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Long Island Indicator Service Inc

Swiss Precision Tool Repairs, Sales & Spare Parts







Dorsey Standard Bore Gage
replacement bore gage dial indicator

The same indicator unit is used for Size 2, 3, 4, and 5 dial bore gages. A slightly larger version is used for bore gage size 6. A simple hex screw will fasten it to your various measuring heads. If you don't use more than one head at a time, you can save some money by using only one indicator for all your measuring heads. You might also want to buy a new indicator simply to replace an old or defective indicator. Perhaps you want to replace the obsolete "made in Poughkeepsie" indicator, or the equally obsolete "made in Switzerland" indicator with the new model made by Dorsey Metrology, USA. You can also convert your metric bore gage to inch and vice-versa.

Digital versions are also available with the option of converting your dial bore gage into a digital electronic gage.


Standard Bore Gage indicator model D1-20241-B-1 made in Europe is now obsolete. Replace with the Dorsey indicator which will fit perfectly. (see below)

New! Dorsey replacement indicator - a Great Idea!


You have an opportunity to replace the Swiss-German Standard Gage indicator, or the old Poughkeepsie indicator with the American-made
Dorsey indicator shown at left. Just like the European version in the photo above, it comes complete in a housing.

The bright yellow dial (on metric indicators) and white dials on inch versions feature a revolution counter to help you keep track of any possible over-travel. A popular 1-revolution version is also offered and we recommend it for better accuracy and easier reading.

You'll find that it's of comparable quality, is completely interchangeable, offers more options, costs less and is made in our own back-yard. Go for it.

Older model bore gage No.6 had a 1-inch diameter stem. It will be necessary to buy the appropriate indicator shown in the listing below. All other models and current No.6 models have 5/8" inside diameter housings.


Standard no. (Ø)

Graduations / range

Order no.



No. 2, 3, 4, 5, 6 (5/8")

.0001" / .050" (3 rev)




No. 2, 3, 4, 5, 6 (5/8")

.0001" / .009" (1 rev)




No. 2, 3, 4, 5, 6 (5/8")

.0005" / .100" (3 rev)




No. 2, 3, 4, 5, 6 (5/8")

.0005" / .018" (1 rev)




No. 6 (1-inch Ø special)

.0001" / .009" (1 rev)






Accuracy in bore gages is determined on the basis of the indicator's performance. For gage sizes 0 and 1, the accuracy is ± 1/2 graduation over the entire range. For gage sizes 2 through 6, the accuracy is ± one graduation. In all cases, repeatability is 1/5 graduation.

You will find more information on bore gages, including calibration, by perusing the index page.


Installing a new bore gage dial indicator


In new bore gages, the dial indicator housing is already installed and need not be reset or adjusted by the customer unless the user wishes to rotate the indicator in another direction for ease of reading.

These instructions apply for changing the orientation of the indicator and for installing a newly purchased replacement unit.

1. Loosen the unit's lock screw.
2. Rotate the indicator into any desired position or remove the unit and replace it with a new one.
3. Push the indicator housing onto the measuring head until contact is made. You will notice the indicator's hand will begin to move at this point. It is now necessary to back off slighty to create a gap. The manufacturer suggests .002" to .005" so that there is no contact made when at rest.
4. Tighten the screw but be careful you don't use too much force.
5. Check the setting. When you press the gaging plunger, the indicator hand should move about .030" (on all models other than No.1)

[These instructions are based on the manufacturer's own publication which is provided with all new dial bore gages.]


from our bookshelf

The Companion Reference Book on Dial and Test Indicators … page 178
BesTest and TesaTast Indicator Repair Manual … page 177
Starrett 711 Last Word Indicator Repair Manual … page 199
Interapid Indicator Repair Manual … page 208
Compac Test Indicator Repair Manual … page 194
Mitutoyo Test Indicator Repair Manual … page 102

Long Island Indicator Service Inc
14 Sarah Drive — Hauppauge NY 11788 — USA

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This page's most recent revision: 4 MAY 2017
All Rights Reserved

Original photographs and content copyright 2017 by JWGrum


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