The A-510 Target is a general-purpose, 2-axis bore target comprised of a target and an insertion pole or handle. It is used with our A-510STA (2” to 5”) or A-510LTA (4.25 to 16”) Bore Adapters Hubs and a set of M-705CL Customized Set of 4 Measuring Legs to measure bores from 2.0" to 16" (50.8mm to 406.4 mm). The M-705CL legs are replaceable for each bore, so you only need 1 bore adapter hub for the specified range.

The adapter can be attached to the target in either Self-Centering Mode or Measurement Mode.In Self-Centering Mode, the target automatically centers itself in any bore size that is +/- .030" (0.8 mm mm) from the adapter bore diameter. The self-centering concept works by carefully centering the target PSD sensor axially between the feet. This puts the target cell on the pivot point of the adapter and legs and allows it to vary by up to 45º without affecting the center. One pair of adapter legs are offset from the other, so when it is inserted in the bore (by pulling on the cord and tipping it forward) and the cord is released and the weight of the pole or handle "jams" the target/adapter into the bore, centering itself.

In Measurement Mode, the target will measure changed in bore diameter. First, a reference diameter is measured with an inside micrometer. Next, the target is placed in the reference bore and the reading is noted. The target is then inverted and the readings averaged to calculate the target centering error. The corrected reading becomes the benchmark diameter. Subsequent measurement points in the bore are compared to the benchmark and the difference in target readings is the increase or decrease in bore diameter.

The accuracy of the measurement of the A-510 with the bore adapter and legs is .0005” (0.013 mm) with repeatability to .0002” (0.005 mm) in well machined bores.


  • Any bore application with minimum of 2" (50.4 mm) diameter
  • Extruders-single or twin barrel up to 25 feet (7.6 m)
  • Boring bar bearing supports
  • Engine block crankcase bores
  • Cylinder bores


  • Self-centering, 2-axis target accurate to .0005" (.013 mm) with a resolution of .00002" (0.0005 mm).
  • Measures bore straightness in Self-Centering Mode, or bore diameters in Measuring Mode.
  • Tips on adapter feet use hardened carbide steel balls that rarely wear out.
  • Target with adapters can handle diameter variations up to of +/- .030" (0.8 mm).
  • Rugged, portable and very lightweight.
  • Uses the following bore adapters:
    • A-510STA Small-Bore Adapter Hub for bores from 2” to 5” (50.4 –170.0 mm)
    • A-510LTA Large-Bore Adapter Hub for bores from 4.250” to 16” (107.9mm to 406.4 mm)
    • M-705CL Customized Set of 4 Measuring Legs. Note legs are replaceable and each bore diameter requires 1 set of M-705CL legs.


Weight: 14 oz (392 g)
Material Hardness: 440C stainless Rockwell RC55-60
Target Cell
.0003" (0.0075 mm) T.I.R. to 1.1248" (28.6 mm) OD of target housing
Target Resolution: .00002" (0.0005 mm) with the R-1307 Readout
Target Cell
+/- .100" (2.5 mm) with 5 mm diameter laser beam
Linearity: Within 5% (See Target Cell Accuracy for details)
Cord Dimensions: Target to connector 10 ft. (3 M) with steel cover
1.1248" O.D. (28.570mm)