Parallel surface bore gauges 6-8 mm

Used to measure square holes, extruded profiles, even at great depth.

Built with high-quality material and a very low coefficient of thermal expansion which, together with the special transmission system, allows very high measuring accuracy. In the case of thousandth measurements, the influence of temperature—for example hand heat—is decisive and leads to errors; in the BORLETTI-SUBITO bore gauge, since the materials are temperature-stabilised, these errors are reduced by 1/10 compared with normal bore gauges and therefore are 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 to ensure accuracy.

The instrument repeatability is 0.0005 mm. Linearity over the entire travel of the moving feeler is 0.002 mm max. The instrument’s moving centring bracket has a spherical sector configuration, which makes insertion easier 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 tips. On request, centring brackets with hard metal contact points can also be supplied. They can be used in the inspection room, for measuring individual parts, for checking series of parts, and for measurements during machining on machine tools. To facilitate instrument set-up, it is recommended to mount the comparator on its support without performing the final locking, and to carry out this operation when registering the instrument; this can be done easily using a workpiece with a hole taken as the reference sample measurement, or by using a suitable instrument (micrometer or other). The bore gauges are supplied in wooden cases without a comparator. For thousandth measurements, the A1 and CM1 comparators are recommended; for hundredth measurements, the SC001 comparators. 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.