By projecting a magnified shadow or image of your part onto a screen, these optical comparators give you an easy way to measure and inspect its precise features. They work similarly to overhead projectors, but with fixed magnification to preserve proportions. Because of how easy they are to set up and use, they’re a staple in most machine shops. They shine light from above, so they’re best for inspecting flat parts, such as gaskets and O-rings. Unlike traditional optical comparators, these comparators are compact to fit easily on a benchtop.

To use these comparators, choose profile or surface lighting. Profile lighting creates a shadow of your part, which you can use to plot points for precise measurements. To plot each point, move the stage the part rests on until the point lines up with the crosshair on the projector screen. For precision, the stage moves in increments thinner than a sheet of paper. Surface lighting makes these comparators work like an illuminated magnifier, blanketing the part with even light to reveal scratches, dents, and other surface flaws.

Save the measurements you’ve gathered for later by exporting the data as a text file using an RS-232 cord (not included).