There can be ways to estimate acceptable engineering tolerances in SIMION. Generally, this can involve slightly perturbing some parameter and observing how this how this causes the final results to deviate in order to establish acceptable bounds for that parameter.
Mechanical tolerances affect how critical electrodes need to be when machined and positioned, which affects time, cost and stability [Wannberg1985]. For mechanical tolerancing, you might vary electrode position and examine to what degree this affects the particle trajectories. SIMION Example: geometry_optimization (in SIMION 8.0 and improved in 8.1) might also help automate this. Electrode Surface Enhancement / Fractional Grid Units may also be useful here if perturbed positions or angles are less than a grid unit (note: SIMION Example: surface_enhancement tilted_plates.iob is an example of angular tilt).
Other examples include perturbing electrode voltage and beam starting size/position/energy, which are very easy to check.
- Wannberg1985 B. Wannberg. Effects of mechanical imperfections in a hemispherical electron spectrometer Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. volume 239, issue 2, year 1985, pages 269-272 doi:10.1016/0168-9002(85)90725-9
- Qinghao Wu, Yuan Tian, Ailin Li, Daniel E. Austin. doi:10.1016/j.ijms.2015.10.011 Simulations of electrode misalignment effects in two-plate linear ion traps. (Also preseted at ASMS 2015, Tue Poster 71. Simulations of alignment tolerance in two-plate linear ion traps Brigham Young University.) – Studied a linear ion trap consisting of two ceramic plates, with effect of plate alignment displacements in six degrees (pitch, yaw, roll, X, Y and Z) on resolution and transmission using SIMION.
-  Machining division of SIS, specializing in precision, tight tolerances, and fine finishes for scientific instruments.