The measured thickness of a compressible material (unlike a non compressible material like metal, glass, stone etc) is evaluated by measuring the material under a specified applied load. The thickness of a compressible material varies according to the applied load.
To evaluate relative thicknesses of compressible materials, the applied load must be specified. This is usually done by specifying a standard sized presser foot and specified weight acting on that presser foot. These measurements are often used to evaluate changes in thickness due to wear, usage, manufacturing changes, etc. and are very helpful in evaluating comparisons between different materials for specific uses.
The Frazier Thickness Gauge is unique in that it can be used to evaluate materials in place without cutting a sample. For example the comparative wear of installed carpets in an ongoing test can be evaluated by means of this instrument with the addition of a needle like probe to the instrument.
The thickness gauge for measuring the wear of carpet is provided with a base on which the measuring head is mounted. The specimen is located directly underneath the 1-in circular foot. A foot is fastened to the stem of the dial micrometer with a ball-and-socket connection. A weight is placed on top of the stem to make the pressure which the foot will exert on the specimen commonly equal to 0.75 lbs per square inch. (Custom size presser feet and weights are available.) The dial-micrometer assembly may be moved vertically by means of a rack and pinion with adjustment knob. A needle is fastened to this assembly. The point of the needle is in the plane of the bottom surface of the foot when the indicator needle of the dial micrometer coincides with the zero of the scale. It is apparent that when the dial-micrometer assembly is lowered, the foot will rest on the specimen and exert a pressure of 0.75 lb/in^2 and the needle will pierce the carpet until the point comes in contact with the denser backing on which the carpet is mounted. This distance between the point of the needle and the bottom surface of the foot is equal to the thickness of the carpet. This value is read directly from the dial to the nearest 0.001 in. The entire gauge mounting may be rotated 180 degrees around the post and then the thickness of carpets which are laid on hard-surfaced floors may be measured. Be sure not to snag the specimen on the presser foot or needle when removing it or moving the thickness gage.
The Frazier Thickness Gauge can also be used as a heavy duty thickness gage when the probe is removed.
The Thickness Gauge is used by adjusting the presser foot/indicator frame with the adjustment knob so that the indicator reads zero when the presser foot is flat against the base anvil or gage block. The presser foot is then raised by hand without turning the adjustment knob and the material to be measured is slipped between the presser foot and the base anvil. The presser foot is then allowed to descent onto the sample and the thickness is read on the indicator. Be sure not to snag the specimen on the presser foot when removing it.
The Frazier Thickness Gauge is different from other thickness gauges in that it is more versatile. Different combinations of weights and sizes of presser feet can be utilized. Unusual configurations of presser feet sizes (other than the standard round presser feet) can be custom ordered for unusual or difficult measurements. The thickness of certain installed materials may be measured.
For measuring resilience and compression / recovery as well as thickness see: The Frazier Schiefer Compressometer.