As designed by William Smith
I had received a clock to repair and wasn’t sure if the mainspring was correctly dimensioned. I remembered that William Smith had described a gauge for checking this in his book ‘Clockmaking & Modelmaking Tools and Techniques’ (pages 21 – 26). This gauging tool consists of two profiled plates that slide together to overlay the end view into the clock barrel. Bill’s design used 1/16″ brass plate but it struck me that a 3D printed version would be equally suitable and much quicker and easier to make.
In use the gauge is overlaid on the end view of the barrel as shown below. The point A is aligned with the outer diameter of the barrel arbor. The top plate is then slide until the inside edge of the barrel wall is aligned with point B. For a correctly chosen mainspring it should align with the corners C and D.
I sketched Bill’s design in Fusion 360 and extruded the two component parts to have a 2mm thickness before printing on my Qidi X Smart 3 in PLA. The two parts are fastened together to be a sliding fit with two M4 screws. The threads for these are modelled in the 3D print. A handling knob can be added in a similar fashion.
Here is my PLA printed equivalent.
The STL print files can be downloaded on the link below. It is not something that you will use every day but just a ‘useful to have when needed’ item. “Better to have it and not need it, than need it and not have it” (Jimmy Diresta).
Links to similar or related post are listed below : –
- Arduino Processor Reference Clock Accuracy
- The “Modern Clock” by Goodrich
- Microset Timer interface using Fusion 360 3D model with Fusion Electrical
- Clock adjuster rod for measuring spring and fusee drive power
- Update notes on modifications to the Devon Sea Clock
- A church clock problem and lockdown timekeeping
- Repairs to an ancient Thwaites clock completed
- Further 3D printed soft jaws for the Thwaites clock escape wheel
- Vice soft jaws and then soft soft vice jaws
- Workshop resources all coming together like clockwork
