The Micrometer

The engineering of time

Issue 22   January 2026

 Decorative heat bluing of steels

Trials on a PID-controlled* bluing box

Bluing box

After a brief introduction to methods of heat bluing steels, the author comments on the dependency of the achieved colour on both temperature and ‘soaking’ time at this temperature before describing the design, manufacture and uses for an electrically-heated bluing box under digital temperature control.

Components ranging from 15 mm long clock hands and small screws through larger instrument hands right up to machine toool ball handles have been successfully heat blued in the PID-controlled bluing box.   Fully illustrated with photographs and schematic drawings, there is no single solution to all decorative bluing issues, and the bluing box is not entirely without limitations in its performance.   The paper concludes that it is a valuable, mess-free addition to the workshop, and those needing primarily to colour steel components may wish to consider its merits.

* PID: A Proportional-Integral-Derivative digital controller capable of maintaining the bluing box hotplate temperature to within ±1°C of the Set Value (SV).

Decorative heat bluing of steels (6 MB)

Readers are invited to share their own experiences with decorative heat bluing of steel and, in particular, their experiences with a PID-controlled bluing box.


 A balance vibrating tool

A year 2/3 project for students of horology

Balance vibrating tool

The author presents the design and construction of a balance vibrating tool suitable for second year clock and watch students or those with a good understanding of workshop and horological practices.   Not only does the construction of this tool provide an advanced project for students but also results in a tool that enables a quick selection and adjustment of a balance spring in subsequent spring-balance clock and watch repair work.

Suitable for both watch and clock pathway students, all standard parts are available from horological requisites suppliers.   A degree of skill is needed for its successful completion, and any person achieving success should not only be congratulated but can also consider him or herself well on the way to becoming a skilled craftsperson.


Balance vibrating tool book (3.3MB)        





 Clock lines

An exploration of driving lines for weight-driven and fusee clocks

Clock lines

Clock lines have received little engineering assessment in the horological press, with much opinion being based on received wisdom and what has been found to work.  

Part 1 investigates the different types of construction of stranded steel and brass/bronze lines.   Part 2, which is perhaps the most significant, reports on the author's creep trials on natural gut and nylon-6 synthetic lines conducted over a 6-month period and their extrapolation to a 20-year in-service life.   Part 3 discusses the possible implications of creep on non-metallic weight-driven and fusee lines before drawing together a few overall remarks.  To complement the three part paper, an Appendix has now been added describing the manufacture and testing of crimps for eye splices.

Clock lines Part 1 (689KB)         Clock lines Part 2 (1.6MB)         Clock lines Part 3 (212KB)         Clock lines Appendix (666KB)

Readers are invited to comment on the papers and make any recommendations leading to a greater validation of the author's concluding remarks.



 A spherical turning attachment

The design and construction of an attachment suitable for the Myford Super 7 lathe

Spherical turning attachment

The ability to make ball handles is essential for the serious workshop accessory constructor, and the design anmd full engineering drawings here presented bolts directly to the cross-slide so making it far sturdier than a toolpost mounted variant.   It has also been used to cut 'spiders' for the spherical centres of Hooke universal joints.

The tool is fitted to an adjustable block, and the feed is provided by rotary handle via a 12:1 worm drive. The cast iron base is a modified casting for the Geo. H Thomas dividing head tailstock, and the worm and worm wheel are proprietary items.

Spherical turning tool (1.7MB)        


        

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