ISO 17025 accredited

Chamfer Gage Calibration



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Standards followed:

  • ISO 17025
  • Mil Std 45662A
  • Manufacturers Specifications
  • Customer Specifications


Countersink Gage vs. Chamfer Gage “What’s the difference?”

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When should a person choose a countersink gage over a chamfer gage? Ultimately they do the same thing: Both types of Gages utilize a plunger and special ratio indicator to measure the top diameter of a tapered/countersink bore.

But…there is more to the story.  This article will explain the basic advantages and disadvantages of both types of gages.

Chamfer Gage

chamfer gage calibration_alliance calibration

Chamfer Gage has a 3 blade plunger that covers a range of angles 0-90° or 90-127° through a specific range of diameters in up to 1” increments.  See table  

within ± .001" in 0°-90° models
within ± .002" in 90°-127° models

Analog Indicator: .001" graduation

(+) Relatively long range and versatile.

(-) Long range = an indicator with a rev counter. You will need to count the revs on a dial chamfer gage to calculate your reading.

(+) you can “set” a Chamfer Gage on any good, flat surface (a surface plate, gage block, face of a ring gage) to master the gage.  If desired, a special sharp-edge setting ring made close to the I.D. to be measured for higher accuracy can be used.

Note: The plunger of the Chamfer Gage is not sharp.  If it was, it would become dull over time and throw off the “setting” of the gage.  To compensate for the truncated plunger, a preset number is located on the back of the gage.  This number should be verified to read on the dial face when the Chamfer Gage plunger is pushed flush to the datum surface to set the gage. Since the Chamfer gage (and Countersink Gage for that matter) are in fact a depth gages that rely on the form of the plunger to give an accurate diameter, if the plunger is damaged or worn, your measurements will be off! 

(-) Since the Chamfer Gage covers a wide range of diameters you will not have as sure of a “fit” into the bore as you would with a countersink gage

Countersink Gage

countersink gage calibration_alliance calibration

Countersink Gage has a solid cone (under normal circumstances) ground to an exact angle that measures a specific range of countersink diameters in approximately .200” increments.  See table

± .0005" or ± .015mm

Analog Indicator: .002" graduation

(+) Analog/Dial countersink gages are 1 rev, direct read, so there no need to count revolutions on the indicator. That is convenient!

(-) Since the measuring range of the dial indicator is relatively small on an analog Countersink Gage, you cannot master the gage on a flat surface to set the gage.  A sharp-edge ring gage must be used.  These are included with the analog models.

Note: This is not the case for a digital Countersink Gage which has a much larger range on the indicator.  A setting ring is not needed to set the gage.

(+) Although the Countersink Gage is designed to give you the top I.D. of the bore, you are not only checking the top ID with a Countersink Gage but also you are checking the form (angle) of the countersink at the same time.  If there is some problem with the actual countersink itself, you will get a bad reading for the I.D.  In a sense, you are getting 2 measurements for the price of one! Form and diameter.

Note: Could you use a Chamfer Gage to get the top diameter of a Countersink Bore?  The answer is yes.  However, the Countersink Gage checks Countersink Angle and Diameter at the same time and the Chamfer Gage will not check the angle because it’s plunger only contacts at the very top of the bore. 

(-) Since the countersink gage is dedicated and has short range compared to the chamfer gage, you will need to purchase a lot of them if you have a big range of countersinks to measure.


Frequently Asked Questions


Gage ID Number

Description and Size of Gage

Calibration Cycle

Check Points (if not specified, we adhere to our quality policy)

Gage ID is the unique identifier you use to identify the specific piece of equipment.

Calibration Cycle is the interval between calibrations.

 We use this information to provide a sticker for the calibrated instrument to show when it was calibrated and when you want it calibrated again.






Please include power cords, leads, and any accessories necessary for us to perform the calibration.



All ISO 17025 accredited calibrations are traceable through NIST or another NMI(National Metrology Institute) to the SI Unit. 

Calibration certificates include as-found data, as-left data, and measurement uncertainty.

Alliance Calibration

11402 Reading Road

Cincinnati, OH 45241

We do offer onsite calibration service within a 150-mile radius. Not all calibrations are best suited for onsite calibration.

Please contact Customer Service with your specific question.

The minimum order is $100.


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