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There are many reasons to put an opening in a machine guard. The operator may need to insert or retrieve material, watch the work in progress, adjust the equipment or clean machinery.

Openings should meet the needs of production, but ensure that entry through the guard prevents reaching into danger. Hazards of the machine are isolated by restricting the distance a person can reach through the opening.

Safe separation distances for smaller openings are subject to rules depending on whether they are slots, squares, or circles.

Example of slot size and distance from dangerous part

If the distance of a guard from a dangerous part is 300 mm, find the maximum opening size of a slot.

x = 300 mm

y = X/10 + 6

y = 300/10 + 6

y = 36 mm

This calculator calculates the maximum opening size of a slot using distance of a guard from a dangerous part values.