Gauge Ball Sets

I found these gauge ball sets for sale:

They come in metric or imperial and contain pairs of balls up to 1" or 25mm diameter. Can anyone tell me what they are used for in industry? All I can think of is measuring internal cone angles or measuring dovetails.

Thanks

Ball bearings are produced, or should be, to very tight tolerances, so they can be used as masters to check measuring instruments, or as comparators for a dimension on a component.

They could also be used as length standards for machine tools such as jig borers.

As a consumable they could be used for ball broaching to size a bore accurately in a component such as a tube.

Howard

Seems odd that the set has pairs of each size, presumably in 1 mm increments.

Standard practice used to be three of each size to allow stable set-ups on surface plates or inside bores to measure groove width with the aid of a gauge pin.

Short discussion here :- **LINK**

https://www.practicalmachinist.com/vb/general-archive/what-precision-gage-balls-used-96384/

Professional version with more notes on applications here :- **LINK**

https://www.opus.co.uk/products/precision-spheres-balls/

For far more than you ever wanted to know on the subject :- **LINK**

https://www.precisionballs.com/all_ball_gages.php

Clive

Can be used to measure tapered holes, measure depth to two different balls and work out angle etc.

Nice shiny things to have but I doubt will be used much. In 40 odd years Toolmaking I can't remember the use of ball bearings very often. BTW I use dowel pins for dovetail measurement.

Tony