Boring micrometer, interchangeable 18-100 mm

Built with high-quality material and a very low coefficient of thermal expansion which, together with the special transmission system, enables very high measuring accuracy. In the case of thousandth measurements, the influence of temperature, for example hand heat, is decisive and causes errors; in the BORLETTI-SUBITO boring micrometer, since the materials are temperature-stabilised, these errors are reduced by 1/10 compared with normal boring micrometers and are therefore practically zero.

The absence of play in the transfer of the feeler movement to the indicating instrument, obtained by means of the circular segment, is decisive for ensuring accuracy.

The instrument repeatability is 0.0005 mm. The linearity over the entire travel of the moving feeler is 0.002 mm max. The mobile centring bracket of the instrument has a spherical sector configuration and this facilitates insertion even if the instrument is not perfectly aligned with the hole.

The instruments with a measuring range from 4.5 mm to 20 mm have both fixed feelers and the measuring feeler with hard metal inserts. On request, centring brackets with hard metal contacts can also be supplied. They can be used in inspection rooms, for measuring individual parts, for series part checking, and for measurements during machining on machine tools. To facilitate instrument set-up, it is recommended to mount the comparator on the relevant support without performing the final locking, and to carry out this operation at the time of instrument calibration, which is easily done using a part with a hole assumed as the reference sample; or by using a suitable instrument (micrometer or other). The boring micrometers are supplied in wooden cases without a comparator. For thousandth measurements, comparators A1, CM1 are recommended; for hundredth measurements, comparators SC001. Since it is a comparative instrument, it is necessary first to zero it using the special ATA support, zeroing rings, or by means of reference sample parts.