Blake Co-Ax Indicator Feelers

Straight feelers are used for inside diameters and curved feelers are used for outside diameters. They are easy to interchange. The maximum measurable diameter is twice the length of the feeler (with the exception of the standard feeler which will indicate a maximum diameter of 4.25 inches). Thus, a 3" long feeler can indicate a diameter of 6 inches, etc.
The 9" and 10" long feeler is suitable for working with tire rims indicating a maximum diameter of 18 or 20 inches. The manufacturer does not make this size feeler, so we have had them custom made. The manufacturer advises us that the gage should work correctly even with this extra long size feeler installed. However, we can not take any responsibility for the function of the indicator when non-standard feelers are used.

  • Standard ball diameters on these feelers is 1/8" steel. These are also available in carbide for certain lengths.
Ordering No. Style Ball Ø Length Max diameter US$
851 straight steel .125" 1.8" 4.25" 21.00
852 curved steel .125" 1.8" 4.25" 21.00
852-C2 curved carbide .125" 1.8" 4.25" 55.00
851-3 straight steel .125" 3" 6" 36.00
852-3 curved steel .125" 3" 6" 36.00
851-4 straight steel .125" 4" 8" 36.00
851-C4 straight carbide .125" 4" 8" 55.00
852-4 curved steel .125" 4" 8" 40.00
852-C4 curved carbide .125" 4" 8" 55.00
851-5 straight steel .125" 5" 10" 40.00
852-5 curved steel .125" 5" 10" 45.00
851-6 straight steel .125" 6" 12" 40.00
852-6 curved steel .125" 6" 12" 45.00
851-7 straight carbide .125" 7" 14" 55.00
852-7 curved carbide .125" 7" 14" 55.00
851-9 straight steel .125" 9" 18" 85.00
851-10 straight steel .125" 10" 20" 95.00

Blake Co-Ax Repair Notes

Spare parts can be bought directly from the manufacturer. A parts breakdown is conveniently included with new indicators. We only offer replacement contact points as shown above.

Parts for the movement are not sold separately. It will be necessary to buy the entire movement #825.

Co-Ax body #803 comes with the bushings installed but it requires special fixtures for proper assembly and do-it-yourself repairs are strongly discouraged.

Shaft #841 is different in inch and metric Co-Ax indicators. It's the top, short end of the shaft diameter that is measured. The long end is the same for both types.

Pin #846 is a press fit into rocker #844. It will slide easily through the shaft. Choose two spacers of an appropriate thickness to eliminate side play. When tapping the pin into place take care not to bend shaft #841. Use some form of support to prevent damage. The straightness of this shaft is the critical element in the Co-Ax indicator's function. Two spacers will also be used under screw #863 and nut #864 to eliminate side play in that location.
The glass crystal #834 is .020" larger in diameter on the new models (1.465"). If you're trying to fit it into an old model, use a diamond file to modify it. The alternative is to replace the old bezel with a new style bezel so that the crystal fits. Old style crystals are not available.

The new style bezel #826 easily replaces the old style. It will, however, need the new crystal #834 (see note above).

Spacer #847 is used to eliminate sideways play. Trial and error will tell you which size to use, although we find that .004" is the most common in our repairs.

If you would rather have us repair these co-axial indicators for you, please
click here for details.

Be aware that cheap Asian imitations also exist. There is no guarantee that these original Blake parts would work on the Chinese indicators.

The "other" Swiss indicator still made in Switzerland.

Long Island Indicator Service
Long Island Indicator Service was founded in 1960. We provide professional repair service for precision measuring tools and gages with an emphasis on Swiss made test indicators, dial indicators, dial calipers and micrometers. We are pleased to be a recognized service partner for Brown & Sharpe.

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