Measuring of contact gaps by the absolute interference method

Summary

The accidental error ∈ which is introduced by the measuring contacts is contained in the variations of readings on the gage scale, and requires no special investigation.

Systematic errorsη introduced by the measuring contacts must be calculated or measured for each type of measurement and taken into account during the accurate determination of dimensions in precision measurements.

In measuring gage blocks (OST 85,000-39) on the contact devices, the optimum results were obtained with spherical corundum tips with R 14 mm, operating with loads of up to 300 g. In these cases the contact pressures for gage blocks are only a third to a fifth of the permissible values, while the contact gaps δ are so small and constant that the measurements can be made with the utmost precision.

The measurements of δ showed that for best contactsη=0 when the lengths of these gages is determined by the method of comparison, andη=0.06μ when it is determined by the absolute method.