The small-size threaded connection is one of the main connection methods for complex and precision electromechanical products such as aerospace equipment. The geometric deviation is unavoidable in the thread manufacturing process, which will lead to the problem of excessive dispersion of the connection preload and uneven stress distribution, resulting in a low product qualification rate and a short stability period. In this paper, the influence of thread geometric deviation on preload and stress distribution is studied by taking the small-size M2 thread commonly used in high-end aerospace precision products. Firstly, the thread engagement model with geometric parameters is established, and the influence of different types of geometric deviations on the preload is analyzed. Secondly, the mechanism of non-uniform stress distribution on the connector in the process of thread engagement is analyzed. Finally, the accuracy of the simulation model and the analysis results are verified by the small-size thread-tightening experiment. The results show that the pitch diameter deviation, profile angle deviation, and pitch deviation of precision thread affect the preload and stress distribution, among which the profile angle deviation has a significant influence on the preload and stress distribution.

Air-floating supports are the core component of precision gyroscopes. The precision of their assembly directly determines the degree of gyroscope drift and plays a decisive role in the device’s output precision and service life. Existing air-floating support assembly precision analysis techniques have not yet considered interface deformation, resulting in poor theoretical accuracy and large deviations in actual performance. To address the issue of imprecise predictions in assembly precision for air-floating supports under process loads, this study performs a predictive analysis and impact assessment of assembly precision with uncertainties in the connection process. Firstly, based on bolt elastic interactions, a method for calculating interface assembly deformations is proposed and integrated into a predictive model under process loads. Secondly, numerical computations and assembly deformation tests are carried out to confirm the model’s accuracy. Finally, the distribution law of gyroscope drift is analyzed, considering uncertainty in the connection process. The results show that the maximum deviation of the assembly accuracy prediction model for air-floating supports is less than 5%. Drift in air-floating supports under normally distributed loads shows a skewed normal distribution pattern; the mean drift value decreased sequentially from about 0.03023°/h/g to 0.01995°/h/g, which was reduced by 34% with variation in the dispersion of the pretension force (from 15% to 5%). These findings provide novel insights to enhance assembly precision processes and optimize the fabrication of high-end, complex equipment.