A bore gauge and its usage

A bore gauge is a convenient term for the measuring or transfer tools that are used in the process of accurately measuring holes, These are a range of gauges that are used to measure a bore’s size, by transferring the internal dimension to a remote measuring tool. They are a direct equivalent of inside calipers and require the operator to develop the correct feel to obtain repeatable results. The gauges are locked by twisting the knurled end of the handles, this action is performed to exert a small amount of friction on the telescopic portions of the gauge (the smaller diameter rods found at the T head of the gauge). Once gently locked to a size slightly larger than the bore, the gauges are inserted at an angle to the bore and slowly brought to align themselves radially, across the hole. This action compresses the two anvils where they remain locked at the bores dimension after being withdrawn. The gauge is then removed and measured with the aid of a micrometer or caliper, Dial bore gauges (DB) or dial indicators, when used in conjunction with a micrometer, can give very accurate and precise inside measurements. Used for holes of at least two inches in diameter, they consist of a base that houses an interchangeable anvil that sets the range of the measurement and a small sliding stud that when compressed will give a reading on the gauge or dial portion of the tool. The dial will have a rotating bezel that is rotated to “zero’ the gauge at the target measurement, which is set by a separate micrometer. Dial-bore gauges are useful in checking for taper or out-of- round conditions in a cylinder bore as well as many other inside machinists measurements, 1.Determine the rough opening with a machinist’s rule. Lay the rule across the top of the bore and dress the zero end of the rule to one edge of the hole. Orient the rule so that the point measured is 180 degrees away from the zero end. Slide the clip down the rule to mark the edge of the hole and record the measurement.2Select and install the appropriate anvil. The anvil should be long enough to contact the side of the bore and slightly compress the stud when inserted into the hole. Do not use an oversized anvil and try to force the indicator, as this will likely destroy the accuracy of the tool. 3Select a micrometer in the appropriate range. Most cylinder bores will be in the two-to-three-inch or three-to-four-inch range. Set the micrometer for the target Telescopic Bore Gauge measurement or for an arbitrary measurement. The arbitrary measurement should be close to the target measurement and be an even number that will be easy to do quick math on to arrive at the actual measurement. Record this number on paper with room to do simple addition problems. 4 Insert the anvil and stud between the micrometers machined surfaces. Rotate the bezel until the “zero” is in line with the needle position. The DB indicator is now ready to read a measurement relative to the setting. from http://wwww.roktools.com/
This entry was posted in Uncategorized. Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *