Microset Timer interface using Fusion 360 3D model with Fusion Electrical

Sorry it has been a bit quiet but we had a few weeks in France and got distracted catching up on jobs there.  A minor update on this will follow.

I brought back a 30 day rope driven clock to work on for a fellow engineer who lives in France.  The movement has a 1 second pendulum and is marked as being made by Lawson of Bingley.   I haven’t found much wrong with it other than the hands were a loose fit on their arbors and were rubbing against each other and the dial.

In the course of working on the clock I needed a different style pendulum sensing optical sensor to interface to my Mumford Microset Timer.   This evolved before being modelled in Fusion 360 and then 3D printed.   A small sensor interface PCB module was also created in Fusion Electrical and milled on my Tormach CNC mill.  The body integrates the laser emitter, detector and PCB.   Below is a visual image from Fusion.   The pendulum swings through the U channel to break the optical beam and give pendulum timing pulses.

There are various M6 modelled mounting holes around the body.   The complete unit is powered from the Microset internal 5V supply.

A complete write up is available for download on the link below.

Interface to Microset Timer v4

Update : – I could not get the clock to accurate time while using a 3600 beat reference in the Microset.   I did a train count and discovered that the clock is actually a 3584 beat movement.  The clock is now doing very well with a few seconds per day error.

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Clock adjuster rod for measuring spring and fusee drive power

 I was presented with a clock that seemed to be low on drive power and it was proving difficult to diagnose where the fault lay. I remembered seeing articles by both William Smith and John Wilding about a device that could give a relative measure of the drive power from the fusee.  There is also a brief mention of this in Donald de Carle’s – Practical Clock Repairing.

This will be difficult to describe but in essence it is an adjustable balancing rod that is mounted on the fusee winding square.  The movement’s centre wheel and second wheel are left in place but the escapement is removed.   The rod has a sliding weight that can be adjusted to counter the drive power from the spring through the fusee chain to the fusee itself.    By winding the fusee one step at a time and resetting and noting the counter weight position it is possible to derive a graph of fusee turns against drive power.  Here is a pictorial view of the device and below that a picture of my version.

A sketch of the principle of the balance rod for fusee drive checking
A sketch of the principle of the balance rod for fusee drive checking
Image of my version of the balance rod
My version of the balance rod. The winding socket is interchangeable for different fusee square sizes.

William Smith suggested making the mass of the sliding weight equal to 1lb and measuring the weight position in inches from the balance centre to the centre of the weight.   This results in a graph of drive in lbs/inches.

In practice the balance point is a little subjective to set.   You need to move the weight back and forth such that the rod remains horizontally balanced against the drive from the fusee square.  Once a balance point is achieved the distance from the moveable weight centre to the winding axis centre is recorded.

On this particular clock I plotted the results of the each turn of the full wind range of the fusee and the balance distance seemed to be reasonably repeatable and overall fairly flat. This suggested that perhaps there was not an individual fusee positional problem but something that was common mode across the range of the winding.   To me this indicated that the drive transfer through the centre wheel and the second wheel was potentially the issue.

Checking the arbors against the plate pivots did not reveal a great deal of wear but on dismantling and checking more closely one of the centre wheel pivots had a worn curved profile.   I re-made the pivot and re-bushed the plate and reassembled the movement. On re-running the test with the rod I found I had gained an extra 1″ movement of the balance weight along the rod.  This suggested that more power was now being transmitted to the train, that is the train was not presenting such a high resistance to motion and more power was being created to drive the clock.  

This appeared to solve the problem with the clock having a much stronger beat.   This result is indicative of the value of this simple tool.

William Smith also suggests that the balance rod is useful as a temporary drive source.  Suppose you have a clock stripped down and want to quickly check the train.  Without fitting the barrel and fusee chain, the balance rod and balance weight can be mounted on the fusee square to provide quite a few minutes of drive to quickly exercise the train without having to undertake a full movement rebuild.

