Why do some Rapid RH® Smart Sensors fit very tightly in the drilled holes?

Rapid RH® Smart Sensors are designed to fit tightly in a ¾” drilled hole in order to seal ambient air away from the testing area of the hole. However, it should NOT require excessive force to push the sensor into the hole. Smart Sensors should be placed in holes drilled with a 4 fluted, carbide-tipped drill bit that falls within the specifications for an ANSI standard ¾” bit. This range is from 0.775” to 0.787”.

An overly tight-fitting Smart Sensor is most likely caused by one of two reasons:

  1. It could be that your drill bit has “worn” down with use and has lost some of its “diameter.” This will most likely become noticeable after about 60 to 70 holes are drilled.
  2. It could be that you have purchased a new drill bit that is on the lower end of the tolerance spectrum for diameter.

Pro Tip: To make sure the hole is the correct diameter before installing a Smart Sensor, use your green insertion tool as a gauge. If the insertion tool can fit snugly into the hole, the Smart Sensor should install correctly as well.