Ball Plug Gages

Ball Plug GagesBall Plug Gages
Tungsten carbide Ball Plug Gages are quick and easy to use because they can be inserted at any angle. “Go” gages go freely and “no go” gages won’t bind. They are particularly effective for giving a feel for bell-mouth, barrel or taper problems. These gages are widely used for spherical seat and bearing race “go” and “no go” gages.

Ball gages are available in 4,550+ sizes from 0.0500” in 0.0001” increments.  Custom length stems are available both straight and with bends.  ITI also has the capability to braze gage balls to stranded wire cable.

ITI standard gages feature polished tungsten carbide balls available in four tolerance classes which are mounted on stainless steel shanks.  ITI offers both single and double ended ball gages, with or without handles.  For convenience defining your requirements, the following files are available: Single ended no handle, Single ended with handle, Double-ended with handle.  Please contact ITI if you have questions or send the completed form for a quote.

Standard ball plug gage

  • Gage hole sizes
  • Identify ball-mouth, barrel, or taper conditions of a hole
  • Measuring radius accuracy
  • Determine true radius
  • Measure pitch diameters
  • Measure hole center distances
  • I.D. and O.D. gaging
  • Radius to face measurements
  • Calibiration of mechanical calipers
STANDARD SIZES: .0500 – .750″ diameter
MATERIAL: Balls – tungsten carbide
Stems – 316 stainless steel or tool steel
Handles – aluminum; colored – red/silver/green
Bushing – brass/bronze


  1. All plug gage tolerances are considered unilateral (i.e., GO + .0001/NO GO – .0001).
  2. All plug gages are of brazed assembly.
  3. Tolerances designated as class XX, X, and Y are available.
  4. All handles and brushings available in assorted colors.

The GO Ball Plug Gage is able to pass inside the bore diameter, and has a positive unilateral tolerance. If the proper GO Ball Plug Gage is used and does not pass into bore diameter, then the bore is not yet within specification.

The NO-GO Ball Plug Gage is not able to pass inside the specified bore tolerance and has a negative unilateral tolerance its self. If the NO-GO Ball Plug Gage is able to pass into the bore diameter, the bore diameter is past its specified tolerance. Referance: American Gage Society Standard Tolerances.

Above  To and Including  XX X Y  Z*
 .050  .825  .000020  .000040  .000070  .000100
 .825  1.510  .000030  .000060  .000090  .000120
 1.510  2.510  .000040  .000080  .000120  .000160

*ITI Standard Tungsen Carbide Ball Plug Gages are manufactured to Class Z specifications with unilateral tolerances.