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Update notes on modifications to the Devon Sea Clock

Finally Documented my Devon Sea Clock modifications

Following on from a number of enquiries I have updated my notes on the modifications I made to my Devon Sea Clock.   This includes creation of a new set of pallets and also set up notes.  A link is provided to download the details.

devon sea clock notes on modifications
My Devon Sea Clock as featured in these notes

I hope you find this useful and it allows a few more clocks to begin ticking reliably. 

The link will download a ZIP file with the written notes and 2D drawings of the components.

Sea Clock Notes May 2021

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A church clock problem and lockdown timekeeping

Keeping the village clock going

From previous posts you will be aware that I am regarded as ‘Tech Support’ for the local church clock.   The clock is a Cooke of York design dated from 1869. It has been running very well over the past months until a few days ago when ….twang … one strand of the strike wire rope gave way and twirled back up the rope and got wedged in the strike mechanism.   The going train continued to keep time and display on the dials but no bell strikes.  An eerie silence fell over the village. 

Strike chain drum showing the errant strand in the barrel wheel
Strike chain drum showing the errant strand in the barrel wheel and also the soft eye fastening onto the strike barrel.  The going train barrel can be seen in the background.

The errant stand of wire was easily cleared but on further inspection the strike weight rope looked to be in a dangerous condition.  I resolved to replace the rope and while doing this I would also replace the cable on the going train. 

The strike chain had jammed with the weight almost at the top so this needed to be gently let down to floor level.

Strike train weight stopped almost at full wind
Strike train weight stopped almost at full wind and needed to be lowered before any work could start on replacing the cable.

New fibre cored 6 x 19 galvanised wire rope was ordered.  The strike train had 6mm diameter and the going train 5mm and both needed around 30m of cable.   The chosen supplier was RAMS Lifting Gear in London and they agreed to put a 20mm diameter soft loop at one end of each cable.   This would loop over a button on each of the two barrels to anchor the cable.   RAMS delivered the cables very quickly.

Given the social distancing restrictions in place, my normal assistants were not available to help.  Instead I persuaded my wife to climb the bell tower with me to assist with the cable changes.   It is a bit intimidating to ascend up the two ladders for the first time but she overcame her nerves and after a few up and downs became quite at home with the surroundings. 

The new cables were unreeled and laid out down the stairs from the tower into the church so they could take their own path and not twist. We had decided to use the existing cables to pull through the new ones.   This meant the soft loops and the associated crimps had to be pulled through each pulley.  This was tight on a couple of them but we managed.   

With the cables pulled through and into the clock cabinet we then pulled off the old cable from the drums and ran on the new ones.  Inspecting the old cables revealed that they were not in the best condition and could have been an accident waiting to happen had they snapped clean through.   There is no clock record to indicate when they were last changed.

The clock was soon up and running with its new shiny cables and normality was restored in the village and surrounds.

We received a number of appreciative comments from the villagers for getting the clock up and running again so quickly.  Considering these comments suggested that perhaps the chimes of the clock had taken on a new meaning in COVID lockdown.   Time precision had recalibrated.   Watches and clocks in and around the home had ceased to be the reference in the slow world of lockdown.  Nowhere to go or to be, meant watches lay on bedside tables unworn and unwanted.  Instead people had moved from watching minutes to referencing life by hours.   The village clock now subconsciously marked the passage of time with its hourly chimes.   Everything in between had become a slowed down lifestyle.   When to come or go into the garden or to the shops, when to think about a meal – all now seemed more likely to be triggered by the hourly chimes of the village clock.

Which is probably how life was in 1869 when the clock first broadcast its notes over the village.   

Did we perhaps lose something somewhere along the way ?

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Repairs to an ancient Thwaites clock completed

I have mentioned my activity on the Thwaites clock in a couple of blog posts and I can now confirm the work is complete.

Thwaites clock as originally received prior to the work taking place
The Thwaites clock as received before work commenced

This has been an interesting challenge and I am pleased with how it has worked out.  Once again I am impressed by the way that modern techniques and technology can all play their part in achieving a result that once upon a time would have been impossible using traditional circumscribed knowledge.

There is a full write up here on the Thwaites Clock Activity for anyone interested.

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