A-221 2-Axis Small-Bore, Self-Centering Target for Bores from 1.18-10 in. (30-255 mm)


Hamar Laser’s A-221 Self-Centering, Small-Bore Target is designed specifically to measure the straightness and alignment of small to medium sized bores, from 1.18 in. (30 mm) to 10 in. (255 mm). This small, lightweight, compact target self-centers to an accuracy of .0007 in. (0.018 mm) and has a sensor area of 10×10 mm.


  • Cylinders
  • Single-barrel extruders
  • Twin-barrel extruders
  • Tube sheet bores


  • Self-centering bore adapters with customized legs to fit the bore diameter, but can accomodate diameter changes of ±.040 in. (0.001 mm) without affecting the self-centering feature.
  • 5 ft. (1.5 mm) insertion pole with connector for extra lengths up to a total of 15 ft. (4.5 m) insertion length.
  • 10×10 mm PSD (Position Sensing Detector) is concentric to bore ID within .0005 in. (0.013 mm).
  • Measurement resolution of .0004 in. (0.001 mm) when used with the R-1307 Readout.
  • Can be used with the R-1307C or R-1307-2.4ZB target readouts.  Use the A-910-2.4ZB Radio Receiver for a PC with the R-1307-2.4ZB for wireless data downloads to our Bore9 software.
  • Accommodates bores from 1.18-10.0 in. (30-255 mm) when used with A-221STA/A-221LTA Bore Adapters and M-221 CLS-II/M-221CLL-II Customized Measuring Legs.
  • Bullseye level orients the PSD sensor axes to the alignment axes of the bore.


1.12 in. (28.5 mm) OD. and 3.56 in. (92.0 mm) long without pole
Sensor Size/Resolution:
10x10 mm PSD with .0004 in. (1.0 micron) resolution when used with the R-1307
Sensor Concentricity to Bore ID:
< .0005 in. (0.013 mm)
303 stainless steel
Hard-mounted 10 ft. (3 m) cable with Lemo connector
5 oz. (85 g)
Bore Diam. Range:
Can accommodate ± .040 in. (1 mm) diameter change and still self-center
Insertion Pole:
5 ft. (1.5 m) insertion pole with connector for extra lengths for up to a total of 15 feet (4.5 m) insertion length
Bore Adapters - Small:
A-221STA Small Bore Adapter Hub for 1.18 - 3.5 in. (30 - 90 mm) bores. Use M-221CLS-II Customized Measuring Legs for each bore ID.
Bore Adapters - Medium:
A-221LTA Bore Adapter Hub for 3.5 - 10 in. (90 - 255 mm) bores. Use M-221CLL-II Customized Measuring Legs for each bore ID.