During reconditioning work, bore sizes can be measured directly off the 1P2352 or 1P2353 Boring Bar when the new FT1481 Bracket is used to hold the 1P2371 Micrometer in place (Illustration 1). Formerly, some bore sizes were measured with inside micrometers and dial bore gauges. With other bores, the tool holder was removed from the boring bar and installed on the 1P2370 Micrometer Bracket Assembly.
Illustration 1. Bracket with micrometer in position.
Both of these methods caused problems when very fine adjustments needed to be made to the carbide cutting tool. The FT1482 Bracket fits around the boring bar and holds the 1P2371 Micrometer in position to measure the carbide cutting tool depth as shown in Illustration 2. With this arrangement, during reconditioning operations bores can be measured with speed and precision.
Illustration 2. FT1481 Bracket and 1P2371 Micrometer in position around the boring bar.
NOTE: During machine work, several factors can cause small differences between the measurement shown by the 1P2371 Micrometer and the size of the bore after the cut is finished. Some of these factors are: The depth of cut; the grind of the cutting tool; the speed and feed, or rate of cut; etc. Generally, if these factors are kept constant, the difference in measurements will be constant, and necessary compensation can be made for the finish bore cut. In most conditions, the difference in bore size will not be more than 0.05-0.10 mm (.002-.004"), and will be smaller than the micrometer indication. The recommendation is to use a dial bore gauge to measure the bore size.
The 1P2371 Micrometer must be calibrated (adjusted) before bore sizes can be measured. Recommendations to calibrate the micrometer follow:
2. Set the micrometer to this dimension.
3. Loosely fasten the micrometer in place on the bracket and put this assembly into position on the boring bar as shown in Illustration 3.
Illustration 3. Calibration of the 1P2371 Micrometer.
4. Push the micrometer down until it comes in contact with the centering ring.
5. Tighten the 3L2540 Screw on the bracket to hold the micrometer in place.
The tool is now calibrated and can be used to measure the diameter of the salvage bore directly off the carbide cutting tool on the boring bar.
The FT1481 Bracket can be used on both the 1P2352 and 1P2353 Boring Bar. This bracket can be fabricated from the 6V2122 Holder. Prints for the FT1481 Bracket are available from your divisional service manager.