The original chamfer checking gage with SPC output or analog reading

This chamfer checking dial gage will give you a direct reading of the outer diameter of a chamfered hole. The larger gages such as the one shown above, have 3-winged plungers. They are available with dial indicators from Starrett or with digital SPC output from American-made Barcor. Barcor uses CDI digital indicators and no longer supplies analog gages.

• The Chamfer Gage only measures the top major large diameter of the chamfered or tapered hole. Hence, when you put the three blade Gaging Plunger into a sharp cornered (0º) Master or part, the gage reads the top diameter, which in this case is a straight hole. As you use it on a chamfered part having an angle less than the angle of the Gaging Plunger, the gage still picks up only the top major diameter, and so any angle up to the 90º included is correctly measured. Mind you, we are NOT measuring the angle or the depth of the chamfer, just the top diameter. Likewise on the 90º-127º Models, any angle from a straight hole to the 127º will be read correctly. So WHY have two Models? This is because the 90º has a 2:1 ratio and the shallower (harder to centralize and read) 127º has a 4:1 ratio and correspondingly an indicator twice as sensitive. Since most chamfers are 45º (90º included) the 90º gage is better and easier to use.Two forms are available: for chamfers with an angle of less than 90° and for chamfers with angles from 90° to 127° — [usage description as provided by the manufacturer]

The standard dial indicator is graduated in .001" but also available with .0001" digital or .0001" mechanical graduations. The accuracy for reading chamfers is ±.001" on 0-90° models and ±.002" on 90-127° models, regardless of which indicator you use.

The base of the Chamfer Gage is manufactured by Barcor (USA) but the indicator varies from supplier to supplier. You'll most often find this tool with a Starrett indicator or a CDI indicator, usually with a vanity dial. AccuPro Gold Chamfer Gage, SPI Chamfer Gage, Starrett Chamfer Gage, Dialsink (Brunswick Instrument) and the Dyer Chamfer Gage are examples.

It's a sturdy gage with a cleverly simple design. It does require "mastering" and this is done as follows: on the back cover of the gage you'll find the words "Set To" followed by a value, such as .020. Now it's a matter of setting the gage to this value while it's being held flat on a surface plate (the plunger pushed all the way in). We suggest you inscribe this value into the metal or plastic back cover because the label will eventually wear off. Unless you've lost this value, no other setting masters are needed.

Chamfer Gage for 0-90° and 90-127° angles

The chamfer gage will have to be pre-set according to instructions provided with the instrument. Setting rings are not necessary. Graduations for analog (dial indicator) models are limited to .001" while digital models can easily switch between inch and metric. The accuracy shown below is the accuracy of the entire gage even though the digital indicator alone may have higher accuracies.

Starrett and Barcor digital models use the same digital indicator, made by CDI.

Since Barcor no longer makes an OD chamfer gage with analog (dial) indicators you may wish to use gages made by Starrett. Barcor gages are made in USA while country of origin can not be verified for the Starrett gages.

Barcor digital and Starrett analog or digital models can be used for direct readings of holes with chamfers less than or greater than 90°.

Q: Is there any leeway in the measuring range?

• Not really: the range is only slightly extended. For example: the 1-2" range actually measures from .950" to 2.040"

Q: What if someone insists you check the chamfer gage against a master ring?

• This will work only if the ring does not have any chamfers. It's also the only way to recover the "Set To" value if it's been lost.

• Standard master rings, which you may already use in your shop, all have a slight chamfer. If you're not convinced, use a magnifying glass. The chamfer can be removed by grinding the surface of the ring. Only trust a master machinist for such an operation since these rings are too much of an investment to toy with.

• If you routinely use your chamfer gage for just one dimension, then you may want to invest in a custom ring of that particular size. If you use multiple ranges, then we suggest getting a setting ring for the middle of the range as shown below.

• There is no difference between masters used for 0-90° or 90-127° gages.

Q: Are SPC digital models easily switched from inch to metric?

• Yes, however, for calibration and setting you will have to use the inch mode before switching to metric.

Q: Are spare parts and repair services available?

• If the digital indicator malfunctions, we will not be able to repair it. In the event that the Barcor or Starrett digital indicator is damaged, it is possible to buy a replacement. They both use the same digital indicator made specifically for these chamfer gages by CDI.

(The following parts are available from us on request. Please inquire about current pricing.)

• Replacement digital indicator 90° ... part no. BAR10910-SPC
• Replacement digital indicator 127° ... part no. BAR10710-SPC

Q: What will go wrong?

• The base of the Chamfer Gage will probably never fail you. If the gaging plunger becomes damaged or worn, it can be replaced without any special tools. Simply unscrew the knurled ring, remove the old plunger and reassemble.

• More than likely, you will find that the indicator no longer functions. In that case, just buy a new indicator and you can replace it yourself. But these indicators have special ranges, so you can't simply insert another model into the base. You may end up forgetting what the "Set To" value is if you don't write it down or permanently mark it on the gage. If the Starrett models require repair, it's best to return them directly to the manufacturer.

Q: Why doesn't my chamfer gage repeat?

• There are two reasons why the chamfer gage readings may not repeat. The first is operator "feel" especially if the angle is greater than 90º and you are using the much shallower 127º models. The other reason is the nature of the part. If the chamfer diameter is not concentric or true, you will encounter poor repeatability. — manufacturer's statement

• Suggestion: practice before you begin to take readings. Take many measurements until you notice that you've gotten the "feel" and that the readings are beginning to repeat. Then compare these with a co-worker—or two—until you get a consensus. Unfortunately this kind of measurement is not as absolute as we'd like and - as you've noticed - variation is to be expected. You will have to establish acceptable tolerances not only for the chamfer but also for the operator's shortcomings.

• The guaranteed accuracy of the 90º mechanical gages when used in a NIST traceable master is ±.001", a total of .002", and ±.002", a total of .004" for the 127º models.