a constant angular relationship, so that angle gauge blocks can be used as a support. Although it is not strictly necessary, their use introduces technicians to the handling of laboratory instruments. A minimum of 8 divisions are recommended. 2. Before assembly, a reference diameter value, \(D_{ref}\), of the part must be considered on both endings (it could be an average), just in the supporting area on the V-block, as this area is assumed to have the best roundness quality and it is considered ideal as a reference for the optimum surface. 3. After placing the cylinder in the V-blocks, the dial indicator must be positioned vertically on the ideal reference section previously mentioned, recording the reference value in the dial indicator, \(dc_{ref}\). In this way, the corresponding set-up operation has been performed. 4. Using the guided support, the dial indicator is moved to the first section to be evaluated. The reading of the dial indicator, \(c_{i}\), must be recorded at 8 equally spaced points of the section by manual rotation of the cylinder (it is possible to increase the number of points if necessary).