Swing time targets

After playing with the swing time figures, I've now calculated the target times for each bell and what is needed to achieve this.

Slow down the treble by 25ms, the 6th by 10ms and the 7th by 7ms. This will be done by fixing 

 counter weights at the top of the wheel.

Speed up the 4th by 14ms and the 5th by 6ms. This will be done by fixing ballast weights at the bottom of the wheel.

There are no changes to the 2nd, 3rd or tenor.

Compare this graph with the one in the previous post.

The amount of correction for each bell seems very small but there is a good reason for setting them up as accurate as this. Experiments I have done in the past indicate that the human ear can detect errors in rhythm down to about 20ms, ie +/-10ms.

Setting up the swing times is the only the first part of getting the bells set up. The second part is to get the average clapper swing times set up, and the third and final part is to cancel out any oddstruckness.

So in order to achieve this +/-10ms target, it's important to get the swing timings as good as possible so that the accumulated errors across all three stages are within limits.

The results will be well worth the effort!

Measuring the bell swing times

The first job tonight was to measure the swing times of each bell. To do this I used one of the Oddstruckness Meters I make.

This shines a light at a reflective tape on the wheel, and when the bell is swung gently from side to side, the meter measures the swing each way, and then adds them together to display the period of swing.

 The figures for each bell are then entered into a spreadsheet which produces the above graph. The blue line is the raw data, and the black line is a 2nd order polynomial which helps analyise the results.

From this, it is possible to see that the bells 1, 3 and 6 need slowing down, and this will be done with counterbalance weights which will be bolted to the spokes at the top of the wheel.

It is possible, but much harder to speed 2 and 4 up as there are no spokes in a suitable place for mounting any weights.

This will be an iterative process to get the line as smooth as possible.

The other job was to install a temporary rope spider to hold the ropes up out of the way. This will be replaced at some point with a bespoke one made by my Nephew who is studying to be a blacksmith.

Visiting ringers

Word is starting to spread about Strensham's bells!

Here is a visiting band, mainly from the Worcester area, but there were also people in the group from Reddich, Guildford and Basingstoke.

A fantastic sound, which will only get better when everything in the belfry has been accurately set up.

So far, there have been 3 ringing sessions on the new eight, and the total head count is 58!